Ian Yew San Yeo

Development and Validation of a Deep Learning System for Diabetic Retinopathy and Related Eye Diseases Using Retinal Images From Multiethnic Populations With Diabetes

Importance A deep learning system (DLS) is a machine learning technology with potential for screening diabetic retinopathy and related eye diseases. Objective To evaluate the performance of a DLS in detecting referable diabetic retinopathy, vision-threatening diabetic retinopathy, possible glaucoma, and age-related macular degeneration (AMD) in community and clinic-based multiethnic populations with diabetes. Design, Setting, and Participants Diagnostic performance of a DLS for diabetic retinopathy and related eye diseases was evaluated using 494 661 retinal images. A DLS was trained for detecting diabetic retinopathy (using 76 370 images), possible glaucoma (125 189 images), and AMD (72 610 images), and performance of DLS was evaluated for detecting diabetic retinopathy (using 112 648 images), possible glaucoma (71 896 images), and AMD (35 948 images). Training of the DLS was completed in May 2016, and validation of the DLS was completed in May 2017 for detection of referable diabetic retinopathy (moderate nonproliferative diabetic retinopathy or worse) and vision-threatening diabetic retinopathy (severe nonproliferative diabetic retinopathy or worse) using a primary validation data set in the Singapore National Diabetic Retinopathy Screening Program and 10 multiethnic cohorts with diabetes. Exposures Use of a deep learning system. Main Outcomes and Measures Area under the receiver operating characteristic curve (AUC) and sensitivity and specificity of the DLS with professional graders (retinal specialists, general ophthalmologists, trained graders, or optometrists) as the reference standard. Results In the primary validation dataset (n = 14 880 patients; 71 896 images; mean [SD] age, 60.2 [2.2] years; 54.6% men), the prevalence of referable diabetic retinopathy was 3.0%; vision-threatening diabetic retinopathy, 0.6%; possible glaucoma, 0.1%; and AMD, 2.5%. The AUC of the DLS for referable diabetic retinopathy was 0.936 (95% CI, 0.925-0.943), sensitivity was 90.5% (95% CI, 87.3%-93.0%), and specificity was 91.6% (95% CI, 91.0%-92.2%). For vision-threatening diabetic retinopathy, AUC was 0.958 (95% CI, 0.956-0.961), sensitivity was 100% (95% CI, 94.1%-100.0%), and specificity was 91.1% (95% CI, 90.7%-91.4%). For possible glaucoma, AUC was 0.942 (95% CI, 0.929-0.954), sensitivity was 96.4% (95% CI, 81.7%-99.9%), and specificity was 87.2% (95% CI, 86.8%-87.5%). For AMD, AUC was 0.931 (95% CI, 0.928-0.935), sensitivity was 93.2% (95% CI, 91.1%-99.8%), and specificity was 88.7% (95% CI, 88.3%-89.0%). For referable diabetic retinopathy in the 10 additional datasets, AUC range was 0.889 to 0.983 (n = 40 752 images). Conclusions and Relevance In this evaluation of retinal images from multiethnic cohorts of patients with diabetes, the DLS had high sensitivity and specificity for identifying diabetic retinopathy and related eye diseases. Further research is necessary to evaluate the applicability of the DLS in health care settings and the utility of the DLS to improve vision outcomes.

Optical Coherence Tomographic Angiography in Type 2 Diabetes and Diabetic Retinopathy

Importance Optical coherence tomographic angiography (OCT-A) is able to visualize retinal microvasculature without the need for injection of fluorescein contrast dye. Nevertheless, it is only able to capture a limited view of macula and does not show leakage. Objectives To evaluate the retinal microvasculature using OCT-A in patients with type 2 diabetes as well as the association of OCT-A characteristics with diabetic retinopathy (DR) and systemic risk factors. Design, Setting, and Participants A prospective, observational study was conducted from January 1 to June 30, 2016, at medical retina clinics at the Singapore National Eye Center among 50 patients with type 2 diabetes with and without DR (n = 100 eyes). We examined the retinal microvasculature with swept-source OCT-A and a semiautomated software to measure the capillary density index (CDI) and fractal dimension (FD) at the superficial vascular plexus (SVP) and deep retinal vascular plexus (DVP). We collected data on histories of patients’ glycated hemoglobin A1c, hypertension, hyperlipidemia, smoking, and renal impairment. Main Outcomes and Measures The CDI and FD at the SVP and DVP for each severity level of DR and the association of systemic risk factors vs the CDI and FD. Results The mean (SD) glycated hemoglobin A1c of the 50 patients (26 men and 24 women; 35 Chinese; mean [SD] age, 59.5 [8.9] years) was 7.9% (1.7%). The mean (SD) CDI at the SVP decreased from 0.358 (0.017) in patients with no DR to 0.338 (0.012) in patients with proliferative DR (P < .001) and at the DVP decreased in patients with no DR from 0.361 (0.019) to 0.345 (0.020) in patients with proliferative DR (P = .04). The mean (SD) FD at the SVP increased from 1.53 (0.05) in patients with no DR to 1.60 (0.05) in patients with proliferative DR (P < .01) and at the DVP increased from 1.55 (0.06) in patients with no DR to 1.61 (0.05) in patients with proliferative DR (P = .02). For systemic risk factors, hyperlipidemia (odds ratio [OR], 9.82; 95% CI, 6.92-11.23; P < .001), smoking (OR, 10.90; 95% CI, 8.23-12.34; P < .001), and renal impairment (OR, 3.72; 95% CI, 1.80-4.81; P = .05) were associated with reduced CDI, while increased glycated hemoglobin A1c (≥8%) (OR, 8.77; 95% CI, 5.23-10.81; P < .01) and renal impairment (OR, 10.30; 95% CI, 8.21-11.91; P < .001) were associated with increased FD. Conclusions and Relevance Optical coherence tomographic angiography is a novel imaging modality to quantify the retinal capillary microvasculature in patients with diabetes. It can be potentially used in interventional trials to study the effect of systemic risk factors on the microvasculature that was previously not accessible in a noninvasive manner. The relevance of these findings relative to visual acuity, however, remains largely unknown at this time.

Trends and factors related to outcomes for primary rhegmatogenous retinal detachment surgery in a large asian tertiary eye center.

Purpose: To describe trends and outcomes of vitreoretinal surgery for primary rhegmatogenous retinal detachment in a large Asian tertiary eye center. Methods: Retrospective review of 1,530 eyes with primary retinal detachment between 2005 and 2011 managed at the Singapore National Eye Center by one of the following: scleral buckling (SB), pars plana vitrectomy (PPV), and combined SB and PPV (SB + PPV). Anatomical and functional outcomes were assessed. Results: There was a trend toward PPV and PPV + SB as the primary reattachment procedure from 2005 to 2011. The primary anatomical success rate for PPV (78.6%) was worse than that for SB (88.8%) or SB + PPV (89.0%, P = 0.000). Final anatomical success rates were similar for all 3 procedures: SB 97.7%, PPV 95.2%, and SB + PPV 96.4%. Better functional success was achieved in the SB group (86.1%) than both the PPV (72.5%) and SB + PPV groups (77.5%, P = 0.000), partly attributable to the less complex nature of retinal detachments in the SB group. Older age and proliferative vitreoretinopathy were related to the poor functional outcomes in both phakic and pseudophakic eyes. Conclusion: There was an increasing trend toward PPV and PPV + SB as the primary retinal reattachment surgery from 2005 through to 2011. High rates of anatomical and functional outcomes were achieved with SB, PPV, and SB + PPV, proliferative vitreoretinopathy and older age were negatively correlated with the functional success in both phakic and pseudophakic eyes.

SCLERAL BUCKLING VERSUS VITRECTOMY IN THE MANAGEMENT OF MACULA-OFF PRIMARY RHEGMATOGENOUS RETINAL DETACHMENT: A Comparison of Visual Outcomes.

Purpose: To compare visual outcomes between pars plana vitrectomy (PPV) with or without scleral buckling (SB) and SB alone in the management of uncomplicated macula-off primary rhegmatogenous retinal detachment. Methods: Case–control study of 723 patients with uncomplicated macula-off primary rhegmatogenous retinal detachment seen at the Singapore National Eye Centre from 2005 to 2011. The primary outcome measure was the proportion of eyes achieving functional success, defined as logMAR best-corrected visual acuity of ⩽0.3 logMAR at 6 months postoperatively. Multivariable logistic regression analysis was performed adjusting for the following preoperative covariates: age, gender, race, lens status, number of tears found, presence of proliferative vitreoretinopathy, operative procedure, logMAR best-corrected visual acuity, and duration of symptoms. Results: Three hundred and eight eyes underwent SB alone, and 415 eyes underwent PPV ± SB. In the SB group, 133 eyes (43.2%) achieved functional success compared with 116 eyes (28.0%) in the PPV ± SB group. This difference was statistically significant on both univariate (P < 0.001) and multivariable analyses (OR: 1.51, 95% CI: 1.03–2.21, P = 0.03). Conclusion: Scleral buckling alone may achieve visual outcomes that are at least comparable with PPV ± SB in the management of macula-off primary rhegmatogenous retinal detachment.

Trends in age-related macular degeneration management in Singapore.

Purpose To describe the trends and patterns of anti–vascular endothelial growth factor (anti-VEGF) therapy and photodynamic therapy (PDT) use for age-related macular degeneration (AMD) in the National Eye Centre in Singapore over a 4-year period. Methods Data on the total number of intravitreal anti-VEGF injections and PDT treatment over a 4-year period at the Singapore National Eye Centre were obtained from centralized electronic records. Patients aged 40 years and older treated for AMD were included. Data retrieved included the annual treatment load in terms of number of new patients and total treatment episodes, and treatment burden for patients was studied in terms of number of injections per year and cumulative injection numbers over 3 years. Potential influence on retreatment by choice of drug, use of adjunct PDT, and diagnosis of polypoidal choroidal vasculopathy were further analyzed. Results From 2009 to 2012, a total of 6157 injections were performed on 1380 unique individual patients. The total number of injections performed per calendar year increased from 962 in 2009 to 2278 in 2012. The number of unique incident cases increased from 287 in 2009 to 446 in 2012. The mean number of injections over the first year increased from 2.62 in 2009 to 3.19 in 2012 (p < 0.001). Choice of anti-VEGF therapy did not significantly alter the cumulative injections required. Patients diagnosed as having polypoidal choroidal vasculopathy had similar injection episodes (p = 0.178), whereas choice of anti-VEGF and adjunct PDT had no effect on the overall treatment. Conclusions Anti-VEGF treatment of AMD continues to increase substantially year on year in the past few years, in alignment with experience from other countries. However, the cumulative number of injections per patient remains low, and many patients discontinue treatment within the first year. These data demonstrate that undertreatment remains a significant concern in clinical settings.

Choroidal Remodeling in Age-related Macular Degeneration and Polypoidal Choroidal Vasculopathy: A 12-month Prospective Study

Choroid thinning occurs in age-related macular degeneration (AMD). However, it remains unclear whether the reduction is due to reduction in choroidal vessels or shrinkage of choroidal stroma, or both. The purpose of this study was to evaluate the changes of the choroidal vascular and stromal area in 118 patients with typical AMD (t-AMD) and polypoidal choroidal vasculopathy (PCV) over a 12-month period. We used spectral-domain optical coherence tomography (SD-OCT) with enhanced depth imaging (EDI) mode to measure the subfoveal choroidal thickness (CT), central retinal thickness (CRT) and choroidal vascularity index (CVI - ratio of luminal area to total choroidal area). At baseline, PCV eyes had higher CRT (471.6 µm vs 439.1 µm, p = 0.02), but comparable subfoveal CT and CVI, compared to t-AMD. Eyes with high CVI at baseline showed marked reduction in stromal area compared with eyes with average or low CVI. Over 12 months, CRT and subfoveal CT significantly decreased (p < 0.001) in both subtypes. Eyes with high baseline CVI showed significant CVI reduction from baseline to month 12 (p < 0.001), whereas eyes with average to low baseline CVI showed increase in CVI. These differences in choroidal vascularity may reflect different predominant pathogenic processes and remodeling in AMD eyes with varying spectrum.

Extracapsular cataract extraction training: junior ophthalmology residents’ self-reported satisfaction level with their proficiency and initial learning barrier

Purpose To investigate residents’ self-reported satisfaction level with their proficiency in extracapsular cataract extraction (ECCE) surgery and the initial barriers to learning the procedure. Methods This is a single-centre prospective descriptive case series involving eight first-year ophthalmology residents in Singapore National Eye Center. We recorded the demographics, frequency of review by the residents of their own surgical videos and their satisfaction level with their proficiency at each of the ECCE steps using a 5-point Likert scale. All ECCE surgical videos between October 2013 and May 2014 were collected and analysed for the overall time taken for the surgery and the time taken to perform the individual steps of the procedure. Results The mean age of the residents was 27.6±1.5 years and 62.5% (5/8) were women. More than half (62.5%, 5/8) reviewed their own surgical videos while 37.5% (3/8) discussed the surgical videos with their peers or supervisors. Of the ECCE steps, the residents were most dissatisfied with their proficiency in performing irrigation and aspiration (87.5%, 7/8), followed by suturing (62.5%, 5/8), intraocular lens insertion (62.5%, 5/8) and tin can capsulotomy (62.5%, 5/8). The average time taken for each ECCE case was 55.0±12.2 min and, of all the steps, most time was spent on suturing (20.5±6.8 min), followed by irrigation and aspiration (5.5±3.6 min) and tin can capsulotomy (3.3±1.8 min). Conclusions The first-year ophthalmology residents were most dissatisfied with their proficiency in irrigation/aspiration, suturing and tin can capsulotomy. More training needs to be directed to these areas during teaching sessions in the operating room, wet laboratory or cataract simulation training sessions.

The Surgical Outcomes, Complications and Predictive Surgical Factors of Diabetic Retinopathy Vitrectomy in a Large Asian Tertiary Eye Center

Purpose: To evaluate the visual, anatomical outcomes, complications and the predictive preoperative and intraoperative factors of pars plana vitrectomy (PPV) for proliferative diabetic retinopathy (PDR) in a large Asian tertiary eye center. Methods: This is a consecutive retrospective review of 106 eyes that underwent PPV for PDR complications in 2013. The functional success was defined as visual acuity of 20/200 or better while the anatomical success was defined as 360° flat retina without endo-tamponade at one year. Results: The overall functional and anatomical success was 77.4% and 94.3%, respectively. The common complications were iatrogenic break (14.2%), raised intraocular pressure (IOP) (13.2%), cataract (13.2%) and recurrent vitreous hemorrhage (12.3%). The use of intraoperative triamcinolone (OR: 0.36, p=0.04) and silicone oil (OR: 0.08, p<0.001) were associated with poorer visual success. The iatrogenic breaks occurred more often in 20G PPV than 23G PPV (OR: 5.89, p=0.02) whereas intraoperative silicone oil were associated with postoperative raised IOP (OR: 3.71, p=0.04). The use of bevacizumab was not found to reduce recurrent vitreous hemorrhage (OR: 0.53, 95%CI: 0.11-2.53, p=0.43). Conclusions: In the era of small gauge vitrectomy, the visual, anatomical outcomes and complication rates of PPV for PDR patients in Singapore had improved significantly, as compared to the Diabetic Retinopathy Vitrectomy Study.