Colin S. Tan

Ophthalmic complications of dengue.

A case series suggests that the spectrum of complications in dengue infection is widening.

Polypoidal choroidal vasculopathy: an angiographic discussion

The understanding of polypoidal choroidal vasculopathy has evolved rapidly in the past three decades. The hallmark of the disease is the presence of typical hyperfluorescent nodules in the early phase of indocyanine green angiography. Although the classical clinical presentation is recurrent serosanguinous detachment of the retinal pigment epithelium, it may present with clinical features indistinguishable from exudative age-related macular degeneration secondary to choroidal neovascularization. Some cases may present initially with submacular haemorrhage, but later with features of exudative age-related macular degeneration. Studying the associated network of vessels using confocal scanning laser ophthalmoscopy indocyanine green dynamic angiography revealed in many cases feeder vessels, branching pattern, and leakage similar to choroidal neovascularization. Owing to the overlap of clinical and angiographic features, it may be considered as a vascular subtype of exudative age-related macular degeneration. However, having seemingly better natural history, better response to photodynamic therapy, and incomplete response to anti-vascular endothelial growth factor therapy suggests that it should be studied as a separate entity from choroidal neovascularization. Combining angio-occlusion of the polyps using photodynamic therapy and anti-permeability effect of anti-vascular endothelial growth factor therapy on the branching vascular network may provide a synergistic effect. We await the result of EVEREST trial, a multi-centre randomized controlled trial comparing photodynamic therapy, with or without ranibizumab, with ranibizumab monotherapy.

Epidemiology of postoperative endophthalmitis in an Asian population: 11-year incidence and effect of intracameral antibiotic agents

PURPOSE: To describe the incidence of postoperative endophthalmitis after cataract surgery in a multiethnic Asian population over an 11‐year period, compare the endophthalmitis rates before and after the use of intracameral antibiotic agents, and identify potential risk factors for endophthalmitis. SETTING: Department of Ophthalmology, Tan Tock Seng Hospital, Singapore. DESIGN: Cohort study. METHODS: The incidence and risk factors for postoperative endophthalmitis in patients who had cataract surgery over 11 years were reviewed. Subconjunctival antibiotic agents only were administered over 7 years; in the subsequent 4 years, intracameral cefazolin (1.0 mg/0.1 mL) was used. RESULTS: The overall incidence of postoperative endophthalmitis in 50 177 was 0.042%. Over the 7 years without intracameral antibiotics, the endophthalmitis rate was 0.064% (19/29 539). With the use of intracameral cefazolin, the incidence decreased to 0.01% (2/20 638) (multivariate odds ratio [OR], 13.6; 95% confidence interval [CI], 3.15‐58.58; P<.001). The independent risk factors for endophthalmitis were age (OR, 1.05; 95% CI, 1.01‐1.09; P=.025) and male sex (0.06% versus 0.02%; OR, 2.96; 95% CI; 1.15‐7.65; P=.025). CONCLUSIONS: There was a significant reduction in the rate of postoperative endophthalmitis in a multiethnic Asian population with the use of intracameral cefazolin. Men and older patients were at a higher risk for endophthalmitis. Financial Disclosure: No author has a financial or proprietary interest in any material or method mentioned.

Topographic variation of choroidal and retinal thicknesses at the macula in healthy adults.

Background/aims To determine the topographic variation of macular choroidal and retinal thicknesses (RTs) in normal eyes and their relationship with refractive error. Methods Spectral domain optical coherence tomography with enhanced depth imaging was performed on 124 healthy participants using a standardised imaging protocol. Manual segmentation of choroidal boundaries was performed by trained graders, and mean choroidal thickness (CT) was compared with mean RT in corresponding sectors of the Early Treatment Diabetic Retinopathy Study (ETDRS) grid. Results Mean central subfield CT was 322.2 µm. The choroid was thickest at the temporal and superior sectors (323.1–338.1 µm), followed by inferior sectors (314.0–321.8 µm), and thinnest at the nasal sectors (232.8–287.8 µm). In contrast, the retina was thicker nasally (343.4 µm) and thinner temporally (287.1 µm). CT was thickest among emmetropes in all ETDRS subfields and became thinner progressively among low, moderate and high myopes (p<0.001). The variation of both choroidal and RTs among refractive error groups resulted in different topographic patterns at the macula. Conclusion There is significant topographic variation of choroidal and RTs at different regions of the macula, with progressive change of choroidal thickness in all sectors based on the refractive status of the eye.

Phacoemulsification versus manual small-incision cataract surgery for white cataract

PURPOSE: To compare the safety and efficacy of phacoemulsification and manual small‐incision cataract surgery (SICS) to treat white cataracts in southern India. SETTING: Aravind Eye Hospital, Pondicherry, India. DESIGN: Randomized prospective study. METHODS: Consecutive patients with white cataract were randomly assigned to have phacoemulsification or manual SICS by 1 of 3 surgeons experienced in both techniques. Surgical complications, operative time, uncorrected (UDVA) and corrected (CDVA) distance visual acuities, and surgically induced astigmatism were compared. RESULTS: On the first postoperative day, the UDVA was comparable in the 2 groups (P = .805) and the manual SICS group had less corneal edema (10.2%) than the phacoemulsification group (18.7%) (P = .047). At 6 weeks, the UDVA was 20/60 or better in 99 patients (87.6%) in the phacoemulsification group and 96 patients (82.0%) in the manual SICS group (P = .10) and the CDVA was 20/60 or better in 112 (99.0%) and 115 (98.2%), respectively (P = .59). The mean time was statistically significantly shorter in the manual SICS group (8.8 minutes ± 3.4 [SD]) than in the phacoemulsification group (12.2 ± 4.6 minutes) (P<.001). Posterior capsule rupture occurred in 3 eyes (2.2%) in the phacoemulsification group and 2 eyes (1.4%) in the manual SICS group (P = .681). CONCLUSIONS: Both techniques achieved excellent visual outcomes with low complication rates. Because manual SICS is significantly faster, less expensive, and less technology‐dependent than phacoemulsification, it may be a more appropriate technique in eyes with mature cataract in the developing world. Financial Disclosure: No author has a financial or proprietary interest in any material or method mentioned.

Comparison of choroidal thicknesses using swept source and spectral domain optical coherence tomography in diseased and normal eyes

Background/aims Choroidal thickness measurements are reported to differ between swept source optical coherence tomography (SS-OCT) and spectral domain OCT (SD-OCT). This study aimed to assess the comparability of choroidal thickness measurements using SS-OCT and SD-OCT devices among patients with retinal diseases and normal participants. Methods In a prospective cohort study of 100 subjects, comprising patients with retinal disease and normal volunteers, OCT scans were performed sequentially with the DRI OCT-1 and Spectralis OCT using standardised imaging protocols. Subfoveal choroidal thicknesses were independently measured by masked reading-centre certified graders. Paired t tests and intraclass correlation coefficients (ICCs) were used to compare the measurements. Results Among all 100 participants, mean subfoveal choroidal thickness was 264.3 µm and 272.4 µm for DRI OCT-1 and Spectralis OCT respectively (p=0.001), with ICC of 0.989. The mean difference in choroidal thickness between OCT devices was larger among eyes with retinal diseases compared with normal eyes (8.4 µm vs 7.3 µm). Eyes with choroidal thickness ≤200 µm had smaller differences between OCT devices compared with those with thicker choroids (mean 3.6 µm vs 10.0 µm, p=0.021). Conclusions Subfoveal choroidal thickness measurements are comparable between DRI OCT-1 and Spectralis OCT. The presence of retinal disease increases the variability of choroidal thickness measurements between OCT devices.

Epidemiology of pterygium on a tropical island in the Riau Archipelago

ObjectivesTo describe the epidemiology of pterygium among residents of an island in Indonesia and to examine the roles of age and gender as determinants of bilaterality and severity of the disease.MethodsVoluntary eye screening on Pulau Jaloh, Riau Archipelago, Indonesia. Gender difference was tested using the χ2 test. The difference in age between subjects with and without disease was tested using unpaired Students t-test. Odds ratio (relative risk) for gender was calculated using logistic regression model with adjustment for age.ResultsOf the 550 inhabitants, 477 (86.7%) responded to the eye screening. The overall prevalence rate of pterygium was 17.0%. Out of 211, 48 male (22.7%) and 33 out of 266 female subjects (12.4%) had the disorder, with the gender difference being statistically significant. Adjusted for age, the risk of disease was 3.1-fold higher among the males. In all, 71.6% of subjects with pterygium had bilateral disease. Subjects with pterygium were significantly older, their mean age being 42.9 years compared to 18.7 years among those without disease. The prevalence rates in male subjects increased from age 20 to reach a plateau of 63.6% at age 35 and remained stable thereafter. In the female subjects, the rates also increased with age, albeit at a slower rate, from age 20 to reach a plateau of 46.7% at age 55 and remained stable thereafter.ConclusionsThere is a high prevalence rate of pterygium among the study subjects, with the rates increasing rapidly with age.

Charles Bonnet syndrome in Asian patients in a tertiary ophthalmic centre

Aims: To describe the epidemiology of Charles Bonnet syndrome (CBS) among patients in an Asian tertiary ophthalmic centre and to describe the characteristics of the hallucinations experienced. Methods: 1077 consecutive patients aged 50 years and above were asked a standardised question to determine if they had ever experienced formed visual hallucinations. All patients who experienced these symptoms were further interviewed using a detailed, standardised questionnaire to ascertain if they met the diagnostic criteria established for CBS. Results: There were 491 men (45.6%) and 586 women (54.4%). The best corrected visual acuity ranged from 20/20 to light perception in the better seeing eye and from 20/20 to no light perception in the worse seeing eye. Four patients (0.4%) were diagnosed with CBS; two men and two women. There were two Chinese and two Indians. The average age of the CBS patients was 76.3 years (range 65–90 years). Two patients had cataracts, one had glaucoma, and one had both cataracts and glaucoma. A wide variety of visual hallucinations were reported. Three out of four patients experienced a negative reaction to their hallucinations. Only one patient had discussed his symptoms with a doctor. Conclusions: This is the first report on the epidemiology of CBS in Asian patients. The prevalence rate of CBS (0.4%) is slightly lower than in comparable studies in non-Asian populations. The nature of the hallucinations experienced were similar to those previously reported.

Peripheral Autofluorescence and Clinical Findings in Neovascular and Non-neovascular Age-related Macular Degeneration

PURPOSE To characterize peripheral fundus autofluorescence (FAF) abnormalities in patients with age-related macular degeneration (AMD), correlate these with clinical findings, and identify risk factors associated with these FAF abnormalities. DESIGN Clinic-based, cross-sectional study. PARTICIPANTS A total of 119 consecutive patients: 100 patients with AMD (200 eyes) and 19 patients without AMD (38 eyes). METHODS In a prospective study performed at the Doheny Eye Institute, University of Southern California, widefield 200-degree FAF and color images were obtained by the Optos 200Tx Ultra-Widefield device (Optos, Dunfermline, Scotland) using a standardized imaging protocol. The FAF images were captured centered on the fovea, and additional images were captured after steering the field of view inferiorly and superiorly. All FAF and color images were graded independently by 2 masked ophthalmologists with respect to the presence, location, extent, and type of peripheral (defined as outside the central 30 degrees) FAF abnormality. MAIN OUTCOME MEASURES Presence and type of peripheral FAF abnormalities. RESULTS Peripheral FAF abnormalities were evident in 164 eyes (68.9%), with several distinct FAF patterns identified: granular (46.2%), mottled (34.0%), and nummular (18.1%). A 90% concordance of FAF patterns was observed between both eyes. Abnormal FAF occurred more frequently in neovascular compared with non-neovascular AMD or normal eyes (86% vs. 72.8% vs. 18.4%, respectively, P<0.001). Significant risk factors for peripheral FAF abnormalities were AMD type (neovascular AMD odds ratio [OR], 12.7 and non-neovascular AMD OR, 6.2 compared with normal eyes, P<0.001), older age (OR, 6.5; 95% confidence interval [CI], 2.4-17.8; P<0.001 for the oldest quartile compared with the youngest), and female sex (OR, 4.1; 95% CI, 1.9-8.9; P<0.001). Clinical features on color photography were detected in 174 eyes (73.1%): peripheral drusen (51.7%), retinal pigment epithelium (RPE) depigmentation (34.9%), RPE hyperpigmentation (branching reticular pigmentation) (22.7%), and atrophic patches (16.8%). There was a high correlation between specific FAF and clinical findings: granular FAF with peripheral drusen (P<0.001) and mottled FAF with RPE depigmentation (P<0.001). CONCLUSIONS Several distinct patterns of peripheral FAF abnormalities were observed in 68.9% of patients, with AMD type, female sex, and age being independent risk factors. The peripheral FAF patterns correlate strongly with specific clinical features seen in eyes with AMD. FINANCIAL DISCLOSURE(S) Proprietary or commercial disclosure may be found after the references.

Prevalence and risk factors for refractive errors and ocular biometry parameters in an elderly Asian population: the Singapore Longitudinal Aging Study (SLAS)

PurposeTo determine the prevalence rates of refractive errors and pattern of ocular biometry in a multi-ethnic elderly Asian population.MethodsA population-based study of 1835 residents aged 55–85 years, evaluating the refractive error and ocular biometry parameters, including axial length (AL) and anterior chamber depth.ResultsThe age-standardized prevalence of myopia, hyperopia, astigmatism, and anisometropia were 30.0% (95% confidence interval (CI): 29.6, 30.4), 41.5% (95% CI: 41.1, 41.9), 43.5% (95% CI: 43.1, 44.0), and 22.1% (95% CI: 21.7, 22.4), respectively. Male gender (P=0.02), age ≥75 years (P=0.033), and higher educational level (P<0.001) were significantly associated with higher rates of myopia in multivariate analyses. The prevalence of astigmatism was higher in persons with diabetes (odds ratio (OR) 1.4, 95% CI: 1.03, 1.90, P=0.031). AL was longer in Chinese than other ethnic groups (23.7 vs23.4 mm, P=0.018), and in men compared with women (24.2 vs23.4 mm, P<0.001). AL was associated with increasing height (AL increased by 0.3 mm for every 10 cm increase in height, P<0.001).ConclusionThere is a high prevalence of myopia in elderly Singaporeans, consistent with trends seen in younger populations in Asia. Male gender and higher education were independent risk factors for myopia. These data suggest that higher rates of myopia in East Asians compared with Caucasians may not be a recent phenomenon.