eLetters

105 e-Letters

published between 2018 and 2021

  • Influence of corneal guttae and nuclear cataract on contrast sensitivity

    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...

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  • Dimness and blur

    I read with interest the paper by Gagrani and colleagues, regarding the self-characterisation of visual field loss by glaucoma patients, and the development of an app to allow this to be measured.1

    The study helps to further understand the experience of glaucoma patients. Their experimental results support the view that patients experience their visual field defects as blur rather than 'black holes'. Hu et al found the most common subjective symptoms in glaucoma were "needing more light" (57%) and "blurry vision" (55%).2 In the study by Gagrani et al., subjects were able to modify both dimness and blur, though in practice they did not choose to use the dimness response at all.

    It is possible that differences in the measurement tools might potentially influence these findings. For example, patients may have found the dim response more difficult to use.

    The potential for this app to allow patients to better understand and self-pictoralise their visual disability is poignant and important. It will be interesting to see whether this novel approach yields similar results when replicated in future.

    References
    1. Gagrani M, Ndulue J, Anderson D, Kedar S, Gulati V, Shepherd J, et al. What do patients with glaucoma see: a novel iPad app to improve glaucoma patient awareness of visual field loss. Br J Ophthalmol. 2020 Nov 20.
    2. Hu CX, Zangalli C, Hsieh M, et al. What do patients with glaucoma see? Visual symptoms...

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  • B-scan ultrasound, visual electrophysiology and perioperative videoendoscopy for predicting functional results in keratoprosthesis candidates

    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,...

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  • Letter: Optimised retinopathy of prematurity screening guideline in China

    We were intrigued by the study by Yang et al[1] recently published in the British Journal of Ophthalmology. They conducted a detailed analysis of the fundus screening results of 5606 infants over 5 years in tertiary neonatal intensive care units (NICUs) in four medical centres in Shanghai, China. They found the detection rate of retinopathy of prematurity (ROP)to be 15.9%, and the detection rate of type 1 ROP (1.1%) was lower than that previously reported. The mean gestational age (GA) and birth weight (BW) of infants with ROP have also decreased. Therefore, they suggest modifying the criteria of Chinese ROP screening to GA <32 weeks or BW <1600 g. Application of these criteria to the studied cohort yielded a 98.4% sensitivity, with the infants requiring fundus screening reduced by 43.2%. Therefore, these criteria would reduce medical costs significantly. This is of great significance to the screening and treatment of ROP in China, which has a huge population and regional medical resource imbalances.
    However, the study also had issues that need further discussion. First, the patient cohort was not a continuous population-based cohort, and the authors did not clearly state the specific criteria for screening. Therefore, the rate could be the detection rate rather than the true incidence. In addition, the development and general conditions of these patients from NICUs are significantly different from those of the general population. Therefore, although it was a r...

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  • B-scan ultrasound, visual electrophysiology and perioperative videoendoscopy for predicting functional results in keratoprosthesis candidates

    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...

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  • Orbital MRI versus fundus photography and OPTOS in the diagnosis of optic nerve hypoplasia and prediction of vision

    Kruglyakova, et al recently published an excellent paper about visually pertinent correlation of optic nerve hypoplasia (ONH) with intra-operative photographic measurements1. We recently reported similar findings without subjecting children to general anesthesia if ultra-widefield imaging (OPTOS; Dunfermline, UK) is available2. We agree that a MD/DD ratio greater than 3.22 (≥3.51) is consistent with clinical optic nerve hypoplasia but our direct measure of horizontal optic nerve size was even more predictive utilizing our definition of logMAR for pediatric and low vision patients3. Instead of starting from the temporal edge of the optic nerve to determine MD (macula-disk) distance, we found the center of the optic nerve more uniform. In addition, we have also noted a worrisome relationship between ONH and threshold retinopathy of prematurity4 and wonder if the authors also found any association between the two common pediatric blinding conditions ONH and ROP?

    References:
    1. Kruglyakova J, Garcia-Filion P, Nelson M, Borchert M. Orbital MRI versus fundus photography in the diagnosis of optic nerve hypoplasia and prediction of vision. Br J Ophthalmol. 2020;104(10):1458-1461.
    2. Arnold AW, Eller AM, Smith KA, Grendahl RL, Winkle RK, Arnold RW. Direct nerve size determination and prevalent optic nerve hypoplasia in Alaska. Clin Ophthalmol. 2020;14:491—499.
    3. Arnold RW. Digital values for alpha acuities. JPOS. 2020:In Press.
    4. Arnold RW. Opti...

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  • 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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