Abstract
Purpose:
We previously reported that large-sized retrodots (RD) reduced retinal image contrast more than small-sized RD (ARVO 2013). Here we examined the relationship between size of RD and contrast sensitivity (CS) in eyes with RD.
Methods:
Right eyes of participants aged ≧60 yrs old of the Monzen Eye Study(MES), 2006 to 2012, were graded under mydriasis for RD. Fifty-eight (68.5±3.2 yrs old) had transparent lenses (T), 54 (68.4 ±7.0 yrs old) had fewer than four RD in the central 3 mm diameter zone (RD1), 14 (71.2 ± 8.8 yrs old) had RD occupying up to 25% of this zone (RD2), and 4 (76.3 ± 4.4 yrs old) had RD occupying from 25% to 50% of the zone (RD3). RD were classified as small ≤50um(S), medium >50um ≤300um (M) or large >300um (L) from retroillumination images by anterior eye segment analysis system (EAS-1000, NIDEK). CS was measured with contrast sensitivity testing system (CAT-2000, NEITZ) under distance refractive correction in four visual environments (day with/without glare, night with/without glare).
Results:
Compared with T eyes, average CS was significantly lower in RD eyes by size under the four visual environments as follows: day with glare, RD2(L) (P=0.004), RD3(L) (P=0.003); day without, RD2(L) (P=0.02), RD3(L) (P=0.0005); night with, RD2(L) (P=0.004), RD3(M) (P=0.01), RD3(L) (P=0.03); night without, RD2(L) (P=0.02), and RD3(L) (P=0.01), respectively. Compared with T eyes, CS did not differ significantly in RD2(S), RD2(M), or RD3(S) eyes.
Conclusions:
As RD2(L) significantly reduced CS whereas RD2(S), RD2(M), or RD3(S) did not, it suggests size of RD (>300um) has a significant influence on contrast sensitivity.