Fig. 7. The Lens Opacity Classification System II (LOCS II) photographic grading standards. N = Nuclear photographs. Stage 0 = normal; I–III = various stages of nuclear cataract. For nuclear opalescence, the average opalescence across the entire nuclear region is used. An opalescence that is less than or equal to Photographic Standard 0 = grade 0; if the opalescence is less than or equal to Standard I, the grade is 1, and so on. For Color Grading of the nucleus, only the N2 standard is used. (<N2 for color=0, equal to N2 in color=1, and N2 for color = 2) C = Cortical photographs. 0-Trace (Tr) = normal; I–IV = various steps of cortical cataract (roughly CII ¼, CIII ½, CIV ¾. CV > ¾). P = Posterior subcapsular photographs. 0 = normal; I–III = various stages of posterior subcapsular cataracts (Chylack LT, Leske MC, McCarthy D, et al: Lens opacities classification system II \[LOCS II\]. Arch Ophthalmol 107:991, 1989. Copyright 1989, American Medical Association with permission.)