Abstract
Purpose :
To investigate distributions of ocular biometry and its associations with cycloplegic refraction in young adults, as well as exploring a complex model to predict the cycloplegic refraction.
Methods :
A school-based study including 7971 undergraduates was conducted in central China. Biometric parameters including axial length (AL), corneal power (CP), anterior chamber depth (AD) and lens thickness (LT) were obtained by an ocular biometry system (Lenstar LS900). Corneal radius of curvature (CR), lens position (LP), lens power (PBennett), vitreous chamber depth (VCD) and axial length to corneal radius ratio (AL/CR) were calculated. Cycloplegic refraction (2 drops of 1% cyclopentolate) was measured by an autorefractor with spherical equivalent refraction (SE) calculated. Multiple linear regression analysis was used to explore associations between SE and ocular biometry. Bland-Altman analysis and ROC curves were applied to analyze consistency between the predicted SE and actual values.
Results :
Among the 7650 students (96.0%) included, mean age was 20.0±1.4 years. Overall, biometric parameters followed Gaussian distributions with means of 24.78±1.21mm for AL and 4.97±0.23mm for LP; and non-Gaussian distributions with means of 7.79±0.27mm for CR, 3.23±0.25mm for AD, 3.47±0.18mm for LT, 25.00±1.07D for PBennett, 17.55±1.15mm for VCD and 3.18±0.15 for AL/CR. Male showed longer AL, deeper AD and VCD, whereas female had more powerful cornea and thicker lens, with similar AL/CR. Myopia had longer AL, shorter CR, thinner and posterior lens, deeper AD and VCD, and larger AL/CR than emmetropia and hyperopia. AL/CR, AL, and VCD correlated strongly with SE (r= -0.914, -0.755, -0.751). When AL/CR, LT, AD and VCD were included in the multiple linear regression model, 92.1% of the variance in SE could be explained, with one unit increase in AL/CR associated with -14.43D of SE. The difference between the predicted SE and the actual value was 0.00±0.69D, and the area under ROC curve was 0.979.
Conclusions :
Male shows longer AL, deeper AD and VCD, whereas female has more powerful corneas and thicker lens. Cycloplegic refraction is strongest associated with AL/CR than any biometric parameter alone. Besides, variance in SE could be well explained by ocular biometric parameters, making it possible to predict SE with a complex model, with age and gender adjusted.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.