Straylight and Visual Quality on Early Nuclear and Posterior Subcapsular Cataracts

Abstract

Purpose: To measure log(s) and OSI parameters, both related to forward light scattering in the eye, in subjects with different kinds of early cataracts—nuclear or posterior subcapsular—and corrected visual acuity (CVA). Methods: 34 eyes of 19 patients ranged between 50 and 75 years old with diagnosed nuclear (14 eyes) or posterior subcapsular cataract (20 eyes) were recruited. Only NO1, NO2, P1, and P2 opacity scores according to LOCS III were included. Observer examination included visual acuity, contrast threshold (Ct), and measurements performed by straylightmeter (straylight parameter log(s)) and double-pass instrument (objective scatter index (OSI)). Results: OSI and log(s) were correlated with LOCSIII in nuclear opacities (p = 0.015 and 0.004, respectively) and in the whole data (p = 0.027 and 0.019, respectively) but did not for posterior subcapsular opacities alone. OSI was strongly correlated with log(s) in nuclear (r = 0.885 and p < 0.001) but not in posterior subcapsular cases (r = 0.382 and p = 0.097). Ct was correlated with log(s) for both cataract types (p = 0.043 for nuclear and p= 0.005 for posterior subcapsular cataract) but not with OSI (p = 0.093 for nuclear and p = 0.064 for posterior subcapsular cataract). Conclusions: OSI and log(s) discriminate early stages of nuclear cataracts when taking LOCS III as reference, so these opacities could be graded by any of those parameters. LOCSIII does not represent the visual condition for posterior subcapsular cataract. Straylightmeter measurements express the loss in contrast sensitivity caused by nuclear and posterior subcapsular opacities. Studies of lens opacities must be separated according to the type of opacity present in eyes.