eLetters

563 e-Letters

  • Response to: Response to "Preoperative aqueous humour flare values do not predict proliferative vitreoretinopathy in patients with rhegmatogenous retinal detachment"

    Thank you for your interest in our publication entitled "Preoperative aqueous humour flare values do not predict proliferative vitreoretinopathy in patients with rhegmatogenous retinal detachment".

    As per request, we would like to provide more details on our protocol.

    As described in our discussion, centre 1 used the mean of ten correct measurements making sure these measurements did not differ more than 2 standard deviations from each other. In centre 2, seven correct measurements were recorded of which the highest and lowest value were discarded leaving an average of five measurements. A correct measurement meant that the background readings did not differ more than 15% (indicated by the code ‘BG’ on the output) and that single “cell/C” measurements were replaced by an additional measurement. In addition, measurements with a small signal to noise ratio (indicated by the code ‘s/n’) were avoided as much as possible. However, with low flare values this was not always feasible. The flare meters were located in a room with blinds (centre 1) and a room without windows (centre 2); computer screens and lights were turned off during measurements. Both flare meters were calibrated monthly to assure correct readings. We therefore believe that the included mean values are artefact free.

    Despite the exclusion of patients with additional conditions such as AMD, CRVO and preoperative PVR grade C or higher, we did end up with patients with a preopera...

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  • Eye health system strengthening to improve health outcomes in the Caribbean

    I read with interest the article by Pawiroredjo et al1 which described an intervention programme to increase the cataract surgical rate in Suriname. I commend the team at the Suriname Eye Centre (SEC) for their efforts towards eliminating avoidable cataract blindness and visual impairment. The Suriname Rapid Assessment of Avoidable Blindness (2013-2014) survey showed that the proportion of eyes with a postoperative visual acuity <6/60 (poor outcome) was lowest in eyes operated at the SEC (8.5%), higher for the Cuban Mission Milagros (18.8%) and highest in surgeries performed by foreign humanitarian ophthalmic missions (33.3%).

    In neighbouring Trinidad and Tobago, Persad and Bhola reported higher complication rates following cataract surgery performed by a foreign visiting team over a 2-week period compared to those done by local surgeons2. Despite a similar case mix, the visiting team had a sixfold higher vitreous loss rate and a fourfold higher overall surgical complication rate. The authors recommended careful screening of visiting surgical teams by relevant authorities. This supports Pawiroredjo’s suggestion of lowering complication rates and improving outcomes by regulating and limiting access of less experienced foreign ophthalmic teams to eye camps, where 50% of poor outcome was caused by intraoperative complications.

    Suriname has achieved cataract surgical coverage (for all VA levels) of 90% in bilaterally blind or visually impaired individuals age...

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  • Early response to ranibizumab predictive of functional outcome after dexamethasone for unresponsive diabetic macular oedema

    Early response to ranibizumab predictive of functional outcome after dexamethasone for unresponsive diabetic macular oedema
    Dan Calugaru, Mihai Calugaru
    Department of Ophthalmology, Univ of Medicine Cluj-Napoca/Romania

    Re: Early response to ranibizumab predictive of functional outcome after dexamethasone for unresponsive diabetic macular oedema. Cicinelli et al. Br J Ophthalmol 2017; http: /dx.doi. org/ 10.1136/bjophthalmol-2017-310242.

    Dear Editor
    We would like to address several challenges that have arisen from the study by Cicinelli et al (1), which can be specifically summarized below.
    1. The study was retrospectively conducted, with a selection bias attributable to the heterogeneity of the patients included, for example, six patients were affected by the type 1 diabetes mellitus; eighteen eyes were phakic; twenty seven eyes underwent cataract extraction and intraocular lens implant; and thirteen eyes received grid macular photocoagulation for diabetic macular oedema (DME) prior to ranibizumab (RNB).
    2. After undergoing three loading-dose intravitreal injections of RNB performed at fixed 4-week intervals for the first 12 weeks, all the patients regardless of functional and anatomical characteristics, were shifted to dexamethasone implant (DEX implant 0.7 mg; Ozurdex; Allergan, Irvine, California, USA) continued at 4-month intervals until stable best-corrected visual acuity (BCVA) was reached. However, nothing was...

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  • Obstructive sleep apnoea, primary open angle glaucoma and age-related macular degeneration

    We thank the authors[1] but wish to clarify several points. Stating that ‘glaucoma diagnosis is more common in OSA populations’ is controversial. Glaucoma diagnosis was not more common in our study (RR 1.01, CI 0.85-1.19), which censored prospectively from time of OSA coding throughout England from 1999-2011[2]. This is the largest and longest individual study conducted in this area. Several previous studies also observed no association.

    The authors recommend accounting for ‘risk-associated conditions’. Accounting for potential confounders is important in evaluation of positive associations but less relevant in their absence. We agree that studies in different populations would be useful, particularly in Asia where OAG may differ.

    In recommending a prospective RCT assessing ‘IOP/visual field progression before and after CPAP’, the authors are asking a different question. We have previously advocated this: ‘even in the absence of a positive association, it might still be relevant to identify those patients with genuine co-existence of OSA and POAG, particularly if evidence were to emerge … that OSA treatment could reduce glaucomatous progression’[2].

    Our study never aimed to measure OSA point prevalence, so it is inappropriate to compare a speculative ‘base rate of 2.5%’ with prevalence estimates from a different continent/age-group. Moreover, our OSA cohort represented more severe disease; this should have exaggerated rather than ‘blurred’ any potentia...

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  • Incorrect study design and statistical analysis

    We read with interest the recently published study by Kim et al, which the authors described as a cross-sectional, observational, case-control study. As a single study such a design is not possible since cross-sectional and case-control studies are two distinct types of study designs. The authors compared the percent with lower lid epiblepharon between those with and without congenital glaucoma and reported that controls were matched on age and date of outpatient visit to the cases, which would suggest this is a matched case-control study. However, the statistical analysis employed did not account for the matched nature of the study design and therefore was not appropriate. Statistical procedures that account for the matched nature of the study should have been employed. The authors are urged to conduct a reanalysis of their study, amending their interpretation as warranted.

  • Ophthalmologists wake obstructive sleeping dogma

    We read with great interest the article by Keenan et al. “Associations between obstructive sleep apnoea, primary open angle glaucoma and age-related macular degeneration: record linkage study” (Br J Ophthalmol. 2017 Feb;101(2):155-159), which concluded that Obstructive Sleep Apnoea (OSA) is not associated with Primary Open Angle Glaucoma (POAG). Potential POAG aetiology inflammatory markers are higher in OSA patients, and glaucoma diagnosis is more common in OSA populations.

    While retrospective studies have great value, it is important to account for risk-associated conditions, including family history of OSA, racial disparities [1], smoking, hypertension, floppy eyelids, Type II diabetes [2], COPD and obesity.

    To determine a causal relationship between OSA and POAG, it is necessary to assess intraocular pressures/visual field progression before and after continuous positive airway pressure (CPAP) treatment, using prospective randomised control trial designs. Further, the OSA base rate in Keenan et al. was 2.5%, while the estimated OSA prevalence rate may exceed 20% for those over 55 years of age [3]. Missing 90+% of apnoea sufferers may have blurred the true apnoea-POAG relationship. The risk rate for apnoea in the first year after initial POAG episode was 1.5, but declined to less than 1.0 in subsequent years, which suggests the possibility of increasing neglect of apnoea risk over the course of POAG. These findings highlight the lack of OSA screening and...

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  • Short-term efficacy of intravitreal aflibercept depending on angiographic classification of polypoidal choroidal vasculopathy

    Short-term efficacy of intravitreal aflibercept depending on angiographic classification of polypoidal choroidal vasculopathy
    Dan Calugaru, Mihai Calugaru
    Department of Ophthalmology, Univ of Medicine Cluj-Napoca/Romania

    Re: Short-term efficacy of intravitreal aflibercept depending on angiographic classification of polypoidal choroidal vasculopathy. Jeong and Sagong. Br J Ophthalmol 2016; http: /dx.doi. org/ 10.1136/bjophthalmol-2016-309144.

    Dear Editor
    We would like to address several challenges that have arisen from the study by Jeong and Sagong (1), which can be specifically summarized below.
    1. The study included a relatively small sample size of cases examined with a fairly short follow-up period.
    2. Several relevant data are missing in the study. For example, the anatomic types of macular edema (diffuse/cystic changes within neurosensory retina/subretinal/sub retinal pigment epithelium (RPE) fluid/ mixed type) at baseline and at months 3 and 6; the qualitative status of the 4 outer retinal layers (eg, the external limiting membrane band, the ellipsoid zone, the interdigitation zone, and the retinal pigment epithelial band) at presentation as well as the magnitude of changes (disruption/absence) during the study as potential predictors of visual loss/improvement after aflibercept (Eylea; Regeneron Pharmaceuticals Inc., Tarrytown, New York, USA) treatment; the percentages of patients with complete polyp regression and...

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  • How should we call POEMS syndrome associated optic neuropathy?

    We have read with great interest Yokouchi et al’s article on the correlation between vascular endothelial growth factor (VEGF) levels and peripapillary retinal thickness in patients with POEMS syndrome(1) and we would like to share some reflections onthis mysterious form of optic neuropathy.
    The acronym that gives name to the disorder does not include any ocular manifestation. However these patients frequently do develop ocular manifestations. Bilateral optic disc involvement appears in half of the patients and it has been considered an independent prognostic factor.(2)POEMS syndrome associated optic disc swelling constitutes a form of optic neuropathy that is not easy to classify. It is usually bilateral, but intracranial pressure is not elevated in most patients, so the term papilledema (although commonly used) is probably inaccurate. Most authors believe this optic neuropathy is related to increased VEGF levels, and Yokouchi et al’s work seems to support this theory.(1) From a pathogenic point of view optic disc swelling induced by cytokines should probably be considered a form of optic neuritis. However, inflammatory neuropathies often associate pain with eye movements and usually produce visual loss (reduced visual acuity and visual field damage) while POEMS patients present only minor visual disturbance and the visual prognosis is good.(3)
    We suggest that POEMS associated optic disc swelling should be considered a new form of optic neuropathy. This neuro...

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  • Response to "Preoperative aqueous humour flare values do not predict proliferative vitreoretinopathy in patients with rhegmatogenous retinal detachment"

    We noticed the article entitled "Preoperative aqueous humour flare values do not predict proliferative vitreoretinopathy in patients with rhegmatogenous retinal detachment" by Mulder and associates with interest.(1)

    Several studies have been published concluding that elevated aqueous flare values seem to be associated with increased risk for PVR redetachment.(2-4) Schroeder et al reported that values >15 photon counts per milliseconds (pc/ms) increases the risk for PVR 16-fold.(4) Hoerster et al showed that the odds ratio for PVR development with preoperative flare values >15pc/ms was 30.7 (p=0.0001) with a sensitivity of 80% and specificity of 79%.(3) Conart et al verified these findings (OR 12.3, p<0.0001 for later PVR in flare values >15 pc/ms).(2)

    In contrast Mulder et al concluded on their data compilation that laser flare measurements are inaccurate in predicting PVR.(1) Logistic regression analyses showed a significant increase in odds with increasing flare at least for the second centre (1) supporting the notion that high flare measurements herald PVR. However, the large variation precluded sufficient sensitivity and specificity to separate between groups. We assume the reason for the large variation is that high-level outliers were included. For center 2 only the highest and the lowest values were excluded, no information is provided for center 1. Values of 100pc/ms, here up to 312pc/ms, are uncommon for the low-level type of i...

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  • Morphological and functional changes in recalcitrant diabetic macular oedema after intravitreal dexamethasone implant
    Mihai Calugaru

    Morphological and functional changes in recalcitrant diabetic macular oedema after intravitreal dexamethasone implant. Dan Calugaru, Mihai Calugaru Department of Ophthalmology, Univ of Medicine Cluj-Napoca/Romania

    Re: Morphological and functional changes in recalcitrant diabetic macular oedema after intravitreal dexamethasone implant. Iacono et al. Br J Ophthalmol 2016;http:/dx.doi.org/10.1136/bjophthalmol-201...

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