Effect of cataract on a scotopic sensitivity screening test for glaucoma

We investigated whether cataract decreases whole-field scotopic sensitivity, a measurement used for the detection of early glaucoma damage. The study population consisted of 33 patients scheduled for cataract surgery. Patients were >/=50 years old and had no ocular disease except senile cataract. The whole-field scotopic sensitivity of one eye of each subject was measured 1 day before and 3 months after cataract surgery. That of six persons of similar age without cataract was also measured twice, 3 months apart. Cataract extraction was associated with significantly improved sensitivity (p = 0.005). With stratification by cataract type, only persons with nuclear sclerosis demonstrated a significantly improved sensitivity after cataract surgery (p = 0.03). The magnitude of sensitivity improvement after surgery did not differ significantly between patients with mild compared to moderate cataract. Multiple regression analysis revealed that age, preoperative intraocular pressure, change in visual acuity, cataract type, and cataract severity were not independently significant predictors of change in sensitivity after cataract surgery. We conclude that cataract may alter the whole-field scotopic sensitivity score and may need to be taken into account in its use for glaucoma screening.