Refractive Error, Ocular Biometry, and Lens Opalescence: The Chinese American Eye Study

Abstract

Purpose: : To characterize age- and gender-related differences in refractive error (RE), ocular biometry, and lens nuclear opalescence (NOP) in a population-based sample of adult Chinese Americans in the city of Monterey Park, California.

Methods: : Participants in the Chinese American Eye Study (CHES), a population-based study of Chinese Americans aged 50 years and older, underwent an ophthalmic examination, including ultrasonic measurements of axial length (AL), central corneal thickness (CCT), vitreous chamber depth (VCD), anterior chamber depth (ACD), lens thickness (LT), and noncycloplegic automated and subjective refraction. Corneal curvature/power (CP) was measured using an autorefractor. NOP was graded at the slit lamp by ophthalmologists using the Lens Opacity Classification System II. Only the phakic eyes were included in the analyses. Age- and gender-related differences were assessed with adjustment for age and height when applicable. Multiple regression models were used to identify the determinants of refractive differences.

Results: : A total of 2286 CHES participants (1553 women, 915 men) were included in the analysis. Overall, the mean (±standard deviation) RE was -0.59 (± 3.00). No gender-related difference was found. Women had significantly shorter AL (23.6±1.4, vs. 24.2±1.3, p=0.0216) and ACD (3.3±0.4 vs. 3.4±0.4, p<0.0001) compared to men, after adjusting for age and height. No statistical differences were found in CP, VCD, LT and NOP between men and women. The statistical difference in CCT between genders was clinically insignificant. Older individuals had shallower ACD (3.4±0.3 vs. 3.1±0.4 for women, 3.5±0.3 vs. 3.2±0.4 for men), thicker lenses (4.4±0.4 vs. 4.7±0.6 for women, 4.4±0.4 vs. 4.8±0.5 for men), and more NOP compared to younger individuals (all p < 0.001). There were no age-related differences noted in CP, AL, VCD and CCT. AL was found to be the strongest determinant of RE; when individual components of AL were evaluated, VCD had the greatest contributing effect, followed by CP, LT, ACD and CCT.

Conclusions: : This study supports the finding observed in the Los Angeles Latino Eye Study that AL is a significant determinant of RE. Future studies should be considered to look at the differences in risk factors associated with RE among other Asian/Chinese population-based studies.

Keywords: clinical (human) or epidemiologic studies: biostatistics/epidemiology methodology • anatomy • anterior segment