The effect of cataract extraction on the results of automated perimetry in glaucoma

Purpose. To investigate the effect of cataract extraction on global indices and to evaluate the spatial relationships of change in sensitivity at individual test locations in individuals with glaucomatous visual field loss. Methods. 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, and had at least seven Humphrey 24-2 or 30-2 visual fields over five or more years, with an abnormal glaucoma hemifield test on the first two 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 53 subjects (mean age=71.8 years) were included in the analysis. A mean improvement in MD of +1.68 dB (p<0.001), and a mean worsening in CPSD of +0.54 dB (p=0.06) 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 Pointwise comparison of pre- and post-operative thresholds revealed a significant correlation between greater pre-operative sensitivity and improvement (p<0.01). A significant correlation between improvement in visual acuity and improvement in MD was also found. Conclusions. Cataract extraction is associated with improvement in the global index MD. Improvement in MD correlates with improved visual acuity. Areas of the field less affected by glaucoma tend to show greater improvement in sensitivity, which may account for the small mean increase in CPSD observed.