Anantharaman Giridhar

Normative spectral domain optical coherence tomography data on macular and retinal nerve fiber layer thickness in Indians

Aim: To provide the normative data of macular and retinal nerve fiber layer (RNFL) thickness in Indians using spectral domain OCT (Spectralis OCT, Heidelberg Engineering, Germany) and to evaluate the effects of age, gender, and refraction on these parameters. Design: Observational, cross-sectional study. Materials and Methods: The eyes of 105 healthy patients aged between 20-75 years, with no ocular disease and best corrected visual acuity of 20/20, were scanned using standard scanning protocols by a single examiner. Exclusion criteria included glaucoma, retinal diseases, diabetes, history of prior intraocular surgery or laser treatment. The mean macular and RNFL thickness were recorded, and the effects of age, gender, and refraction on these parameters were evaluated. This data was compared with published literature on Caucasians to assess the ethnic variations of these parameters. Results: The normal central foveal thickness in healthy Indian eyes measured using Spectralis OCT was 260.1 ± 18.19 μm. The nasal inner quadrant showed maximum retinal thickness (338.88 ± 18.17 μm). The mean RNFL thickness was 101.43 ± 8.63 μm with maximum thickness in the inferior quadrant. The central foveal thickness showed a gender-based difference (P = 0.005) but did not correlate significantly with age (P = 0.134), whereas the parafoveal, perifoveal thickness, macular volume, and RNFL thickness showed significant negative correlation with age. Conclusions: Our study provides the normative database for Indians on Spectralis OCT. It also suggests that age should be considered while interpreting the macular thickness and RNFL, whereas gender should also be given consideration in central foveal thickness.

An Insight Into the Pathogenesis of Optic Disc Pit–Associated Maculopathy With Enhanced Depth Imaging

IMPORTANCE Optic disc pit with associated maculopathy is a known entity. However, controversy exists regarding the source of subretinal fluid in these cases. In our series, we attempted to analyze the morphologic changes seen in the optic disc pit and evaluate the source of subretinal fluid. OBSERVATIONS In this prospective observational case series of 4 patients with optic pit maculopathy, a complete ophthalmic evaluation, with fundus color photography and enhanced depth imaging spectral-domain optical coherence tomography scanning of the optic disc, was carried out between January 2013 and November 2013. The optical coherence tomographic section was mapped with infrared image and color photography, and the characteristics of the retina and optic nerve head were analyzed. All the cases had outer layer retinal schisis; 2 of them had associated serous macular detachment while inner retinal schisis was present in 3 cases. A hyporeflective tract was observed in our study connecting the retinal schisis cavity and gap in the lamina cribrosa corresponding to the optic pit. CONCLUSIONS AND RELEVANCE In our study, we demonstrated the connectivity between retinal schisis and the gap in the lamina cribrosa present in the optic disc pit, supporting the hypothesis of cerebrospinal fluid as the source of subretinal fluid.

Drug-induced acute myopia following chlorthalidone treatment.

We report a case of sudden loss of vision due to the development of acute myopia after the intake of chlorthalidone used for treating systemic hypertension. Clinically this was associated with ciliary spasm, shallow peripheral choroidal effusion and retinal striae at the macula with increase in macular thickness seen on optical coherence tomography. All these findings were reversed completely once the drug was discontinued. Development of acute myopia should be kept in mind as an adverse effect of a commonly used antihypertensive drug, namely chlorthalidone.

Knowledge and awareness about diabetes mellitus and diabetic retinopathy in suburban population of a South Indian state and its practice among the patients with diabetes mellitus: A population-based study

Context: Ocular complications due to diabetes mellitus (DM) were on the rise despite good literacy levels in South India. Aims: To assess the knowledge and attitude toward DM and diabetic retinopathy of the general population in a suburban town of South India. Settings and Design: Door-to-door population survey in suburban town of South India in May 2013. Materials and Methods: A 30-point questionnaire was prepared and the data were collected and analyzed to determine statistically the knowledge, attitude, and practice (KAP) scores of the general and diabetic population and also to determine significant demographic associations. Results: In this study, 6211 people (3528 [56.8%] women and 2683 [43.2%] men) with a mean age of 55.6 ± 11.7 years (range 21-98 years) were included. Good knowledge and positive attitude were observed in 3457 (55.6%) and 3280 (52.8%) people. Among 1538 (25.4%) people known to have DM, only 619 (40.7%) had good knowledge, 828 (53.8%) had a positive attitude, and 886 (57.6%) had good practice patterns. Although half of them followed general diabetic care, only 9.6% had undergone screening for retinopathy. Literacy showed a significant association with good KAP (P < 0.001 each) in general population and those with DM. Overall, women had significantly better knowledge (P < 0.001). Conclusions: Better literacy, especially among women, is contributory to better public awareness; however, the trend for poor practice patterns needs to be radically changed with aggressive public motivation emphasizing on the necessity of retinopathy screening and periodic follow-ups.

COMPARATIVE ANALYSIS OF OUTCOMES WITH VARIABLE DIAMETER INTERNAL LIMITING MEMBRANE PEELING IN SURGERY FOR IDIOPATHIC MACULAR HOLE REPAIR.

Purpose: To analyse whether the size of internal limiting membrane peeling influences the outcome of macular hole surgery. Methods: Prospective, comparative, interventional study. Fifty eyes were included. Twenty-five eyes had smaller (3-mm) peel (Group 1), whereas the other 25 had larger (5-mm) peel (Group 2). Outcome measures were macular hole closure rate, improvement in best corrected visual acuity, retinal nerve fiber layer, and ganglion cell layer thickness (0.5 mm, 1.5 mm, and 2.5 mm temporal and medial to the fovea), external limiting membrane, inner segment outer segment layer, and cone outer segment tip restoration. Results: Both the groups were matched for demographic parameters, spectral-domain optical coherence tomography–based macular hole staging and dimensions. Hole closure rates were similar, 80% and 65% in Group 1 and 2, respectively (P = 0.20). No difference was observed in anatomical success rate, irrespective of size, stage, or duration of hole. Visual improvement was better in Group 1 (4 lines vs. 2-line Early Treatment Diabetic Retinopathy Study equivalent; P = 0.04); the retinal nerve fiber layer was thinner at all locations in Group 2, with the difference being significant, 2.5 mm temporal to the fovea (P < 0.05), whereas the ganglion cell layer was thicker in the 3-mm group, significantly so at the location, 1.5 mm temporal to the fovea (P = 0.01). Outer layer restoration rates were also similar in both the groups. Conclusion: Macular hole closure rate was similar in both the groups; however, smaller (3-mm) peel group demonstrated better functional improvement and nerve fiber layer preservation.

SULFURHEXAFLUORIDE (SF6) VERSUS PERFLUOROPROPANE (C3F8) GAS AS TAMPONADE IN MACULAR HOLE SURGERY.

Purpose: To compare outcomes of macular hole surgery using sulfurhexafluoride (SF6) versus perfluoropropane (C3F8) gas. Methods: This is a retrospective, interventional, comparative study. A total of 177 eyes of 166 patients operated over a 3-year period for idiopathic macular holes were included. Sixty-seven eyes had tamponade with SF6 gas (Group 1), whereas 111 eyes received C3F8 (Group 2) as the tamponading agent. The primary outcome measure was the macular hole closure rate. Statistical analysis was done using SPSSv16. Results: Spectral domain optical coherence tomography-based stagewise distribution of macular holes were similar across both groups (P = 0.99). The hole closure rate was 57/66 (86.4%) with SF6 and 96/111 (86.5%) with C3F8 gas (P = 0.98). Subanalysis demonstrated no significant difference in closure rates regarding macular hole size, stage, or duration. Best-corrected visual acuity improved by a mean of 0.28 logMAR in the SF6 group (P = 0.00) and 0.42 logMAR in the C3F8 group, corresponding to 3 lines and 4 lines of improvement, respectively, on the Early Treatment Diabetic Retinopathy Study chart (P < 0.05). The difference was not significant (P = 0.06). Rise in intraocular pressure was higher in the C3F8 group (P < 0.05). Progression of cataract was also greater in the C3F8 group (83.3 vs.73.9%), but it was not statistically significant (P = 0.20). Resurgery was done in 9/177 eyes. The closure rate with C3F8 and SF6 reinjections was 3/4 (75%) and 1/5 (20%). Moreover, anatomical hole closure after resurgeries was better in Group 1 (4/5 eyes) than in Group 2 (0/4 eyes). Conclusion: The macular hole closure rate was similar with sulfurhexafluoride and perfluoropropane, irrespective of hole size, stage, or duration. However, sulfurhexafluoride exhibited a decreased incidence of cataract and ocular hypertension with shorter tamponade duration. Perfluoropropane may have a role as the preferred endotamponading agent in failed primary surgeries.

SPECTRAL DOMAIN OPTICAL COHERENCE TOMOGRAPHY-BASED MICROSTRUCTURAL ANALYSIS OF RETINAL ARCHITECTURE POST INTERNAL LIMITING MEMBRANE PEELING FOR SURGERY OF IDIOPATHIC MACULAR HOLE REPAIR.

Purpose: Spectral domain optical coherence tomography–based analysis of retinal architecture after internal limiting membrane peeling for macular hole surgery. Methods: Prospective, interventional study. Fifty eyes underwent the surgical procedure with minimum internal limiting membrane peel of 3 mm diameter. Automatic segmentation software was used to assess individual layers preoperatively and postoperatively, 1.5 millimeters medial and lateral to fovea at 3 months postoperative visit. Main outcome measures were final central macular thickness and variation in individual retinal layer thickness. Results: Mean central macular thickness postoperatively was 201 microns. Retinal thickening was observed, 1.5 mm medial to fovea (P < 0.01) with significant increment in thickness of inner nuclear layer (P < 0.01), whereas significant retinal thinning was observed 1.5 mm temporal to fovea (P < 0.01) with maximum thinning observed in ganglion cell layer (P < 0.01). Ganglion cell and inner plexiform were the only layers to demonstrate thinning on both sides of the fovea. External limiting membrane (ELM), inner segment outer segment junction (ISOS) and cone outer segment tips zone (COST) restoration was seen in 100%, 69%, and 17% of eyes. Best corrected visual acuity (BCVA) improved significantly with mean postoperative BCVA of 0.7logMAR (6/30 Snellens equivalent) (P < 0.001). Anatomical closure rate of 72% was achieved (P < 0.001). Conclusion: Internal limiting membrane peel is associated with significant alteration in inner retinal architecture, especially in ganglion cell layer, which can adversely influence functional outcome of the surgery and makes it imperative to avoid peeling internal limiting membrane over a larger surface area.

CHARACTERIZATION OF MACULAR CHOROIDAL THICKNESS IN ISCHEMIC AND NONISCHEMIC DIABETIC MACULOPATHY

Purpose: To evaluate changes in macular choroidal thickness in eyes with ischemic and nonischemic diabetic maculopathy. Methods: Cross-sectional study of enhanced depth imaging optical coherence tomography of patients with diabetes. The diabetic eyes were divided into 3 groups: 1) eyes with no diabetic retinopathy (NDR); 2) those with diabetic retinopathy without macular ischemia (DR/MI−); and 3) those with diabetic retinopathy and macular ischemia (DR/MI+). Results: This analysis included 261 eyes of 160 patients. Eighty-eight eyes belonged to the NDR, 90 to the DR/MI−, and 83 to the DR/MI+ group. The choroidal thickness was significantly reduced in the DR/MI+ group as compared with the other 2 groups in the subfoveal region (NDR: 285.94 ± 80.38 &mgr;m, DR/MI−: 311.22 ± 94.55 &mgr;m, DR/MI+: 216.06 ± 58.41 &mgr;m; P < 0.001), nasally and temporally (P < 0.01). Between the NDR and DR/MI− groups, the choroidal thickness was significantly reduced nasally (P = 0.02) in the NDR group, but not subfoveally (P = 0.1) and temporally (P = 0.2). Notably, no statistically significant difference in central macular thickness was found between the DR/MI− (328.68 ± 103.28 &mgr;m) and DR/MI+ (341.99 ± 130.63 &mgr;m) groups (P = 1), although it was found to significantly increase in both these groups as compared with the NDR group (264.03 ± 27.74 &mgr;m; P < 0.001). Conclusion: In diabetic maculopathy, an overall significant reduction was observed in macular choroidal thickness in eyes in ischemic stage as compared with nonischemic stage. In vivo evaluation of choroidal structural changes in the form of choroidal thickness may possibly be intuitive in understanding the pathogenesis of progression of diabetic maculopathy from nonischemic to ischemic stage, and associated functional damage.

Autofluorescence and Infrared Fundus Imaging for Detection of Retinal Emboli and Unmasking Undiagnosed Systemic Abnormalities.

A 31‐year‐old healthy man presented with sudden onset visual field defect in his left eye for 2 days. The best‐corrected visual acuity (BCVA) was 20/20 in the right eye and 20/40 in the left eye. Fundus examination of the left eye revealed a superior hemi‐central retinal artery occlusion [Figure 1a], sparing the fovea with a white embolus at the arterial bifurcation on the optic nerve head. The embolus was visible on both red free and infrared imaging. However, fundus autofluorescence imaging revealed a corresponding bright hyperautofluorescent lesion within a vessel at the optic nerve head, suggestive of a probable calcific embolus [Figure 1b]. Immediate referral to a cardiologist and a subsequent 2D echocardiogram revealed severe calcific aortic stenosis, which was rectified with early aortic valve replacement surgery. Autofluorescence and Infrared Fundus Imaging for Detection of Retinal Emboli and Unmasking Undiagnosed Systemic Abnormalities

Varicella Zoster-related Occlusive Retinal Vasculopathy—A Rare Presentation

Abstract Purpose: To report a case of occlusive retinal vasculopathy following varicella zoster infection in an immunocompetent adult. Design: Observational case report. Methods: A patient with defective vision following chickenpox was evaluated with fluorescein angiography, spectral domain optical coherence tomography and fundus auto fluorescence. Results: Fundus showed multiple cotton wool spots and a well-demarcated zone of retinal ischemia in the posterior pole with normal optic disc without any evidence of anterior or posterior uveitis. Fluorescein angiography, spectral domain optical coherence tomography and fundus auto fluorescence findings revealed occlusive vasculopathy as the cause of defective vision. Conclusions: We report a hitherto undescribed case of purely occlusive vasculopathy following varicella zoster infection without features of vasculitis or anterior and posterior uveitis in an immunocompetent individual.