711 e-Letters

  • Factors affecting circumpapillary retinal nerve fibre layer thickness

    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...

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  • Honey eye drops, the effect of sugars

    I read the interesting manuscript entitled “Effect of a formulated eye drop with Leptospermum spp honey on tear film properties”. Authors have compared a formulated eye drop made of honey and regular lubricant drops finding some advantages of the honey eye drop. While the natural honey mainly composed of sugars, the beneficial effect might merely related to these simple carbohydrates. If authors have decided to find any effect, peculiarly attributed to the honey, they might design a control group with similar composition of simple carbohydrates to disclose the unclouded actual effect of the honey. On the other side, there might be some possible complications of promoting such agents as proved treatments, that have been already in use as alternative home made remedies; we have reported a case of Acanthamoeba keratitis using non-sterile honey eye drop (1).

    1. Peyman A, Pourazizi M, Peyman M, Kianersi F. Natural Honey-Induced Acanthamoeba keratitis. Middle East Afr J Ophthalmol. 2020 Jan 29;26(4):243-245. doi: 10.4103/meajo.MEAJO_56_18. PMID: 32153338; PMCID: PMC7034153.

  • Response to Travel burden and clinical presentation of retinoblastoma; they travel more than papers say.

    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...

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  • Travel burden and clinical presentation of retinoblastoma; they travel more than papers say.

    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...

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  • ROCK THE MEDIA ! Adding ROCK inhibitors to donor corneal storage media to improve corneal endothelial cell function

    We read with interest this article by Ong HS et al on “Evolution of therapies for the corneal endothelium: past, present and future approaches”.

    As the article mentions, Rho kinase (ROCK) inhibitors have been described in the regenerative approach to corneal endothelial injury by aiding cell proliferation.1 Due to the wide range of cellular responses controlled by the Rho kinase signalling pathway, ROCK inhibitors play a part in increasing cell adhesion and proliferation of the corneal endothelium. Their clinical use has also been reported with success in Fuch’s endothelial dystrophy and pseudophakic corneal decompensation. 0.4% Ripasudil eye drop is the common agent used in these studies.2
    Enriching nutrients, antibiotics and other additives have been described in literature to add value to corneal preservation media. It would be interesting to see if addition a Rho kinase inhibitor to the donor corneal preservation medium could enhance the endothelial cell count or limit attrition over longer preservation times. The parameters of the drop in terms of strength, solubility, minimum concentration, side effects if any etc. need to be evaluated prior. Of all the methods described to improve the corneal endothelial health, this is the only one that may be extrapolated to donor corneal tissue also, for better surgical outcomes
    It may be worthwhile to test if adding a ROCK inhibitor may enhance donor corneal tissue viability in storage media, under controlled...

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  • Subclinical Corneal Edema and Contrast Sensitivity in Fuchs Endothelial Corneal Dystrophy

    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...

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  • Response to Svasti-Salee, Snead and Alexander

    Dear Editor,

    We thank Svasti-Salee, Snead and Alexander [1] for their interest in our study and their comment regarding the reliability of spectral domain optical coherence tomography (SD-OCT) in differentiating a completely attached hyaloid versus complete posterior vitreous detachment (PVD).

    To address the author’s question, in our post-hoc analysis, only SD-OCT was used to diagnose PVD status. A slit-lamp examination specifically assessing for PVD was not performed per protocol in the TREND study, [2] therefore data other than SD-OCT were not available for post-hoc analysis.

    The accepted clinical methods to determine PVD include slit-lamp examination, dynamic ultrasonography and SD-OCT, while previous generations of OCT (time-domain OCT) potentially offered insufficient resolution and field of view. Of those methods, SD-OCT has the main advantage of being operator independent and allowing systematic, standardized evaluation in a reading center setting. The approach chosen for the analysis of the TREND dataset has been repeatedly performed in several prior studies, with similar outcome data. [3-5]

    A recent study cited by the authors [6] reports that PVD status on SD-OCT did not correlate well to intraoperative findings when patients underwent vitrectomy. However, vitrectomy surgery is performed in patients with vitreomacular interface disease, where often a multi-layered posterior vitreous cortex cleaving into separate planes is found, making...

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  • Authors Response to Dr. Dhananjay Shukla's Correspondence

    We thank Dr. Shukla for his interest in our article and his comments 1, 2.
    In our study all consecutive cases of rhegmatogenous retinal detachment (RD) that underwent pars plana vitrectomy (PPV) were included in the study regardless of complexity, type of tear, lens or refractive status, or use of supplemental buckle in order to reduce selection bias and to allow study of various subgroups of patients. For the same reason the 13 cases with silicone oil present at the time of last follow-up were not excluded. The paper referenced by Dr. Shukla reports a retinal re-detachment rate of 13.2% after removal of silicone oil (ROSO), with many of the cases performed prior to the era of small gauge vitrectomy and wide-angle viewing systems (WAVS) 3. Encircling endolaser photocoagulation further reduces the re-detachment rate to 8.6% 4. More recent surgical techniques are likely associated with a lower retinal re-detachment rate. Nevertheless, a presumed retinal re-detachment of 13.2% following ROSO corresponds to an estimated 1.7 eyes with recurrent RD out of the 13 eyes with residual silicone oil in our series 3. This in turn corresponds to a 0.5% difference in the overall single surgery success rate (SSSR) in 312 eyes. It could therefore be safely assumed that inclusion of the small group with silicone oil at the last follow-up visit did not affect the overall success rate significantly, but reduced chances of introducing a selection bias.

    In our series a supplemental...

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  • Will children with hypermetropia still need glasses when they grow older?

    Dear Editor,

    Bonafede et al1 analyzed the change over time in hypermetropia in children from the USA with partially and fully accommodative esotropia. This study complements a previous long-term follow-up multi-center publication on 164 hypermetropic children from USA, Germany, and Israel2. The follow-up was comparable: ages 3.5-10.5 years in the previous article compared to 3-12 years in the current paper. The range of spherical equivalent refractive error in the previous paper was categorized as +1-3Diopters (D) (mild hypermetropes) and +5-8D (high hypermetropes). In contrast, the current study included also moderate hypermetropes, because it involved a group with less than +4D hypermetropes and a group of children with hypermetropia of +4D or more. Esotropia in the previous study was not present in any of the mild hypermetropes but was present in half (48%) of the high hypermetropes. Due to a decrease in hypermetropia over time beyond the age of 6 years old, mild hypermetropes in the previous study were weaned from glasses (-0.095 D/year), while the high hypermetropes remained in glasses (-0.037 D/year). Similarly, because of a mean decrease of -0.17 D/year that occurred only from age 7 to 15 years, subjects in the current study with a “smaller baseline” (i.e., mild) hypermetropia stopped wearing glasses. However, most moderate and high hypermetropes beyond the age of 12 years remained in glasses (-0.18 D/year).

    In conclusion, data derived from both...

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  • Reply to: The Effect of Posterior Vitreous Detachment on Aflibercept Response in Diabetic Macular Oedema


    To the Editor:
    We appreciate the comments by Wei Gui and J. Sebag about Ozsaygili Cemal’s article titled ‘The effect of posterior vitreous detachment on aflibercept response in diabetic macular oedema.’1 In our study, we used the video display mode to obtain more reliable results while evaluating the posterior vitreous detachment (PVD) status with spectral-domain optical coherence tomography (SD-OCT). In a recent clinical study comparing the PVD status with ocular ultrasonography (US) and SD-OCT in patients with diabetic macular oedema (DMO), it was reported that video display mode SD-OCT showed total agreement (100% in video display mode) with US.2 We used the video display mode in all patients instead of a single cross-sectional view and excluded patients with poor image quality. Since it was a retrospective study, we could not have the chance to perform US, but excluding these patients from the study in patients where any of the 2 independent retina specialists (CO, BK) disagreed on the PVD status draws attention as factors that increase the validity of our data. In addition, the International Vitreomacular Traction Study Group, including doctor J. Sebag, has classified the posterior vitreous-macular relationship based on OCT and has mostly replaced USG with OCT in our current clinical practice.3
    All eyes in our study were examined for vitreoschisis and similar anomalous PVD using SD-OCT video display mode. As you mentioned, SD-OCT has the abili...

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