Refractive associations with cataract: the Blue Mountains Eye Study

Area of Science:

• Ophthalmology
• Gerontology
• Epidemiology

Background:

• Age-related cataract is a leading cause of vision impairment in older adults.
• Myopia, or nearsightedness, is a common refractive error with potential links to ocular pathologies.
• Understanding the relationship between myopia and cataract is crucial for eye health management in aging populations.

Purpose of the Study:

• To investigate the association between myopia and the development and severity of age-related cataract.
• To determine if different types of cataract (nuclear, cortical, posterior subcapsular) are differentially related to myopia.
• To explore potential dose-response relationships between myopia severity and cataract risk.

Main Methods:

• A cross-sectional study involving 3654 participants aged 49-97 years in Australia.
• Ophthalmic examinations included refraction assessment and masked grading of lens photographs using the Wisconsin Cataract Grading System.
• Statistical analysis using generalized estimating equations adjusted for known cataract risk factors.

Main Results:

• History of wearing distance glasses (proxy for myopia) was associated with increased odds of nuclear cataract, particularly when myopia onset was after age 40.
• Early-onset myopia (before age 20) showed a strong association with posterior subcapsular cataract (PSC) risk (OR 3.9).
• A dose-response relationship was observed between myopia severity and PSC cataract risk; high myopia was linked to PSC, cortical, and nuclear cataracts.

Conclusions:

• Early-onset myopia is a significant independent risk factor for posterior subcapsular cataract.
• Findings suggest a potential dose-response effect between myopia levels and PSC cataract.
• Acquired myopia is linked to nuclear cataract, while high myopia is associated with all three cataract types studied.