Impact of age, various forms of cataract, and visual acuity on whole-field scotopic sensitivity screening for glaucoma in rural Taiwan.

Abstract

To evaluate the impact of age, various forms of cataract, and visual acuity on whole-field scotopic sensitivity screening for glaucoma in a rural population. Clinic-based study with population-based recruitment. Jin Shan Township near Taipei, Taiwan. Three hundred forty-six residents (ages, > or = 40 years) of Jin Shan Township. Whole-field scotopic testing, ophthalmoscopy with dilation of the pupils, cataract grading against photographic standards, and screening visual field testing in a random one-third subsample. Whole-field scotopic sensitivity (in decibels) and diagnostic status as a case of glaucoma, glaucoma suspect, or normal. Participants in Jin Shan Township did not differ significantly in the rate of blindness, low visual acuity, or family history of glaucoma from a random sample of nonrespondents. Scotopic sensitivity testing detected 100% (6/6) of subjects with open-angle glaucoma at a specificity of 80.2%. The mean +/- SE scotopic sensitivity for six subjects with open-angle glaucoma (32.78 +/- 1.51 dB) differed significantly from that of 315 normal individuals (38.51 +/- 0.22 dB), when adjusted for age and visual acuity (P = .05, t test). With linear regression modeling, factors that correlated significantly with scotopic sensitivity were intraocular pressure, screening visual field, best corrected visual acuity, presence of cortical cataract, and increasing age. Although cataract affects the whole-field scotopic threshold, it appears that scotopic testing may be of value in field-based screening for glaucoma.