Relationship between 10-Year-Change in Refraction of Crystalline Lens and Aging

Abstract

Purpose: : Although the reason remains unclear, it is reported that hyperopic shift in spherical equivalent refraction (SE) with aging is seen in the elderly. Likewise, it is also known that the crystalline lens undergoes transubstantiation with age. We examined 10-year-change of transparent crystalline lens in power, opacification and shape.

Methods: : Subjects comprised 27 right eyes of participants of Monzen Eye Study, ongoing longitudinal epidemiological study for 1038 Japanese subjects aged over 50 years living in Monzen town (N37°), with crystalline lenses which remained transparent at10 year follow-up. Axial length (AL) was measured by ultrasound A-mode, and SE and corneal power (CP) were determined by Auto-ref-keratometer. The formula LP=(110.0-2.43*AL-0.89*CP-SE)/0.62), propounded by Olsen and Sasaki et al, was used to calculate lens power (LP). Light scattering intensity and axial thickness of the anterior part of the lens were evaluated from Scheimpflug images (EAS-1000, NIDEK) to estimate opacity.

Results: : The mean±SD age at the first examination was 59.9±5.7 years. There was a mean hyperopic shift in SE of +0.47D (p<0.01) in 10 years, from +0.61±1.46D to +1.08±1.37D. LP decreased by 1.07D (P<0.01), from 23.85±1.46D to 22.78±1.77D. Multiple regression analysis of change in LP showed a significant correlation between thicknesses of anterior cortex (AC) and the anterior half of the lens (AHL). (Change in LP = -13.959*AC +7.011*AHL-0.433).

Conclusions: : Regarding change in LP seen in the elderly, it was clarified that hyperopic shift is attributed to thickening of the cortical part of the lens. Meanwhile, change in thickness of the anterior part of the lens including the cortex and nuclear affects myopic shift.

Keywords: crystallins • refraction • aging