Factors Influencing Retinal Image Contrast in Eyes with Retrodots(Reykjavik Eye Study)

Abstract

Purpose: : We reported that retrodots (RD) are very common among Icelanders aged ≥50 yrs old. Here we examined retinal image contrast (RIC) in eyes with early stage RD and the influence of higher order aberration (HOA) and backward light scattering intensity (LSI) on RIC in Icelanders

Methods: : Participants aged ≥60 yrs old of the Reykjavik Eye Study (RES) in 2008 were graded for RD; 261 participants 432 eyes (mean±SD age : 67.1±4.7yrs) had transparent lenses (T); 78 cases, 47 eyes aged 71.4±6.8 yrs had less than four RD in the 3 mm diameter central pupil zone (Grade RD1); and 24 cases, 15 eyes mean±SD aged 73.1±6.3 yrs had RD present in up to 25% of the 3mm diameter zone (Grade RD2). Both latter groups had only RD opacity. Lenses, under mydriasis, were graded for RD from retroillumination images by anterior eye segment analysis system (EAS-1000, NIDEK).A point spread function analyzer (PSF-1000, TOPCON) was used to measure retinal image contrast under condition of best corrected refractive error with mydriasis, through Landolt ring simulation with 3mm entrance pupils. Wave Front Analyzer (9000PW, TOPCON) was used to measure ocular total HOA (μm) with 4mm pupils. LSI was estimated from scheimpflug slit images photographed by anterior segment analysis system (EAS-1000, NIDEK).

Results: : While there were no significant difference between RIC of group T and RD1, RIC in RD2 was significantly lower than in groups T and RD1 (P<0.05).There were no significant differences among all groups in total HOA, coma, trefoil and spherical aberration. RD1 and RD2 groups showed higher integrated value of LSI from the lens of anterior capsule to the central clear zone than did the T group.

Conclusions: : RIC in eyes with grade 2 RD (more than 5 and up to 25% of the 3mm diameter zone) is lower than in transparent lens. Early stage RD does not affect internal HOA,but the effect of increased backward LSI which has a positive correlation with forward scattering could impair visual function.

Keywords: cataract • clinical (human) or epidemiologic studies: treatment/prevention assessment/controlled clinical trials