Abstract
Purpose:
Presence of retrodots (RD) occupying 25% of the area of the 3mm diameter central pupil zone causes reduced contrast sensitivity and occupying 50% impairs vision. However, size of each RD differs. We examined the influence of size of RD under the same total area occupied.
Methods:
Participants aged ≧60 yrs old of the Monzen Eye Study (MES), 2006 to 2012, were graded for RD; 261 participants 432 eyes (mean±SD age : 69.5±5.1yrs) had transparent lenses (T): 52 cases, 82 eyes (69.5±6.8 yrs) had fewer than four RD in the 3 mm diameter zone (Grade RD1): and 11 cases, 18 eyes (68.6±8.1 yrs) had RD occupying up to 25% of the 3mm diameter zone (Grade RD2); and 5 cases, 5 eyes (74±5.3 yrs) RD occupied from 25% to 50% of the 3mm diameter zone (Grade RD3). Lenses under mydriasis, were graded for RD and classified by RD size (Small(S): ≦50μm; Medium(M) ≥50μm ≦300μm; Large(L)≥300μm) 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 (RIC) under condition of best corrected refractive error with mydriasis, through Landolt ring simulation with 3mm entrance pupils. Wavefront analyzer (9000PW, TOPCON) was used to measure ocular total HOA (μm) with 4mm pupils.
Results:
Comparing average RIC in RD with that in T there was no significant difference among RD1 sizes S and M, but it was significantly lower in size L (P<0.0001). Among RD2, RIC in sizes M and L were significantly lower than in T.(P<0.0001) There was no significant difference in RIC among size groups of RD3. There were no significant differences among all groups in total HOA, coma, trefoil and spherical aberration.
Conclusions:
In eyes with RD, total area occupied by RD is an important factor in visual function. However, size of RD also plays a role as larger RD decreases visual function more.