Singapore Chinese Eye Study: key findings from baseline examination and the rationale, methodology of the 6-year follow-up series

Rationale, Design and Methodology of a Population-Based Ocular Study in a Suburbanization Region in Tianjin, China: The Beichen Eye Study

PURPOSE

The urbanization of suburbs has a significant impact on ocular health, however, the effect of this phenomenon on the epidemiology of eye diseases in the sub-urbanization region of China remains unclear. In this context, the population-based Beichen Eye Study (BCES) was conducted in the Beichen District of Tianjin, China. This article aims to summarize the background, design scheme and operation process of the study. The Chinese Clinical Trial Registry number was ChiCTR2000032280.

METHODS

In total, 8218 participants were randomly selected by a multi-stage sampling method. After their qualification was confirmed, participants were mainly invited to a centralized clinic via telephone interviews after promotion of the study in the community. Examinations included a standardized interview, anthropometric assessment, autorefraction, ocular biometry, visual acuity, anterior and posterior segment examinations, dry eye disease (DED), intra-ocular pressure, visual field testing, gonioscopy, and imaging of anterior segment, posterior segment, fundus, and optic disc. A peripheral venous blood sample was also collected for biochemical testing. For observational purposes, a community-based type II diabetes mellitus management mode was created and assessed for its effect in preventing the progression of diabetic retinopathy (DR).

RESULTS

Of the 8,218 residents, 7,271 were eligible for inclusion, and 5,840 (80.32%) subjects were enrolled in the BCES. Most of the participants were female (64.38%) with a median age of 63 years, and 98.23% representing Han Chinese descent. Conclusions: This study provides insights into the epidemiological characteristics of major ocular diseases and their moderators in a suburbanized region of China.

A deep network DeepOpacityNet for detection of cataracts from color fundus photographs

BACKGROUND

Cataract diagnosis typically requires in-person evaluation by an ophthalmologist. However, color fundus photography (CFP) is widely performed outside ophthalmology clinics, which could be exploited to increase the accessibility of cataract screening by automated detection.

METHODS

DeepOpacityNet was developed to detect cataracts from CFP and highlight the most relevant CFP features associated with cataracts. We used 17,514 CFPs from 2573 AREDS2 participants curated from the Age-Related Eye Diseases Study 2 (AREDS2) dataset, of which 8681 CFPs were labeled with cataracts. The ground truth labels were transferred from slit-lamp examination of nuclear cataracts and reading center grading of anterior segment photographs for cortical and posterior subcapsular cataracts. DeepOpacityNet was internally validated on an independent test set (20%), compared to three ophthalmologists on a subset of the test set (100 CFPs), externally validated on three datasets obtained from the Singapore Epidemiology of Eye Diseases study (SEED), and visualized to highlight important features.

RESULTS

Internally, DeepOpacityNet achieved a superior accuracy of 0.66 (95% confidence interval (CI): 0.64-0.68) and an area under the curve (AUC) of 0.72 (95% CI: 0.70-0.74), compared to that of other state-of-the-art methods. DeepOpacityNet achieved an accuracy of 0.75, compared to an accuracy of 0.67 for the ophthalmologist with the highest performance. Externally, DeepOpacityNet achieved AUC scores of 0.86, 0.88, and 0.89 on SEED datasets, demonstrating the generalizability of our proposed method. Visualizations show that the visibility of blood vessels could be characteristic of cataract absence while blurred regions could be characteristic of cataract presence.

CONCLUSIONS

DeepOpacityNet could detect cataracts from CFPs in AREDS2 with performance superior to that of ophthalmologists and generate interpretable results. The code and models are available at https://github.com/ncbi/DeepOpacityNet ( https://doi.org/10.5281/zenodo.10127002 ).

A deep learning system for retinal vessel calibre improves cardiovascular risk prediction in Asians with chronic kidney disease

Backgraund

Cardiovascular disease (CVD) and mortality is elevated in chronic kidney disease (CKD). Retinal vessel calibre in retinal photographs is associated with cardiovascular risk and automated measurements may aid CVD risk prediction.

Methods

Retrospective cohort study of 860 Chinese, Malay and Indian participants aged 40-80 years with CKD [estimated glomerular filtration rate (eGFR) <60 ml/min/1.73 m2] who attended the baseline visit (2004-2011) of the Singapore Epidemiology of Eye Diseases Study. Retinal vessel calibre measurements were obtained by a deep learning system (DLS). Incident CVD [non-fatal acute myocardial infarction (MI) and stroke, and death due to MI, stroke and other CVD] in those who were free of CVD at baseline was ascertained until 31 December 2019. Risk factors (established, kidney, and retinal features) were examined using Cox proportional hazards regression models. Model performance was assessed for discrimination, fit, and net reclassification improvement (NRI).

Results

Incident CVD occurred in 289 (33.6%) over mean follow-up of 9.3 (4.3) years. After adjusting for established cardiovascular risk factors, eGFR [adjusted HR 0.98 (95% CI: 0.97-0.99)] and retinal arteriolar narrowing [adjusted HR 1.40 (95% CI: 1.17-1.68)], but not venular dilation, were independent predictors for CVD in CKD. The addition of eGFR and retinal features to established cardiovascular risk factors improved model discrimination with significantly better fit and better risk prediction according to the low (<15%), intermediate (15-29.9%), and high (30% or more) risk categories (NRI 5.8%), and with higher risk thresholds (NRI 12.7%).

Conclusions

Retinal vessel calibre measurements by DLS were significantly associated with incident CVD independent of established CVD risk factors. Addition of kidney function and retinal vessel calibre parameters may improve CVD risk prediction among Asians with CKD.

Relationship between vision impairment and employment

AIMS

To examine the relationship between vision impairment (VI) and employment outcomes in a multiethnic Asian population.

METHODS

We included 7608 Asian individuals aged ≥40 years (mean (SD) age: 58.4 (10.3) years; 64.8% male) from the Singapore Epidemiology Eye Disease Study (response rate: 78.8%), a population-based cohort study (mean follow-up period: 6.2 years). Presenting visual acuity (VA) was assessed using a logarithm of the minimum angle of resolution (logMAR) chart, with VI defined as mild (VA >0.3 to <0.6 logMAR) and moderate to severe (VA ≥0.6 logMAR). Self-reported employment statuses at both baseline and follow-up were used as outcomes. Underemployment was defined as a decline in occupational skill level, categorised by International Standard Classification of Occupations, at follow-up compared with baseline. Multinomial logistic regression models were used to determine independent associations between VI and various employment outcomes, adjusted for variables that were found to significantly differ across employment statuses.

RESULTS

Presenting VI was prevalent in 20.2% (N=1536) of participants. Compared with those without VI, participants with mild and moderate to severe VI were more likely to be unemployed at baseline (OR 1.47, 95% CI 1.15 to 1.87, p=0.002 and 2.74, 95% CI 1.94 to 3.89, p<0.001, respectively). At follow-up, participants with any VI at baseline were more likely to be underemployed (OR 1.46, 95% CI 1.03 to 2.05, p=0.033).

CONCLUSION

VI, even when mild, is associated with unemployment and underemployment. Future studies should investigate whether visual interventions could be used as part of a multipronged strategy to improve employment outcomes for the population.

PATTERN AND CHARACTERISTICS OF DRUSEN SUBTYPES IN CHINESE AND INDIAN POPULATIONS IN SINGAPORE

PURPOSE

To report the pattern and characteristics of drusen subtypes in Asian populations and the association with choroidal thickness.

METHODS

This is the cross-sectional analysis of the population-based cohort study. Two thousand three hundred and fifty-three eyes of 1,336 Chinese and Indian participants aged older than 50 years, eyes with best-corrected visual acuity better than 20/60, and without other retinal diseases were recruited. Pachydrusen, reticular pseudodrusen, soft and hard drusen were graded on both color fundus photographs, and optical coherence tomography imaging with automated segmentation yielding and measurements of choroidal thickness.

RESULTS

Nine hundred and fifty-five Chinese and 381 Indians were included in the final analysis. The pattern of pachydrusen, soft drusen, hard drusen, and reticular pseudodrusen was 14.0%, 3.7%, 12.5%, and 0.2%, respectively. Mean choroidal thickness was the thickest in eyes with pachydrusen (298.3 μm; 95% confidence interval: 290.5-306.1), then eyes with hard (298.1 μm; 95% confidence interval: 290.6-305.5) and soft drusen (293.7 μm; 95% confidence interval: 281.9-305.4) and thinnest in eyes without drusen (284.6 μm; 95% confidence interval: 280.5-288.7). Systemic associations of the various drusen subtypes also differed.

CONCLUSION

Patterns, characterization and choroidal thickness of drusen subtypes, and their associations provide insights into the Asian phenotypic spectrum of age-related macular degeneration and the underlying pathogenesis.

Genetic Variability of Complement Factor H Has Ethnicity-Specific Associations With Choroidal Thickness

Purpose

To identify genetic alleles associated with differences in choroidal thickness (CT) in a population-based multiethnic Asian cohort.

Methods

A population-based multiethnic Asian cohort without retinal pathology was subjected to spectral-domain OCT (SD-OCT) and genotyping of risk alleles in CFH, VIPR2, ARMS2, and CETP. Subfoveal choroidal thickness (SFCT) values were assessed from SD-OCT, and associations with the risk alleles were determined for each cohort.

Results

A total of 1045 healthy Asian individuals (550 Chinese, 147 Indians, 348 Malays) were prospectively enrolled in the study. Several CFH alleles (rs800292, rs1061170, and rs1329428) were associated with increased SFCT in Indians (+18.7 to +31.7 µm; P = 0.001-0.038) and marginally associated with decreased SFCT in Malays (-12.7 to -20.6 µm; P = 0.014-0.022). Haplotype analysis of CFH revealed variable associations with SFCT among races, with the H6 haplotype being associated with a 29.08-µm reduction in SFCT in the Chinese cohort (P = 0.02) but a 35.2-µm increase in SFCT in the Indian cohort (P < 0.001). Finally, subfield analysis of the Chinese cohort identified associations between the CFH risk allele rs1061170 and reduced CT in the nasal and superior sectors (-20.2 to -25.8 µm; P = 0.003-0.027).

Conclusions

CFH variants are variably associated with CT among Asian ethnic groups. This has broad implications for the pathogenesis of common diseases such as age-related macular degeneration and central serous choroidopathy, the pathogenesis of which is associated with CT.

An Overview of Deep-Learning-Based Methods for Cardiovascular Risk Assessment with Retinal Images

Cardiovascular diseases (CVDs) are one of the most prevalent causes of premature death. Early detection is crucial to prevent and address CVDs in a timely manner. Recent advances in oculomics show that retina fundus imaging (RFI) can carry relevant information for the early diagnosis of several systemic diseases. There is a large corpus of RFI systematically acquired for diagnosing eye-related diseases that could be used for CVDs prevention. Nevertheless, public health systems cannot afford to dedicate expert physicians to only deal with this data, posing the need for automated diagnosis tools that can raise alarms for patients at risk. Artificial Intelligence (AI) and, particularly, deep learning models, became a strong alternative to provide computerized pre-diagnosis for patient risk retrieval. This paper provides a novel review of the major achievements of the recent state-of-the-art DL approaches to automated CVDs diagnosis. This overview gathers commonly used datasets, pre-processing techniques, evaluation metrics and deep learning approaches used in 30 different studies. Based on the reviewed articles, this work proposes a classification taxonomy depending on the prediction target and summarizes future research challenges that have to be tackled to progress in this line.

The longitudinal association between cognitive impairment and incident visual impairment in a multiethnic Asian population: a prospective cohort study

BACKGROUND

The relationship between baseline cognitive impairment (CI) and incident visual impairment (VI) in Asians is unclear.

OBJECTIVE

To determine the associations between baseline CI with incident VI and visual acuity (VA) at 6-year follow-up in multiethnic Asians.

DESIGN

Cohort.

SETTING

Population-based.

SUBJECTS

Two thousand three hundred and twenty-four adults aged ≥60 years from the Singapore Epidemiology of Eye Diseases Study (response rate 64%).

METHODS

CI was defined using the validated Abbreviated Mental Test (AMT). VA was objectively measured using a LogMAR chart. Any incident VI was defined as having no VI (Snellen's VA better than or equal to 20/40) at baseline but present (VA worse than 20/40) at 6-year follow-up. VI severity was defined according to the International Classification of Diseases, 11th Revision. Associations were assessed using logistic and linear regression models.

RESULTS

Of the 2,324 participants, 248 had CI at baseline. Presence of baseline CI was associated with more than twice the odds of any incident VI, incident mild and moderate-severe VI (OR [95% confidence interval]: 2.48 [1.55-3.90], 2.07 [1.17-3.55], and 2.61 [1.36-4.93], respectively) and worse VA (β [95% confidence interval]: 0.026 [0.006-0.046]) at 6-year follow-up. The leading causes of incident VI were cataract and under-corrected refractive error.

CONCLUSIONS

Older adults with CI had more than double the odds of VI development and poorer VA than their cognitively intact counterparts, and most causes of incident VI were correctable. Strategies such as targeted vision screening and early intervention for early detection and management of vision loss in patients with cognitive decline are warranted.

Clinical Analysis of Color Doppler Ultrasound Diagnosis of Senile Cataract Based on Intelligent Processor

In order to improve the effect of on-the-spot diagnosis of senile cataract, this paper combines the intelligent processor to explore the application of color Doppler ultrasound in the clinical analysis of senile cataract. Moreover, this paper measures and calculates the diameter, perimeter, area, volume, or velocity of blood flow reflected by color Doppler ultrasound images. In addition, this paper adopts the measurement method provided by composite measurement to design the intelligent processor. Each measurement analysis package is defined as an independent class, and the data, properties, and methods are encapsulated in a class, which is beneficial to the modular design of the program and the overall management of the system. The experimental results verify that the intelligent processor proposed in this paper has a certain effect in the clinical analysis of color Doppler ultrasound diagnosis of senile cataract.

The Fujian eye cross sectional study: objectives, design, and general characteristics

Purpose

To describe the objective and design of the Fujian Eye Study and to introduce the general characteristics and vision condition of this study.

Methods

The Fujian Eye Study (FJES) is a population-based cross-sectional survey on the public eye health status of residents over 50 years old in the entire Fujian Province of Southern China, which contains both urban and rural areas and coastal and inland regions. 10,044 participants were enrolled using a two-stage cluster sampling design and underwent a questionnaire and a series of standard examinations both physical and ocular. The main subgroups of data collection included age, sex, region, refractive error, education background, income, eating habits, smartphone usage in the dark, complaints of eye discomfort, history of chronic diseases, consumption of tobacco, alcohol, or tea.

Results

8211 (81.8%) participants were finally included and were divided into urban populations (4678 subjects) and rural populations (3533 subjects) and coastal residents (6434 subjects) and inland residents (1777 subjects); 4836 participants were female. The mean age was 64.39 (SD 8.87) years (median 64 years; range 50–98 years). 227 (3.33%) had vision impairment (VI), 195 (2.87%) had low vision and 14 (0.21%) were blind. The mean presenting near visual acuity (PNVA) was 0.28 (0.17), the mean presenting distance visual acuity (PDVA) was 0.61 (0.30), and the mean best corrected visual acuity (BCVA) was 0.82 (0.28).

Conclusions

The FJES collected detailed questionnaire information and overall ocular and physical examinations, which provide the opportunity to identify risk factors and images of VI and eye diseases and to evaluate their associations with chronic diseases and basic personal information.

Three-dimensional modelling of the choroidal angioarchitecture in a multi-ethnic Asian population

This study aimed to describe the topographic variation of the macula's choroidal angioarchitecture using three-dimensional (3D) choroidal vascularity index (CVI) of healthy eyes from an Asian population and to investigate the associations of CVI. 50 participants were recruited via stratified randomisation based on subfoveal choroidal thickness from the Singapore Epidemiology of Eye Diseases Study. Macular volume scans were acquired using spectral-domain optical coherence tomography with enhanced depth imaging. CVI was assessed based on B-scan binarisation and choroid segmentation. The 3D CVI of the whole, superior, central, and inferior macula were 62.92 ± 1.57%, 62.75 ± 1.93%, 63.35 ± 1.72%, and 62.66 ± 1.70%, respectively, pairwise comparisons P all > 0.05). 3D CVI (Whole Macula) and 2D CVI (Subfoveal) were associated only with each other and not with other ocular and systemic factors. 2D CVI (Subfoveal) had a moderate agreement with 3D CVI (Central Macula) [intraclass corelation coefficient (ICC) = 0.719], and had poorer agreement with 3D CVI of the whole macula, superior, and inferior macula (ICC = 0.591, 0.483, and 0.394, respectively). Scanning volume did not influence 3D CVI measurements. In conclusion, 3D CVI demonstrated no significant topographic variation. CVI was not correlated with demographic or ocular structural features. 2D CVI of the fovea is partially representative of 3D CVI of the macula.

Application of machine learning techniques to understand ethnic differences and risk factors for incident chronic kidney disease in Asians

INTRODUCTION

Chronic kidney disease (CKD) is increasing in Asia, but there are sparse data on incident CKD among different ethnic groups. We aimed to describe the incidence and risk factors associated with CKD in the three major ethnic groups in Asia: Chinese, Malays and Indians.

RESEARCH DESIGN AND METHODS

Prospective cohort study of 5580 general population participants age 40-80 years (2234 Chinese, 1474 Malays and 1872 Indians) who completed both baseline and 6-year follow-up visits. Incident CKD was defined as an estimated glomerular filtration rate (eGFR) <60 mL/min/1.73 m² in those free of CKD at baseline.

RESULTS

The 6-year incidence of CKD was highest among Malays (10.0%), followed by Chinese (6.1%) and Indians (5.8%). Logistic regression showed that older age, diabetes, higher systolic blood pressure and lower eGFR were independently associated with incident CKD in all three ethnic groups, while hypertension and cardiovascular disease were independently associated with incident CKD only in Malays. The same factors were identified by machine learning approaches, gradient boosted machine and random forest to be the most important for incident CKD. Adjustment for clinical and socioeconomic factors reduced the excess incidence in Malays by 60% compared with Chinese but only 13% compared with Indians.

CONCLUSION

Incidence of CKD is high among the main Asian ethnic groups in Singapore, ranging between 6% and 10% over 6 years; differences were partially explained by clinical and socioeconomic factors.

High-Density Lipoprotein 3 Cholesterol and Primary Open-Angle Glaucoma: Metabolomics and Mendelian Randomization Analyses

PURPOSE

We hypothesized that the effect of blood lipid-related metabolites on primary open-angle glaucoma (POAG) would differ according to specific lipoprotein particles and lipid sub-fractions. We investigated the associations of blood levels of lipoprotein particles and lipid sub-fractions with POAG.

DESIGN

Cross-sectional study.

PARTICIPANTS

Individuals recruited for the baseline visit of the population-based Singapore Epidemiology of Eye Disease study (n = 8503).

METHODS

All participants underwent detailed standardized ocular and systemic examinations. A total of 130 blood lipid-related metabolites were quantified using a nuclear magnetic resonance metabolomics platform. The analyses were conducted in 2 stages. First, we investigated whether and which lipid-related metabolites were directly associated with POAG using regression analyses followed by Bayesian network modeling. Second, we investigated if any causal relationship exists between the identified lipid-related metabolites, if any, and POAG using 2-sample Mendelian randomization (MR) analysis. We performed genome-wide association studies (GWAS) on high-density lipoprotein (HDL) 3 cholesterol (after inverse normal transformation) and used the top variants associated with HLD3 cholesterol as instrumental variables (IVs) in the MR analysis.

MAIN OUTCOME MEASURE

Primary open-angle glaucoma.

RESULTS

Of the participants, 175 (2.1%) had POAG. First, a logistic regression model showed that total HDL3 cholesterol (negatively) and phospholipids in very large HDL (positively) were associated with POAG. Further analyses using a Bayesian network analysis showed that only total HDL3 cholesterol was directly associated with POAG (odds ratio [OR], 0.72 per 1 standard deviation increase in HDL3 cholesterol; 95% confidence interval [CI], 0.61-0.84), independently of age, gender, intraocular pressure (IOP), body mass index (BMI), education level, systolic blood pressure, axial length, and statin medication. Using 5 IVs identified from the GWAS and with the inverse variance weighted MR method, we found that higher levels of HDL3 cholesterol were associated with a decreased odds of POAG (OR, 0.91; 95% CI, 0.84-0.99, P = 0.021). Other MR methods, including weighted median, mode-based estimator, and contamination mixture methods, derived consistent OR estimates. None of the routine lipids (blood total, HDL, or low-density lipoprotein [LDL] cholesterol) were associated with POAG.

CONCLUSIONS

Overall, these results suggest that the relationship between HDL3 cholesterol and POAG might be causal and specific, and that dysregulation of cholesterol transport may play a role in the pathogenesis of POAG.

Prevalence of polypoidal choroidal vasculopathy using non-ICGA based criteria

Polypoidal choroidal vasculopathy (PCV) is a form of neovascular AMD characterized by polypoidal lesions and branching vascular networks. Diagnosis has traditionally required the use of invasive indocyanine green angiography, though recently a validated non-invasive diagnostic system has been developed that identified PCV-specific features using optical coherence tomography (OCT) and color fundus photography. In this work we applied this new system to a large population-based cohort of ethnic Chinese and successfully identified PCV and related anatomical features. We estimated a population prevalence of 0.31% (95% CI, 0.06-0.91%) and additionally demonstrate that PCV-related retinal findings were relatively rare in the population.

COVID-19 awareness, knowledge and perception towards digital health in an urban multi-ethnic Asian population

This study aimed to determine COVID-19-related awareness, knowledge, impact and preparedness among elderly Asians; and to evaluate their acceptance towards digital health services amidst the pandemic. 523 participants (177 Malays, 171 Indians, 175 Chinese) were recruited and underwent standardised phone interview during Singapore’s lockdown period (07 April till 01 June 2020). Multivariable logistic regression models were performed to evaluate the associations between demographic, socio-economic, lifestyle, and systemic factors, with COVID-19 awareness, knowledge, preparedness, well-being and digital health service acceptance. The average perception score on the seriousness of COVID-19 was 7.6 ± 2.4 (out of 10). 75.5% of participants were aware that COVID-19 carriers can be asymptomatic. Nearly all (≥ 90%) were aware of major prevention methods for COVID-19 (i.e. wearing of mask, social distancing). 66.2% felt prepared for the pandemic, and 86.8% felt confident with government’s handling and measures. 78.4% felt their daily routine was impacted. 98.1% reported no prior experience in using digital health services, but 52.2% felt these services would be helpful to reduce non-essential contact. 77.8% were uncomfortable with artificial intelligence software interpreting their medical results. In multivariable analyses, Chinese participants felt less prepared, and more likely felt impacted by COVID-19. Older and lower income participants were less likely to use digital health services. In conclusion, we observed a high level of awareness and knowledge on COVID-19. However, acceptance towards digital health service was low. These findings are valuable for examining the effectiveness of COVID-19 communication in Singapore, and the remaining gaps in digital health adoption among elderly.

Prevalence, Associated Factors and Health-related Quality of Life of Dual Sensory Impairment in Residential Care Facilities in Singapore

Purpose: To investigate the prevalence of dual sensory impairment (DSI), its associated factors and relationship with health-related quality of life (HR-QoL) in residential care facilities (RCF) in Singapore.Methods: This was a cross-sectional study of 123 residents aged ≥40 years from six RCFs, conducted between 2016 and 2018. DSI was defined as concomitant presenting visual acuity (better-eye) >0.3 logarithm of the minimum angle of resolution and a pure-tone air conduction threshold (better-ear) >40 dB HL in any of the four tested frequencies (500, 1000, 2000 and 4000 Hz). HR-QoL was quantified using the EuroQol five-dimension questionnaire. Multivariable Poisson regression was used to determine the associated factors of DSI. Multivariable linear regression was used to determine the association between DSI and HR-QoL adjusted for traditional confounders.Results: Of the 123 residents (age [mean±standard deviation] 75.3 ± 10.8 years; 56.9% male), 97 (78.9%[95% confidence interval(CI):71.6%, 86.1%]) had DSI, with 110 (98.2%) not on follow-up care for their sensory disabilities. In multivariable models, male gender (prevalence ratio(PR) [95%CI] = 1.3[1.1, 1.6]), older age (per 10-year increase (1.2[1.1, 1.3])), education ≤6 years (1.3[1.1, 1.7]) and the presence of cataract (1.3[1.0, 1.7]) were independently associated with DSI. DSI was independently associated with a substantial worsening in HR-QoL (β = -0.61; 95%CI: -0.76, -0.45; p < .001).Conclusions: DSI affects four in five residential care residents and is substantially associated with reductions in HR-QoL in these residents. Our finding highlights an urgent need for the implementation of routine vision and hearing screening and follow-up care for residents living in these facilities.

Impact of incident age-related macular degeneration and associated vision loss on vision-related quality of life

BACKGROUND

We examined the associations between the 6-year incidence of age-related macular degeneration (AMD) and vision-related quality of life (VRQoL), and the contribution of presenting visual acuity (VA), in an Asian population.

METHODS

Fundus images from the Singapore Chinese Eye Study, a population-based cohort study (baseline: 2009-2011; follow-up: 2015-2017), were graded using a modified Wisconsin age-related maculopathy grading system. Incident AMD was defined as no baseline AMD in both eyes and early/late AMD in the worse eye at follow-up. Presenting VA was assessed using the logarithm of the minimum angle of resolution chart at 4 m under standard lighting conditions with habitual correction. Multiple linear regression models determined the associations between AMD incidence with changes in the Rasch-transformed scores of the Reading, Mobility and Emotional VRQoL domains of the 32-item Impact of Visual Impairment (IVI-32) questionnaire, adjusted for traditional confounders. The contribution of presenting VA to changes in VRQoL was also estimated.

RESULTS

Of the 2251 participants without AMD at baseline (mean age (SD): 57.7 (9) years, 51.4% women), 101 (4.5%) and 11 (0.5%) developed incident early and late AMD at follow-up, respectively. Incident late AMD was associated with significant 30.3%, 32.5% and 30.9% decrements in Reading, Mobility and Emotional IVI scores, respectively. The contribution of presenting VA ranged between 1.62% and 4.35% of the observed decrements. No significant associations were noted with incident early AMD.

CONCLUSION

Incident late AMD had a substantial impact on all aspects of VRQoL, with presenting VA contributing only minimally to this longitudinal relationship.

Six-year incidence and systemic associations of retinopathy in a multi-ethnic Asian population without diabetes

PURPOSE

We described the 6-year incidence and changes of retinopathy, and their associated risk factors in a multi-ethnic Asian population without diabetes.

METHODS

We included 4374 participants with non-diabetes from a population-based cohort, the Singapore Epidemiology of Eye Disease Study, with gradable retinal photographs at baseline and 6-year follow-up visit. Retinopathy was assessed according to the modified Airlie House classification system.

RESULTS

Over the 6-year period, the cumulative rates were 2.5% (106/4279) for retinopathy incidence, 1.0% (1/95) for retinopathy progression and 68.4% (65/95) for retinopathy regression. In multivariable analysis, higher diastolic blood pressure (DBP) (risk ratio (RR)=1.02; 95% CI: 1.00 to 1.04; per 10 mm Hg increase in DBP) and wider retinal arteriolar calibre (RR=1.36; 95% CI: 1.13 to 1.63; per SD increase in central retinal artery equivalent) were associated with higher risk of incident retinopathy, while higher level of high-density lipoprotein (HDL) was associated with lower risk of incident retinopathy (RR=0.56; 95% CI: 0.32 to 0.99; per mmol/L increase in HDL). Compared with Chinese, Malays were more likely to have retinopathy regression (RR=1.63; 95% CI: 1.20 to 2.22), while overweight (RR=0.47; 95% CI: 0.26 to 0.84) and higher glycosylated haemoglobin (HbA1c) level (RR=0.58; 95% CI: 0.37 to 0.93; per per cent increase in HbA1c) were associated with lower likelihood of retinopathy regression.

CONCLUSION

Risk of developing retinopathy in Asians without diabetes is generally low. However, regression of retinopathy over time is common, suggesting that these retinopathy signs may reflect subclinical reversible microvascular dysfunction. Several metabolic risk factors are associated with incidence or regression of retinopathy, suggesting that good metabolic control may still be important in the management of non-diabetic retinopathy.

Ethnic differences in the incidence of pterygium in a multi-ethnic Asian population: the Singapore Epidemiology of Eye Diseases Study

We evaluated the 6-year incidence and risk factors of pterygium in a multi-ethnic Asian population. Participants who attended the baseline visit of the Singapore Epidemiology of Eye Diseases Study (year 2004–2011) and returned six years later, were included in this study. Pterygium was diagnosed based on anterior segment photographs. Incident pterygium was defined as presence of pterygium at 6-year follow-up in either eye, among individuals without pterygium at baseline. Multivariable logistic regression models were used to determine factors associated with incident pterygium, adjusting for baseline age, gender, ethnicity, body mass index, occupation type, educational level, income status, smoking, alcohol consumption, presence of hypertension, diabetes and hyperlipidemia. The overall age-adjusted 6-year incidence of pterygium was 1.2% (95% confidence interval [CI] 1.0–1.6%); with Chinese (1.9%; 95% CI 1.4%-2.5%) having the highest incidence rate followed by Malays (1.4%; 95% CI 0.9%-2.1%) and Indians (0.3%; 95% CI 0.3–0.7%). In multivariable analysis, Chinese (compared with Indians; odds ratio [OR] = 4.21; 95% CI 2.12–9.35) and Malays (OR 3.22; 95% CI 1.52–7.45), male (OR 2.13; 95% CI 1.26–3.63), outdoor occupation (OR 2.33; 95% CI 1.16–4.38), and smoking (OR 0.41; 95% CI 0.16–0.87) were significantly associated with incident pterygium. Findings from this multi-ethnic Asian population provide useful information in identifying at-risk individuals for pterygium.

Machine learning to determine relative contribution of modifiable and non-modifiable risk factors of major eye diseases

AIMS

To use machine learning (ML) to determine the relative contributions of modifiable and non-modifiable clinical, metabolic, genetic, lifestyle and socioeconomic factors on the risk of major eye diseases.

METHODS

We conducted analyses in a cross-sectional multi-ethnic population-based study (n=10 033 participants) and determined a range of modifiable and non-modifiable risk factors of common eye diseases, including diabetic retinopathy (DR), non-diabetic-related retinopathy (NDR); early and late age-related macular degeneration (AMD); nuclear, cortical and posterior subcapsular (PSC) cataract; and primary open-angle (POAG) and primary angle-closure glaucoma (PACG). Risk factors included individual characteristics, metabolic profiles, genetic background, lifestyle patterns and socioeconomic status (n~100 risk factors). We used gradient boosting machine to estimate the relative influence (RI) of each risk factor.

RESULTS

Among the range of risk factors studied, the highest contributions were duration of diabetes for DR (RI=22.1%), and alcohol consumption for NDR (RI=6.4%). For early and late AMD, genetic background (RI~20%) and age (RI~15%) contributed the most. Axial length was the main risk factor of PSC (RI=30.8%). For PACG, socioeconomic factor (mainly educational level) had the highest influence (20%). POAG was the disease with the highest contribution of modifiable risk factors (cumulative RI~35%), followed by PACG (cumulative RI ~30%), retinopathy (cumulative RI between 20% and 30%) and late AMD (cumulative RI ~20%).

CONCLUSION

This study illustrates the utility of ML in identifying factors with the highest contributions. Risk factors possibly amenable to interventions were intraocular pressure (IOP) and Body Mass Index (BMI) for glaucoma, alcohol consumption for NDR and levels of HbA1c for DR.

Patterns and Determinants of Choroidal Thickness in a Multiethnic Asian Population: The Singapore Epidemiology of Eye Diseases Study

PURPOSE

To describe the distribution and determinants of choroidal thickness (CT) in participants in a population study based on spectral-domain (SD)-OCT measurements.

DESIGN

Population-based, cross-sectional study.

PARTICIPANTS

Ethnic Chinese, Indian, and Malay adults aged more than 50 years without any retinal diseases (e.g., diabetic retinopathy, macular edema, age-related macular degeneration, central serous chorioretinopathy) that might affect the CT were recruited from the Singapore Epidemiology of Eye Diseases Study.

METHODS

Choroidal imaging was performed by SD-OCT (Spectralis, Heidelberg Engineering, Heidelberg, Germany) in enhanced depth imaging (EDI) mode. Subfoveal choroidal thickness (SFCT) was measured on the foveal line scan by 2 retinal experts independently (YS and KT), and the average was used in the analyses. In Chinese and Indian cohorts in whom macular raster scans were captured, the manufacturer-supplied research software (Heyex SP-X version 6.4.8.116; Heidelberg Engineering) was used to obtain automated segmentation yielding mean choroidal thickness in each of the 9 ETDRS grid sectors.

MAIN OUTCOME MEASURES

Subfoveal choroidal thickness and regional CT in the 9 ETDRS grid sectors.

RESULTS

For the SFCT analysis, 2794 eyes of 1619 participants (Chinese, Indian, and Malay ) were included. The mean age was 60.9 years (standard deviation, 7.7), and 797 (49.2%) were male. Mean SFCT was 255.2 μm (standard deviation, 102.6). The normal range of SFCT was 106 to 447 μm (corresponding to 5^th and 95^th percentile limits of SFCT, respectively). In multivariable models, thinner SFCT was associated with older age, female gender, longer axial length, and Malay (vs. Chinese) ethnicity. In the subset of Chinese and Indian eyes (n = 1842) in whom regional variation was evaluated, the choroid was thickest at the superior and temporal sectors and thinner at the inferior and nasal sectors.

CONCLUSIONS

Subfoveal choroidal thickness is influenced by age, gender, and ethnicity along with regional differences even within individual eyes. Subfoveal choroidal thickness also shows a wide range in physiologic limits. These data may be used as a reference in future studies.

Characteristics of myopic traction maculopathy in myopic Singaporean adults

PURPOSE

To investigate the characteristics, risk factors and visual impact of myopic traction maculopathy (MTM) among adults with myopia in Singapore.

METHODS

We analysed 3316 myopic eyes of adults aged over 40 years who participated in the Singapore Epidemiology of Eye Diseases-2 study. Detailed questionnaires and ophthalmic examinations were conducted. A total of 2913 myopic eyes of 1639 subjects were graded for MTM by spectral-domain optical coherence tomography. MTM is defined as the presence of retinoschisis, lamellar or full-thickness macula hole and foveal retinal detachment. Fundus photographs were graded for myopic macular degeneration (MMD).

RESULTS

Of these 2913 myopic eyes, the mean and SD of age was 60.1±8.0 years; the spherical equivalent (SE) was -2.5±2.3 D; and the axial length (AL) was 24.6±1.3 mm. MTM was found in 0.9% of myopic eyes and 7.3% of highly myopic eyes. In the multivariate analysis, myopic SE (p<0.001), longer AL (p<0.001), MMD (p=0.01) and epiretinal traction (p<0.001) were independent risk factors for MTM. MTM was not associated with age (p=0.38). MTM was significantly associated with poorer best-corrected visual acuity (BCVA) (p<0.01).

CONCLUSIONS

Our population-based study revealed that MTM was present in 0.9% of myopic eyes and 7.3% of highly myopic eyes. While greater myopic SE, longer AL, MMD and epiretinal traction are risk factors of MTM, age was not related to MTM. MTM has a negative effect on BCVA.

Using Uniocular Visual Acuity Substantially Underestimates the Impact of Visual Impairment on Quality of Life Compared with Binocular Visual Acuity

PURPOSE

Although the impact of vision-related quality of life (VRQoL) is assessed optimally using binocular visual acuity (VA), uniocular VA remains the preferred measurement method in clinic-based and epidemiologic studies. We compared the impact of distance presenting binocular VA and uniocular VA in the better-seeing (better-eye VA) and worse-seeing (worse-eye VA) eye on VRQoL.

DESIGN

The Singapore Chinese Eye Study 2 (2015-2017), a population-based, cross-sectional study.

PARTICIPANTS

One thousand eight hundred twenty-two individuals (mean age, 66.2 years [standard deviation, 8.9 years]; 51.1% women) were included.

METHODS

Presenting uniocular VA and binocular VA were assessed using a logarithm of the minimum angle of resolution number chart at a distance of 4 m under standard lighting by trained and certified study optometrists. Multiple linear regression models were constructed to determine the independent associations between binocular VA, better-eye VA, and worse-eye VA and the outcome (VRQoL), adjusted for potential confounders, including age, gender, socioeconomic status, and presence of comorbidities. In addition, a cluster sandwich estimator was used to determine if any differences in β estimates between the associations were statistically significant.

MAIN OUTCOME MEASURES

Vision-related quality of life was measured using Rasch-transformed scores from the emotional, mobility, and reading domains of the Impact of Visual Impairment (IVI) questionnaire.

RESULTS

Although every 2-line increase (worsening) in binocular VA and uniocular VA was associated independently with decrements in emotional, mobility, and reading IVI scores (P < 0.05 for all), the reductions in all VRQoL domains were substantially lower (P < 0.1) when using either the better-eye VA (compared with binocular VA β-estimates, -27.8%, -19.4%, and -24.2% difference in emotional, mobility, and reading IVI scores, respectively) or worse-eye VA (compared with binocular VA β estimates, -38.9%, -58.1%, and -57.5% reduction in emotional, mobility, and reading IVI scores, respectively) to quantify vision loss.

CONCLUSIONS

Uniocular VA seems to underestimate the impact of vision loss on VRQoL indices compared with binocular VA. Our data suggest that researchers, clinicians, and policy planners should consider using binocular instead of uniocular measures of VA in patient-reported outcome evaluation of vision loss because it may better reflect its impact on VRQoL.