We read with great interest the recent paper by Zhang and Ying exploring statistical approaches in published ophthalmic clinical science papers.1 We very much agree with the main conclusion drawn by the authors that collaborative efforts should be made in the vision research community to improve statistical practise for ocular data. In this vein, however, we were disappointed not to see reference to the Statistics Notes Series that has been published in this very journal. These have been written with a view to tackling some of the more prevalent statistical issues within ophthalmology and we would encourage readers to make use of these.2- 12. Within the UK this view that there needs to be greater collaboration in the vision research community has led to the formation of the Ophthalmology Research Section of the NIHR Statistics group which is championing cross- professional collaboration and active discussion in relation to statistical issues. It is always important when reviewing misuse of statistics in biomedical research to distinguish between misuse that leads to distorted or incorrect results and those methods which do not fully use data to maximum potential given that this loss of information might be viewed as unethical. In this regard we find the results from Zhang et al pleasing in that the proportion of papers which analysed at the level of the individual because of the nature of the observation rose from 15.2 % in 1995 to 50 % in 2017. A finding which is...
We read with great interest the recent paper by Zhang and Ying exploring statistical approaches in published ophthalmic clinical science papers.1 We very much agree with the main conclusion drawn by the authors that collaborative efforts should be made in the vision research community to improve statistical practise for ocular data. In this vein, however, we were disappointed not to see reference to the Statistics Notes Series that has been published in this very journal. These have been written with a view to tackling some of the more prevalent statistical issues within ophthalmology and we would encourage readers to make use of these.2- 12. Within the UK this view that there needs to be greater collaboration in the vision research community has led to the formation of the Ophthalmology Research Section of the NIHR Statistics group which is championing cross- professional collaboration and active discussion in relation to statistical issues. It is always important when reviewing misuse of statistics in biomedical research to distinguish between misuse that leads to distorted or incorrect results and those methods which do not fully use data to maximum potential given that this loss of information might be viewed as unethical. In this regard we find the results from Zhang et al pleasing in that the proportion of papers which analysed at the level of the individual because of the nature of the observation rose from 15.2 % in 1995 to 50 % in 2017. A finding which is statistically significant (P< 0.001, two-tailed Chi-square test). This is pertinent in that historically single person-level responses were often created by ophthalmologists (taking the worse eye only for example or combining information from each eye) prior to the development of the more advanced techniques that make better use of the data (by using data from both eyes instead of one) such as generalised estimating equations. A review by Gange et al has shown that point estimates and tests of significance that used this simple person-level approach are similar to those obtained from the more complex methods and concluded that there would therefore be unlikely benefit from a reanalysis with more sophisticated methods 13 . Misuse of statistics in medical research is unethical and this is a message that has been strongly advocated by Professor Doug Altman since 1980. 14 Professor Altman died in June of 2018 and his loss is hugely felt by the applied statistics community. Let us make 2019 a year of improved statistics throughout all research in vision and eyes.
1 Zhang HG, Ying GS. Statistical approaches in published ophthalmic clinical science papers: a comparison to statistical practice two decades ago. Br J Ophthalmol. 2018 Sep;102(9):1188-1191.
2 Stephenson J, Bunce C, Doré CJ, Freemantle N; Ophthalmic Statistics Group. Ophthalmic statistics note 11: logistic regression. Br J Ophthalmol. 2016 Dec;100(12):1594-1595.
3 Bunce C, Stephenson J, Doré CJ, Freemantle N; Ophthalmic Statistics Group.Ophthalmic statistics note 10: data transformations.Br J Ophthalmol. 2016 Dec;100(12):1591-1593.
4 Skene SS, Bunce C, Freemantle N, Doré CJ; Ophthalmic Statistics Group. Ophthalmic statistics note 9: parametric versus non-parametric methods for data analysis. Br J Ophthalmol. 2016 Jul;100(7):877-878.
5 Bunce C, Quartilho A, Freemantle N, Doré CJ; Ophthalmic Statistics Group. Ophthalmic statistics note 8: missing data--exploring the unknown. Br J Ophthalmol. 2016 Mar;100(3):291-4.
6 Cipriani V, Quartilho A, Bunce C, Freemantle N, Doré CJ; Ophthalmic Statistics Group. Ophthalmic statistics note 7: multiple hypothesis testing—to adjust or not to adjust. Br J Ophthalmol. 2015 Sep;99(9):1155-7.
7 Cook JA, Bunce C, Doré CJ, Freemantle N; Ophthalmic Statistics Group. Ophthalmic statistics note 6: effect sizes matter. Br J Ophthalmol. 2015 May;99(5):580-1.
8 Saunders LJ, Zhu H, Bunce C, Doré CJ, Freemantle N, Crabb DP; Ophthalmic Statistics Group. Ophthalmic statistics note 5: diagnostic tests—sensitivity and specificity. Br J Ophthalmol. 2015 Sep;99(9):1168-70.
9 Nash R, Bunce C, Freemantle N, Doré CJ, Rogers CA; Ophthalmic Statistics Group.
Ophthalmic Statistics Note 4: analysing data from randomised controlled trials with baseline and follow-up measurements. Br J Ophthalmol. 2014 Nov;98(11):1467-9.
10 Ophthalmic statistics note: the perils of dichotomising continuous variables. Cumberland PM, Czanner G, Bunce C, Doré CJ, Freemantle N, García-Fiñana M; Ophthalmic Statistics Group.Br J Ophthalmol. 2014 Jun;98(6):841-3.
11 Bunce C, Patel KV, Xing W, Freemantle N, Doré CJ; Ophthalmic Statistics Group. Ophthalmic statistics note 2: absence of evidence is not evidence of absence. Br J Ophthalmol. 2014 May;98(5):703-5.
12 Bunce C, Patel KV, Xing W, Freemantle N, Doré CJ; Ophthalmic Statistics Group Ophthalmic statistics note 1: unit of analysis. Br J Ophthalmol. 2014 Mar;98(3):408-12.
13 Gange SJ, Linton KL, Scott AJ, DeMets DL, Klein R. A comparison of methods for correlated ordinal measures with ophthalmic applications. Stat Med. 1995 Sep 30;14(18):1961-74
14 Altman DG. Statistics and ethics in medical research. Misuse of statistics is unethical. Br Med J. 1980 Nov 1;281(6249):1182-4.
We read with great interest the nice series from Sternfeld et al. about so-called “benign positional vertical opsoclonus in infants”. [1] As stated by the authors, the very specific condition they describe is not uncommon in the population, yet still poorly described in the scientific literature. Additionally, it is called differently by different authors, one reason for it being the difficulty to assess through the naked eye the very nature of the high frequency eye movements, as shown in video n°1.
The condition combines a positional tonic downgaze and abnormal vertical eye movements. Oculomotor recordings of infants presenting with this clinical picture do actually confirm that these movements comprise downbeating slow phases and upbeating saccades 2, as clinically seen in video n°2, and are therefore a vertical kind of nystagmus. We therefore proposed to refer to them as benign intermittent upbeat nystagmus in infancy. [2] As stated by the authors, the association of a tonic downgaze and an upbeat nystagmus is logical and has been related to posterior semicircular canal predominance. [3]
In addition to the evidence of slow phases in this condition and to the fact that, to the best of our knowledge, no pulse of purely vertical saccades has ever been recorded, the very possibility for the oculomotor system to produce such movements is questionable. Opsoclonus, by definition, designates a succession of multidirectional saccades. We therefo...
We read with great interest the nice series from Sternfeld et al. about so-called “benign positional vertical opsoclonus in infants”. [1] As stated by the authors, the very specific condition they describe is not uncommon in the population, yet still poorly described in the scientific literature. Additionally, it is called differently by different authors, one reason for it being the difficulty to assess through the naked eye the very nature of the high frequency eye movements, as shown in video n°1.
The condition combines a positional tonic downgaze and abnormal vertical eye movements. Oculomotor recordings of infants presenting with this clinical picture do actually confirm that these movements comprise downbeating slow phases and upbeating saccades 2, as clinically seen in video n°2, and are therefore a vertical kind of nystagmus. We therefore proposed to refer to them as benign intermittent upbeat nystagmus in infancy. [2] As stated by the authors, the association of a tonic downgaze and an upbeat nystagmus is logical and has been related to posterior semicircular canal predominance. [3]
In addition to the evidence of slow phases in this condition and to the fact that, to the best of our knowledge, no pulse of purely vertical saccades has ever been recorded, the very possibility for the oculomotor system to produce such movements is questionable. Opsoclonus, by definition, designates a succession of multidirectional saccades. We therefore believe that the term “vertical opsoclonus” should be avoided.
1. Sternfeld A, Lobel D, Leiba H, Luckman J, Michowiz S, Goldenberg-Cohen N. Long-term follow-up of benign positional vertical opsoclonus in infants: retrospective cohort. Br J Ophthalmol. 2018; 102: 757-60.
2. Robert MP, Michel S, Adjadj E, Boddaert N, Desguerre I, Vidal PP. Benign intermittent upbeat nystagmus in infancy: a new clinical entity. Eur J Paediatr Neurol. 2015; 19: 262-5.
3. Brodsky MC, Donahue SP. Primary oblique muscle overaction: the brain throws a wild pitch. Arch Ophthalmol. 2001; 119: 1307-14.
I read with great interest the article by Bae and collegues.1 In their retrospective study, the authors concluded that the presence of atypical epiretinal tissue (AET) in a full-thickness macular hole (FTMH) was related to poorer anatomical success and less visual recovery after surgery.
I agree with the authors on the association of their OCT findings with the visual prognosis. I also agree with them that it is important to identify a good indicator of visual prognosis based on OCT findings. However, there are many confounders to be addressed in this study. For example, preoperative MH size with OCT has been known as a prognostic factor for postoperative visual outcome and anatomical success rate of MH surgery.2,3 A previous study also demonstrated that ERM prevalence increased with severity and size of the FTMH.4 In addition, preoperative visual acuity or preoperative photoreceptor integrity also seems to correlate with visual prognosis.
Thus, their results should be supported by appropriate statistical analysis, that is, multivariate regression analyses. I hope that the authors will comment on the results of multivariate regression analyses to identify the most significant factor to predict visual prognosis after MH surgery.
References
1. Bae K, Lee SM, Kang SW, et al. Atypical epiretinal tissue in full-thickness macular holes: pathogenic and prognostic significance. Br J Ophthalmol. 2018 (in press)
2. Ullrich S, Haritoglou C, Gass...
I read with great interest the article by Bae and collegues.1 In their retrospective study, the authors concluded that the presence of atypical epiretinal tissue (AET) in a full-thickness macular hole (FTMH) was related to poorer anatomical success and less visual recovery after surgery.
I agree with the authors on the association of their OCT findings with the visual prognosis. I also agree with them that it is important to identify a good indicator of visual prognosis based on OCT findings. However, there are many confounders to be addressed in this study. For example, preoperative MH size with OCT has been known as a prognostic factor for postoperative visual outcome and anatomical success rate of MH surgery.2,3 A previous study also demonstrated that ERM prevalence increased with severity and size of the FTMH.4 In addition, preoperative visual acuity or preoperative photoreceptor integrity also seems to correlate with visual prognosis.
Thus, their results should be supported by appropriate statistical analysis, that is, multivariate regression analyses. I hope that the authors will comment on the results of multivariate regression analyses to identify the most significant factor to predict visual prognosis after MH surgery.
References
1. Bae K, Lee SM, Kang SW, et al. Atypical epiretinal tissue in full-thickness macular holes: pathogenic and prognostic significance. Br J Ophthalmol. 2018 (in press)
2. Ullrich S, Haritoglou C, Gass C, et al. Macular hole size as a prognostic factor in macular hole surgery. Br J Ophthalmol 2002;86:390-3.
3. Duker JS, Kaiser PK, Binder S, et al. The International Vitreomacular Traction Study Group classification of vitreomacular adhesion, traction, and macular hole. Ophthalmology 2013;120:2611-9.
4. Cheng L, Freeman WR, Ozerdem U, et al. Prevalence, correlates, and natural history of epiretinal membranes surrounding idiopathic macular holes. Vitrectomy for Macular Hole Study Group. Ophthalmology 2000;107:853-9.
We thank Dr. Sarnicola and family for their interest in our work and at the same time we apologize for not mentioning their preliminary results published in 2010; in this regard, some issues need be clarified.
We used an acronym to shorten the text and facilitate the readers of our article by eliminating this way long descriptive wording of the procedure. This did not imply by any means an attempt at modifying the terminology of surgical techniques, which is usually a task of the ophthalmological community. In fact, a particular acronym becomes a standard only when it is cited as such by numerous papers in the literature. This is not seeming the case, for the acronym “AVB”, that has never been used after its initial introduction by Sarnicola et al., thus failing to achieve the purpose aimed at.
In addition, we had a reason to introduce a new acronym because of a substantial difference in the surgical technique: in fact, instead of creating a new corneal tunnel into the emphysematous tissue, we inject ophthalmic viscoelastic device (OVD) in the same track created for pneumatic dissection, thus increasing surgical reproducibility and safety.
The lack of previous data we indicated (“…little data are available on the success rate…type of cleavage obtained, visual results and complications of this approach”) was simply related to the new concept of performing the injection of the OVD in the same corneal path where the air had failed.
In our series visual...
We thank Dr. Sarnicola and family for their interest in our work and at the same time we apologize for not mentioning their preliminary results published in 2010; in this regard, some issues need be clarified.
We used an acronym to shorten the text and facilitate the readers of our article by eliminating this way long descriptive wording of the procedure. This did not imply by any means an attempt at modifying the terminology of surgical techniques, which is usually a task of the ophthalmological community. In fact, a particular acronym becomes a standard only when it is cited as such by numerous papers in the literature. This is not seeming the case, for the acronym “AVB”, that has never been used after its initial introduction by Sarnicola et al., thus failing to achieve the purpose aimed at.
In addition, we had a reason to introduce a new acronym because of a substantial difference in the surgical technique: in fact, instead of creating a new corneal tunnel into the emphysematous tissue, we inject ophthalmic viscoelastic device (OVD) in the same track created for pneumatic dissection, thus increasing surgical reproducibility and safety.
The lack of previous data we indicated (“…little data are available on the success rate…type of cleavage obtained, visual results and complications of this approach”) was simply related to the new concept of performing the injection of the OVD in the same corneal path where the air had failed.
In our series visual acuity was significantly better after big bubble-DALK than after viscobubble-DALK in the first postoperative months, suggesting a transient negative effect of the OVD; this is an original result never described in any of the papers cited by the Sarnicola et al. in addition, they classified as dDALK all those procedures with a successful pneumatic dissection, whereas we now know that most of big bubbles created with air injection are actually pre-descemetic. This has been demonstrated by several authors after the initial observation by Dua.1 This mistake due to the lack of knowledge of the true anatomy of the floor is combined with the procedural error of putting together all cases with a successful bubble creation, without distinction between those obtained with air injection and those obtained with OVD injection. Our original results show a significant difference in postoperative vision between these two subgroups and represents the main original contribution of the paper. Instead, the methodology used by the Sarnicola group leads to a completely false analysis of the results because it is based to the erroneous assumption that all successful bubbles are descemetic.
References:
1. Dua HS, Faraj LA, Said DG, et al. Human corneal anatomy redefined: a novel pre-
Descemet’s layer (Dua’s layer). Ophthalmology 2013;120:1778–85.
Tuning Of The Literature Related To The Airviscobubble (AVB) DALK Technique
Corresponding author:
Vincenzo Sarnicola
Address: Clinica degli Occhi Sarnicola,
Via Mazzini no. 62, Grosseto 58100, Italy.
Fax: +39-0564-413023
Tel: +39-3201158500
e-mail address: v.sarnicola@hotmail.it or sarnicolavincenzo@gmail.com
Affiliation:
1 Clinica degli Occhi Sarnicola, Grosseto, Italy
2 Ospedale Oftalmico di Torino, Struttura Complessa Oculistica 2, Turin, Italy
3 Ospedale San Giovanni Bosco, Struttura Complessa Oculistica 2, Turin, Italy
4 Department of Biomedical and Specialty Surgical Sciences, University of Ferrara, Ferrara, Italy;
We read with interest the article published by Scorcia et al.[1] It is encouraging to see others, such as Scorcia et al, embracing the use of ophthalmic viscoelastic device (OVD) injection as a second bubble a...
Tuning Of The Literature Related To The Airviscobubble (AVB) DALK Technique
Corresponding author:
Vincenzo Sarnicola
Address: Clinica degli Occhi Sarnicola,
Via Mazzini no. 62, Grosseto 58100, Italy.
Fax: +39-0564-413023
Tel: +39-3201158500
e-mail address: v.sarnicola@hotmail.it or sarnicolavincenzo@gmail.com
Affiliation:
1 Clinica degli Occhi Sarnicola, Grosseto, Italy
2 Ospedale Oftalmico di Torino, Struttura Complessa Oculistica 2, Turin, Italy
3 Ospedale San Giovanni Bosco, Struttura Complessa Oculistica 2, Turin, Italy
4 Department of Biomedical and Specialty Surgical Sciences, University of Ferrara, Ferrara, Italy;
We read with interest the article published by Scorcia et al.[1] It is encouraging to see others, such as Scorcia et al, embracing the use of ophthalmic viscoelastic device (OVD) injection as a second bubble attempt after a failed air big bubble (BB) with air. However, it looks unreasonable to use new acronym (VB-DALK).[1] We would like to highlight that the orginal technique was first described by Sarnicola et al in 2010 and named airviscobubble (indicated with the acronym “AVB”).[2] Scorcia et al probably did not notice this paper in literature, citing only a later study by Muftuoglu et al from 2013.[1-3] Consistency of terms that are well-established in literature should be maintained. Attempting to rename both the name (viscobubble DALK instead of airviscobubble) and the acronym (VB-DALK instead of AVB) of a recognized technique without specific reasons does not serve any purpose as it is confusing for to readers and problematic for the comparison of future studies.
The Authors also stated in the introduction of their paper that “…little data are available on the success rate, type of cleavage obtained, visual results and complications of this approach”.[1] A more complete review of the literature would demonstrate the inaccuracy of this statement.[4-9] Several studies have reported the efficacy of AVB as a rescue bubble technique, showing a 15% increase of descemetic DALK in 507 eyes, the advantages of using a cannula for the OVD injection, the usefulness of the technique even in cases of herpetic corneal scar, and the importance of performing a paracentesis before the AVB formation.[4-9]
Despite the manuscript is very well written and pleasant to read, we would like to draw attention to another small inaccuracy. The consideration statement reported in the 6th paragraph of the discussion section (“The loss of pressure … trephination size.”) is missing the appropriate reference.[1,3]
REFERENCES:
1. Scorcia V, DE Luca V, Lucisano A, et al. Br J Ophthalmol 2018;102:1288–1292. doi:10.1136/bjophthalmol-2017-311419
2. Sarnicola V, Toro P, Gentile D, et al: Descemetic DALK and predescemetic DALK: outcomes in 236 cases of keratoconus. Cornea 2010;29:53-9.
3. Muftuoglu O, Toro P, Hogan RN, et al. Sarnicola air-visco bubble technique in deep anterior lamellar keratoplasty. Cornea 2013;32:527-32.
4. Sarnicola V, Toro P. Blunt cannula for descemetic deep anterior lamellar keratoplasty. Cornea 2010;30:859-8.
5. Sarnicola V, Toro P. Deep anterior lamellar keratoplasty. In herpes simplex corneal opacities. Cornea 2011;29:60-4.
6. Sarnicola V, Toro P, Sarnicola C, et al. Long-term graft survival in deep anterior lamellar keratoplasty. Cornea. 2012;31:621-6.
7. Sarnicola E, Sarnicola C, Sarnicola V. Deep anterior lamellar keratoplasty: surgical technique, indications, clinical results and complications. In: Guell JL, ed. Cornea ESASO Course Series. Basel, Switzerland: Karger; 2015:81-101.
8. Sarnicola V, Sarnicola E, Sarnicola C. Recovery techniques in DALK, Chapter 120 In: Mannis M, Holland E Cornea 4th edition 2016. Editor: Elsevier - Health Sciences Division.
9. Sarnicola E, Sarnicola C, Sabatino F, et al. Cannula DALK versus Needle DALK for Keratoconus. Cornea 2016;35:1508-11.
We thank Dr. Tobon for his comments regarding our recently published article on refractive errors frequency in Colombia.1
Initially he referred to the exclusion of the participants with less than 20/40 of distance corrected vision. The explanation of the application of this criterium was that, since as it has been shown, reproducibility of manifest refraction is less in patients with bad distance corrected visual acuity, and in this study we needed to have a very reliable manifest refraction examination.2
However, we believe that Dr. Tobon highlights a very interesting point, which is worth analyzing in more detail. Ours and other studies that have analyzed the prevalence of refractive errors in a population have excluded eyes with other ocular conditions, including amblyopia. For example, in the study conducted in Mexico by Gomez-Salazar et al, which included a very large sample (more than 670,000 patients), they excluded patients with amblyopia.3 This made it impossible to analyze the frequency of amblyopia or anisometropia.
In our study we excluded those patients with less than 20/40 of distance corrected visual acuity in any eye. Unfortunately, we did not keep the information on those patients excluded, and therefore we cannot determine the exact number or diagnosis of those cases. For future studies we will record such information.
With regard to the second query of Dr. Tobon, we decided not to use cyclopegic refraction in this study, performed...
We thank Dr. Tobon for his comments regarding our recently published article on refractive errors frequency in Colombia.1
Initially he referred to the exclusion of the participants with less than 20/40 of distance corrected vision. The explanation of the application of this criterium was that, since as it has been shown, reproducibility of manifest refraction is less in patients with bad distance corrected visual acuity, and in this study we needed to have a very reliable manifest refraction examination.2
However, we believe that Dr. Tobon highlights a very interesting point, which is worth analyzing in more detail. Ours and other studies that have analyzed the prevalence of refractive errors in a population have excluded eyes with other ocular conditions, including amblyopia. For example, in the study conducted in Mexico by Gomez-Salazar et al, which included a very large sample (more than 670,000 patients), they excluded patients with amblyopia.3 This made it impossible to analyze the frequency of amblyopia or anisometropia.
In our study we excluded those patients with less than 20/40 of distance corrected visual acuity in any eye. Unfortunately, we did not keep the information on those patients excluded, and therefore we cannot determine the exact number or diagnosis of those cases. For future studies we will record such information.
With regard to the second query of Dr. Tobon, we decided not to use cyclopegic refraction in this study, performed around our country, because this additional intervention would have required more complex logistical necessities, ethical requirements. Since the participants would have been exposed to an additional risk,4 although small, it should have been expressly indicated in the informed consent, and accepted by the potential participants (or in the case of the children by the parents or guardians), issue that at a given moment could have decreased the confidence of the population and made it more difficult to recruit patients in certain areas of the country, distant from our usual care center, being us a group of researchers not known in those areas to which we move for the study. Instead, we decided to perform a sequential examination by experienced optometrists: first a non-cycloplegic retinoscopy, making it as static as possible by requesting the patients to keep the fixation in a distant object in order to relax the accommodation and secondly, we carried out a careful manifest refraction. The results of the latter were the one taken into account in the study. If there was a discrepancy between the retinoscopy and the manifest refraction, the optometrist rechecked the patient. As other experts have indicated (see the explanation by Marsh-Tootle and Frazier), this approach is valid, but as we recognized it, it could be considered a weakness of our study. It is correct that despite the meticulousness in performing these non-cycloplegic examinations, we could have overestimated the frequency of myopia and underestimated that of hyperopia, especially in patients with ages between 8 and 11 years.
REFERENCES
1. Galvis V, Tello A, Otero J, et al. Prevalence of refractive errors in Colombia: MIOPUR study. Br J Ophthalmol 2018;102:1320-3.
2. Leinonen J, Laakkonen E, Laatikainen L. Repeatability (test-retest variability) of refractive error measurement in clinical settings. Acta Ophthalmol Scand 2006;84:532-6.
3. Gomez-Salazar F, Campos-Romero A, Gomez-Campaña H, et al. Refractive errors among children, adolescents and adults attending eye clinics in Mexico. Int J Ophthalmol 2017;10:796-802.
4. Bhatia SS, Vidyashankar C, Sharma RK, et al. Systemic toxicity with cyclopentolate eye drops. Indian Pediatr 2000;37:329-31.
5. Marsh-Tootle WL, Frazier MG. Infants, toddlers and children. Borish's Clinical
Refraction. 2nd edn. Philadelphia: Buiterworth Heinemann Elsevier, 2006:1415–6.
I have read with great interest the article of Galvis et al about Prevalence of refractive errors in Colombia: MIOPUR study. It is a great effort and it might be the first study of its type in our country. In the discussion section, the inclusion criteria needs to be better explained.
1: Why did they exclude the participants with less than 20/40 corrected vision?
2: Is the vision exclusion criteria based on any eye or the better eye?
3: Why didn’t they use cyclopegic medication for the refraction exam?
These concerns affect the results because all of the amblyopic patients are excluded from the study and the hyperopic patients and those with an astigmatism that induce amblyopia are underreported, as seen in the table that shows a very low incidence in those refractive errors.
We thank Drs Sabherwal and Sood for their interest in our article.(1) We would like to respond to the interesting points they raise.
Table 3 presents our analyses of potential predictors of the correct diagnosis by rural doctors of diabetic retinopathy (DR) requiring treatment. Details on a number of the characteristics assessed in this table are presented in the first paragraph of the Results section, but not, as Drs Sabherwal and Sood point out, the proportion having received didactic training. Among the 28 rural doctors, 13 (46.4%) received such training and 15 (53.6%) did not.
In the Methods, we describe in detail the training received by ophthalmologists in the CREST (Comprehensive Rural Eye Service and Training) program. As described there, only two doctors per hospital (not all of whom examined patients in the current study) could attend the didactic phase of training at the Zhongshan Ophthalmic Center (ZOC). This is due to the limited number of ophthalmologists at a typical rural Chinese county hospital, and the heavy load of clinical duties. For more doctors to have left their facilities for the two-month didactic training would not have been practical. However, all ophthalmologists participating in the CREST network and in the current study received intensive hands-on training by medical retina experts from ZOC at their own facilities, which included the diagnosis and laser treatment of diabetic retinopathy (DR) as well as the u...
We thank Drs Sabherwal and Sood for their interest in our article.(1) We would like to respond to the interesting points they raise.
Table 3 presents our analyses of potential predictors of the correct diagnosis by rural doctors of diabetic retinopathy (DR) requiring treatment. Details on a number of the characteristics assessed in this table are presented in the first paragraph of the Results section, but not, as Drs Sabherwal and Sood point out, the proportion having received didactic training. Among the 28 rural doctors, 13 (46.4%) received such training and 15 (53.6%) did not.
In the Methods, we describe in detail the training received by ophthalmologists in the CREST (Comprehensive Rural Eye Service and Training) program. As described there, only two doctors per hospital (not all of whom examined patients in the current study) could attend the didactic phase of training at the Zhongshan Ophthalmic Center (ZOC). This is due to the limited number of ophthalmologists at a typical rural Chinese county hospital, and the heavy load of clinical duties. For more doctors to have left their facilities for the two-month didactic training would not have been practical. However, all ophthalmologists participating in the CREST network and in the current study received intensive hands-on training by medical retina experts from ZOC at their own facilities, which included the diagnosis and laser treatment of diabetic retinopathy (DR) as well as the use of the United Kingdom National Health Service Diabetic Eye Screening Program (UK NHS DESP) DR grading system assessed in our study. The median number (inter-quartile range) of hands-on training sessions received in managing DR was 3 (1, 9). As mentioned in our article, CREST is a fully-funded program by Orbis International. It provides DR training well beyond what the typical rural county-level ophthalmologist in China would receive. Training in the UK NHS DESP system was comparable between non-medical graders and doctors. For these reasons, the authors would respectfully disagree with Drs Sabherwal and Sood’s suggestion that our study was biased in favour of non-medical graders. These graders achieved a level of accuracy consistent with the standards of the UK NHS DESP, and the use of non-medical graders has been recommended by bodies such as the UK Royal College of Ophthalmologists.(2)
Drs Sabherwal and Sood also indicate that our use of an arbiter may have improved the accuracy of non-medical graders and added to the expense of the program. Use of an arbiter is standard practice in the UK NHS DESP, whose protocols we follow in CREST, and in most DR screening programs of which we are aware. As noted in our article, performance of graders on those images where the grade was unchanged by arbitration remained good: the median sensitivity was 0.80, specificity was 0.98 and kappa ranged from 0.78-0.88. Use of arbitration is an inherent cost of most such programs, and will be included in our forthcoming paper on cost-effectiveness for DR screening of non-medical graders versus local ophthalmologists. It should be noted that task-shifting approaches such as the use of non-medical graders, by reducing even when they do not eliminate the role of more expensive ophthalmologists, are very likely to be more cost-effective than traditional ophthalmologist-driven approaches.
Finally, Drs Sabherwal and Sood point out 33% of images being deemed of inadequate quality as a short-coming of our program. As clearly described in the Results section of our paper, the majority of such images were “inadequate” only in the sense that a single image, rather than two as required under UK NHS DESP protocols, had been made of the eye. In fact, as we reported, the proportion of eyes to which non-medical graders were unable to assign DR grades was 3.28% (24/732).
The authors would again like to thank Drs Sabherwal and Sood for their interest in our work, and the Editors for the opportunity to clarify the interesting and important issues they have raised.
1. Sabherwal S, Sood I. Comments on: "Accuracy of trained rural ophthalmologists versus non-medical image graders in the diagnosis of diabetic retinopathy in rural China". Br J Ophthalmol 2018. https://bjo.bmj.com/content/102/11/1471.responses
We read the article ‘Acute retinal toxicity associated with a mixture of perfluorooctane and perfluorohexyloctane: Failure of another indirect cytotoxicity analysis ’ by Coco et al. with great interest.[1] In this study, the authors reported on ocular toxicity due to perfluorooctane (PFO). They advised that the protocols used to determine the cytotoxicity of intraocular medical devices (which have been approved by the Organisation for the Standardisation of International Standards based on indirect methods) should be revised to ensure safety. We congratulate Coco et al.1 for their report because we believe that it has the potential to be a significant contribut or to the literature on this topic.
As is commonly known, PFO is saturated with PFO liquids, which have highly stable carbon-fluorine bonds that consequently make them inert. PFO has highly specific gravity, low viscosity, optical clarity immiscibility in water and interface tension towards water. It is regularly used in vitreoretinal surgery for complex retinal detachment repair because it displaces subretinal fluid and blood anteriorly, unfolds the retina in giant retinal tear cases and provides counter traction and retinal stabilisation during membrane peeling in eyes with proliferative vitreoretinopathy.[2,3] These properties make PFO useful for intraocular surgery. However, some limitations exist regarding PFO use as a long- term tamponade such as amaurosis, a lack of light perce...
We read the article ‘Acute retinal toxicity associated with a mixture of perfluorooctane and perfluorohexyloctane: Failure of another indirect cytotoxicity analysis ’ by Coco et al. with great interest.[1] In this study, the authors reported on ocular toxicity due to perfluorooctane (PFO). They advised that the protocols used to determine the cytotoxicity of intraocular medical devices (which have been approved by the Organisation for the Standardisation of International Standards based on indirect methods) should be revised to ensure safety. We congratulate Coco et al.1 for their report because we believe that it has the potential to be a significant contribut or to the literature on this topic.
As is commonly known, PFO is saturated with PFO liquids, which have highly stable carbon-fluorine bonds that consequently make them inert. PFO has highly specific gravity, low viscosity, optical clarity immiscibility in water and interface tension towards water. It is regularly used in vitreoretinal surgery for complex retinal detachment repair because it displaces subretinal fluid and blood anteriorly, unfolds the retina in giant retinal tear cases and provides counter traction and retinal stabilisation during membrane peeling in eyes with proliferative vitreoretinopathy.[2,3] These properties make PFO useful for intraocular surgery. However, some limitations exist regarding PFO use as a long- term tamponade such as amaurosis, a lack of light perception, optic nerve atrophy, acute retinal necrosis and retinal vascular occlusion (both arterial and/or venous) with disseminated haemorrhages.
Notably, there are controversial results regarding PFO toxicity in the literature. [3-9] The present study was one of the few reports to discuss ocular toxicity due to PFO in the last few years.
Using the current study by Coco et al.1 as a foundation, we would like to share our findings regarding the ocular toxicity of PFO. In our clinic, four patients underwent uneventful vitreoretinal surgery with PFO on the same day by two experienced surgeons (BB, SG). Each patient presented with vitritis, hypopyon and acute retinal toxicity, with no increases seen in either postoperative increased intraocular pressure or pain. Figure 1 (https://i.hizliresim.com/6NQWR0.jpg) shows macular atrophy due to PFO toxicity.
Ocular toxicity may be either mechanical or chemical due to inhibition of and/or changes to tissue functionality and/or rearrangement of tissue parts and inflammatory reactions and/or immune reactions that result in function loss. In the past, intraocular injections of aminoglycoside caused occlusive vascular changes, which were attributed to the pH of the antibiotic.[10] The mechanism of PFO ocular toxicity may be similar. In addition, concentration and contact time may lead to toxicity. For instance, in 2013, some cases of acute blindness due to PFO were reported by Chile’s Health Authorities, while four cases were reported in Spain to the Agency of Medicines and Medical Devices. The problems were attributed to careless manipulation of the Turkish product ; variable concentrations of perfluorodecalin were found in the octane, after which the product was withdrawn.
Unfortunately, scientific reports have yet to clarify the causes of acute blindness. These results may help clinicians choose a short-term ocular tamponade when performing a vitrectomy. In addition, when faced with severe early postoperative intraocular inflammation, such as either vitritis or hypopyon, they should use PFO with care due to the possibility of toxicity and consider early systemic steroid treatment.
In conclusion, more chemical research is needed to clarify the acute ocular toxicity of PFO to ensure the safety of human patients. Additionally, immediate updates to both the European and Organisation for the Standardisation of International Standards guidelines for the biological evaluation of ophthalmic devices are needed.
REFERENCES
1. Coco RM, Srivastava GK, Andrés-Iglesias C, et al. Acute retinal toxicity associated with a mixture of perfluorooctane and perfluorohexyloctane: Failure of another indirect cytotoxicity analysis British Journal of Ophthalmology Published Online First: 29 March 2018. doi: 10.1136/bjophthalmol-2017-311471.
2. Loewenstein A, Humayun MS, de Juan E Jr, et al. Perfluoroperhydrophenanthrene versus perfluoro-n-octane in vitreoretinal surgery. Ophthalmology. 2000;107:1078–1082.
3. Abboud EB, Al-Falah M. Nine Years of Retained Perfluoro-n-octane in the Anterior Chamber after Retinal Detachment Repair with No Signs of Ocular Toxicity. Middle East African Journal of Ophthalmology. 2014;21(3):279-282. doi:10.4103/0974-9233.134697.
4. Stefano Zenoni, Mario R Romano, Sonia Palmieri, Natalia Comi, Edoardo Fiorentini, Piero Fontana. Ocular tolerance and efficacy of short-term tamponade with double filling of polydimethyloxane and perfluoro-n-octane. Clinical Ophthalmology 2011:5 443–449.
5. Zeana D, Becker J, Kuckelkorn R, Kirchhof B. Perfluorohexyloctane as a long-term vitreous tamponade in the experimental animal. Experimental perfluorohexyloctane substitution. Int Ophthalmol. 1999;23(1):17-24.
6. Chang S, Sparrow JR, Iwamoto T, Gershbein A, Ross R, Ortiz R. Experimental studies of tolerance to intravitreal perfluoro-n-octane liquid. Retina. 1991;11(4):367-74. PMID: 1813951.
7. Alharbi SS, Asiri MS. Reversible Corneal Toxicity of Retained Intracameral Perfluoro-n-octane. Middle East African Journal of Ophthalmology. 2016;23(3):277-279. doi:10.4103/0974-9233.186160.
8. Pastor JC, Coco RM, Fernandez-Bueno I, Alonso-Alonso ML, Medina J, Sanz-Arranz A, Rull F, Gayoso MJ, Dueñas A, Garcia-Gutierrez MT, Gonzalez-Buendia L, Delgado-Tirado S, Abecia E, Ruiz-Miguel M, Serrano MA, Ruiz-Moreno JM, Srivastava GK. Acute retinal damage after using a toxic perfuoro-octane for vitreo-retinal surgery. Retina. 2017 Jun;37(6):1140-1151. doi: 10.1097/IAE.0000000000001680.
9. Pradeep S, Chhablani JK, Patel B, Rani P. Delayed inflammation associated with retained perfluorocarbon liquid. Indian J Ophthalmol. 2011 Sep-Oct;59(5):396-8. doi: 10.4103/0301-4738.83623. PMID: 21836352.
10. Waltz K, Margo CE. Intraocular gentamicin toxicity. Arch Ophthalmol 1991;109:911.
Figure Legends:
Figure 1: A 34-year-old man with a macula on a bullous retinal detachment of his right eye. His preoperative visual acuity was 16/20. He was operated on with a 23-G pars plana vitrectomy plus SF6 and a laser. One week after surgery, he complained of very low visual acuity, and he had vitritis, hypopyon and acute retinal toxicity. The patient treated with intravenous methylprednisolone ( 1 mg/kg) and topical prednisolone, moxifloxacin, nepafenac eyedrops four times a day during 4 weeks. One month after surgery, profound atrophy of all layers of the retina were seen on optical coherence tomography. His final visual acuity was counting fingers.
We read with interest the masterly review of the neuro-ophthalmology of Behcet’s disease by Alghamdi et al (1). One small aspect we question. The authors state that in their patients with papilledema: “The diagnosis of CVT was documented in all patients by cerebral angiography and MRI showing partial or total lack of filling of at least one dural sinus and an elevated CSF opening pressure (>25 mm Hg) on lumbar puncture.” We have recently reported 8 BD patients with pseudotumor cerebri who did not have cerebral venous thrombosis (CVT) on MRI or MRV (2). Partial or total lack of filling of one venous sinus does not constitute the pathophysiological basis for intracranial hypertension; either the sagittal sinus must be occluded, or if only one transverse sinus is occluded then the other needs to be stenosed (3). It would be interesting to know what a review of their patient’s images by a neuro-radiologist would reveal.
1: Alghamdi A, Bodaghi B, Comarmond C, Desbois AC, Domont F, Wechsler B, Depaz R, Le Hoang P, Cacoub P, Touitou V, Saadoun D. Neuro-ophthalmological manifestations of Behçet's disease. Br J Ophthalmol. 2018 Apr 26. pii: bjophthalmol-2017-311334. doi: 10.1136/bjophthalmol-2017-311334.
2: Akdal G, Yaman A, Men S, Çelebisoy N, Toydemir HE, Bajin MS, Akman-Demir G. Pseudotumor cerebri syndrome without cerebral venous sinus thrombosis in Behçet's disease. J Neurol Sci. 2017;383:99-100.
3: Halmagyi GM, Ahmed RM, Johnston IH. The Pseudo...
We read with interest the masterly review of the neuro-ophthalmology of Behcet’s disease by Alghamdi et al (1). One small aspect we question. The authors state that in their patients with papilledema: “The diagnosis of CVT was documented in all patients by cerebral angiography and MRI showing partial or total lack of filling of at least one dural sinus and an elevated CSF opening pressure (>25 mm Hg) on lumbar puncture.” We have recently reported 8 BD patients with pseudotumor cerebri who did not have cerebral venous thrombosis (CVT) on MRI or MRV (2). Partial or total lack of filling of one venous sinus does not constitute the pathophysiological basis for intracranial hypertension; either the sagittal sinus must be occluded, or if only one transverse sinus is occluded then the other needs to be stenosed (3). It would be interesting to know what a review of their patient’s images by a neuro-radiologist would reveal.
1: Alghamdi A, Bodaghi B, Comarmond C, Desbois AC, Domont F, Wechsler B, Depaz R, Le Hoang P, Cacoub P, Touitou V, Saadoun D. Neuro-ophthalmological manifestations of Behçet's disease. Br J Ophthalmol. 2018 Apr 26. pii: bjophthalmol-2017-311334. doi: 10.1136/bjophthalmol-2017-311334.
2: Akdal G, Yaman A, Men S, Çelebisoy N, Toydemir HE, Bajin MS, Akman-Demir G. Pseudotumor cerebri syndrome without cerebral venous sinus thrombosis in Behçet's disease. J Neurol Sci. 2017;383:99-100.
3: Halmagyi GM, Ahmed RM, Johnston IH. The Pseudotumor Cerebri Syndrome: A Unifying Pathophysiological Concept for Patients with Isolated Intracranial Hypertension with Neither Mass Lesion Nor Ventriculomegaly. Neuroophthalmology. 2014;38:249-253.
We read with great interest the recent paper by Zhang and Ying exploring statistical approaches in published ophthalmic clinical science papers.1 We very much agree with the main conclusion drawn by the authors that collaborative efforts should be made in the vision research community to improve statistical practise for ocular data. In this vein, however, we were disappointed not to see reference to the Statistics Notes Series that has been published in this very journal. These have been written with a view to tackling some of the more prevalent statistical issues within ophthalmology and we would encourage readers to make use of these.2- 12. Within the UK this view that there needs to be greater collaboration in the vision research community has led to the formation of the Ophthalmology Research Section of the NIHR Statistics group which is championing cross- professional collaboration and active discussion in relation to statistical issues. It is always important when reviewing misuse of statistics in biomedical research to distinguish between misuse that leads to distorted or incorrect results and those methods which do not fully use data to maximum potential given that this loss of information might be viewed as unethical. In this regard we find the results from Zhang et al pleasing in that the proportion of papers which analysed at the level of the individual because of the nature of the observation rose from 15.2 % in 1995 to 50 % in 2017. A finding which is...
Show MoreDear Editor,
We read with great interest the nice series from Sternfeld et al. about so-called “benign positional vertical opsoclonus in infants”. [1] As stated by the authors, the very specific condition they describe is not uncommon in the population, yet still poorly described in the scientific literature. Additionally, it is called differently by different authors, one reason for it being the difficulty to assess through the naked eye the very nature of the high frequency eye movements, as shown in video n°1.
Show MoreThe condition combines a positional tonic downgaze and abnormal vertical eye movements. Oculomotor recordings of infants presenting with this clinical picture do actually confirm that these movements comprise downbeating slow phases and upbeating saccades 2, as clinically seen in video n°2, and are therefore a vertical kind of nystagmus. We therefore proposed to refer to them as benign intermittent upbeat nystagmus in infancy. [2] As stated by the authors, the association of a tonic downgaze and an upbeat nystagmus is logical and has been related to posterior semicircular canal predominance. [3]
In addition to the evidence of slow phases in this condition and to the fact that, to the best of our knowledge, no pulse of purely vertical saccades has ever been recorded, the very possibility for the oculomotor system to produce such movements is questionable. Opsoclonus, by definition, designates a succession of multidirectional saccades. We therefo...
I read with great interest the article by Bae and collegues.1 In their retrospective study, the authors concluded that the presence of atypical epiretinal tissue (AET) in a full-thickness macular hole (FTMH) was related to poorer anatomical success and less visual recovery after surgery.
I agree with the authors on the association of their OCT findings with the visual prognosis. I also agree with them that it is important to identify a good indicator of visual prognosis based on OCT findings. However, there are many confounders to be addressed in this study. For example, preoperative MH size with OCT has been known as a prognostic factor for postoperative visual outcome and anatomical success rate of MH surgery.2,3 A previous study also demonstrated that ERM prevalence increased with severity and size of the FTMH.4 In addition, preoperative visual acuity or preoperative photoreceptor integrity also seems to correlate with visual prognosis.
Thus, their results should be supported by appropriate statistical analysis, that is, multivariate regression analyses. I hope that the authors will comment on the results of multivariate regression analyses to identify the most significant factor to predict visual prognosis after MH surgery.
References
Show More1. Bae K, Lee SM, Kang SW, et al. Atypical epiretinal tissue in full-thickness macular holes: pathogenic and prognostic significance. Br J Ophthalmol. 2018 (in press)
2. Ullrich S, Haritoglou C, Gass...
We thank Dr. Sarnicola and family for their interest in our work and at the same time we apologize for not mentioning their preliminary results published in 2010; in this regard, some issues need be clarified.
Show MoreWe used an acronym to shorten the text and facilitate the readers of our article by eliminating this way long descriptive wording of the procedure. This did not imply by any means an attempt at modifying the terminology of surgical techniques, which is usually a task of the ophthalmological community. In fact, a particular acronym becomes a standard only when it is cited as such by numerous papers in the literature. This is not seeming the case, for the acronym “AVB”, that has never been used after its initial introduction by Sarnicola et al., thus failing to achieve the purpose aimed at.
In addition, we had a reason to introduce a new acronym because of a substantial difference in the surgical technique: in fact, instead of creating a new corneal tunnel into the emphysematous tissue, we inject ophthalmic viscoelastic device (OVD) in the same track created for pneumatic dissection, thus increasing surgical reproducibility and safety.
The lack of previous data we indicated (“…little data are available on the success rate…type of cleavage obtained, visual results and complications of this approach”) was simply related to the new concept of performing the injection of the OVD in the same corneal path where the air had failed.
In our series visual...
Tuning Of The Literature Related To The Airviscobubble (AVB) DALK Technique
Corresponding author:
Vincenzo Sarnicola
Address: Clinica degli Occhi Sarnicola,
Via Mazzini no. 62, Grosseto 58100, Italy.
Fax: +39-0564-413023
Tel: +39-3201158500
e-mail address: v.sarnicola@hotmail.it or sarnicolavincenzo@gmail.com
Authors:
Vincenzo Sarnicola, MD1
v.sarnicola@hotmail.it
Enrica Sarnicola, MD1-3
e.sarnicola@hotmail.it
Caterina Sarnicola, MD 4
c.sarnicola@hotmail.it
Affiliation:
1 Clinica degli Occhi Sarnicola, Grosseto, Italy
2 Ospedale Oftalmico di Torino, Struttura Complessa Oculistica 2, Turin, Italy
3 Ospedale San Giovanni Bosco, Struttura Complessa Oculistica 2, Turin, Italy
4 Department of Biomedical and Specialty Surgical Sciences, University of Ferrara, Ferrara, Italy;
Competing interests: None.
Keywords: DALK; airviscobubble; AVB; dDALK; descemetic DALK.
Word Count: 303
To the Editor:
We read with interest the article published by Scorcia et al.[1] It is encouraging to see others, such as Scorcia et al, embracing the use of ophthalmic viscoelastic device (OVD) injection as a second bubble a...
Show MoreWe thank Dr. Tobon for his comments regarding our recently published article on refractive errors frequency in Colombia.1
Show MoreInitially he referred to the exclusion of the participants with less than 20/40 of distance corrected vision. The explanation of the application of this criterium was that, since as it has been shown, reproducibility of manifest refraction is less in patients with bad distance corrected visual acuity, and in this study we needed to have a very reliable manifest refraction examination.2
However, we believe that Dr. Tobon highlights a very interesting point, which is worth analyzing in more detail. Ours and other studies that have analyzed the prevalence of refractive errors in a population have excluded eyes with other ocular conditions, including amblyopia. For example, in the study conducted in Mexico by Gomez-Salazar et al, which included a very large sample (more than 670,000 patients), they excluded patients with amblyopia.3 This made it impossible to analyze the frequency of amblyopia or anisometropia.
In our study we excluded those patients with less than 20/40 of distance corrected visual acuity in any eye. Unfortunately, we did not keep the information on those patients excluded, and therefore we cannot determine the exact number or diagnosis of those cases. For future studies we will record such information.
With regard to the second query of Dr. Tobon, we decided not to use cyclopegic refraction in this study, performed...
Best regards,
I have read with great interest the article of Galvis et al about Prevalence of refractive errors in Colombia: MIOPUR study. It is a great effort and it might be the first study of its type in our country. In the discussion section, the inclusion criteria needs to be better explained.
1: Why did they exclude the participants with less than 20/40 corrected vision?
2: Is the vision exclusion criteria based on any eye or the better eye?
3: Why didn’t they use cyclopegic medication for the refraction exam?
These concerns affect the results because all of the amblyopic patients are excluded from the study and the hyperopic patients and those with an astigmatism that induce amblyopia are underreported, as seen in the table that shows a very low incidence in those refractive errors.
Dear Editor,
We thank Drs Sabherwal and Sood for their interest in our article.(1) We would like to respond to the interesting points they raise.
Table 3 presents our analyses of potential predictors of the correct diagnosis by rural doctors of diabetic retinopathy (DR) requiring treatment. Details on a number of the characteristics assessed in this table are presented in the first paragraph of the Results section, but not, as Drs Sabherwal and Sood point out, the proportion having received didactic training. Among the 28 rural doctors, 13 (46.4%) received such training and 15 (53.6%) did not.
In the Methods, we describe in detail the training received by ophthalmologists in the CREST (Comprehensive Rural Eye Service and Training) program. As described there, only two doctors per hospital (not all of whom examined patients in the current study) could attend the didactic phase of training at the Zhongshan Ophthalmic Center (ZOC). This is due to the limited number of ophthalmologists at a typical rural Chinese county hospital, and the heavy load of clinical duties. For more doctors to have left their facilities for the two-month didactic training would not have been practical. However, all ophthalmologists participating in the CREST network and in the current study received intensive hands-on training by medical retina experts from ZOC at their own facilities, which included the diagnosis and laser treatment of diabetic retinopathy (DR) as well as the u...
Show MoreDear Editor:
We read the article ‘Acute retinal toxicity associated with a mixture of perfluorooctane and perfluorohexyloctane: Failure of another indirect cytotoxicity analysis ’ by Coco et al. with great interest.[1] In this study, the authors reported on ocular toxicity due to perfluorooctane (PFO). They advised that the protocols used to determine the cytotoxicity of intraocular medical devices (which have been approved by the Organisation for the Standardisation of International Standards based on indirect methods) should be revised to ensure safety. We congratulate Coco et al.1 for their report because we believe that it has the potential to be a significant contribut or to the literature on this topic.
As is commonly known, PFO is saturated with PFO liquids, which have highly stable carbon-fluorine bonds that consequently make them inert. PFO has highly specific gravity, low viscosity, optical clarity immiscibility in water and interface tension towards water. It is regularly used in vitreoretinal surgery for complex retinal detachment repair because it displaces subretinal fluid and blood anteriorly, unfolds the retina in giant retinal tear cases and provides counter traction and retinal stabilisation during membrane peeling in eyes with proliferative vitreoretinopathy.[2,3] These properties make PFO useful for intraocular surgery. However, some limitations exist regarding PFO use as a long- term tamponade such as amaurosis, a lack of light perce...
Show MoreWe read with interest the masterly review of the neuro-ophthalmology of Behcet’s disease by Alghamdi et al (1). One small aspect we question. The authors state that in their patients with papilledema: “The diagnosis of CVT was documented in all patients by cerebral angiography and MRI showing partial or total lack of filling of at least one dural sinus and an elevated CSF opening pressure (>25 mm Hg) on lumbar puncture.” We have recently reported 8 BD patients with pseudotumor cerebri who did not have cerebral venous thrombosis (CVT) on MRI or MRV (2). Partial or total lack of filling of one venous sinus does not constitute the pathophysiological basis for intracranial hypertension; either the sagittal sinus must be occluded, or if only one transverse sinus is occluded then the other needs to be stenosed (3). It would be interesting to know what a review of their patient’s images by a neuro-radiologist would reveal.
1: Alghamdi A, Bodaghi B, Comarmond C, Desbois AC, Domont F, Wechsler B, Depaz R, Le Hoang P, Cacoub P, Touitou V, Saadoun D. Neuro-ophthalmological manifestations of Behçet's disease. Br J Ophthalmol. 2018 Apr 26. pii: bjophthalmol-2017-311334. doi: 10.1136/bjophthalmol-2017-311334.
Show More2: Akdal G, Yaman A, Men S, Çelebisoy N, Toydemir HE, Bajin MS, Akman-Demir G. Pseudotumor cerebri syndrome without cerebral venous sinus thrombosis in Behçet's disease. J Neurol Sci. 2017;383:99-100.
3: Halmagyi GM, Ahmed RM, Johnston IH. The Pseudo...
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