Myopia and incident cataract and cataract surgery: the blue mountains eye study

To assess whether an association exists between myopia and incident cataract and cataract surgery in an older population-based cohort study.

The Blue Mountains Eye Study examined 3654 participants aged 49 years or more during 1992 to 1994 and then 2334 (75.1%) of the survivors after 5 years. A history of using eyeglasses for clear distance vision was obtained. Objective refraction was performed with an autorefractor, followed by subjective refraction with a logarithm of minimum angle of resolution (logMAR) chart. Emmetropia was defined as a spherical equivalent refraction between +1 D and -1 D, hyperopia as more than +1 D, and myopia as less than -1 D. Slit lamp and retroillumination lens photographs were graded for presence of cortical, nuclear, or posterior subcapsular cataract, according to the Wisconsin Cataract Grading System. Generalized estimating equation models analyzed data by eye.

There was a statistically significant association between high myopia (-6 D or less) and incident nuclear cataract (odds ratio [OR] 3.3, 95% confidence interval [CI] 1.5-7.4). Incident posterior subcapsular cataract was associated with any myopia (OR 2.1, 95% CI 1.0-4.8), moderate to high myopia (-3.5 D or less, OR 4.4, 95% CI 1.7-11.5), and use of distance glasses before age 20 (OR 3.0, 95% CI 1.0-9.3), after adjustment for multiple potential confounders, including severity of nuclear opacity. Incident cataract surgery was significantly associated with any myopia (OR 2.1, 95% CI 1.1-4.2) as well as moderate (-3.5 to more than -6D; OR 2.9, 1.2-7.3) and high myopia (OR 3.4, 95% CI 1.0-11.3).

These epidemiologic data provide some evidence of an association between myopia and incident cataract and cataract surgery, after adjustment for multiple confounders and severity of nuclear opacity. These data support other cross-sectional and longitudinal population-based findings.