Effect of cataract extraction on the results of automated perimetry in glaucoma

Objective: To investigate the effect of cataract extraction on the results of automated perimetry in persons with glaucomatous visual field loss. Subjects: Subjects from a retrospective study of visual field progression who underwent cataract extraction during follow-up were identified. Subjects came from the glaucoma service of a hospital-based tertiary referral center. Methods: Subjects had at least 7 Humphrey 24-2 or 30-2 visual fields over 5 years or more, with an abnormal glaucoma hemifield test result on the first 2 examinations. Visual field data were transferred to a microcomputer and comparison of the visual fields immediately before and after cataract extraction was performed. Results: Sixty-five eyes of 50 subjects (mean age, 71.8 years) were included in the analysis. A mean improvement in mean deviation (MD) of 1.68 dB (P<.001), and a mean worsening in corrected pattern SD (CPSD) of 0.54 dB (P=.09) was observed. The mean unweighted change in threshold in the 52 points of program 24-2 was 1.58 dB, corresponding to a 43.9% increase in sensitivity. A significant correlation between improvement in visual acuity and improvement in MD was also found. A mean increase in CPSD of 1.61 dB (P=.005) occurred in subjects with dense scotomas (minimum threshold value less than or equal to 5 dB) and preoperative CPSD of 8 dB or less. Conclusions: In persons with glaucomatous visual field defects, cataract extraction produces only a modest improvement in MD. After cataract surgery, the CPSD index worsened in many subjects with dense scotomas. This suggests that the development of cataract can mask progressive glaucomatous visual field loss in such persons.