Prevalence, Risk Factors, and Impact of Undiagnosed Visually Significant Cataract: The Singapore Epidemiology of Eye Diseases Study

Abstract

Objective: To determine the prevalence, risk factors, and impact of undiagnosed visually significant cataract in an Asian population.

Methods: The Singapore Epidemiology of Eye Diseases is a population-based study where 8,697 adults of Malay, Indian, and Chinese ethnicities aged > 40 years were invited for an eye examination, including lens photograph, to establish cataract diagnosis. Visually significant cataract was defined by Wisconsin Cataract Grading System and a best-corrected visual acuity <20/40 with cataract as the primary cause of vision impairment. Participants were deemed 'undiagnosed' if they had visually significant cataract and reported no prior physician diagnosis of cataract. Visual functioning (VF) was assessed with the VF-11 questionnaire validated using Rasch analysis.

Results: Among the 925 participants with visually significant cataract, 636 (68.8%) were unaware of their cataract status. Age-standardized prevalence varied according to ethnicity, with Malays having higher rates than Chinese and Indians. Factors independently associated with having undiagnosed visually significant cataract were: Malay ethnicity, lower educational attainment, in employment, and without a history of diabetes (all P<0.05). In those with undiagnosed visually significant cataract, half had bilateral visual impairment, which was significantly associated with 24.8% poorer visual functioning compared to those with unilateral visual impairment (P<0.001).

Conclusions: Two-thirds of Singaporean adults with visually significant cataract were previously undiagnosed. Half of these cases had bilateral visual impairment and substantially reduced quality of life. Public health strategies targeting elderly patients, such as regular screening for visual impairment and timely referral to ophthalmologists in order to prevent progression to bilateral visual impairment when visual function is compromised are warranted.

Fig 1. Flow chart of study participants.

Among those with visually significant cataract, 68.8% (n = 636) had previously undiagnosed cataract. Unknown responses were not reported.

Fig 2. Distribution of the visual functioning scores of participants with undiagnosed vs. diagnosed visually significant cataract stratified by laterality of visual impairment.

50.5% (n = 321) of the undiagnosed participants suffered from bilateral visual impairment, which resulted in a significantly lower visual functioning score than those with unilateral visual impairment (P<0.001 for both undiagnosed and diagnosed groups). Error bars represent 95% confidence intervals. Data and P values shown are after adjustment for age, gender, ethnicity, housing type, living arrangement, education, employment, diabetes, smoking, and awareness of vision deterioration.