We thank Dr Velez-Montoya and colleagues for their interest in our study.1 We reported that there was an increase in the prevalence of endophthalmitis after vitrectomy in Japan and found that it was probably related to the face masks during the COVID period.2 Although the cause for the increase definitively determined, we need to report these findings to the ophthalmologic community to alert them of this possibility.
First, we address the indicated point, “the definition of postoperative endophthalmitis was not rigorous”. We used the definition of the Endophthalmitis Vitrectomy Study group.3 Although this definition is relatively old, many subsequent studies have used it, and it has the advantage that our findings could be compared to these other studies with the same definition.
They also stated that the latest studies have shown that the sclerotomies after a pars plana vitrectomy seal within 15 days after the surgery even after a suture-less closure. Thus, the site of the incision was unlikely the entry port for the infectious micro-organisms after that time. This is generally true but the cause of infectious endophthalmitis after vitrectomy is complex. Because the cause of infectious endophthalmitis is varied, it is not surprising that anything can happen with postoperative endophthalmitis. For example, it is possible for a patient to inadvertently touch the eye in the early postoperative period and cause the incision to open. Once...
We thank Dr Velez-Montoya and colleagues for their interest in our study.1 We reported that there was an increase in the prevalence of endophthalmitis after vitrectomy in Japan and found that it was probably related to the face masks during the COVID period.2 Although the cause for the increase definitively determined, we need to report these findings to the ophthalmologic community to alert them of this possibility.
First, we address the indicated point, “the definition of postoperative endophthalmitis was not rigorous”. We used the definition of the Endophthalmitis Vitrectomy Study group.3 Although this definition is relatively old, many subsequent studies have used it, and it has the advantage that our findings could be compared to these other studies with the same definition.
They also stated that the latest studies have shown that the sclerotomies after a pars plana vitrectomy seal within 15 days after the surgery even after a suture-less closure. Thus, the site of the incision was unlikely the entry port for the infectious micro-organisms after that time. This is generally true but the cause of infectious endophthalmitis after vitrectomy is complex. Because the cause of infectious endophthalmitis is varied, it is not surprising that anything can happen with postoperative endophthalmitis. For example, it is possible for a patient to inadvertently touch the eye in the early postoperative period and cause the incision to open. Once opened, the scleral wound becomes a point of entry for infectious organisms. Additionally, the vitreous wick syndrome has been reported to occur especially after sutureless vitrectomy.4 Exposure to oral bacteria through masks can also result in infections. Considering the fatigue of the surgical team (human error) at the peak of the COVID epidemic, it is understandable that the source of infection most likely was during the vitrectomy. Nevertheless, other possibilities must be considered. Thus, the present definition of endophthalmitis, even in cases of infection after 42 days, is meaningful
Second, it is fair to point out that bacteria such as Streptococcus mitis are usually low pathogenic or opportunistic pathogens. However, S. mitis was the second most common organism found in cultures in post vitrectomy endophthalmitis.5 Exposure to exhaled air containing endemic oral bacteria for more than a certain amount of time can cause this.
Third, regarding Velez-Montoya and colleagues’ statement, “the results observed for the prevalence of postoperative endophthalmitis in the phacoemulsification-only group is not consistent with the main hypothesis”. We explained these findings as follows in the original paper. There was no difference in the frequency of endophthalmitis after cataract surgery before and after the masking period. Cataract surgery and vitreous surgery are different procedures. The incidence of endophthalmitis was significantly higher after vitrectomy, even when exposed to the same species and dosages.2 It is because the defense system against pathogenic microorganisms is weaker in the vitreous than in the anterior chamber.6 This is possibly the reason why an increase was detected only in the post-vitrectomy cases. This may also be related to the fact that the concentration of bacteria around the eye was somewhat increased by the strict mask wearing. This explains our finding that the incidence of endophthalmitis is the same in cataract surgery before and during COVID19-mask period, but is higher in vitrectomy during the COVID19-mask period. This is consistent with our assumption that the masked period is associated with a higher incidence of infective endophthalmitis after vitrectomy.
We again thank Dr Velez-Montoya and colleagues for their advice and the British Journal of Ophthalmology for providing us with a space to share our comments with the medical community.
References
1. Velez-Montoya, Raul, et al. Letter to the editor on "Increased incidence of endophthalmitis after vitrectomy relative to face mask wearing during COVID-19 pandemic.". Brit J Ophthalmol 2023
2. Sakamoto T, Terasaki H, Yamashita T, Shiihara H, Funatsu R, Uemura A; Japanese Retina and Vitreous Society. Increased incidence of endophthalmitis after vitrectomy relative to face mask wearing during COVID-19 pandemic. Br J Ophthalmol. 2022 Jun 21:bjophthalmol-2022-321357. doi: 10.1136/bjophthalmol-2022-321357. Epub ahead of print. PMID: 35728937.
3. Results of the Endophthalmitis Vitrectomy Study. A randomized trial of immediate vitrectomy and of intravenous antibiotics for the treatment of postoperative bacterial endophthalmitis. Endophthalmitis Vitrectomy Study Group. Arch Ophthalmol. 1995;113:1479-1496.
4. Venkatesh P, Verma L, Tewari H. Posterior vitreous wick syndrome: a potential cause of endophthalmitis following vitreo-retinal surgery. Med Hypotheses. 2002 Jun;58(6):513-5. doi: 10.1054/mehy.2001.1490. PMID: 12323120.
5. Li AL, Wykoff CC, Wang R, Chen E, Benz MS, Fish RH, Wong TP, Major JC Jr, Brown DM, Schefler AC, Kim RY, OʼMalley RE. Endophthalmitis after intravitreal injection: Role of Prophylactic Topical Ophthalmic Antibiotics. Retina. 2016 Jul;36(7):1349-56. doi: 10.1097/IAE.0000000000000901. PMID: 26655622.
6. Shockley RK, Jay WM, Fishman PH, Aziz MZ, Rissing JP. Effect of inoculum size on the induction of endophthalmitis in aphakic rabbit eyes. Acta Ophthalmol (Copenh). 1985;63:35-38.
Chauhan and co-workers [1] have provided Table 1, showing times taken to detect significant field progression with 80% power, based on a number of modelling parameters: frequency of examinations, rate of field progression, intrasession variability of field assessment. They have also provided Table 2 showing the number of annual eye examinations required to detect different total visual field changes, for different time periods, and for moderate variability. I have checked the calculations of Chauhan and co-workers, using Monte Carlo modelling, assuming a one-tailed significance value of 0.025. Of the 36 outcome values in Table 1, 33 are incorrect. Of the 12 outcome values in Table 2, 11 are incorrect.
Chauhan and co-workers have made 2 main errors in their calculations for Table 1. The first is in applying their estimates of power. The curves shown in Figure 2 (statistical power plotted against number of field examinations) are appropriate for the case of 2 field examinations per year, but Chauhan and co-workers appear to have incorrectly also used them for the cases of 1 examination per year and 3 examinations per year. Separate sets of curves should have been calculated for those conditions. The effect on Table 1 is that the time taken to detect a field change is incorrectly reported as being inversely proportional to the number of examinations per year. This anomalous relationship was commented on by Albert Alm in his 2008 Rapid Response, “Is a field every 4...
Chauhan and co-workers [1] have provided Table 1, showing times taken to detect significant field progression with 80% power, based on a number of modelling parameters: frequency of examinations, rate of field progression, intrasession variability of field assessment. They have also provided Table 2 showing the number of annual eye examinations required to detect different total visual field changes, for different time periods, and for moderate variability. I have checked the calculations of Chauhan and co-workers, using Monte Carlo modelling, assuming a one-tailed significance value of 0.025. Of the 36 outcome values in Table 1, 33 are incorrect. Of the 12 outcome values in Table 2, 11 are incorrect.
Chauhan and co-workers have made 2 main errors in their calculations for Table 1. The first is in applying their estimates of power. The curves shown in Figure 2 (statistical power plotted against number of field examinations) are appropriate for the case of 2 field examinations per year, but Chauhan and co-workers appear to have incorrectly also used them for the cases of 1 examination per year and 3 examinations per year. Separate sets of curves should have been calculated for those conditions. The effect on Table 1 is that the time taken to detect a field change is incorrectly reported as being inversely proportional to the number of examinations per year. This anomalous relationship was commented on by Albert Alm in his 2008 Rapid Response, “Is a field every 4 month a significant improvement over a field every 6 months?”. He wrote, “… increasing the duration is much more efficient than increasing the frequency of examinations. Thus, 5 examinations in 1.7 years will not be able to detect the same slope as 5 examinations in 5 years!” My calculations for the values in Table 1 show that increasing examination frequency, from once per year to 3 times per year, reduces time to detect a field change to between 71% and 50%, not 33% as implied by the original paper.
The second error made by Chauhan and co-workers is in converting from the number of fields (S) required to the duration required (D) for a given annual frequency of testing (f). From equation 5 in another paper,[2] this relationship is: D=(S-1)/f. Chauhan and co-workers appear to have used D=S/f.
In Table 1, three values are correct. One of those correct values, that it takes 2 years to detect fast progression (MD rate =-2dB/Year) with moderate field variability (SD=1dB) with 3 examinations/year, seems to be the basis for the paper’s recommendation that “six visual field examinations should be performed in the first 2 years.” This is slightly incorrect. A testing frequency of 3 examinations per year over 2 years will yield 7 examinations.
Table 2 contains significant errors. For example, its results imply that detecting a total field change of 1 dB will require between 15 and 21 measurements with SD= 1dB, depending on the number of years measurements are spread over. My calculations give an estimate of 95 total measurements required (irrespective of the time span).
This paper has been, and continues to be, influential. For example, Table 1 has been included in clinical glaucoma management guidelines.[3] The journal’s article metrics show 371 citations for the paper at the time of writing. Yet, the paper incorrectly overemphasises the value of increasing visual field test frequency. That is a core message for the paper. Given the paper’s influence those errors should be corrected.
References
1. Chauhan BC, Garway-Heath DF, Goñi FJ, et al. Practical recommendations for measuring rates of visual field change in glaucoma. Br J Ophthalmol 2008;92(4):569-73. doi: 10.1136/bjo.2007.135012 [published Online First: 2008/01/24]
2. Schlesselman JJ. Planning a longitudinal study. II. Frequency of measurement and study duration. J Chronic Dis 1973;26(9):561-70. doi: 10.1016/0021-9681(73)90061-1
3. NHMRC. NHMRC Guidelines for the screening, prognosis, diagnosis, management and prevention of glaucoma 2010: National Health and Medical Research Council, Canberra., 2010.
We read the paper on non-invasive intracranial pressure determination by Zhang et al(1) with great interest and hope. We fully agree that the search for non-invasive intracranial pressure (ICP) evaluations is of high importance and should be continued. The Bland-Altman plot showing the difference between predicted and intracranially measured pressure looks very impressive. There are, however, still a few points and limits we would like to address concerning the anatomy of the optic nerve, the optic canal, and the basic concept the authors used.
Cerebrospinal fluid (CSF) from the intracranial subarachnoid spaces and the subarachnoid space of the optic nerve (SAS -ON) communicate via the optic canal. Using three-dimensional reconstruction of the optic canal in normal tension glaucoma (NTG) patients, this was found to be narrower than in an age-related cohort of normals,(2) thus questioning the patency of the CSF pathway between the pituitary cistern and the SAS-ON. Further, optic canal dimensions in a normal population are quite variable amongst individuals, and even between orbits within the same individual.(3) These facts largely influence the results the authors present. Further, studies in patients with NTG and patients with elevated ICP (such as patients with idiopathic intracranial hypertension) were shown to have developed an optic nerve sheath compartment syndrome. In such cases, the CSF dynamics between the intracranial CSF and the CSF in...
We read the paper on non-invasive intracranial pressure determination by Zhang et al(1) with great interest and hope. We fully agree that the search for non-invasive intracranial pressure (ICP) evaluations is of high importance and should be continued. The Bland-Altman plot showing the difference between predicted and intracranially measured pressure looks very impressive. There are, however, still a few points and limits we would like to address concerning the anatomy of the optic nerve, the optic canal, and the basic concept the authors used.
Cerebrospinal fluid (CSF) from the intracranial subarachnoid spaces and the subarachnoid space of the optic nerve (SAS -ON) communicate via the optic canal. Using three-dimensional reconstruction of the optic canal in normal tension glaucoma (NTG) patients, this was found to be narrower than in an age-related cohort of normals,(2) thus questioning the patency of the CSF pathway between the pituitary cistern and the SAS-ON. Further, optic canal dimensions in a normal population are quite variable amongst individuals, and even between orbits within the same individual.(3) These facts largely influence the results the authors present. Further, studies in patients with NTG and patients with elevated ICP (such as patients with idiopathic intracranial hypertension) were shown to have developed an optic nerve sheath compartment syndrome. In such cases, the CSF dynamics between the intracranial CSF and the CSF in the SAS-ON differ significantly. This was proven by applying computer-assisted cisternography, diffusion-weighted MRI sequences and gradients of biochemical CSF proteins.(4-6)
In Zhang’s study, CSF pressures (CSFP) larger than 30 mm Hg were excluded. The majority of the patients in whom CSFP needs to be known are those with markedly elevated ICP. Therefore, this study should have been expanded to this group. As the compliance to pressure in the optic nerve sheath is most likely notlinear, this adds a further difficulty to measuring methods.
The authors found that CSF pressure was more significantly correlated with the area of the optic nerve sheath subarachnoid space than with the optic nerve sheath diameter. In an idealized fashion the optic nerve subarachnoid space resembles an annulus with a fractal circumference. The area A itself is not homogeneously filled with CSF but is interspersed with an interindividually variable amount of space-occupying trabeculae. The diameter in an annulus – compared to a circle - is represented twice in the formula for the area. Therefore, the diameter is involved in the SAS area as well. Its therefore difficult to understand why using the area instead of the diameter should render more accurate calculations, especially when the diameter is represented twice in the formula:
A total = π/4 (D2 -d2 ) - A trabecula = π (R2 - r2) - A trabecula
Our prior experience with formulae utilizing biophysical data such as body mass index (BMI), diastolic blood pressure (DBP), and age – all factors known to correlate to CSF pressure to variable degrees – were that they are quite poor at predicting actual CSF pressure.(7) The study excluded the analysis of formulae that utilized anatomic measures of MRI-determined optic nerve sheath width. However, as Zhang’s study is utilizing a similar method except with ultrasonographic determination of nerve sheath width, it would be assumed that the strongest predictor of CSF pressure would be the optic nerve sheath width. This subject has been repeatedly studied, and it does not seem that ultrasonographic evaluation of the optic nerve sheath diameter has ever been able to determine accurate estimates of true CSF pressures, but mostly the determination of normal versus elevated.(8-10)
Lastly, ultrasonography is a subjective method that depends on the user’s ability and reliability. In a study comparing optic nerve sheath diameter measurement between computed tomography, magnetic resonance imaging and ultrasound there was a good comparability between computed tomography and magnetic resonance imaging while the comparability between ultrasound and computed tomography or magnetic resonance tomography seems to be less reliable.(11)
We highly encourage efforts to expand our knowledge of the interrelation of cerebrospinal fluid and ophthalmic disease. But our desire to increase accessibility to study this by using formulae (in which the relationship between the variables is not understood) as opposed to current gold standard measurements of CSF pressure determination should not lead us to the path of using doubtful formulae that will confuse our body of literature.
References:
1) Non-invasive intracranial pressure estimation using ultrasonographic measurement of area of optic nerve subarachnoid space.Zhang Y, Cao K, Pang R, Wang N, Qu X, Kang J, Wang N, Liu H. Br J Ophthalmol. 2022 Aug 24:bjophthalmol-2022-321065.
2) The Optic Canal: A Bottleneck for Cerebrospinal Fluid Dynamics in Normal-Tension Glaucoma?Pircher A, Montali M, Berberat J, Remonda L, Killer HE. Front Neurol. 2017 Feb 23;8:47
3) Evaluation of optic canal anatomy and symmetry. Zhang X, Lee Y, Olson D, Fleischman D. BMJ Open Ophthalmology 2019;4:e000302
4) Cerebrospinal fluid dynamics between the intracranial and the subarachnoid space of the optic nerve. Is it always bidirectional? Killer HE, Jaggi GP, Flammer J, Miller NR, Huber AR, Mironov A. Brain. 2007 Feb;130(Pt 2):514-20
5) Case Report: Cerebrospinal Fluid Dynamics in the Optic Nerve Subarachnoid Space and the Brain Applying Diffusion Weighted MRI in Patients With Idiopathic Intracranial Hypertension-A Pilot Study. Berberat J, Pircher A, Gruber P, Lovblad KO, Remonda L, Killer HE. Front Neurol. 2022 Apr 15;13:862808
6) The optic nerve: a new window into cerebrospinal fluid composition? Killer HE, Jaggi GP, Flammer J, Miller NR, Huber AR. Brain. 2006 Apr;129(Pt 4):1027-30
7) Analysis of cerebrospinal fluid pressure estimation using formulae derived from clinical data. Fleischman D, Bicket AK, Stinnett SS, Berdahl JP, Jonas JB, Wang N, Fautsch MP, Allingham RR. Invest Ophthalmol Vis Sci. 2016;57:5625-5630.
8) Effect of intracranial pressure on the diameter of the optic nerve sheath. Watanabe A, Kinouchi H, Horiokoshi T, Uchida M, Ishigame K. J Neurosurg 2008 109(2): 255-8.
9) Optic nerve ultrasound for the detection of raised intracranial pressure. Rajajee V, Vanaman M, Fletcher JJ, Jacobs TL. Neurocrit Care 2011;15(3):506-15.
10) Sonographic assessment of the optic nerve sheath in idiopathic intracranial hypertension. Bauerle J, Nedelmann M. J Neurol 2011; 258(11):2014-9.
11) Measurement of Optic Nerve Sheath Diameter: Differences between Methods? A Pilot Study. Giger-Tobler C, Eisenack J, Holzmann D, Pangalu A, Sturm V, Killer HE, Landau K, Jaggi GP. Klin Monbl Augenheilkd. 2015 Apr;232(4):467-70
We read with great interest the article of Gokhale et al [1] on their retrospective study of metformin use and risk of age-related macular degeneration (AMD) in individuals with type 2 diabetes mellitus (T2DM). In this study Gokhale and colleagues used data derived from IQVIA Medical Research Data (IMRD-UK), formerly known as The Health Improvement Network (THIN), and found no change in AMD risk in those taking metformin.
An issue with this study is the quality of the GP coding and data on AMD. The authors cite a validation study of THIN data [2] but this study only validated cases identified as having AMD. There was no validation of the quality of data on the absence of AMD. So, the confirmation of positives was high (confirmed AMD cases quoted as 97%) but the false negative rate, is unknown. Also, the validation was by an ophthalmologist reviewing all the GP data, not using recognised diagnostic criteria or a grading scheme for AMD. Furthermore, the authors included a code for “drusen” into their AMD group which was not a code included in the validation study by Vassilev et al [2]. It is likely that this code includes patients with common physiological drusen and not an AMD diagnosis.
We have previously performed a systematic review and meta-analysis [3] of five studies [4–8] on the relationship between metformin use and AMD, which we have now updated to include Gokhale et al [1] and Jiang et al [9]. Including their data, we found a beneficial odds ratio of...
We read with great interest the article of Gokhale et al [1] on their retrospective study of metformin use and risk of age-related macular degeneration (AMD) in individuals with type 2 diabetes mellitus (T2DM). In this study Gokhale and colleagues used data derived from IQVIA Medical Research Data (IMRD-UK), formerly known as The Health Improvement Network (THIN), and found no change in AMD risk in those taking metformin.
An issue with this study is the quality of the GP coding and data on AMD. The authors cite a validation study of THIN data [2] but this study only validated cases identified as having AMD. There was no validation of the quality of data on the absence of AMD. So, the confirmation of positives was high (confirmed AMD cases quoted as 97%) but the false negative rate, is unknown. Also, the validation was by an ophthalmologist reviewing all the GP data, not using recognised diagnostic criteria or a grading scheme for AMD. Furthermore, the authors included a code for “drusen” into their AMD group which was not a code included in the validation study by Vassilev et al [2]. It is likely that this code includes patients with common physiological drusen and not an AMD diagnosis.
We have previously performed a systematic review and meta-analysis [3] of five studies [4–8] on the relationship between metformin use and AMD, which we have now updated to include Gokhale et al [1] and Jiang et al [9]. Including their data, we found a beneficial odds ratio of metformin use for “any AMD” remained (OR 0.75, 95% CI 0.54-0.97, I2=98.5%). This information should be interpreted with caution due to the high heterogeneity between studies including racial differences. We agree that further studies into the potential benefit of metformin for AMD are certainly warranted, including population-based datasets with accurate AMD diagnoses and prospective clinical trials.
Sincerely
References:
1. Gokhale KM, Adderley NJ, Subramanian A, et al. Metformin and risk of age-related macular degeneration in individuals with type 2 diabetes: a retrospective cohort study. British Journal of Ophthalmology Published Online First: 3 February 2022. doi:10.1136/bjophthalmol-2021-319641
2. Vassilev ZP, Ruigómez A, Soriano-Gabarró M, et al. Diabetes, Cardiovascular Morbidity, and Risk of Age-Related Macular Degeneration in a Primary Care Population. Invest Ophthalmol Vis Sci 2015;56:1585–92. doi:10.1167/iovs.14-16271
3. Romdhoniyyah DF, Harding SP, Cheyne CP, et al. Metformin, A Potential Role in Age-Related Macular Degeneration: A Systematic Review and Meta-Analysis. Ophthalmol Ther 2021;10:245–60. doi:10.1007/s40123-021-00344-3
4. Brown EE, Ball JD, Chen Z, et al. The Common Antidiabetic Drug Metformin Reduces Odds of Developing Age-Related Macular Degeneration. Invest Ophthalmol Vis Sci 2019;60:1470–7. doi:10.1167/iovs.18-26422
5. Stewart JM, Lamy R, Wu F, et al. Relationship between Oral Metformin Use and Age-Related Macular Degeneration. Oph Retina 2020;0. doi:10.1016/j.oret.2020.06.003
6. Blitzer AL, Ham SA, Colby KA, et al. Association of Metformin Use With Age-Related Macular Degeneration: A Case-Control Study. JAMA Ophthalmology Published Online First: 21 January 2021. doi:10.1001/jamaophthalmol.2020.6331
7. Chen Y-Y, Shen Y-C, Lai Y-J, et al. Association between Metformin and a Lower Risk of Age-Related Macular Degeneration in Patients with Type 2 Diabetes. Journal of Ophthalmology. 2019. doi:10.1155/2019/1649156
8. Lee H, Jeon H-L, Park SJ, et al. Effect of Statins, Metformin, Angiotensin-Converting Enzyme Inhibitors, and Angiotensin II Receptor Blockers on Age-Related Macular Degeneration. Yonsei Med J 2019;60:679–86. doi:10.3349/ymj.2019.60.7.679
9. Jiang J, Chen Y, Zhang H, et al. Association between metformin use and the risk of age-related macular degeneration in patients with type 2 diabetes: a retrospective study. BMJ Open 2022;12:e054420. doi:10.1136/bmjopen-2021-054420
Author: Dewi Fathin Romdhoniyyah (1), Nicholas AV Beare (1,2)
(1) Department of Eye and Vision Science, Institute of Life Course and Medical Sciences, University of Liverpool, Liverpool, UK
(2) St. Pauls Eye Unit, Liverpool University Hospitals NHS Foundation Trust, Liverpool, UK
Mauschitz et al. (1) conducted a meta-analysis to investigate the association of systemic medications with age-related macular degeneration (AMD) in the general population. A pooled odds ratios (95% confidence intervals [CIs]) of lipid-lowering drugs (LLD) and antidiabetic drugs for any AMD were 0.85 (0.79 to 0.91) and 0.78 (0.66 to 0.91), respectively. In contrast, late AMD was not significantly associated with systemic medications. There is an information that antidiabetics, lipid-lowering agents, and antioxidants could theoretically be repurposed for AMD treatment (2). I present information regarding the effect of antidiabetic medications on the risk of AMD.
Blitzer et al. (3) conducted a case-control study and metformin use was significantly associated with reduced odds of AMD, presenting dose dependent manner. But metformin did not have an effect of protecting diabetic retinopathy. In contrast, Gokhale et al. (4) conducted a retrospective cohort study to evaluate the effect of metformin on the risk reduction of AMD. The adjusted hazard ratio (95% CI) of patients prescribed metformin (with or without other antidiabetic medications) against those prescribed any other antidiabetic medication only for AMD was 1.02 (0.92 to 1.12). Vergroesen et al. (5) conducted a cohort study and a lower risk of AMD was not observed in patients with metformin, but other diabetes medication was significantly associated with a lower risk of AMD.
Mauschitz et al. (1) conducted a meta-analysis to investigate the association of systemic medications with age-related macular degeneration (AMD) in the general population. A pooled odds ratios (95% confidence intervals [CIs]) of lipid-lowering drugs (LLD) and antidiabetic drugs for any AMD were 0.85 (0.79 to 0.91) and 0.78 (0.66 to 0.91), respectively. In contrast, late AMD was not significantly associated with systemic medications. There is an information that antidiabetics, lipid-lowering agents, and antioxidants could theoretically be repurposed for AMD treatment (2). I present information regarding the effect of antidiabetic medications on the risk of AMD.
Blitzer et al. (3) conducted a case-control study and metformin use was significantly associated with reduced odds of AMD, presenting dose dependent manner. But metformin did not have an effect of protecting diabetic retinopathy. In contrast, Gokhale et al. (4) conducted a retrospective cohort study to evaluate the effect of metformin on the risk reduction of AMD. The adjusted hazard ratio (95% CI) of patients prescribed metformin (with or without other antidiabetic medications) against those prescribed any other antidiabetic medication only for AMD was 1.02 (0.92 to 1.12). Vergroesen et al. (5) conducted a cohort study and a lower risk of AMD was not observed in patients with metformin, but other diabetes medication was significantly associated with a lower risk of AMD.
Anyway, clinical trials are needed to specify the inconsistent relationship between antidiabetic medications and the risk reduction of AMD.
References
1. Mauschitz MM, Verzijden T, Schuster AK, et al. Association of lipid-lowering drugs and antidiabetic drugs with age-related macular degeneration: a meta-analysis in Europeans. Br J Ophthalmol 2022 doi: 10.1136/bjo-2022-321985
2. Nadeem U, Xie B, Xie EF, et al. Using advanced bioinformatics tools to identify novel therapeutic candidates for age-related macular degeneration. Transl Vis Sci Technol 2022;11(8):10.
3. Blitzer AL, Ham SA, Colby KA, Skondra D. Association of metformin use with age-related macular degeneration: A case-control study. JAMA Ophthalmol 2021;139(3):302-309.
4. Gokhale KM, Adderley NJ, Subramanian A, et al. Metformin and risk of age-related macular degeneration in individuals with type 2 diabetes: a retrospective cohort study. Br J Ophthalmol 2022 doi: 10.1136/bjophthalmol-2021-319641
5. Vergroesen JE, Thee EF, Ahmadizar F, et al. Association of diabetes medication with open-angle glaucoma, age-related macular degeneration, and cataract in the Rotterdam Study. JAMA Ophthalmol 2022;140(7):674-681.
The paper advises that the population inspected was predominately of white background and is looking to find ways of expanding its knowledge of non-white ethnicity within the sphere of retina testing. Within the following paper : Ethnicity and Type 2 diabetes in the UK by
L. M. Goff; it states that the prevalence of Type 2 diabetes within the non-white community is particularly high. a quote from this paper:
"Among minority ethnic communities, the prevalence is alarmingly high, approximately three to five times higher than in the white British population. "
Which brings me to my response: All UK Type 2 diabetics are offered eye screening during which the retina is photographed every year. These digital photographs are examined by medical staff looking for vein bleeding and are held by the NHS. Given the hign incidence of Type 2 diabetes in non-white citizens a very large number of these records will be available and so allow a useful extension to the work done by Professor Rudnicka.
It is generally believed that retinal neurons stop growing in number after birth in humans.1, 2 But recent research has shown retinal neurogenesis in neonatal 1-3 month old monkeys.3 This poses the question of how the sclera and the retina grow during emmetropization. The ora serrata is reported to be 2 mm wide growing to 6-7mm (approximately 5mm difference) in adult life as the scleral tunic grows more than the retina.4 The vitreous chamber depth in newborns is 10.6mm long and also grows roughly by 6 mm to an adult axial value of 17mm on average.5 It is then possible that during the first 3 months of human life, at that rapid growth phase from 17mm to 19mm in mean axial length,6 the retina could grow at least 1mm to compensate in part for that rapid elongation. The eyes of males and females have only a 0.1mm difference at birth with very small differences in body length and head circumference, but bigger born babies have longer eyes with less powerful corneas,7 so a bigger born girl may have a bigger eye with flatter cornea than a smaller born male. When adulthood is reached, women have eyes shorter than those of men by 0.7mm, with steeper corneas and more powerful crystalline lenses.8 As the cornea stabilizes by ages 2-3 in infants, these differential growth patterns are probably established early in life.4 And as usually happens not only among males and females, emmetropic or low hyperopic eyes that develop low corneal powers are longer than eyes that stay with steep co...
It is generally believed that retinal neurons stop growing in number after birth in humans.1, 2 But recent research has shown retinal neurogenesis in neonatal 1-3 month old monkeys.3 This poses the question of how the sclera and the retina grow during emmetropization. The ora serrata is reported to be 2 mm wide growing to 6-7mm (approximately 5mm difference) in adult life as the scleral tunic grows more than the retina.4 The vitreous chamber depth in newborns is 10.6mm long and also grows roughly by 6 mm to an adult axial value of 17mm on average.5 It is then possible that during the first 3 months of human life, at that rapid growth phase from 17mm to 19mm in mean axial length,6 the retina could grow at least 1mm to compensate in part for that rapid elongation. The eyes of males and females have only a 0.1mm difference at birth with very small differences in body length and head circumference, but bigger born babies have longer eyes with less powerful corneas,7 so a bigger born girl may have a bigger eye with flatter cornea than a smaller born male. When adulthood is reached, women have eyes shorter than those of men by 0.7mm, with steeper corneas and more powerful crystalline lenses.8 As the cornea stabilizes by ages 2-3 in infants, these differential growth patterns are probably established early in life.4 And as usually happens not only among males and females, emmetropic or low hyperopic eyes that develop low corneal powers are longer than eyes that stay with steep corneas (first described by Sorsby9). It is believed that this coordination between ocular components is produced by defocus mechanisms that affect the retino-scleral message that governs ocular growth.10
It has been shown that the limit after which a long axial length ends in myopic maculopathy is shorter in women vs. men.11 One of the believed reasons for myopic maculopathy, besides hypoxia, is retinal thinning as the non-growing retina adapts to an increased rate of myopic scleral elongation during school years. The case is that when environmental triggers (like lagging when reading black text in low illuminated environments) begin to act after age 6 and myopia develops, some of those developing myopic eyes have normal corneas of 43.00D and medium axial lengths of 23mm for 6 year old children, but others have 46.00D corneas with 22mm long eyes, and even some have 40.00D corneas with 24mm long eyes. These ones will grow 1mm in the next 10 years if remaining emmetropic, but about 2-3mm if developing myopia. Following what is suggested about ocular growth, these eyeballs with low powered corneas (or lenses) may be longer eyes which are at higher risk of reaching the threshold for myopic maculopathy.
It is possible that not only the axial length and gender should be monitored with ocular growth curves,12 but the unique data of the keratometry could be split by tertiles in ocular growth curves of boys and girls (as keratometry will not change with growth during school years). This relationship between fundus myopic changes in children and keratometry has been also shown in the recent paper by Gong et al. which has motivated our short report.13 Those children with flatter corneas could be devoted to special care as they are the ones who possibly rank high in axial length dimensions and may be the ones more prone to myopic maculopathy.14
1. Young RW. Cell proliferation during postnatal development of the retina in the mouse. Brain Res 1985;353(2):229-39.
2. Kubota R, Hokoc JN, Moshiri A, et al. A comparative study of neurogenesis in the retinal ciliary marginal zone of homeothermic vertebrates. Brain Res Dev Brain Res 2002;134(1-2):31-41.
3. Tkatchenko AV, Walsh PA, Tkatchenko TV, et al. Form deprivation modulates retinal neurogenesis in primate experimental myopia. Proc Natl Acad Sci U S A 2006;103(12):4681-6.
4. Iribarren R. Crystalline lens and refractive development. Prog Retin Eye Res 2015;47:86-106.
5. Rozema JJ, Herscovici Z, Snir M, Axer-Siegel R. Analysing the ocular biometry of new-born infants. Ophthalmic Physiol Opt 2017.
6. Mutti DO, Mitchell GL, Jones LA, et al. Axial growth and changes in lenticular and corneal power during emmetropization in infants. Invest Ophthalmol Vis Sci 2005;46(9):3074-80.
7. Blomdahl S. Ultrasonic measurements of the eye in the newborn infant. Acta Ophthalmol (Copenh) 1979;57(6):1048-56.
8. Iribarren R, Morgan IG, Hashemi H, et al. Lens power in a population-based cross-sectional sample of adults aged 40 to 64 years in the Shahroud Eye Study. Invest Ophthalmol Vis Sci 2014;55(2):1031-9.
9. Benjamin B, Davey JB, Sheridan M, et al. Emmetropia and its aberrations; a study in the correlation of the optical components of the eye. Spec Rep Ser Med Res Counc (G B) 1957;11(293):1-69.
10. Wallman J, Winawer J. Homeostasis of eye growth and the question of myopia. Neuron 2004;43(4):447-68.
11. Hashimoto S, Yasuda M, Fujiwara K, et al. Association between Axial Length and Myopic Maculopathy: The Hisayama Study. Ophthalmol Retina 2019;3(10):867-73.
12. Tideman JWL, Polling JR, Vingerling JR, et al. Axial length growth and the risk of developing myopia in European children. Acta Ophthalmol 2018;96(3):301-9.
13. Gong W, Cheng T, Wang J, et al. Role of corneal radius of curvature in early identification of fundus tessellation in children with low myopia. Br J Ophthalmol 2022.
14. Galan MM TW, Iribarren R. El rol de la longitud axial y la queratometría en el seguimiento de niños miopes Oftalmologia Clinica y Experimental 2021;14(2).
Randomized controlled trials (RCTs) are considered to be the best method for evaluating the effectiveness of medical interventions.1 Despite their strengths, RCTs have substantial limitations.1 Although RCTs have strong internal validity, they occasionally lack external validity and generalizations of findings outside the study population may be invalid. More specifically in retinal surgery, there are many obstacles to conducting RCTs to address the specific questions asked, so the analysis using real-world data is useful.2 Drs Anguita and Charteris wrote an editorial in the British Journal of Ophthalmology (BJO) on the merits and limitations of studies using real-world data.3 They cited our papers that were recently published in BJO which used the data collected in the Japan Retinal Detachment Registry (J-RD registry), and I would like to comment on with a focus on the retinal surgery.4,5
As correctly stated by Drs Anguita and Charteris, studies using the propensity score matching method cannot be performed well if one is not familiar with the limitations of this technique. 3 However, this is also true for those who do not have a deep understanding of the disease and may make incorrect interpretations. This would be the case for our paper4 cited in the editorial. This study compared pars plana vitrectomy (PPV) and scleral buckling for superior RD without macula detachment using the data from the J-RD registry. The results which were analyzed using propensity score...
Randomized controlled trials (RCTs) are considered to be the best method for evaluating the effectiveness of medical interventions.1 Despite their strengths, RCTs have substantial limitations.1 Although RCTs have strong internal validity, they occasionally lack external validity and generalizations of findings outside the study population may be invalid. More specifically in retinal surgery, there are many obstacles to conducting RCTs to address the specific questions asked, so the analysis using real-world data is useful.2 Drs Anguita and Charteris wrote an editorial in the British Journal of Ophthalmology (BJO) on the merits and limitations of studies using real-world data.3 They cited our papers that were recently published in BJO which used the data collected in the Japan Retinal Detachment Registry (J-RD registry), and I would like to comment on with a focus on the retinal surgery.4,5
As correctly stated by Drs Anguita and Charteris, studies using the propensity score matching method cannot be performed well if one is not familiar with the limitations of this technique. 3 However, this is also true for those who do not have a deep understanding of the disease and may make incorrect interpretations. This would be the case for our paper4 cited in the editorial. This study compared pars plana vitrectomy (PPV) and scleral buckling for superior RD without macula detachment using the data from the J-RD registry. The results which were analyzed using propensity score matching showed that there was no significant difference in the best-corrected visual acuity at 6 months after surgery, but there were significantly fewer surgical failures with scleral buckling than with PPV. Thus, we concluded that, “Although the indications for PPV are becoming broader, PPV may not be the optimal approach for repairing all types of RDs. Therefore, careful considerations are needed when selecting the appropriate surgical technique in treating uncomplicated phakic macula-on RD case”, knowing the limitation of evidence level obtained from real-world data study.4 The editorial by Drs Anguita and Charteris indicated that a major problem with this study was the lack of adjustments for the presence or absence of a posterior vitreous detachment (PVD) which is the most important factor in selecting the surgical method.3 Traditionally, the presence of a PVD has been determined by echography, but its accuracy is inferior to that of optical coherence tomography, and above all, it was found to vary from operator to operator.6 On the other hand, it is widely accepted that almost all cases of retinal tears are caused by a PVD,7 so we decided it would be more objective to adjust the evaluations of PVD by using retinal tear or hole instead. We believed that this analysis, in which preoperative factors were adjusted for retinal tear and/or hole, adjusted for PVD to an acceptable level. Without understanding this background, the findings of this paper might be misinterpreted. On the other hand, we mention in the paper by Funatsu et al, which was also cited in the editorial, on the potential toxic effects of silicone.5 There was a misunderstanding of the intent of our study, however because of space limitation, we will not discuss it here.
We agree that the analysis of real-world data using propensity score matching has its limitations.3 However, there are major problems in implementing RCTs in retinal surgery. First, RCTs are very costly, and the overall cost of an RCT study has skyrocketed to a level that cannot be borne by the surgeons or researchers. In recent years, RCTs are no longer conducted unless they are sponsored by large pharmaceutical companies that can profit from the results of RCTs.8 Additionally, if the drug is not effective, it will not necessarily be published.8 Studies in which the company's profit is not clear, such as retinal surgical treatments, are less likely to be adopted as a topic of study. Second, RCT is time-consuming. It usually takes only a few weeks to complete a study using registry data, but it generally takes years to complete RCT studies from planning, implementation, and analyzation. If prospective RCTs were performed for comparing PPV and scleral buckling for superior RD as in our study, it would have taken several years to accomplish the project. Furthermore, it has been noted that RCTs are virtually impossible to perform to compare existing and new surgical methods because surgeons’ preferences already exist and enrollment does not work.9 In general, surgeons want to know how to save the patient in front of them, often an individual problem, as soon as possible. Not only is it extremely difficult to recruit patients for an RCT who meet the inclusion criteria of individual problem of retinal surgery, and it can take several years to obtain the results.9 Thus, it is not practical to use an RCT for this purpose.
The editorial by Drs Anguita and Charteris is very important and I congratulate that. As they stated, we do not believe that the results obtained from real-world data analysis can replace the evidence of RCTs, either. On the other hand, it is true that RCTs cannot answer all of the surgical questions. Most importantly, RCTs are essentially experimental trials of humans. It is unclear whether it will continue to be ethically acceptable to put a large number of subjects at risk even for medical purposes. In contrast, real-world data analyses are basically retrospective studies so it does not expose patients to any new risks. Until better analysis methods are developed, real-world data analysis will provide certain answers to many problems which surgeons have. Nevertheless, I fully agree with them that the researchers and the readers need to recognize the validity and limitations of propensity score matching studies as well as to know the background of the treatment.
REFERENCES
1. Frieden TR. Evidence for Health Decision Making - Beyond Randomized, Controlled Trials. N Engl J Med 2017;377:465-75.
2. Ryan EH, Ryan CM, Forbes NJ, et al. Primary Retinal Detachment Outcomes Study Report Number 2: Phakic Retinal Detachment Outcomes. Ophthalmology 2020;127:1077-85.
3. Anguita R, Charteris D. Could real-world data replace evidence from clinical trials in surgical retinal conditions? Br J Ophthalmol 2022:bjophthalmol-2022-321759. doi: 10.1136/bjophthalmol-2022-321759. Epub ahead of print. PMID: 35580995.
4. Kawano S, Imai T, Sakamoto T; Japan-Retinal Detachment Registry Group. Scleral buckling versus pars plana vitrectomy in simple phakic macula-on retinal detachment: a propensity score-matched, registry-based study. Br J Ophthalmol 2022:857-62.
5. Funatsu R, Terasaki H, Koriyama C, et al. Silicone oil versus gas tamponade for primary rhegmatogenous retinal detachment treated successfully with a propensity score analysis: Japan Retinal Detachment Registry. Br J Ophthalmol 2021:bjophthalmol-2021-319876. doi: 10.1136/bjophthalmol-2021-319876. Epub ahead of print. PMID: 34373251.
6. Moon SY, Park SP, Kim YK. Evaluation of posterior vitreous detachment using ultrasonography and optical coherence tomography. Acta Ophthalmol 2020;98:e29-e35.
7. Michaels RG, Wilkinson CP, Rice TA. Vitreoretinal precursors of retinal detachment. In Retinal detachment, eds Michaels RG, Wilkinson CP, Rice TA, The CV Mosby Company, St Louis, 1990, pp 29-100.
8. Flacco ME, Manzoli L, Boccia S, et al. Head-to-head randomized trials are mostly industry sponsored and almost always favor the industry sponsor. J Clin Epidemiol 2015;68:811-20.
9. Lonjon G, Boutron I, Trinquart L, et al. Comparison of treatment effect estimates from prospective nonrandomized studies with propensity score analysis and randomized controlled trials of surgical procedures. Ann Surg 2014;259:18–25.
We read with interest the manuscript published by Sakamoto et al, on behalf of the Japanese Retina and Vitreous Society, titled: Increased incidence of endophthalmitis after vitrectomy relative to face mask-wearing during COVID-19 pandemic”.[1] In this manuscript, the authors discuss their results after comparing the total prevalence of infectious endophthalmitis among patients that underwent ocular surgery, before and after the peak of the SARS-CoV-2 pandemic in Japan.[1] The authors should be commended due to the level of complexity and significant effort needed to coordinate several centers simultaneously, as well as the detailed description provided in the manuscript regarding the clinical presentation, microbiological results, and outcomes of all cases. Interestingly and despite the low rate of positive vitreous cultures, the authors were able to isolate oral bacteria among several of the cases that developed endophthalmitis during the pandemic, including one caused by Staphylococcus lugdunensis; a pathogen typically hard to eliminate with mechanical washing bacteria, because it accumulates behind the auricle.[1] With all this evidence, the authors provided a compelling argument regarding the inappropriate wearing of face masks could increase the risk of postoperative endophthalmitis. Nevertheless, we believe that there are a few important considerations that the authors may need to address before making such an assumption.
As a start, we ca...
We read with interest the manuscript published by Sakamoto et al, on behalf of the Japanese Retina and Vitreous Society, titled: Increased incidence of endophthalmitis after vitrectomy relative to face mask-wearing during COVID-19 pandemic”.[1] In this manuscript, the authors discuss their results after comparing the total prevalence of infectious endophthalmitis among patients that underwent ocular surgery, before and after the peak of the SARS-CoV-2 pandemic in Japan.[1] The authors should be commended due to the level of complexity and significant effort needed to coordinate several centers simultaneously, as well as the detailed description provided in the manuscript regarding the clinical presentation, microbiological results, and outcomes of all cases. Interestingly and despite the low rate of positive vitreous cultures, the authors were able to isolate oral bacteria among several of the cases that developed endophthalmitis during the pandemic, including one caused by Staphylococcus lugdunensis; a pathogen typically hard to eliminate with mechanical washing bacteria, because it accumulates behind the auricle.[1] With all this evidence, the authors provided a compelling argument regarding the inappropriate wearing of face masks could increase the risk of postoperative endophthalmitis. Nevertheless, we believe that there are a few important considerations that the authors may need to address before making such an assumption.
As a start, we can mention a few methodological irregularities that are hallmarks of any retrospective study and thus unavoidable. However, some may carry a significant relevance to the outcome such as the lack of rigor in the definition of postoperative endophthalmitis in the inclusion/exclusion criteria. In their manuscript, Sakamoto et al considered postoperative endophthalmitis, any intraocular infection that developed within 42 days after surgery. Although we agree with this definition, we must clarify that this definition refers to the maximum time elapsed between the invasion of the intraocular space by the offending bacteria, which is during surgery, and the development of the first clinical symptoms. Which, depending on the bacteria's virulence, could be up to 6 weeks. The latest optical coherence tomography and ultrasound biomicroscopy evidence have shown that sclerotomies after a pars plana vitrectomy seal between 8 and 15 days after surgery, even after a sutureless approach.[2 3] Therefore, it is highly unlikely that the source of infection originated after this time, as the authors seem to imply. Moreover, although the authors’ argument that face masking may increase the contamination of the periocular area makes sense, laboratory evidence has shown that there is no difference between bacterial dispersion toward the ocular surface when comparing different types of masks and masking techniques (tape in the superior border of the mask and no tape).[4] Nevertheless, we do agree that wearing a face mask before or during surgery may induce ocular surface changes such as dry eye disease and subclinical infectious keratitis, which might hypothetically increase the risk of endophthalmitis. If we consider the possible exhaustion of the surgical team (human error), scarcity of surgical disinfectants, and other factors that occurred during the peak of the SARS-CoV-2 pandemic, this should place the source of the infection during surgery and not after it. The high prevalence of Streptococcal endophthalmitis in the SARS-CoV-2 mask period (as defined by the authors), supports indeed the notion that contamination may come from the oral flora, very similar to the reports of post intravitreal injection endophthalmitis. However, bacteria such as Streptococcus mitis and Streptococcus salivarius are usually described as low-virulence or opportunistic pathogens. Therefore, the onset time of the clinical symptoms of endophthalmitis, information not described in the manuscript, could have helped the reader to infer if the contamination occurred during surgery or during the postoperative time.
Finally, the result observed regarding the prevalence of postoperative endophthalmitis in the only-phacoemulsification group, is not consistent with the main hypothesis suggested by the authors, and points in the opposite direction. If how the patient uses the mask during the postoperative period is indeed a determinant factor in endophthalmitis development and, considering that the prevalence of endophthalmitis after vitrectomy is usually lower in comparison to other surgical procedures [5]; we should have expected a proportional increase in the prevalence in all three groups. The latter might be the result of a lack of a sample calculation and therefore an error type 1, which should have been mentioned in the limitation section. A throughout analysis of the surgical circumstance per group is also lacking. Consequently, it is not clear at this time if other significant risk factors (trauma, intraocular foreign body, posterior capsule rupture) for endophthalmitis were present or not during surgery. A multivariate analysis, controlling for several other risk factors should be enough to shed light on this matter.
We congratulate Sakamoto et al for this outstanding contribution. We will look forward to their reply.
References:
1. Sakamoto T, Terasaki H, Yamashita T, et al. Increased incidence of endophthalmitis after vitrectomy relative to face mask wearing during COVID-19 pandemic. Br J Ophthalmol 2022 doi: 10.1136/bjophthalmol-2022-321357[published Online First: Epub Date]|.
2. Keshavamurthy R, Venkatesh P, Garg S. Ultrasound biomicroscopy findings of 25 G Transconjuctival Sutureless (TSV) and conventional (20G) pars plana sclerotomy in the same patient. BMC Ophthalmol 2006;6:7 doi: 10.1186/1471-2415-6-7[published Online First: Epub Date]|.
3. Sawada T, Kakinoki M, Sawada O, Kawamura H, Ohji M. Closure of sclerotomies after 25- and 23-gauge transconjunctival sutureless pars plana vitrectomy evaluated by optical coherence tomography. Ophthalmic Res 2011;45(3):122-8 doi: 10.1159/000318875[published Online First: Epub Date]|.
4. Angaramo S, Law JC, Maris AS, et al. Potential impact of oral flora dispersal on patients wearing face masks when undergoing ophthalmologic procedures. BMJ Open Ophthalmol 2021;6(1):e000804 doi: 10.1136/bmjophth-2021-000804[published Online First: Epub Date]|.
5. AlBloushi B, Mura M, Khandekar R, et al. Endophthalmitis Post Pars Plana Vitrectomy Surgery: Incidence, Organisms' Profile, and Management Outcome in a Tertiary Eye Hospital in Saudi Arabia. Middle East Afr J Ophthalmol 2021;28(1):1-5 doi: 10.4103/meajo.MEAJO_424_20[published Online First: Epub Date]|.
To the editor
We read the article published by Patel et al. with considerable interest [1]. The authors have provided interestingly novel insights into the prevalence and risk factors for chalazion. In their large case-control study comprising 3,453,944 older veteran participants with/without chalazion, the risk factors for chalazion included smoking, conditions of the tear film, conjunctivitis, dry eye, conditions affecting periocular skin, rosacea, allergic conditions, and systemic disorders, such as anxiety. Considering the relationship between chalazion and anxiety, a similar trend as reported in the previous study by Nemet et al. was observed [2]. Moreover, anxiety is generally considered as a psychological reaction to stress [3, 4]. Alsammahi et al. reported that stress is associated with the development of chalazion [5]. In real-world settings, we realize that patients with the onset of chalazion are likely to have anxiety or stress (such as work and examination).
Incidentally, in the c...
To the editor
We read the article published by Patel et al. with considerable interest [1]. The authors have provided interestingly novel insights into the prevalence and risk factors for chalazion. In their large case-control study comprising 3,453,944 older veteran participants with/without chalazion, the risk factors for chalazion included smoking, conditions of the tear film, conjunctivitis, dry eye, conditions affecting periocular skin, rosacea, allergic conditions, and systemic disorders, such as anxiety. Considering the relationship between chalazion and anxiety, a similar trend as reported in the previous study by Nemet et al. was observed [2]. Moreover, anxiety is generally considered as a psychological reaction to stress [3, 4]. Alsammahi et al. reported that stress is associated with the development of chalazion [5]. In real-world settings, we realize that patients with the onset of chalazion are likely to have anxiety or stress (such as work and examination).
Incidentally, in the coronavirus disease 2019 (COVID-19) pandemic era, Silkiss et al. reported that the incidence of chalazion increased with widespread mask wear, possibly resulting from eye dryness and changes in the eyelid microbiome associated with wearing face coverings [6]. Moreover, the widespread COVID-19 vaccinations provide many opportunities to examine the chalazion of patients who had recently received the vaccination at our institution, and most of these patients had anxiety or stress regarding the vaccination. To the best of our knowledge, the association between chalazion and COVID-19 vaccination has not been debated. Moreover, determining whether the chalazion occurred immediately after the vaccination was causation or coincidence is difficult because this disease is common and often observed in unvaccinated patients as well. However, we believe that these cases confirmed the result of Patel et al.’s study, wherein anxiety was associated with the risk of chalazion development. The need for vaccination against COVID-19 will continue because of the increased supply of COVID-19 vaccines for developing nations, recommendation of the third dose of vaccine, and the lowering of the age for vaccination against COVID-19, mainly in developed countries. Therefore, to elucidate the mechanism of chalazion after the vaccination, increasingly reliable care of this symptom following vaccination is warranted.
References
1. Patel S, Tohme N, Gorrin E, Kumar N, Goldhagen B, Galor A. Prevalence and risk factors for chalazion in an older veteran population. Br J Ophthalmol. 2021 Mar 31; bjophthalmol-2020-318420.
doi: 10.1136/bjophthalmol-2020-318420. Online ahead of print.
2. Nemet AY, Vinker S, Kaiserman I. Associated morbidity of chalazia. Cornea 2011; 30: 1376-1381.
3. Robinson L. Stress and anxiety. Nurs Clin North Am 1990; 25: 935-943.
4. American Psychological Association. Stress won’t go away? Maybe you are suffering from chronic stress. Available online: https://www.apa.org/topics/stress/chronic. Accessed March 15, 2022.
5. Alsammahi A, Aljohani Z, Jaad N, Daia OA, Aldayhum M, Almutairi M, Basendwah M, Alzahrani R, Alturki M. Incidence and predisposing factors of chalazion. Int J Community Med Public Health 2018; 5: 4979-4982.
6. Silkiss RZ, Paap MK, Ugradar S. Increased incidence of chalazion associated with face mask wear during the COVID-19 pandemic. Am J Ophthalmol Case Rep 2021; 22: 101032.
To the Editor:
We thank Dr Velez-Montoya and colleagues for their interest in our study.1 We reported that there was an increase in the prevalence of endophthalmitis after vitrectomy in Japan and found that it was probably related to the face masks during the COVID period.2 Although the cause for the increase definitively determined, we need to report these findings to the ophthalmologic community to alert them of this possibility.
First, we address the indicated point, “the definition of postoperative endophthalmitis was not rigorous”. We used the definition of the Endophthalmitis Vitrectomy Study group.3 Although this definition is relatively old, many subsequent studies have used it, and it has the advantage that our findings could be compared to these other studies with the same definition.
They also stated that the latest studies have shown that the sclerotomies after a pars plana vitrectomy seal within 15 days after the surgery even after a suture-less closure. Thus, the site of the incision was unlikely the entry port for the infectious micro-organisms after that time. This is generally true but the cause of infectious endophthalmitis after vitrectomy is complex. Because the cause of infectious endophthalmitis is varied, it is not surprising that anything can happen with postoperative endophthalmitis. For example, it is possible for a patient to inadvertently touch the eye in the early postoperative period and cause the incision to open. Once...
Show MoreChauhan and co-workers [1] have provided Table 1, showing times taken to detect significant field progression with 80% power, based on a number of modelling parameters: frequency of examinations, rate of field progression, intrasession variability of field assessment. They have also provided Table 2 showing the number of annual eye examinations required to detect different total visual field changes, for different time periods, and for moderate variability. I have checked the calculations of Chauhan and co-workers, using Monte Carlo modelling, assuming a one-tailed significance value of 0.025. Of the 36 outcome values in Table 1, 33 are incorrect. Of the 12 outcome values in Table 2, 11 are incorrect.
Chauhan and co-workers have made 2 main errors in their calculations for Table 1. The first is in applying their estimates of power. The curves shown in Figure 2 (statistical power plotted against number of field examinations) are appropriate for the case of 2 field examinations per year, but Chauhan and co-workers appear to have incorrectly also used them for the cases of 1 examination per year and 3 examinations per year. Separate sets of curves should have been calculated for those conditions. The effect on Table 1 is that the time taken to detect a field change is incorrectly reported as being inversely proportional to the number of examinations per year. This anomalous relationship was commented on by Albert Alm in his 2008 Rapid Response, “Is a field every 4...
Show MoreDear Editor:
We read the paper on non-invasive intracranial pressure determination by Zhang et al(1) with great interest and hope. We fully agree that the search for non-invasive intracranial pressure (ICP) evaluations is of high importance and should be continued. The Bland-Altman plot showing the difference between predicted and intracranially measured pressure looks very impressive. There are, however, still a few points and limits we would like to address concerning the anatomy of the optic nerve, the optic canal, and the basic concept the authors used.
Cerebrospinal fluid (CSF) from the intracranial subarachnoid spaces and the subarachnoid space of the optic nerve (SAS -ON) communicate via the optic canal. Using three-dimensional reconstruction of the optic canal in normal tension glaucoma (NTG) patients, this was found to be narrower than in an age-related cohort of normals,(2) thus questioning the patency of the CSF pathway between the pituitary cistern and the SAS-ON. Further, optic canal dimensions in a normal population are quite variable amongst individuals, and even between orbits within the same individual.(3) These facts largely influence the results the authors present. Further, studies in patients with NTG and patients with elevated ICP (such as patients with idiopathic intracranial hypertension) were shown to have developed an optic nerve sheath compartment syndrome. In such cases, the CSF dynamics between the intracranial CSF and the CSF in...
Show MoreWe read with great interest the article of Gokhale et al [1] on their retrospective study of metformin use and risk of age-related macular degeneration (AMD) in individuals with type 2 diabetes mellitus (T2DM). In this study Gokhale and colleagues used data derived from IQVIA Medical Research Data (IMRD-UK), formerly known as The Health Improvement Network (THIN), and found no change in AMD risk in those taking metformin.
An issue with this study is the quality of the GP coding and data on AMD. The authors cite a validation study of THIN data [2] but this study only validated cases identified as having AMD. There was no validation of the quality of data on the absence of AMD. So, the confirmation of positives was high (confirmed AMD cases quoted as 97%) but the false negative rate, is unknown. Also, the validation was by an ophthalmologist reviewing all the GP data, not using recognised diagnostic criteria or a grading scheme for AMD. Furthermore, the authors included a code for “drusen” into their AMD group which was not a code included in the validation study by Vassilev et al [2]. It is likely that this code includes patients with common physiological drusen and not an AMD diagnosis.
We have previously performed a systematic review and meta-analysis [3] of five studies [4–8] on the relationship between metformin use and AMD, which we have now updated to include Gokhale et al [1] and Jiang et al [9]. Including their data, we found a beneficial odds ratio of...
Show MoreMauschitz et al. (1) conducted a meta-analysis to investigate the association of systemic medications with age-related macular degeneration (AMD) in the general population. A pooled odds ratios (95% confidence intervals [CIs]) of lipid-lowering drugs (LLD) and antidiabetic drugs for any AMD were 0.85 (0.79 to 0.91) and 0.78 (0.66 to 0.91), respectively. In contrast, late AMD was not significantly associated with systemic medications. There is an information that antidiabetics, lipid-lowering agents, and antioxidants could theoretically be repurposed for AMD treatment (2). I present information regarding the effect of antidiabetic medications on the risk of AMD.
Blitzer et al. (3) conducted a case-control study and metformin use was significantly associated with reduced odds of AMD, presenting dose dependent manner. But metformin did not have an effect of protecting diabetic retinopathy. In contrast, Gokhale et al. (4) conducted a retrospective cohort study to evaluate the effect of metformin on the risk reduction of AMD. The adjusted hazard ratio (95% CI) of patients prescribed metformin (with or without other antidiabetic medications) against those prescribed any other antidiabetic medication only for AMD was 1.02 (0.92 to 1.12). Vergroesen et al. (5) conducted a cohort study and a lower risk of AMD was not observed in patients with metformin, but other diabetes medication was significantly associated with a lower risk of AMD.
Anyway, clinical trials are nee...
Show MoreThe paper advises that the population inspected was predominately of white background and is looking to find ways of expanding its knowledge of non-white ethnicity within the sphere of retina testing. Within the following paper : Ethnicity and Type 2 diabetes in the UK by
L. M. Goff; it states that the prevalence of Type 2 diabetes within the non-white community is particularly high. a quote from this paper:
"Among minority ethnic communities, the prevalence is alarmingly high, approximately three to five times higher than in the white British population. "
Which brings me to my response: All UK Type 2 diabetics are offered eye screening during which the retina is photographed every year. These digital photographs are examined by medical staff looking for vein bleeding and are held by the NHS. Given the hign incidence of Type 2 diabetes in non-white citizens a very large number of these records will be available and so allow a useful extension to the work done by Professor Rudnicka.
It is generally believed that retinal neurons stop growing in number after birth in humans.1, 2 But recent research has shown retinal neurogenesis in neonatal 1-3 month old monkeys.3 This poses the question of how the sclera and the retina grow during emmetropization. The ora serrata is reported to be 2 mm wide growing to 6-7mm (approximately 5mm difference) in adult life as the scleral tunic grows more than the retina.4 The vitreous chamber depth in newborns is 10.6mm long and also grows roughly by 6 mm to an adult axial value of 17mm on average.5 It is then possible that during the first 3 months of human life, at that rapid growth phase from 17mm to 19mm in mean axial length,6 the retina could grow at least 1mm to compensate in part for that rapid elongation. The eyes of males and females have only a 0.1mm difference at birth with very small differences in body length and head circumference, but bigger born babies have longer eyes with less powerful corneas,7 so a bigger born girl may have a bigger eye with flatter cornea than a smaller born male. When adulthood is reached, women have eyes shorter than those of men by 0.7mm, with steeper corneas and more powerful crystalline lenses.8 As the cornea stabilizes by ages 2-3 in infants, these differential growth patterns are probably established early in life.4 And as usually happens not only among males and females, emmetropic or low hyperopic eyes that develop low corneal powers are longer than eyes that stay with steep co...
Show MoreRandomized controlled trials (RCTs) are considered to be the best method for evaluating the effectiveness of medical interventions.1 Despite their strengths, RCTs have substantial limitations.1 Although RCTs have strong internal validity, they occasionally lack external validity and generalizations of findings outside the study population may be invalid. More specifically in retinal surgery, there are many obstacles to conducting RCTs to address the specific questions asked, so the analysis using real-world data is useful.2 Drs Anguita and Charteris wrote an editorial in the British Journal of Ophthalmology (BJO) on the merits and limitations of studies using real-world data.3 They cited our papers that were recently published in BJO which used the data collected in the Japan Retinal Detachment Registry (J-RD registry), and I would like to comment on with a focus on the retinal surgery.4,5
As correctly stated by Drs Anguita and Charteris, studies using the propensity score matching method cannot be performed well if one is not familiar with the limitations of this technique. 3 However, this is also true for those who do not have a deep understanding of the disease and may make incorrect interpretations. This would be the case for our paper4 cited in the editorial. This study compared pars plana vitrectomy (PPV) and scleral buckling for superior RD without macula detachment using the data from the J-RD registry. The results which were analyzed using propensity score...
Show MoreDear Editor.
We read with interest the manuscript published by Sakamoto et al, on behalf of the Japanese Retina and Vitreous Society, titled: Increased incidence of endophthalmitis after vitrectomy relative to face mask-wearing during COVID-19 pandemic”.[1] In this manuscript, the authors discuss their results after comparing the total prevalence of infectious endophthalmitis among patients that underwent ocular surgery, before and after the peak of the SARS-CoV-2 pandemic in Japan.[1] The authors should be commended due to the level of complexity and significant effort needed to coordinate several centers simultaneously, as well as the detailed description provided in the manuscript regarding the clinical presentation, microbiological results, and outcomes of all cases. Interestingly and despite the low rate of positive vitreous cultures, the authors were able to isolate oral bacteria among several of the cases that developed endophthalmitis during the pandemic, including one caused by Staphylococcus lugdunensis; a pathogen typically hard to eliminate with mechanical washing bacteria, because it accumulates behind the auricle.[1] With all this evidence, the authors provided a compelling argument regarding the inappropriate wearing of face masks could increase the risk of postoperative endophthalmitis. Nevertheless, we believe that there are a few important considerations that the authors may need to address before making such an assumption.
Show MoreAs a start, we ca...
Clinical features of chalazion following COVID-19 vaccination
Yusuke Kameda, Megumi Sugai, Karin Ishinabe, Nichika Fukuoka
Yotsuya-sanchome Ekimae Eye Clinic, Tokyo, Japan
*Corresponding author: Yusuke Kameda, MD, Yotsuya-sanchome Ekimae Eye Clinic, Tokyo, Japan, 3-7-24 Yotsuya, Shinjuku-ku Tokyo 160-0004, Japan.
Phone: 81-3-6380-4101; Fax: 81-3-6380-4133; E-mail: y09025618059@leaf.ocn.ne.jp
To the editor
Show MoreWe read the article published by Patel et al. with considerable interest [1]. The authors have provided interestingly novel insights into the prevalence and risk factors for chalazion. In their large case-control study comprising 3,453,944 older veteran participants with/without chalazion, the risk factors for chalazion included smoking, conditions of the tear film, conjunctivitis, dry eye, conditions affecting periocular skin, rosacea, allergic conditions, and systemic disorders, such as anxiety. Considering the relationship between chalazion and anxiety, a similar trend as reported in the previous study by Nemet et al. was observed [2]. Moreover, anxiety is generally considered as a psychological reaction to stress [3, 4]. Alsammahi et al. reported that stress is associated with the development of chalazion [5]. In real-world settings, we realize that patients with the onset of chalazion are likely to have anxiety or stress (such as work and examination).
Incidentally, in the c...
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