Prevalence and Causes of Visual Impairment and Blindness among Adult Chinese in Hong Kong – The Hong Kong Eye Study

Sector-Based Regression Strategies to Reduce Refractive Error-Associated Glaucoma Diagnostic Bias When Using OCT and OCT Angiography

Purpose

This cross-sectional study aimed to investigate the sectoral variance of optical coherence tomography (OCT) and OCT angiography (OCTA) glaucoma diagnostic parameters across eyes with varying degrees of refractive error.

Methods

Healthy participants, including individuals with axial ametropia, enrolled in the Hong Kong FAMILY cohort were imaged using the Avanti/AngioVue OCT/OCTA system. The OCT and OCTA parameters obtained include peripapillary nerve fiber layer thickness (NFLT), peripapillary nerve fiber layer plexus capillary density (NFLP-CD), and macular ganglion cell complex thickness (GCCT). Sectoral measurements of NFLT, NFLP-CD, and GCCT were based on sectors and hemispheres.

Results

A total of 1339 eyes from 791 participants were stratified based on spherical equivalent refraction: high myopia (<-6 D), low myopia (-6 D to -1 D), emmetropia (-1 D to 1 D), and hyperopia (>1 D). Multivariable broken stick regression models, accounting for age, sex, and signal strength, showed that all NFLT sectors except temporally, the inferior GCCT hemisphere, and half of the NFLP-CD sectors were more affected by ametropia-related covariates than the corresponding global parameters. As expected, the false-positive rates in those sectors were elevated. Finally, sector-specific axial length (AL) and spherical equivalent (SE) adjustments helped reduce the elevated false-positive rates.

Conclusions

The effect of optical magnification is even more prominent among sectors than the global parameters. AL- and SE-based adjustments should be individualized to each sector to mitigate this magnification bias effectively.

Translational Relevance

Identifying sectoral differences among diagnostic parameters and adopting these sector-based adjustments into commercial OCT systems will hopefully reduce false-positive rates related to refractive error.

Determinants of late presentation of glaucoma in Hong Kong

BACKGROUND

Glaucoma is the commonest cause of irreversible blindness worldwide. As it is typically asymptomatic until advanced, the risk of blindness from late presentation is higher than other eye diseases. This study aims to investigate the risk factors for late presentation of primary glaucoma patients.

METHODS

We undertook a hospital-based case-control study of a random sample of glaucoma patients from a hospital in Hong Kong. Structured questionnaires and existing information from the electronic patient record were used, and the odds of presenting late were analysed by logistic regression.

RESULTS

Of 210 recruited participants, 83 (39.5%) presented with advanced glaucoma unilaterally or bilaterally. The mean age of participants was 61.1 ± 11.9 years, with 110 males (52.4%). Univariate analysis revealed that male sex and primary angle-closure glaucoma (PACG) have 3.06 (CI95:1.71-5.48; P < 0.001) and 2.47 (CI95:1.11-5.49; P = 0.03) times higher odds of late presentation, respectively. Multivariate analysis revealed late presenters were 3.54 (CI95:1.35-9.35; P = 0.01) times more likely to have PACG than primary open-angle glaucoma (POAG). Patients with elevated baseline intraocular pressure (IOP) also had 1.06 times higher odds of presenting with advanced glaucoma (CI95:1.02-1.11; P = 0.002). Linear regression revealed that PACG patients present with 7.12 mmHg higher IOP than POAG patients (CI95:4.23-10.0; P < 0.001).

CONCLUSION

In conclusion, a high proportion of glaucoma patients present late in Hong Kong, with gender and type of glaucoma being significant determinants. Our study shows that PACG presents with higher IOP and, along with male gender, are more likely to have advanced disease than POAG.

Prevalence, Causes, and Risk Factors of Presenting Visual Impairment and Presenting Blindness in Adults Presenting to an Examination Center in Suzhou, China

Purpose

To evaluate the prevalence, causes, and risk factors of presenting visual impairment (PVI) and presenting blindness among adults in Suzhou, China.

Methods

A total of 43927 subjects were included in this cross-sectional study. Each subject underwent ophthalmic examinations, including presenting visual acuity (PVA), intraocular pressure (IOP), slit-lamp examination, and fundus examination under the small pupils of each eye.

Results

Using the World Health Organization (WHO) definition, the prevalence of bilateral PVI, bilateral presenting blindness, monocular PVI, and monocular presenting blindness was 1.59% (95% CI, 1.51-1.67), 0.002% (95% CI, 0.0019-0.0021), 3.87% (95% CI, 3.68-4.06), and 0.19% (95% CI, 0.18-0.20), respectively. Using the United States (US) definition, the prevalence of bilateral PVI, bilateral presenting blindness, monocular PVI, and monocular presenting blindness was 5.83% (95% CI, 5.54-6.12), 0.04% (95% CI, 0.038-0.042), 7.43% (95% CI, 7.06-7.80), and 0.45% (95% CI, 0.43-0.47), respectively. The prevalence of PVI was higher in females (WHO criteria, 2.06%, 95% CI, 1.96-2.16; US criteria, 7.27%, 95% CI, 6.91-7.63) than in males (WHO criteria, 1.2%, 95 CI%, 1.14-1.26; US criteria, 4.65%, 95% CI, 4.42-4.89). The leading cause of PVI is an uncorrected refractive error, followed by cataracts and age-related macular degeneration (AMD). Multivariate analysis proved that the prevalence of visual impairment (PVA, better eye, WHO criteria) increased significantly with older age, higher mean arterial pressure (MAP), higher globulin level, and higher fasting blood glucose (FBG). In addition, it also increased significantly with lower hemoglobin, a lower body mass index (BMI), and a lower arterial stiffness index. In this study, serum creatinine, blood urea nitrogen, uric acid, triglycerides, and the systemic immune-inflammation index (SII) showed no association with visual impairment.

Conclusion

The leading causes of PVI in Suzhou were uncorrected refractive error and cataracts. The prevalence of PVI increased with females, older age, higher MAP, higher FBG, higher globulin, lower hemoglobin, lower BMI, and lower arterial stiffness index.

Epidemiology, health policy and public health implications of visual impairment and age-related eye diseases in mainland China

The prevalence of visual impairment (VI) and age-related eye diseases has increased dramatically with the growing aging population in mainland China. However, there is limited comprehensive evidence on the progress of ophthalmic epidemiological research in mainland China to enhance our awareness of the prevention of eye diseases to inform public health policy. Here, we conducted a literature review of the population-based epidemiology of VI and age-related eye diseases in mainland China from the 1st of January 1946 to the 20th of October 2021. No language restrictions were applied. There was significant demographic and geographic variation in the epidemic of VI and age-related eye diseases. There are several factors known to be correlated to VI and age-related eye diseases, including age, gender, family history, lifestyle, biological factors, and environmental exposures; however, evidence relating to genetic predisposition remains unclear. In addition, posterior segment eye diseases, including age-related macular degeneration and diabetic retinopathy, are amongst the major causes of irreversible visual impairments in the senile Chinese population. There remains a significant prevention gap, with only a few individuals showing awareness and achieving optimal medical care with regards to age-related eye diseases. Multiple challenges and obstacles need to be overcome, including the accelerated aging of the Chinese population, the lack of structured care delivery in many underdeveloped regions, and unequal access to care. Despite the progress to date, there are few well-conducted multi-center population-based studies following a single protocol in mainland China, which findings can hopefully provide valuable cues for governmental decision-making and assist in addressing and halting the incidence of VI and age-related eye diseases in China.

Regression-Based Strategies to Reduce Refractive Error-Associated Glaucoma Diagnostic Bias When Using OCT and OCT Angiography

Purpose

The purpose of this study was to correct refractive error-associated bias in optical coherence tomography (OCT) and OCT angiography (OCTA) glaucoma diagnostic parameters.

Methods

OCT and OCTA imaging were obtained from participants in the Hong Kong FAMILY cohort. The Avanti/AngioVue OCT/OCTA system was used to measure the peripapillary nerve fiber layer thickness (NFLT), peripapillary nerve fiber layer plexus capillary density (NFLP-CD), macular ganglion cell complex thickness (GCCT), and macular superficial vascular complex vascular density (SVC-VD). Healthy eyes, including ones with axial ametropia, were enrolled for analysis.

Results

A total of 1346 eyes from 792 participants were divided into 4 subgroups: high myopia (<−6D), low myopia (−6D to −1D), emmetropia (−1D to 1D), and hyperopia (>1D). After accounting for age, sex, and signal strength, multivariable regression showed strong dependence in most models for NFLT, GCCT, and NFLP-CD on axial eye length (AL), spherical equivalent (SE) refraction, and apparent optic disc diameter (DD). Optical analysis indicated that AL-related transverse optical magnification variations predominated over anatomic variations and were responsible for these trends. Compared to the emmetropic group, the false positive rates were significantly (Chi-square test P < 0.003) elevated in both myopia groups for NFLT, NFLP-CD, and GCCT. Regression-based adjustment of these diagnostic parameters with AL or SE significantly (McNemar test P < 0.03) reduced the elevated false positive rates.

Conclusions

Myopic eyes are biased to have lower NFLT, GCCT, and NFLP-CD measurements. AL- and SE-based adjustments were effective in mitigating this bias.

Translational Relevance

Adoption of these adjustments into commercial OCT systems may reduce false positive rates related to refractive error.

An evaluation of a community-based vision care programme for the elderly

Background

This study evaluated the real-world effectiveness and potential cost-effectiveness of a community-based vision care programme for the elderly population aged 60 years or above.

Methods

Data from a total of 8899 subjects participating in a community-based comprehensive vision care programme from 2015 to 2019 were analysed to evaluate the effectiveness of the programme in terms of the prevalence of distance visual impairment (VI), the change in the prevalence of distance VI after refractive error correction, and the types of ocular disorders suspected. Distance VI was defined as a) visual acuity (VA) worse than 6/18 in any eye (worse eye) and b) VA worse than 6/18 in the better eye. The cost-effectiveness from the funder’s perspective was also estimated in terms of cost per distance VI avoided.

Results

Based on the presenting vision of the worse eye, the prevalence of distance VI was 39.1% (3482/8899, 95% CI: 38.1%-40.1%) and reduced to 13.8% (1227/8899, 95% CI: 13.1%-14.5%) based on best-corrected VA. Referenced to the presenting vision of the better eye, the prevalence of distance VI was 17.3% (1539/8899, 95% CI: 16.5%-18.1%) and decreased to 4.2% (373/8899, 95% CI: 3.8%-4.6%) with best optical correction. Uncorrected refractive error was the major cause of presenting distance VI. From the funder’s perspective, the cost per distance VI case prevented was HK$1921 based on VA in the worse eye and HK$3715 based on the better eye.

Conclusion

This community-based programme identified distance VI in the best eye of 17 out of every 100 subjects. With appropriate new or updated distance optical corrections, distance VI was reduced to about 4 in 100 subjects. Visual impairment in the elderly is common even in a relatively affluent city. A model of care which could minimise avoidable distance VI would bring benefits at individual and societal levels.

Incidence and Clinical Practice of Exudative Age-related Macular Degeneration

Purpose

To elucidate the incidence and treatment pattern of active exudative age-related macular degeneration (AMD).

Design

A population-based cohort study conducted using the National Database of Health Insurance Claims and Specific Health Checkups of Japan (NDB), a national claims database managed by the Japanese Ministry of Health, Labour, and Welfare (MHLW).

Participants

The entire Japanese population aged 40 years or older (76 million people).

Methods

With the permission of the MHLW, we accessed the complete NDB dataset and identified patients with newly diagnosed active exudative AMD between 2011 and 2018. The incidence of active exudative AMD was categorized by age and sex per year between 2011 and 2018; moreover, details regarding first-line therapy and number of anti-vascular endothelial growth factor (VEGF) injections per elapsed year since initial treatment were obtained and changes in treatment pattern were investigated.

Main Outcome Measures

Incidence rate of active exudative AMD.

Results

During the specified 8-year period, 246 064 incident cases of active exudative AMD were identified; 61.4% of these patients were men. The overall incidence rate was 40.66 per 100 000 person-years (95% confidence interval [CI], 40.49–40.82) in the general population aged 40 years or older, 53.22 (95% CI, 52.95–53.49) in men, and 29.78 (95% CI, 29.60–29.98) in women. Mean age of onset was lower in men than in women (72.51 ± 10.50 years vs. 73.90 ± 10.46 years). Among patients with newly diagnosed active exudative AMD, 92.9% received anti-VEGF injections for initial treatments, whereas 1.8% underwent combination therapy with photodynamic therapy. The number of anti-VEGF injections in the first year (0–12 months), second year (13–24 months), and third year (25–36 months) after the initial injection was 3.66 ± 2.30, 1.39 ± 2.20, and 1.23 ± 2.19, respectively. Patients who received fewer injections in the first year received fewer injections in subsequent years and vice versa.

Conclusions

This is a relatively large population-based study on the detailed epidemiology and actual treatment patterns of active exudative AMD in clinical practice. Our results can be a fundamental information source to ensure healthy eyes and promote well-being for all at all ages.

Prevalence, Causes, and Risk Factors of Visual Impairment in Emiratis and Non-Emiratis of Dubai: A Subnational Population-Based Cross-Sectional Survey

Purpose

To study the prevalence, causes, and risk factors of visual impairment (VI) among the Dubai Emiratis and non-Emiratis.

Methods

The survey was a population-based cross-sectional eye health study conducted 2019-2020. Cluster sampling was used to randomly select local (Emirati) and expatriate (non-Emirati) Dubai residents aged 40 years and older. Ocular examinations were conducted in selected eye clinics to determine the visual acuity (VA) and cause(s) of VI if any. Trained nurses, optometrists, and ophthalmologists did the examinations. VA was measured using ETDRS visual chart. The World Health Organization VI and blindness definitions and classifications for the cause(s) of VI were used.

Results

A total of 892 participants were included in the final analysis. The mean age [SD] was 52.09 [9.48] years, with 55.8% as males. Prevalence of presenting mild, moderate, and severe VI was 4.7% (2.94–7.11%), 1.8% (0.78–3.5%), and 0% for Emiratis, and 3.6% (2.06–5.76), 1.6% (0.63–3.21), and 0% for non-Emiratis, respectively. Four Emirati participants were blind, with a prevalence of 0.9% (0.25%–2.28%). Men had lower likelihood of VI than women (odds ratio [OR] (95% CI): 0.42 (0.24–0.77)) after adjustment for covariates. Diabetes (OR (95% CI): 1.91 (1.04–3.52)) was an independent risk factor for VI. Higher education level was associated with a lower likelihood of VI (OR (95% CI): 0.34 (0.13–0.89). Leading causes of VI among Emiratis were uncorrected refractive error (52%) and cataract (17.2%). Glaucoma, optic atrophy, and absent globe were the causes of blindness.

Conclusions

Prevalence of VI is comparably low with leading causes readily treatable. An effective strategy to improve spectacle correction and cataract services would reduce the VI burden.

Prospective Comparative Study Investigating Agreement between Tele-Ophthalmology and Face-to-face Consultations in Patients Presenting with Chronic Visual Loss

Introduction

This study aims to investigate the diagnostic accuracy of store-and-forward tele-ophthalmology consultations for non-diabetic patients, aged 40 and above, presenting with vision impairment of 3 months or more, in terms of cataracts, glaucoma, and age-related macular degeneration.

Methods

This is a prospective comparative study. Enrolled subjects were independently assessed by both tele-ophthalmology and face-to-face assessment. Agreement level between the two modalities for diagnosis and severity were compared using kappa statistic. Diagnostic accuracy of tele-ophthalmology was determined using the face-to-face consultation serving as the gold standard. Costs were compared by calculating the downstream costs generated by each modality in terms of investigations and treatment.

Results

A total of 860 eyes of 430 patients were assessed during the study period. Tele-ophthalmology consultations had significantly high agreement with face-to-face consultations in the diagnosis and grading of all three ocular conditions; cataracts, glaucoma, and AMD. Diagnosis and grading of cataracts and AMD reached \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\kappa$$\end{document}κ values of > 0.8, while diagnosis and grading of glaucoma reached \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\kappa$$\end{document}κ values between 0.61 and 0.8. In terms of diagnostic accuracy, tele-ophthalmology consultations were highly sensitive and specific for AMD with greater than 99% sensitivity and specificity achieved by tele-ophthalmology. There was high specificity when diagnosing cataracts, but lower sensitivity at 87.8%. Conversely, there was high sensitivity for diagnosing glaucoma, but lower specificity at 76.5%. Downstream costs were similar between groups.

Conclusions

Store-and-forward tele-ophthalmology consultations are accurate and comparable to face-to-face consultations for diagnosis and grading of cataracts, glaucoma, and AMD.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40123-022-00506-x.

Retinal Nerve Fiber Layer Thickness and Rim Area Profiles in Asians: Pooled Analysis from the Asian Eye Epidemiology Consortium

PURPOSE

To evaluate ethnic variations, ocular and systemic determinants of retinal nerve fibre layer (RNFL) thickness and neuroretinal rim area among Asians, using a large consortium of population-based eye studies.

DESIGN

Cross-sectional pooled-analysis.

PARTICIPANTS

22436 participants (22436 eyes) from 10 population-based studies (China, Hong Kong, India, Japan, Russia and Singapore) of the Asian Eye Epidemiology Consortium.

METHODS

Participants aged ≥40 years without glaucoma were included. All participants underwent spectral domain optical coherence tomography (OCT) imaging, systemic and ocular examinations. Data were pooled from each study. Multivariable regression analysis was performed to evaluate inter-ethnic, inter-machine variations, ocular and systemic factors associated with RNFL thickness and rim area, adjusting for age, gender, diabetes, intraocular pressure (IOP), spherical equivalent (SE), ethnicity, OCT model, and study group. When evaluating body mass index, smoking, and hypertension as exposures, these factors were additionally adjusted in the model.

MAIN OUTCOME MEASURE

Average RNFL thickness (μm) and rim area (mm²) RESULTS: Indian and Japanese eyes showed thinner RNFL, compared to other Asian ethnicities (β values ranging 7.31-12.76μm, P<0.001 for all pair-wise comparisons). Compared to measurements by Cirrus HD-OCT, RNFL was on average 7.29μm thicker when measured by Spectralis, 12.85μm thicker by Nidek, and 17.48μm thicker by Optovue (all P<0.001). Additionally, older age (per decade, β=-2.70; 95% confidence interval [CI], -2.85 to -2.55), diabetes (β=-0.72; 95%CI, -1.20 to -0.24), ), higher IOP (per mmHg, β=-0.07; 95% CI, -0.10 to -0.04), more myopic SE (per dioptre, β=-1.13; 95% CI, -1.19 to -1.07), cardiovascular disease (CVD, β=-0.94; 95% CI, -1.49 to -0.40), and hypertension (β=-0.68; 95% CI, -1.04 to -0.32), were associated with thinner RNFL (all P≤0.003). Similarly, older age (β=-0.019; 95% CI, -0.028 to -0.009), higher IOP (β=-0.010; 95% CI, -0.013 to -0.008) and more myopic SE (β=-0.025; 95% CI, -0.029 to -0.021) were associated with smaller rim area (all P<0.001).

CONCLUSIONS

In this large pooled-analysis of multiple Asian population studies, Indian and Japanese eyes were observed to have thinner RNFL profiles. In addition to previously known determinants, hypertension and CVD were associated with thinner RNFL. These findings further suggest the need of ethnic-specific normative database to improve glaucoma detection.

Prevalence, Causes, and Factors Associated with Visual Impairment in a Chinese Elderly Population: The Rugao Longevity and Aging Study

Purpose

This study aimed to explore the current prevalence, causes, and factors associated with visual impairment in a Chinese elderly population.

Methods

A random sample of 2164 candidates aged ≥70 years was selected. Among them, 1914 participants (response rate: 88.4%) underwent comprehensive eye examinations. The prevalence and causes of visual impairment were estimated, and the associated factors were identified.

Results

The standardized prevalence of mild visual impairment (<6/12 to ≥6/18), moderate to severe visual impairment (MSVI) (<6/18 to ≥3/60), and blindness (<3/60) in the better eye were 20.5%, 25.8%, and 3.4%, respectively. The leading cause of visual impairment was cataract (49.7%), followed by uncorrected refractive error (26.5%), myopic maculopathy (5.8%), and posterior capsular opacification (5.5%). Optical coherence tomography revealed that vitreoretinal interface abnormalities were the third most common cause of monocular mild visual impairment (2.2%) and MSVI (4.4%) in the elderly population. A large number of patients with visual impairment (81.7%) were amenable to undergo the interventions. Visual impairment was associated with advanced age (odds ratio [OR], 1.09 per year; p<0.001), female sex (OR, 1.59; p=0.003), self-reported visual impairment (OR, 1.91; p<0.001), cognitive impairment (OR, 1.40, p=0.005), and high educational level (OR, 0.75; primary, p=0.045; and OR, 0.53, secondary or higher; p<0.001).

Conclusion

Visual impairment was common in the Chinese elderly population and a severe health and social problem. Practicable policies are urgently needed to popularize eye health knowledge and promote treatments for visual impairment in elderly people in rural China.

Global Prevalence of Diabetic Retinopathy and Projection of Burden through 2045: Systematic Review and Meta-analysis

TOPIC

To provide updated estimates on the global prevalence and number of people with diabetic retinopathy (DR) through 2045.

CLINICAL RELEVANCE

The International Diabetes Federation (IDF) estimated the global population with diabetes mellitus (DM) to be 463 million in 2019 and 700 million in 2045. Diabetic retinopathy remains a common complication of DM and a leading cause of preventable blindness in the adult working population.

METHODS

We conducted a systematic review using PubMed, Medline, Web of Science, and Scopus for population-based studies published up to March 2020. Random effect meta-analysis with logit transformation was performed to estimate global and regional prevalence of DR, vision-threatening DR (VTDR), and clinically significant macular edema (CSME). Projections of DR, VTDR, and CSME burden were based on population data from the IDF Atlas 2019.

RESULTS

We included 59 population-based studies. Among individuals with diabetes, global prevalence was 22.27% (95% confidence interval [CI], 19.73%-25.03%) for DR, 6.17% (95% CI, 5.43%-6.98%) for VTDR, and 4.07% (95% CI, 3.42%-4.82%) for CSME. In 2020, the number of adults worldwide with DR, VTDR, and CSME was estimated to be 103.12 million, 28.54 million, and 18.83 million, respectively; by 2045, the numbers are projected to increase to 160.50 million, 44.82 million, and 28.61 million, respectively. Diabetic retinopathy prevalence was highest in Africa (35.90%) and North American and the Caribbean (33.30%) and was lowest in South and Central America (13.37%). In meta-regression models adjusting for habitation type, response rate, study year, and DR diagnostic method, Hispanics (odds ratio [OR], 2.92; 95% CI, 1.22-6.98) and Middle Easterners (OR, 2.44; 95% CI, 1.51-3.94) with diabetes were more likely to have DR compared with Asians.

DISCUSSION

The global DR burden is expected to remain high through 2045, disproportionately affecting countries in the Middle East and North Africa and the Western Pacific. These updated estimates may guide DR screening, treatment, and public health care strategies.