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Supriya Dabir,1 Mohan Rajan,1 Liji Parasseril,1 Vaidehi Bhatt,2 Preetam Samant,3 CAB Webers,4 TTJM Berendschot4 1Department of Retina, Rajan Eye Care Pvt Ltd, Chennai, India; 2Rajiv Gandhi Medical College, Thane, India; 3Department of Retina, PD Hinduja Hospital and Medical Research Center, Mumbai, India; 4University Eye Clinic, Maastricht, the NetherlandsCorrespondence: Supriya DabirRajan Eye Care Hospital Pvt. Ltd, No. 5, Vidyodaya East 2nd Street, T. Nagar, Chennai, Tamil Nadu 600017, IndiaTel +919900974800Email supriad@gmail.comPurpose: Diabetic macular oedema (DME) is a vision-threatening complication of diabetic retinopathy. Spectral domain optical coherence tomography angiography (OCTA) is useful for assessing DME. We performed serial OCTA measurements before and after 3 monthly intravitreal anti-vascular endothelial growth factor (anti-VEGF) injections to understand its relationship with best corrected visual acuity (BCVA), central macular thickness (CMT) and vascular indices.Methods: OCTA assessment consisting of 6 × 6 mm scans centred on fovea and en-face retinal angiograms were obtained. Scans were done at baseline and at 1 month following each of the 3 intravitreal injections of anti-VEGF (ranibizumab, Lucentis®).Results: Our prospective study included 24 eyes of 24 subjects, aged 63.0 ± 5.0 years. There was a mean gain of 0.07 LogMAR (3 letters) and reduction of CMT, vessel density (VD) and perfusion density (PD) by end of 3rd month. CMT was independently associated with improvement in BCVA. There were significant reductions in FAZ area, VD and PD over 3 months from baseline.Conclusion: At three months, intravitreal anti-VEGF therapy is associated with visual function recovery in DME, with reduction in CMT being the most reliable predictor of response. OCTA shows a reduction in VD and PD respectively suggestive of reduced macular perfusion in the short term. Simultaneous reduction in FAZ size can be due to reversal of manual displacement of the retinal capillaries resulting from resolution of intraretinal oedema.Keywords: diabetic macular oedema, superficial capillary plexus, vascular density, perfusion density, foveal avascular zone, optical coherence tomography angiography, macular ischemia

Zia Sultan Pradhan,1 Shruthi Sreenivasaiah,1 Thanemozhi Srinivasan,1 Sujani Shroff,1 Sathi Devi,1 Dhanaraj AS Rao,1 Carroll AB Webers,2 Narendra K Puttaiah,1 Harsha Laxmana Rao1,2 1Department of Glaucoma, Narayana Nethralaya, Bangalore, India; 2Department of Ophthalmology, University Eye Clinic Maastricht, University Medical Center, Maastricht, the NetherlandsCorrespondence: Zia Sultan Pradhan, Department of Glaucoma, Narayana Nethralaya, 121/C, Chord Road, 1st “R” Block, Rajajinagar, Bangalore, 560010, India, Tel +91 80 66121300, Email zedpradhan@gmail.comPurpose: To evaluate the effect of the signal strength index (SSI) on a comparison of the vascular and structural OCT measurements between eyes with pseudoexfoliation syndrome (PXF) and healthy controls of Asian-Indian origin.Methods: In this cross-sectional study, 33 eyes of 33 PXF patients and 40 healthy eyes of 40 controls underwent OCT and OCT angiography (OCTA). Eyes with intraocular pressure (IOP) > 21mmHg, glaucomatous disc changes, or any other ocular pathology were excluded. Peripapillary vessel density (VD) and retinal nerve fiber layer (RNFL) thickness were determined from the optic disc scans. Parafoveal VD and ganglion cell complex (GCC) thickness were measured from the macular scans. These parameters were compared between the groups using mixed effect models after adjusting for clinical confounders such as IOP, as well as SSI of the scans.Results: The 2 groups were demographically similar. Average RNFL (94μm vs 100μm, p = 0.01) and GCC (91μm vs 95μm, p = 0.03) were thinner in the PXF group compared to controls. The average peripapillary VD appeared lower in the PXF groups compared to controls (58.2% vs 58.8%, p = 0.04), but after adjusting for IOP and SSI, no difference was noted (p = 0.39). After accounting for confounders, parafoveal VD in the PXF group was significantly lower compared to controls (44.3% vs 46.8%, p = 0.008).Conclusion: Peripapillary RNFL thickness, parafoveal GCC thickness and parafoveal VD were decreased in eyes with PXF when compared to controls. VD measurements are associated with the SSI and, therefore, clinicians and researchers evaluating OCTA scans quantitatively must consider the SSI value during analysis and interpretation.Keywords: optical coherence tomography angiography, signal strength index, vessel density, pseudoexfoliation syndrome

Hellen CS Römkens, Henny JM Beckers, Jan SAG Schouten, Tos TJM Berendschot, Carroll AB Webers Department of Ophthalmology, Maastricht University Medical Center+, Maastricht, the Netherlands Purpose: The aim of this study is to generate reference values for anterior chamber morphometrics to facilitate the interpretation of anterior chamber images acquired with swept-source optical coherence tomography (SS-OCT) in a Caucasian population.Materials and methods: Non-glaucomatous Caucasian subjects, who were newly referred to the outpatient department of the University Eye Clinic Maastricht UMC+, were asked to undergo anterior segment assessment with SS-OCT imaging prior to routine eye examination (including visual acuity and refractive error measurements, Goldmann applanation tonometry, slit lamp examination and funduscopy).Results: A total of 647 Caucasian subjects, aged 40–80 years, were included. Mean age (± standard deviation) was 61.7±10.3 years, and 294 were male (45%). Mean refractive error was -0.63±3.17 D. OCT images and measurements were obtained in all cases. The mean temporal trabecular iris angle at 500 µm (TIA500) was 27.04°±12.04°, the mean nasal TIA500 was 27.43°±11.75°, the mean anterior chamber depth (ACD) was 2.75±0.39 mm and the mean lens vault (LV) was 0.44±0.30 mm. A smaller temporal TIA500, shallower ACD and higher LV were found in female and hyperopic subjects.Conclusion: Reference values for anterior chamber morphometrics in Caucasians were generated, quantified and presented. These values offer tools for the interpretation of anterior segment images of Caucasians and differentiation between presumed mechanisms of angle closure. Keywords: reference value, anterior chamber, optical coherence tomography, Caucasian

P Mokhles, JSAG Schouten, HJM Beckers, CAB Webers University Eye Clinic Maastricht, Maastricht, the Netherlands Purpose: Blindness in glaucoma is difficult to assess with merely the use of the current World Health Organization (WHO) definition (a visual field restricted to 10° in a radius around central fixation), as this criterion does not cover other types of visual field loss that are encountered in clinical practice and also depict blindness. In this study, a 5-point ordinal scale was developed for the assessment of common visual field defect patterns, with the purpose of comparing blindness as outcome to the findings with the WHO criterion when applied to the same visual fields. The scores with the two methods were compared between two ophthalmologists. In addition, the variability between these assessors in assessing the different visual field types was determined.Methods: Two glaucoma specialists randomly assessed a sample of 423 visual fields from 77 glaucoma patients, stripped of all indices and masked for all patient variables. They applied the WHO criterion and a 5-point ordinal scale to all visual fields for the probability of blindness.Results: The WHO criterion was mostly found applicable and in good agreement for both assessors to visual fields depicting central island of vision or a temporal crescent. The percentage of blindness scores was higher when using the ordinal scale, 21.7% and 19.6% for assessors A and B, respectively, versus 14.4% and 11.3% for the WHO criterion. However, Kappa was lower, 0.71 versus 0.78 for WHO.Conclusions: The WHO criterion is strictly applied and shows good agreement between assessors; however, blindness does not always fit this criterion. More visual fields are labeled as blind when a less stringent criterion is used, but this leads to more interobserver variability. A new criterion that describes the extent, location, and depth of visual field defects together with their consequence for the patient’s quality of life is needed for the classification of glaucoma blindness. Keywords: glaucoma, blindness, visual fields, World Health Organization