Comparison of methods to identify incident cataract in eyes of patients with neovascular maculopathy: Submacular Surgery Trials Report No. 18.

Purpose: To describe and compare methods used to monitor development and progression of presumed vision-limiting lens opacity in study eyes of Submacular Surgery Trials (SST) patients.
Design: Prospective study of patients enrolled in a set of randomized clinical trials.
Participants: Patients enrolled in the SST who were phakic in the study eye at the time of enrollment (n = 690). In a subset of 114 patients, lens photographs were obtained at baseline and 2 years after enrollment.
Methods: Data collection at baseline and annual follow-up examinations included ocular history, ophthalmologic examination including the SST ophthalmologist's assessment of presence or absence of vision-limiting opacity, fundus photography, and lens photography (13 of 27 clinics only). All photographs were assessed by masked graders centrally using the Lens Opacities Classification System III (LOCS III). kappa statistics were calculated to compare LOCS III cataract classifications with fundus photograph quality and with the ophthalmologist's assessment of lens opacity, with the LOCS III classification considered the gold standard.
Main Outcome Measure: Incidence of cataract in study eyes.
Results: Baseline lens photographs were available and graded for 312 (45%) of 690 patients with phakic study eyes; 2-year lens photographs were available for 156 (23%) of 690 initially phakic eyes. Both baseline and 2-year lens photographs were available for 114 eyes that remained phakic. Submacular surgery was associated with significant progression of nuclear color and nuclear opalescence characteristics within 2 years of enrollment. The reliability of fundus photograph quality versus cataract classification using a 4.5 LOCS III score threshold for cataract was poor to good at each time point and for all groups (kappa, 0-0.51), but sensitivity of the photograph quality score as a surrogate was low, and both positive and negative predictive values were low. Agreement between the ophthalmologists' assessments of lens opacity and the 4.5 LOCS III score threshold for cataract was good (kappa, 0.42-0.78).
Conclusions: In the SST, clinical identification of severe cataract (LOCS III scores of 4.5 or worse for nuclear opacity or nuclear color) by the examining ophthalmologist was valid based on comparison with LOCS III scores and may be an adequate method to use in similar trials.