We read with interest the study by Silva and colleagues.[1] The authors investigate the prognostic potential of B-scan ultrasonography, visual electrophysiology and perioperative videoendoscopy (VE) for 13 patients undergoing keratoprosthesis (KPro) surgery and identified perioperative intraocular VE as a predictor of functional visual outcome at 1-year follow-up.[1] While we find this study interesting, we would like to caution against the interpretation and over-generalization of the findings reported therein.
Negative predictive value (NPV) was as defined as the number of patients with abnormal VE findings and subsequent unsatisfactory visual acuity over all patients with unfavourable VE. The authors report a NPV of 50% in 10 patients. By contrast, they report a positive predictive value (PPV) of 100% for this test.[1] Although a high PPV, as reported by the authors, is of great importance when deciding which patients are appropriate KPro candidates preoperatively, once the patient is undergoing surgery, we believe identifying patients at highest risk of poor visual outcome using NPV is more clinically relevant. The small sample size of 10 patients with a low prevalence of patients with unsatisfactory post-operative visual acuity, and NPV of 50% are important limitations of this study. From these findings, we are unable to justify VE's clinical benefit to the surgeon and their patient at the time of surgery. This is especially true give...
We read with interest the study by Silva and colleagues.[1] The authors investigate the prognostic potential of B-scan ultrasonography, visual electrophysiology and perioperative videoendoscopy (VE) for 13 patients undergoing keratoprosthesis (KPro) surgery and identified perioperative intraocular VE as a predictor of functional visual outcome at 1-year follow-up.[1] While we find this study interesting, we would like to caution against the interpretation and over-generalization of the findings reported therein.
Negative predictive value (NPV) was as defined as the number of patients with abnormal VE findings and subsequent unsatisfactory visual acuity over all patients with unfavourable VE. The authors report a NPV of 50% in 10 patients. By contrast, they report a positive predictive value (PPV) of 100% for this test.[1] Although a high PPV, as reported by the authors, is of great importance when deciding which patients are appropriate KPro candidates preoperatively, once the patient is undergoing surgery, we believe identifying patients at highest risk of poor visual outcome using NPV is more clinically relevant. The small sample size of 10 patients with a low prevalence of patients with unsatisfactory post-operative visual acuity, and NPV of 50% are important limitations of this study. From these findings, we are unable to justify VE's clinical benefit to the surgeon and their patient at the time of surgery. This is especially true given the invasive nature, cost and associated complications of this ancillary test. In addition to the risk of elevated intraocular pressure and cataract formation as outlined by the authors, the use of perioperative VE increases the risk of iatrogenic retinal tears, vitreous hemorrhage, and wound leaks,[2] not to mention the risk of retrobulbar anaesthesia,[3] all of which are morbid complications in KPro eyes. Moreover, 23% of the patient cohort (n=3) were excluded from analysis due to technical issues relating to perioperative VE. This highlights the additional challenges this ancillary test may present to the surgeon and their team.
Although prognosticating the visual outcomes of KPro and identifying which patients are at highest risk of KPro failure remain important areas of research and discussion, we believe the data presented by the authors are insufficient to position VE as a predictive perioperative ancillary test and urge readers to consider the associated risks to the patient and medical costs to the healthcare system. B-scan ultrasonography is widely accepted as the gold-standard preoperative imaging modality used to assess the posterior segment in eyes with severe and dense anterior segment opacities.[4] After reading this study, we believe that B-scan ultrasonography remains the method of choice for KPro preoperative evaluations.
References:
1. Silva, L. D. et al. B-scan ultrasound, visual electrophysiology and perioperative videoendoscopy for predicting functional results in keratoprosthesis candidates. Br. J. Ophthalmol. (2020).
2. Nagiel, A. et al. VISUAL AND ANATOMIC OUTCOMES OF PEDIATRIC ENDOSCOPIC VITRECTOMY IN 326 CASES. Retina (2020).
3. Hamilton, R. C. A discourse on the complications of retrobulbar and peribulbar blockade. Can. J. Ophthalmol. (2000).
4. Williamson, S. L. & Cortina, M. S. Boston type 1 keratoprosthesis from patient selection through postoperative management: A review for the keratoprosthetic surgeon. Clinical Ophthalmology (2016).
Luzia Diegues Silva MD1, Albert Santos MD1, Flávio Eduardo Hirai MD. Ph.D1, Norma Allemann MD1,2, Adriana Berezovsky Ph.D1, Solange Rios Salomão Ph.D1, Paulo Ricardo Chaves de Oliveira MD1, Gabriel Costa de Andrade MD1, Andre Maia MD1, Luciene Barbosa de Sousa MD1, Lauro Augusto de Oliveira MD. Ph.D.1,*
1 Department of Ophthalmology and Visual Sciences, Federal University of São Paulo, Brazil
2 Department of Ophthalmology and Visual Sciences, University of Illinois at Chicago, USA
Corresponding author: Lauro Augusto de Oliveira
Dear Editor,
We read with interest the comments about our article by Anchouche and associates.
We agree with the authors that B-scan ultrasonography is widely accepted as the gold-standard preoperative imaging modality used to assess the posterior segment in eyes with severe and dense anterior segment opacities and it has been proven to be a useful tool in the preoperative evaluation of Kpro candidates. We also agree that it is safer, cheaper and a less invasive procedure when compared to VE. However, this image modality offers mostly anatomical information and less functional prognosis prediction when compared to direct visualization of the posterior segment achieved with VE.[1]
We are aware and agree with the authors’ concern regarding the invasive nature, the risk of elevated intraocular pressure, and cataract formation as discussed in our work. However, as it is clearly described in our manuscript,...
Luzia Diegues Silva MD1, Albert Santos MD1, Flávio Eduardo Hirai MD. Ph.D1, Norma Allemann MD1,2, Adriana Berezovsky Ph.D1, Solange Rios Salomão Ph.D1, Paulo Ricardo Chaves de Oliveira MD1, Gabriel Costa de Andrade MD1, Andre Maia MD1, Luciene Barbosa de Sousa MD1, Lauro Augusto de Oliveira MD. Ph.D.1,*
1 Department of Ophthalmology and Visual Sciences, Federal University of São Paulo, Brazil
2 Department of Ophthalmology and Visual Sciences, University of Illinois at Chicago, USA
Corresponding author: Lauro Augusto de Oliveira
Dear Editor,
We read with interest the comments about our article by Anchouche and associates.
We agree with the authors that B-scan ultrasonography is widely accepted as the gold-standard preoperative imaging modality used to assess the posterior segment in eyes with severe and dense anterior segment opacities and it has been proven to be a useful tool in the preoperative evaluation of Kpro candidates. We also agree that it is safer, cheaper and a less invasive procedure when compared to VE. However, this image modality offers mostly anatomical information and less functional prognosis prediction when compared to direct visualization of the posterior segment achieved with VE.[1]
We are aware and agree with the authors’ concern regarding the invasive nature, the risk of elevated intraocular pressure, and cataract formation as discussed in our work. However, as it is clearly described in our manuscript, the VE test was performed perioperatively and did not hinder the surgical decision to proceed with KPro surgery. There was no additional anesthesia risk. Cataract formation was not a concern in this scenario because all Kpro candidates in our series would have their lens removed.
The study does have limitations such as the sample size. But this series allowed for an overall better understanding of the endoscopic findings and their usefulness, particularly with the comparative metrics between the preoperative data and postoperative results.
Optimizing the use of keratoprosthesis as an alternative for corneal blindness is challenging in contexts in which the device is not available or affordable. This is a difficult decision faced by surgeons daily, especially in limited-resource settings such as ours. We will continue to investigate strategies for predicting prognosis to allow us to be more precise in the selection of treatment. We agree with the authors that our findings should not be over-generalized. Ideally one cannot deny keratoprosthesis implantation based on unfavourable findings noted on videoendoscopy, but regarding prognostication, we would counsel these patients on potential visual outcomes.
1. Farias CC, Ozturk HE, Albini TA, et al. Use of intraocular video endoscopic examination in the preoperative evaluation of keratoprosthesis surgery to assess visual potential. Am J Ophthalmol 2014;158:80-6.
Thank you for raising the issue of abbreviations entering the virological lexicon which might give rise to confusion and misunderstanding. Over a decade has elapsed since our patient report was published and the source material is not retrievable. However, our recollection is the patient was discussed contemporaneously at the MDT and the viral aetiology, radiology findings and medical management determined and documented, from which the data was sourced for the 2008 report. Plausible as it may seem, it is not possible to test the veracity of the suggestion that the names ‘Jamestown Canyon’ and ‘John Cunningham’ might have been transposed during that MDT many years after the event, paper records are not kept indefinitely in NHS practice and ethics in medical publishing demands that patient identifiers are not described or retained in order to preserve anonymity. Perhaps the latter should have been considered over half a century ago when JC virus was first identified in the brain of the unfortunate patient after whom the eponymous pathogen was christened
(Padgett BL, Walker DL; et al. (1971). "Cultivation of papova-like virus from human brain with progressive multifocal leucoencephalopathy". Lancet. 1 (7712):
1257–60. doi:10.1016/S0140-6736(71)91777-6)
In their 2008 case report, Muqit, et al. describe a case of “presumptive Jamestown Canyon viral retinitis.”1
Jamestown Canyon virus is a mosquito-borne, single-stranded, ribonucleic acid (RNA) orthobunyavirus that is endemic throughout much of North America.2,3 Infection with Jamestown Canyon virus may be asymptomatic or may result in a general febrile illness, meningitis, and/or meningoencephalitis.2,3 Beyond the above case report by Muqit, et al.,1 and another review article referencing this case report,4 Jamestown Canyon virus has not been reported to cause retinitis or other ocular manifestations.
Upon close review of the case report by Muqit, et al.,1 we believe the authors are likely describing a case of John Cunningham (JC) virus (a ubiquitous, double-stranded, deoxyribonucleic acid [DNA] human polyomavirus known to cause progressive multifocal leukoencephalopathy [PML] among the immunocompromised)5-7 rather than Jamestown Canyon virus.
First, the case patient with viral retinitis had underlying human immunodeficiency virus (HIV) infection and a low CD4 lymphocyte count (240 cells/mm3), making him immunocompromised and susceptible to reactivation of the John Cunningham (JC) virus. Second, the case patient had magnetic resonance imaging (MRI) brain findings (i.e., asymmetric, predominantly posterior, confluent, subcortical white matter hyperintensities involving U-fibers) that are classic for John Cunningham (JC) virus-related PML.6,7 In fact,...
In their 2008 case report, Muqit, et al. describe a case of “presumptive Jamestown Canyon viral retinitis.”1
Jamestown Canyon virus is a mosquito-borne, single-stranded, ribonucleic acid (RNA) orthobunyavirus that is endemic throughout much of North America.2,3 Infection with Jamestown Canyon virus may be asymptomatic or may result in a general febrile illness, meningitis, and/or meningoencephalitis.2,3 Beyond the above case report by Muqit, et al.,1 and another review article referencing this case report,4 Jamestown Canyon virus has not been reported to cause retinitis or other ocular manifestations.
Upon close review of the case report by Muqit, et al.,1 we believe the authors are likely describing a case of John Cunningham (JC) virus (a ubiquitous, double-stranded, deoxyribonucleic acid [DNA] human polyomavirus known to cause progressive multifocal leukoencephalopathy [PML] among the immunocompromised)5-7 rather than Jamestown Canyon virus.
First, the case patient with viral retinitis had underlying human immunodeficiency virus (HIV) infection and a low CD4 lymphocyte count (240 cells/mm3), making him immunocompromised and susceptible to reactivation of the John Cunningham (JC) virus. Second, the case patient had magnetic resonance imaging (MRI) brain findings (i.e., asymmetric, predominantly posterior, confluent, subcortical white matter hyperintensities involving U-fibers) that are classic for John Cunningham (JC) virus-related PML.6,7 In fact, the authors claimed that the MRI brain findings were “confirmatory of the underlying diagnosis.”1 No MRI brain findings are classic or confirmatory for Jamestown Canyon virus infection. Third, the case patient’s cerebrospinal fluid was reportedly positive for viral DNA by polymerase chain reaction. This could only be possible for a DNA virus (i.e., John Cunningham (JC) virus) and not an RNA virus (i.e., Jamestown Canyon virus). Fourth, recovery of John Cunningham (JC) viral nucleic acid from ocular tissues of HIV-infected patients has been previously reported, so there is already precedent for this virus to infect the eye.8 Finally, the case patient had no known travel to or any mosquito exposure in North America, where Jamestown Canyon virus is endemic.2,3
Given John Cunningham (JC) and Jamestown Canyon viruses have different virology, epidemiology, and clinical manifestations, we believe the viruses were mistaken for one another because they share the same first letters of their words (i.e., J and C) and their abbreviations were likely confused. If our suspicion is correct, this case report highlights the possible dangers of abbreviations in medicine and the need to clearly define potentially confusing abbreviations in medical literature.
References
1. Muqit MM, Devonport H, Smith RA, Dhillon B. Presumptive Jamestown Canyon viral retinitis. Br J Ophthalmol. 2008 Dec;92(12):1599-600, 1695-6. doi: 10.1136/bjo.2007.132902. PMID: 19029162.
2. Coleman KJ, Chauhan L, Piquet AL, Tyler KL, Pastula DM. An Overview of Jamestown Canyon Virus Disease. Neurohospitalist. 2021 Jul;11(3):277-278. doi: 10.1177/19418744211005948. Epub 2021 Mar 29. PMID: 34163560; PMCID: PMC8182404.
3. Pastula DM, Hoang Johnson DK, White JL, Dupuis AP 2nd, Fischer M, Staples JE. Jamestown Canyon Virus Disease in the United States-2000-2013. Am J Trop Med Hyg. 2015 Aug;93(2):384-9. doi: 10.4269/ajtmh.15-0196. Epub 2015 Jun 1. PMID: 26033022; PMCID: PMC4530766.
4. Karesh JW, Mazzoli RA, Heintz SK. Ocular Manifestations of Mosquito-Transmitted Diseases. Mil Med. 2018 Mar 1;183(suppl_1):450-458. doi: 10.1093/milmed/usx183. PMID: 29635625.
5. Padgett BL, Walker DL, ZuRhein GM, Eckroade RJ, Dessel BH. Cultivation of papova-like virus from human brain with progressive multifocal leucoencephalopathy. Lancet. 1971 Jun 19;1(7712):1257-60. doi: 10.1016/s0140-6736(71)91777-6. PMID: 4104715.
6. Grebenciucova E, Berger JR. Progressive Multifocal Leukoencephalopathy. Neurol Clin. 2018 Nov;36(4):739-750. doi: 10.1016/j.ncl.2018.06.002. PMID: 30366552.
7. Pinto M, Dobson S. BK and JC virus: a review. J Infect. 2014 Jan;68 Suppl 1:S2-8. doi: 10.1016/j.jinf.2013.09.009. Epub 2013 Oct 8. PMID: 24119828.
8. Eberwein P, Hansen LL, Agostini HT. Genotypes of JC virus, DNA of cytomegalovirus, and proviral DNA of human immunodeficiency virus in eyes of acquired immunodeficiency syndrome patients. J Neurovirol. 2005 Feb;11(1):58-65. doi: 10.1080/13550280590900391. PMID: 15804960.
We read with great interest the article by Forte et al1, "Swept source optical Coherence tomography Angiography in patients treated with hydroxychloroquine: co-relation of the functional and morphological test." Hydroxychloroquine (HCQ) is a widely used drug for the management of systemic lupus erythematosus and rheumatoid arthritis. Non-invasive tests like optical coherence tomography, optical coherence tomography-angiography, 10-2 visual fields and multifocal ERG (mf-ERG) help in the early detection of the toxicity.2 We would like to highlight here importance of adaptive optics, and various studies done for the early detection of HCQ toxicity. In the study by Forte et al, mf-ERG did not co-relate with the flow changes on OCT-A, however in another observation by Penrose et al (n=6) a depression of signals on multifocal ERG was found in the perifoveal region even when the patients had normal visual acuity and a normal fundus.3Costa et al found significant differences between the micro-perimetry in the patients taking hydroxychloroquine and controls.4 It will be interesting to know the authors take on this. Besides these, adaptive optics is emerging as an important tool to detect the early photo-receptor changes in patients with HCQ toxicity. Adaptive optics help in the direct visualization of the cone mosaic. Stepien et al in their observation on 4 patients observed that adaptive optics showed a loss of cone mosaic in the perifoveal region that corresponded with...
We read with great interest the article by Forte et al1, "Swept source optical Coherence tomography Angiography in patients treated with hydroxychloroquine: co-relation of the functional and morphological test." Hydroxychloroquine (HCQ) is a widely used drug for the management of systemic lupus erythematosus and rheumatoid arthritis. Non-invasive tests like optical coherence tomography, optical coherence tomography-angiography, 10-2 visual fields and multifocal ERG (mf-ERG) help in the early detection of the toxicity.2 We would like to highlight here importance of adaptive optics, and various studies done for the early detection of HCQ toxicity. In the study by Forte et al, mf-ERG did not co-relate with the flow changes on OCT-A, however in another observation by Penrose et al (n=6) a depression of signals on multifocal ERG was found in the perifoveal region even when the patients had normal visual acuity and a normal fundus.3Costa et al found significant differences between the micro-perimetry in the patients taking hydroxychloroquine and controls.4 It will be interesting to know the authors take on this. Besides these, adaptive optics is emerging as an important tool to detect the early photo-receptor changes in patients with HCQ toxicity. Adaptive optics help in the direct visualization of the cone mosaic. Stepien et al in their observation on 4 patients observed that adaptive optics showed a loss of cone mosaic in the perifoveal region that corresponded with the OCT findings. OCT findings in their study showed a loss of IS -OS junction with preservation of retinal pigment epithelium and external limiting membrane showing a "sinking hole defect". SD-OCT and adaptive optics also showed defects in the area which were unaffected on 10-2 perimetry, suggesting pre-clinical loss. 5 Similarly, Debellemanière G et al, in their study on eyes found that there was increased cone spacing and moderate cone loss with an increasing cumulative dose of HCQ.6 It will be interesting to know the author's point of view about this, Thus to conclude, the non-invasive investigations may aid in the early detection of HCQ toxicity.
References
1. Forte R, Haulani H, Dyrda A, et al
Swept source optical coherence tomography angiography in patients treated with hydroxychloroquine: correlation with morphological and functional tests. British Journal of Ophthalmology 2021;105:1297-1301.
2. Marmor MF, Kellner U, Lai TY, Melles RB, Mieler WF; American Academy of Ophthalmology. Recommendations on Screening for Chloroquine and Hydroxychloroquine Retinopathy (2016 Revision). Ophthalmology. 2016 Jun;123(6):1386-94
3. Penrose PJ, Tzekov RT, Sutter EE, Fu AD, Allen AW Jr, Fung WE, Oxford KW. Multifocal electroretinography evaluation for early detection of retinal dysfunction in patients taking hydroxychloroquine. Retina. 2003 Aug;23(4):503-12.
4. Martínez-Costa L, Victoria Ibañez M, Murcia-Bello C, Epifanio I, Verdejo-Gimeno C, Beltrán-Catalán E, Marco-Ventura P. Use of microperimetry to evaluate hydroxychloroquine and chloroquine retinal toxicity. Can J Ophthalmol. 2013 Oct;48(5):400-5. doi: 10.1016/j.jcjo.2013.03.018. PMID: 24093187.
5. Stepien KE, Han DP, Schell J, Godara P, Rha J, Carroll J. Spectral-domain optical coherence tomography and adaptive optics may detect hydroxychloroquine retinal toxicity before symptomatic vision loss. Trans Am Ophthalmol Soc. 2009 Dec;107:28-33. PMID: 20126479; PMCID: PMC2814561.
6. Debellemanière G, Flores M, Tumahai P, Meillat M, Bidaut Garnier M, Delbosc B, Saleh M. Assessment of parafoveal cone density in patients taking hydroxychloroquine in the absence of clinically documented retinal toxicity. Acta Ophthalmol. 2015 Nov;93(7):e534-40
Eyes with Fuchs endothelial corneal dystrophy (FECD) are known to have reduced contrast vision from increased glare even if high-contrast acuity is not affected.1 In a retrospective study, Augustin and colleagues suggested that corneal guttae without edema contribute to decreased contrast sensitivity, and that such eyes would benefit from Descemet membrane endothelial keratoplasty (DMEK).2 The topic is important because it is unknown whether guttae in the absence of any corneal edema affect vision and therefore whether such eyes truly benefit from DMEK. The authors enrolled eyes with >5 mm of confluent guttae and without edema (modified Krachmer grade 5); however, they did not state their definition of “edema”. In FECD, when corneal edema is not clinically detectable by slit-lamp examination, it can be detected by Scheimpflug tomography.3 A recent study found evidence of subclinical corneal edema in 88% of eyes with FECD grade 5 and almost 40% of eyes with lesser grades of FECD.4 It is therefore highly likely that many of the FECD eyes examined by Augustin and colleagues did in fact have subclinical corneal edema, so can the authors examine the Scheimpflug tomograms of these eyes and report the contrast sensitivity results based on the presence or absence of subclinical edema? This is important because reduced contrast sensitivity might be caused by subclinical edema and not simply by “guttae without edema”, and cornea surgeons should not conclude that it is appr...
Eyes with Fuchs endothelial corneal dystrophy (FECD) are known to have reduced contrast vision from increased glare even if high-contrast acuity is not affected.1 In a retrospective study, Augustin and colleagues suggested that corneal guttae without edema contribute to decreased contrast sensitivity, and that such eyes would benefit from Descemet membrane endothelial keratoplasty (DMEK).2 The topic is important because it is unknown whether guttae in the absence of any corneal edema affect vision and therefore whether such eyes truly benefit from DMEK. The authors enrolled eyes with >5 mm of confluent guttae and without edema (modified Krachmer grade 5); however, they did not state their definition of “edema”. In FECD, when corneal edema is not clinically detectable by slit-lamp examination, it can be detected by Scheimpflug tomography.3 A recent study found evidence of subclinical corneal edema in 88% of eyes with FECD grade 5 and almost 40% of eyes with lesser grades of FECD.4 It is therefore highly likely that many of the FECD eyes examined by Augustin and colleagues did in fact have subclinical corneal edema, so can the authors examine the Scheimpflug tomograms of these eyes and report the contrast sensitivity results based on the presence or absence of subclinical edema? This is important because reduced contrast sensitivity might be caused by subclinical edema and not simply by “guttae without edema”, and cornea surgeons should not conclude that it is appropriate to offer DMEK for any eye with guttae. Surgeons and clinicians should recognize that Scheimpflug tomography patterns, which are easily acquired and repeatable,5 are more helpful than guttae assessment for guiding clinical decision-making in FECD.4
References
1. van der Meulen IJ, Patel SV, Lapid-Gortzak R, Nieuwendaal CP, McLaren JW, van den Berg TJ. Quality of vision in patients with Fuchs endothelial dystrophy and after Descemet stripping endothelial keratoplasty. Arch Ophthalmol 2011;129:1537-1542.
2. Augustin VA, Weller JM, Kruse FE, Tourtas T. Influence of corneal guttae and nuclear cataract on contrast sensitivity. Br J Ophthalmol 2020.
3. Sun SY, Wacker K, Baratz KH, Patel SV. Determining Subclinical Edema in Fuchs Endothelial Corneal Dystrophy. Revised Classification using Scheimpflug Tomography for Preoperative Assessment. Ophthalmology 2019;126:195-204.
4. Patel SV, Hodge DO, Treichel EJ, Spiegel MR, Baratz KH. Predicting the Prognosis of Fuchs Endothelial Corneal Dystrophy by using Scheimpflug Tomography. Ophthalmology 2020;127:315-323.
5. Patel SV, Hodge DO, Treichel EJ, Spiegel MR, Baratz KH. Repeatability of Scheimpflug Tomography for Assessing Fuchs Endothelial Corneal Dystrophy. Am J Ophthalmol 2020;215:91-103.
I have read with interest the paper by Fabian ID et al. “Travel burden and clinical presentation of retinoblastoma”[1]. I acknowledge the efforts conducted by the authors to build a retinoblastoma knowledge based on a large consortium for the first time. Many publications have agreed that the underprivileged socioeconomic situations affect the presentation and outcome of retinoblastoma patients[2, 3]. The measures used in most publications, including the one by Fabian ID et al., are national-level measures. Such socioeconomic measures on the country level affect the roads and travel quality beside family and healthcare giver education and training. A better measure in such cases is an individual level for each family. In developing countries, a vast gap presents between inhabitants letting a country-level measure, not representative. As mentioned in a glimpse in the paper, patients can spend a long time orbiting multiple physicians before targeting the oncology center. On the other side, people with higher economic status can get better healthcare and travel longer distances comfortably and present to centers with early stages.
Furthermore, Figure 2 shows interestingly similar small catchment areas in Africa; this raised a question on the data that were used for drawing the figure; is it individualized for each center? Additionally, if the analysis depended on the permanent address.
Egypt’s major pediatric oncology center, which was included in the study, cover...
I have read with interest the paper by Fabian ID et al. “Travel burden and clinical presentation of retinoblastoma”[1]. I acknowledge the efforts conducted by the authors to build a retinoblastoma knowledge based on a large consortium for the first time. Many publications have agreed that the underprivileged socioeconomic situations affect the presentation and outcome of retinoblastoma patients[2, 3]. The measures used in most publications, including the one by Fabian ID et al., are national-level measures. Such socioeconomic measures on the country level affect the roads and travel quality beside family and healthcare giver education and training. A better measure in such cases is an individual level for each family. In developing countries, a vast gap presents between inhabitants letting a country-level measure, not representative. As mentioned in a glimpse in the paper, patients can spend a long time orbiting multiple physicians before targeting the oncology center. On the other side, people with higher economic status can get better healthcare and travel longer distances comfortably and present to centers with early stages.
Furthermore, Figure 2 shows interestingly similar small catchment areas in Africa; this raised a question on the data that were used for drawing the figure; is it individualized for each center? Additionally, if the analysis depended on the permanent address.
Egypt’s major pediatric oncology center, which was included in the study, covers the whole country region, and about 10 % of its patients are traveling from other countries to get the treatment in the hospital[4], however, this reality was not reflected on the figure. Beside, In the journey of treatment, patients acquire a temporary or interim residence near the hospital due to the hard return to the permanent residence. In Europe, borders are open, cities are connected with high-speed trains, with 420 kilometers can be traveled in 2-3 hours, while in Africa, 185 kilometers can require a day with a significant part of the distance on foot and months for getting a visa if crossing borders is required. Such factors can bias the results.
So, further clarification is required for this figure to answer these question.
References
1. Fabian ID, Stacey AW, Foster A, et al (2020) Travel burden and clinical presentation of retinoblastoma: analysis of 1024 patients from 43 African countries and 518 patients from 40 European countries. Br J Ophthalmol bjophthalmol-2020-316613. https://doi.org/10.1136/bjophthalmol-2020-316613
2. Canturk S, Qaddoumi I, Khetan V, et al (2010) Survival of retinoblastoma in less-developed countries impact of socioeconomic and health-related indicators. Br J Ophthalmol 94:1432–6. https://doi.org/10.1136/bjo.2009.168062
3. Aziz H a, Lasenna CE, Vigoda M, et al (2012) Retinoblastoma treatment burden and economic cost: impact of age at diagnosis and selection of primary therapy. Clin Ophthalmol 6:1601–6. https://doi.org/10.2147/OPTH.S33094
4. El Zomor H, Nour R, Alieldin A, et al (2015) Clinical presentation of intraocular retinoblastoma; 5-year hospital-based registry in Egypt. J Egypt Natl Canc Inst 27:195–203. https://doi.org/10.1016/j.jnci.2015.09.002
We thank Alfaar for their comment on our paper titled: “Travel burden and clinical presentation of retinoblastoma: analysis of 1024 patients from 43 African countries and 518 patients from 40 European contries”.[1]
In our paper, we compared the stage of presentation of newly diagnosed retinoblastoma patients from African and European countries and investigated possible associations to the travel distance from home to treatment centre. Our findings suggest that treatment centres in African countries serve patients that reside, on average, in closer proximity to the treatment center than in Europe (186 km average distance travelled in Africa compared to an average distance travelled of 422 km in Europe). In reply to Alfaar’s comment, to produce these numbers, we calculated the average travel distance in a country and then calculated the mean of averages in a continent and compared Africa to Europe.
The red circles in Figure 2 in our original paper,[1] representing the mean travel distance in a continent, were superimposed on each centre on a scaled map. All red circles in Africa are similar in size (i.e. radius of 186 km) and all in Europe are similar (i.e. radius of 422 km).
We agree with Alfaar that our analysis has several limitations, some of which are mentioned in our paper and some, rightfully, in his eLetter. In a study, in which patients from over 80 countries in two continents are included, one cannot take into account all considerations, especiall...
We thank Alfaar for their comment on our paper titled: “Travel burden and clinical presentation of retinoblastoma: analysis of 1024 patients from 43 African countries and 518 patients from 40 European contries”.[1]
In our paper, we compared the stage of presentation of newly diagnosed retinoblastoma patients from African and European countries and investigated possible associations to the travel distance from home to treatment centre. Our findings suggest that treatment centres in African countries serve patients that reside, on average, in closer proximity to the treatment center than in Europe (186 km average distance travelled in Africa compared to an average distance travelled of 422 km in Europe). In reply to Alfaar’s comment, to produce these numbers, we calculated the average travel distance in a country and then calculated the mean of averages in a continent and compared Africa to Europe.
The red circles in Figure 2 in our original paper,[1] representing the mean travel distance in a continent, were superimposed on each centre on a scaled map. All red circles in Africa are similar in size (i.e. radius of 186 km) and all in Europe are similar (i.e. radius of 422 km).
We agree with Alfaar that our analysis has several limitations, some of which are mentioned in our paper and some, rightfully, in his eLetter. In a study, in which patients from over 80 countries in two continents are included, one cannot take into account all considerations, especially not at patient (e.g. socioeconomic status) or centre level, as Alfaar suggests.
Alfaar, in the eLetter, indicates, “Egypt’s major paediatric oncology centre, which was included in the study, covers the whole country region”. According to our study,[1] In 2017, more than 100 new retinoblastoma patients presented to this centre. The calculated average travel distance from home to the centre was 178 km (±117), similar to the average in the continent for all African countries. Noteworthy, the western as well as the southern borders of Egypt are each more than 1,000 km long (surface area of more than 1 million km2). The raw data at country level is available at https://zenodo.org/record/3727687#.X4_LgdAzbIU.[2]
Concerning patients traveling abroad to seek medical care, these cases were excluded from the current analysis in both Europe and Africa, but were included in a separate report, titled: “International travel to obtain medical treatment for primary retinoblastoma: a global cohort study”.[3]
The access to care by children with retinoblastoma in Africa, as demonstrated by the estimated proportion of new retinoblastoma cases seen by treatment centres in Europe versus Africa of over 100% to less than 50%,[1] is compromised due to a variety of factors. A multicentre collaboration,[4,5] including most retinoblastoma treatment centres in Europe and Africa, despite its weaknesses, is of importance to highlight the huge gap in access to care in different regions of the world.
References
1 Fabian ID, Stacey AW, Foster A, et al. Travel burden and clinical presentation of retinoblastoma: Analysis of 1024 patients from 43 African countries and 518 patients from 40 European countries. Br J Ophthalmol Published Online First: 2020. doi:10.1136/bjophthalmol-2020-316613
2. Fabian ID, Stacey A, Foster A, Kivelä TT, Munier FL, Cassoux N, & Bowman RJC. (2020). Global Retinoblastoma Presentation 2017 data, on behalf of the Global Retinoblastoma Study Group [Data set]. Zenodo. http://doi.org/10.5281/zenodo.3727687
3. Bowman R, Foster A, Stacey A, et al. International travel to obtain medical treatment for primary retinoblastoma: a global cohort study. Int J cancer 2020; Online ahead of print. doi:10.1002/ijc.33350
4 Global Retinoblastoma Study Group. Global Retinoblastoma Presentation and Analysis by National Income Level. JAMA Oncol 2020;6:1–12. doi:10.1001/jamaoncol.2019.6716
5 Fabian ID, Stacey AW, Bowman R, et al. Retinoblastoma management during the COVID-19 pandemic: A report by the Global Retinoblastoma Study Group including 194 centers from 94 countries. Pediatr. Blood Cancer. 2020. doi:10.1002/pbc.28584
Reply to the comment on: “Influence of corneal guttae and nuclear cataract on contrast sensitivity”
We thank Sanjay V Patel for the comments. Patients with Fuchs endothelial corneal dystrophy (FECD) are known to have reduced contrast sensitivity due to corneal edema and guttae. Before the introduction of endothelial keratoplasty, penetrating keratoplasty had been performed mainly in patients with advanced FECD and clinically significant corneal edema. However, as endothelial keratoplasty procedures such as Descemet membrane endothelial keratoplasty can bring excellent visual acuity outcomes, surgery can be performed earlier and even in cases without any clinical corneal edema. Therefore, it has become even more important to detect the causes of visual impairment in patients with FECD. In our retrospective study, we enrolled FECD patients with >5 mm of confluent guttae and no corneal edema (modified Krachmer grade 5). When analyzed by Scheimpflug tomography, our FECD patients showed no difference in the central corneal thickness and corneal volume when compared to the control group of cataract patients without any corneal pathologies.1 Recently, Sun et al. presented a new method to detect subclinical corneal edema in patients with FECD.2,3 The authors analyzed three Scheimpflug tomography pachymetry map and posterior elevation map patterns to detect subclinical edema in FECD patients: loss of regular isopachs, displacement of the thinnest point of the cornea, and...
Reply to the comment on: “Influence of corneal guttae and nuclear cataract on contrast sensitivity”
We thank Sanjay V Patel for the comments. Patients with Fuchs endothelial corneal dystrophy (FECD) are known to have reduced contrast sensitivity due to corneal edema and guttae. Before the introduction of endothelial keratoplasty, penetrating keratoplasty had been performed mainly in patients with advanced FECD and clinically significant corneal edema. However, as endothelial keratoplasty procedures such as Descemet membrane endothelial keratoplasty can bring excellent visual acuity outcomes, surgery can be performed earlier and even in cases without any clinical corneal edema. Therefore, it has become even more important to detect the causes of visual impairment in patients with FECD. In our retrospective study, we enrolled FECD patients with >5 mm of confluent guttae and no corneal edema (modified Krachmer grade 5). When analyzed by Scheimpflug tomography, our FECD patients showed no difference in the central corneal thickness and corneal volume when compared to the control group of cataract patients without any corneal pathologies.1 Recently, Sun et al. presented a new method to detect subclinical corneal edema in patients with FECD.2,3 The authors analyzed three Scheimpflug tomography pachymetry map and posterior elevation map patterns to detect subclinical edema in FECD patients: loss of regular isopachs, displacement of the thinnest point of the cornea, and presence of posterior surface depression may help identify subclinical corneal edema more accurately in patients with FECD. In our study, the loss of regular isopachs (12/25 [48%] vs. 4/25 [16%]), the displacement of the thinnest point of the cornea (11/25 [44%] vs. 1/25 [4%]), and the posterior surface depression (13/25 [52%] vs. 8/25 [32%]) could be found more frequently in FECD patients, than in the control group without corneal pathology. Eleven of the 25 FECD patients (44%) met at least two of the three criteria, implying the presence of a subclinical corneal edema. However, the preoperative MARS letter contrast sensitivity of these 11 patients (contrast sensitivity: 0.98 ± 0.13 logCS) did not show any statistically significant difference compared to that of the other 14 FECD patients (contrast sensitivity: 1.02 ± 0.09 logCS; p=0.47) in whom the aforementioned criteria were not met. Interestingly, two of the three criteria were also met in 4 cases (16%) of the control group. Indeed, future studies should also include the analysis of these patterns when assessing the contrast sensitivity in FECD patients.
1Augustin VA, Weller JM, Kruse FE, Tourtas T. Influence of corneal guttae and nuclear cataract on contrast sensitivity. Br J Ophthalmol 2020.
2Sun SY, Wacker K, Baratz KH, Patel SV. Determining Subclinical Edema in Fuchs Endothelial Corneal Dystrophy. Revised Classification using Scheimpflug Tomography for Preoperative Assessment. Ophthalmology 2019;126:195-204.
3Patel SV, Hodge DO, Treichel EJ, Spiegel MR, Baratz KH. Predicting the Prognosis of Fuchs Endothelial Corneal Dystrophy by using Scheimpflug Tomography. Ophthalmology 2020;127:315-323.
McCann et al. reported factors of the associations with intraocular pressure (IOP) and circumpapillary retinal nerve fibre layer (cRNFL) thickness (1). Increased IOP and reduced cRNFL were associated with increased age, myopic refractive error, male sex and hypertension. In addition, Alzheimer's disease was associated with thinner average global cRNFL, and Parkinson's disease (PD) and current smoking status were associated with thicker average global cRNFL, and I present recent information regarding their study in patients with PD.
Murueta-Goyena et al. reported the association between the changes of retinal thickness and their predictive value as biomarkers of disease progression in idiopathic PD (2). The authors used macular ganglion-inner plexiform layer complex (mGCIPL) and peripapillary retinal nerve fiber layer (pRNFL) thickness reduction rates, and the Montreal Cognitive Assessment (MoCA) questionnaire was also applied. The adjusted relative risks of lower parafoveal mGCIPL and pRNFL thickness at baseline for an increased risk of cognitive decline at 3 years significantly increased. This means that reduced retinal thickness is a risk factor of cognitive impairment in patients with PD. McCann et al. did not evaluate cRNFL in PD patients with cognitive impairment, and I suppose that progression of cognitive impairment in patients with PD might accelerate reduction of average global cRNFL.
Second, Sung et al. also investigated the association be...
McCann et al. reported factors of the associations with intraocular pressure (IOP) and circumpapillary retinal nerve fibre layer (cRNFL) thickness (1). Increased IOP and reduced cRNFL were associated with increased age, myopic refractive error, male sex and hypertension. In addition, Alzheimer's disease was associated with thinner average global cRNFL, and Parkinson's disease (PD) and current smoking status were associated with thicker average global cRNFL, and I present recent information regarding their study in patients with PD.
Murueta-Goyena et al. reported the association between the changes of retinal thickness and their predictive value as biomarkers of disease progression in idiopathic PD (2). The authors used macular ganglion-inner plexiform layer complex (mGCIPL) and peripapillary retinal nerve fiber layer (pRNFL) thickness reduction rates, and the Montreal Cognitive Assessment (MoCA) questionnaire was also applied. The adjusted relative risks of lower parafoveal mGCIPL and pRNFL thickness at baseline for an increased risk of cognitive decline at 3 years significantly increased. This means that reduced retinal thickness is a risk factor of cognitive impairment in patients with PD. McCann et al. did not evaluate cRNFL in PD patients with cognitive impairment, and I suppose that progression of cognitive impairment in patients with PD might accelerate reduction of average global cRNFL.
Second, Sung et al. also investigated the association between retinal thinning and cognitive impairment in patients with PD (3). There were significant reductions in the thickness of average, temporal, and inferior pRNFL and overall mGCIPL in patients with PD, and the MoCA score was significantly associated with mGCIPL thinning. As the thinning of the mGCIPL was also significantly associated with the volumetric parameters of some brain structures, the relationship between retinal thickness and brain structures in patients with PD should be comprehensively evaluated with special reference to the level of cognitive impairment.
Finally, Matlach et al. reported that thinning of some retinal layers of the ipsilateral eye was observed in the most-affected body side of PD patients (4). In addition, thickness of pRNFL and mGCIPL did not correlate to the severity of PD. As Murueta-Goyena et al. reported that there was no significant association between retinal thickness and motor deterioration (2), the discrepancy in the relationship of cognitive decline and motor deterioration with retinal thickness might be related to the lack of relationship between retinal thickness and the severity of PD.
References
1. McCann P, Hogg R, Wright DM, et al. Intraocular pressure and circumpapillary retinal nerve fibre layer thickness in the Northern Ireland Cohort for the Longitudinal Study of Ageing (NICOLA): distributions and associations. Br J Ophthalmol. 2020 Jul 30 doi: 10.1136/bjophthalmol-2020-316499 [Epub ahead of print]
2. Murueta-Goyena A, Del Pino R, Galdós M, et al. Retinal thickness predicts the risk of cognitive decline in Parkinson's disease. Ann Neurol 2020 Oct 24 doi: 10.1002/ana.25944 [Epub ahead of print]
3. Sung MS, Choi SM, Kim J, et al. Inner retinal thinning as a biomarker for cognitive impairment in de novo Parkinson's disease. Sci Rep 2019;9:11832.
4. Matlach J, Wagner M, Malzahn U, et al. Retinal changes in Parkinson's disease and glaucoma. Parkinsonism Relat Disord 2018 Nov;56:41-46.
Dear Editor,
We read with interest the study by Silva and colleagues.[1] The authors investigate the prognostic potential of B-scan ultrasonography, visual electrophysiology and perioperative videoendoscopy (VE) for 13 patients undergoing keratoprosthesis (KPro) surgery and identified perioperative intraocular VE as a predictor of functional visual outcome at 1-year follow-up.[1] While we find this study interesting, we would like to caution against the interpretation and over-generalization of the findings reported therein.
Negative predictive value (NPV) was as defined as the number of patients with abnormal VE findings and subsequent unsatisfactory visual acuity over all patients with unfavourable VE. The authors report a NPV of 50% in 10 patients. By contrast, they report a positive predictive value (PPV) of 100% for this test.[1] Although a high PPV, as reported by the authors, is of great importance when deciding which patients are appropriate KPro candidates preoperatively, once the patient is undergoing surgery, we believe identifying patients at highest risk of poor visual outcome using NPV is more clinically relevant. The small sample size of 10 patients with a low prevalence of patients with unsatisfactory post-operative visual acuity, and NPV of 50% are important limitations of this study. From these findings, we are unable to justify VE's clinical benefit to the surgeon and their patient at the time of surgery. This is especially true give...
Show MoreLuzia Diegues Silva MD1, Albert Santos MD1, Flávio Eduardo Hirai MD. Ph.D1, Norma Allemann MD1,2, Adriana Berezovsky Ph.D1, Solange Rios Salomão Ph.D1, Paulo Ricardo Chaves de Oliveira MD1, Gabriel Costa de Andrade MD1, Andre Maia MD1, Luciene Barbosa de Sousa MD1, Lauro Augusto de Oliveira MD. Ph.D.1,*
1 Department of Ophthalmology and Visual Sciences, Federal University of São Paulo, Brazil
2 Department of Ophthalmology and Visual Sciences, University of Illinois at Chicago, USA
Corresponding author: Lauro Augusto de Oliveira
Dear Editor,
We read with interest the comments about our article by Anchouche and associates.
We agree with the authors that B-scan ultrasonography is widely accepted as the gold-standard preoperative imaging modality used to assess the posterior segment in eyes with severe and dense anterior segment opacities and it has been proven to be a useful tool in the preoperative evaluation of Kpro candidates. We also agree that it is safer, cheaper and a less invasive procedure when compared to VE. However, this image modality offers mostly anatomical information and less functional prognosis prediction when compared to direct visualization of the posterior segment achieved with VE.[1]
We are aware and agree with the authors’ concern regarding the invasive nature, the risk of elevated intraocular pressure, and cataract formation as discussed in our work. However, as it is clearly described in our manuscript,...
Show MoreThank you for raising the issue of abbreviations entering the virological lexicon which might give rise to confusion and misunderstanding. Over a decade has elapsed since our patient report was published and the source material is not retrievable. However, our recollection is the patient was discussed contemporaneously at the MDT and the viral aetiology, radiology findings and medical management determined and documented, from which the data was sourced for the 2008 report. Plausible as it may seem, it is not possible to test the veracity of the suggestion that the names ‘Jamestown Canyon’ and ‘John Cunningham’ might have been transposed during that MDT many years after the event, paper records are not kept indefinitely in NHS practice and ethics in medical publishing demands that patient identifiers are not described or retained in order to preserve anonymity. Perhaps the latter should have been considered over half a century ago when JC virus was first identified in the brain of the unfortunate patient after whom the eponymous pathogen was christened
(Padgett BL, Walker DL; et al. (1971). "Cultivation of papova-like virus from human brain with progressive multifocal leucoencephalopathy". Lancet. 1 (7712):
1257–60. doi:10.1016/S0140-6736(71)91777-6)
In their 2008 case report, Muqit, et al. describe a case of “presumptive Jamestown Canyon viral retinitis.”1
Jamestown Canyon virus is a mosquito-borne, single-stranded, ribonucleic acid (RNA) orthobunyavirus that is endemic throughout much of North America.2,3 Infection with Jamestown Canyon virus may be asymptomatic or may result in a general febrile illness, meningitis, and/or meningoencephalitis.2,3 Beyond the above case report by Muqit, et al.,1 and another review article referencing this case report,4 Jamestown Canyon virus has not been reported to cause retinitis or other ocular manifestations.
Upon close review of the case report by Muqit, et al.,1 we believe the authors are likely describing a case of John Cunningham (JC) virus (a ubiquitous, double-stranded, deoxyribonucleic acid [DNA] human polyomavirus known to cause progressive multifocal leukoencephalopathy [PML] among the immunocompromised)5-7 rather than Jamestown Canyon virus.
First, the case patient with viral retinitis had underlying human immunodeficiency virus (HIV) infection and a low CD4 lymphocyte count (240 cells/mm3), making him immunocompromised and susceptible to reactivation of the John Cunningham (JC) virus. Second, the case patient had magnetic resonance imaging (MRI) brain findings (i.e., asymmetric, predominantly posterior, confluent, subcortical white matter hyperintensities involving U-fibers) that are classic for John Cunningham (JC) virus-related PML.6,7 In fact,...
Show MoreWe read with great interest the article by Forte et al1, "Swept source optical Coherence tomography Angiography in patients treated with hydroxychloroquine: co-relation of the functional and morphological test." Hydroxychloroquine (HCQ) is a widely used drug for the management of systemic lupus erythematosus and rheumatoid arthritis. Non-invasive tests like optical coherence tomography, optical coherence tomography-angiography, 10-2 visual fields and multifocal ERG (mf-ERG) help in the early detection of the toxicity.2 We would like to highlight here importance of adaptive optics, and various studies done for the early detection of HCQ toxicity. In the study by Forte et al, mf-ERG did not co-relate with the flow changes on OCT-A, however in another observation by Penrose et al (n=6) a depression of signals on multifocal ERG was found in the perifoveal region even when the patients had normal visual acuity and a normal fundus.3Costa et al found significant differences between the micro-perimetry in the patients taking hydroxychloroquine and controls.4 It will be interesting to know the authors take on this. Besides these, adaptive optics is emerging as an important tool to detect the early photo-receptor changes in patients with HCQ toxicity. Adaptive optics help in the direct visualization of the cone mosaic. Stepien et al in their observation on 4 patients observed that adaptive optics showed a loss of cone mosaic in the perifoveal region that corresponded with...
Show MoreEyes with Fuchs endothelial corneal dystrophy (FECD) are known to have reduced contrast vision from increased glare even if high-contrast acuity is not affected.1 In a retrospective study, Augustin and colleagues suggested that corneal guttae without edema contribute to decreased contrast sensitivity, and that such eyes would benefit from Descemet membrane endothelial keratoplasty (DMEK).2 The topic is important because it is unknown whether guttae in the absence of any corneal edema affect vision and therefore whether such eyes truly benefit from DMEK. The authors enrolled eyes with >5 mm of confluent guttae and without edema (modified Krachmer grade 5); however, they did not state their definition of “edema”. In FECD, when corneal edema is not clinically detectable by slit-lamp examination, it can be detected by Scheimpflug tomography.3 A recent study found evidence of subclinical corneal edema in 88% of eyes with FECD grade 5 and almost 40% of eyes with lesser grades of FECD.4 It is therefore highly likely that many of the FECD eyes examined by Augustin and colleagues did in fact have subclinical corneal edema, so can the authors examine the Scheimpflug tomograms of these eyes and report the contrast sensitivity results based on the presence or absence of subclinical edema? This is important because reduced contrast sensitivity might be caused by subclinical edema and not simply by “guttae without edema”, and cornea surgeons should not conclude that it is appr...
Show MoreI have read with interest the paper by Fabian ID et al. “Travel burden and clinical presentation of retinoblastoma”[1]. I acknowledge the efforts conducted by the authors to build a retinoblastoma knowledge based on a large consortium for the first time. Many publications have agreed that the underprivileged socioeconomic situations affect the presentation and outcome of retinoblastoma patients[2, 3]. The measures used in most publications, including the one by Fabian ID et al., are national-level measures. Such socioeconomic measures on the country level affect the roads and travel quality beside family and healthcare giver education and training. A better measure in such cases is an individual level for each family. In developing countries, a vast gap presents between inhabitants letting a country-level measure, not representative. As mentioned in a glimpse in the paper, patients can spend a long time orbiting multiple physicians before targeting the oncology center. On the other side, people with higher economic status can get better healthcare and travel longer distances comfortably and present to centers with early stages.
Show MoreFurthermore, Figure 2 shows interestingly similar small catchment areas in Africa; this raised a question on the data that were used for drawing the figure; is it individualized for each center? Additionally, if the analysis depended on the permanent address.
Egypt’s major pediatric oncology center, which was included in the study, cover...
We thank Alfaar for their comment on our paper titled: “Travel burden and clinical presentation of retinoblastoma: analysis of 1024 patients from 43 African countries and 518 patients from 40 European contries”.[1]
Show MoreIn our paper, we compared the stage of presentation of newly diagnosed retinoblastoma patients from African and European countries and investigated possible associations to the travel distance from home to treatment centre. Our findings suggest that treatment centres in African countries serve patients that reside, on average, in closer proximity to the treatment center than in Europe (186 km average distance travelled in Africa compared to an average distance travelled of 422 km in Europe). In reply to Alfaar’s comment, to produce these numbers, we calculated the average travel distance in a country and then calculated the mean of averages in a continent and compared Africa to Europe.
The red circles in Figure 2 in our original paper,[1] representing the mean travel distance in a continent, were superimposed on each centre on a scaled map. All red circles in Africa are similar in size (i.e. radius of 186 km) and all in Europe are similar (i.e. radius of 422 km).
We agree with Alfaar that our analysis has several limitations, some of which are mentioned in our paper and some, rightfully, in his eLetter. In a study, in which patients from over 80 countries in two continents are included, one cannot take into account all considerations, especiall...
Reply to the comment on: “Influence of corneal guttae and nuclear cataract on contrast sensitivity”
We thank Sanjay V Patel for the comments. Patients with Fuchs endothelial corneal dystrophy (FECD) are known to have reduced contrast sensitivity due to corneal edema and guttae. Before the introduction of endothelial keratoplasty, penetrating keratoplasty had been performed mainly in patients with advanced FECD and clinically significant corneal edema. However, as endothelial keratoplasty procedures such as Descemet membrane endothelial keratoplasty can bring excellent visual acuity outcomes, surgery can be performed earlier and even in cases without any clinical corneal edema. Therefore, it has become even more important to detect the causes of visual impairment in patients with FECD. In our retrospective study, we enrolled FECD patients with >5 mm of confluent guttae and no corneal edema (modified Krachmer grade 5). When analyzed by Scheimpflug tomography, our FECD patients showed no difference in the central corneal thickness and corneal volume when compared to the control group of cataract patients without any corneal pathologies.1 Recently, Sun et al. presented a new method to detect subclinical corneal edema in patients with FECD.2,3 The authors analyzed three Scheimpflug tomography pachymetry map and posterior elevation map patterns to detect subclinical edema in FECD patients: loss of regular isopachs, displacement of the thinnest point of the cornea, and...
Show MoreMcCann et al. reported factors of the associations with intraocular pressure (IOP) and circumpapillary retinal nerve fibre layer (cRNFL) thickness (1). Increased IOP and reduced cRNFL were associated with increased age, myopic refractive error, male sex and hypertension. In addition, Alzheimer's disease was associated with thinner average global cRNFL, and Parkinson's disease (PD) and current smoking status were associated with thicker average global cRNFL, and I present recent information regarding their study in patients with PD.
Murueta-Goyena et al. reported the association between the changes of retinal thickness and their predictive value as biomarkers of disease progression in idiopathic PD (2). The authors used macular ganglion-inner plexiform layer complex (mGCIPL) and peripapillary retinal nerve fiber layer (pRNFL) thickness reduction rates, and the Montreal Cognitive Assessment (MoCA) questionnaire was also applied. The adjusted relative risks of lower parafoveal mGCIPL and pRNFL thickness at baseline for an increased risk of cognitive decline at 3 years significantly increased. This means that reduced retinal thickness is a risk factor of cognitive impairment in patients with PD. McCann et al. did not evaluate cRNFL in PD patients with cognitive impairment, and I suppose that progression of cognitive impairment in patients with PD might accelerate reduction of average global cRNFL.
Second, Sung et al. also investigated the association be...
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