Objective: To investigate the effect of cataract extraction on the visual fiel ds of patients with open-angle glaucoma. Methods: Patients in a prospective coh ort study in a tertiary center underwent standard automated perimetry every 6 mo nths. We compared the mean results of the 2 examinations immediately before and 2 examinations immediately after phacoemulsifi-cation cataract extraction and i ntraocular lens implant (effect analysis) and the mean results of the first 2 an d last 2 examinations from 4 consecutive examinations obtained more than 1 year after the cataract surgery (control analysis). Results: Our sample contained 34 eyes of 26 patients (mean±SD age, 69.2±10.8 years). While the mean log-MAR be st-corrected visual acuity improved significantly by approximately 2 Snellen li nes after surgery (P<.001), the average change in mean deviation in both the eff ect and control analyses was less than 0.1 dB and not statistically significant (P=.85). There was a strong correlation between change in foveal sensitivity and change in mean deviation in the effect analysis but not in the control analysis (r=0.76 [P< .001] and r=0.30 [P=.08], respectively). There was no relations hip between change in visual acuity or initial mean deviation and change in mean dev iation in either analysis. Change in pointwise total deviation was not systemati cally related to the respective baseline value in either analysis; however, the variance of the distribution of change in total deviation was significantly high er in the effect analysis (P< .001). Conclusion: While there was an improvement in best-corrected visual acuity after cataract surgery, the changes in the visu al field as a group were negligible. Objective: To investigate the effect of cataract extraction on the visual fiel ds of patients with open-angle glaucoma. Methods: Patients in a prospective cohort study in a tertiary center underwent standard automated perimetry every 6 mo nths. We compared the mean results of the 2 examinations immediately before and 2 examinations immediately after phacoemulsifi cation-cataract extraction and i ntraocular lens implant (effect analysis) and the mean results of the first 2 an d 2 examinations from 4 consecutive examinations obtained more than 1 year after the cataract surgery (mean ± SD age, 69.2 ± 10.8 years). While the mean log-MAR be st-corrected visual acuity improved significantly by approximately 2 Snellen li nes after surgery ( P <.001), the average change in mean deviation in both the ect and control analyzes was less than 0.1 dB and not substantially significant (P = .85). There was a strong correlatio n between change in foveal sensitivity and change in mean deviation in the effect analysis but not in the control analysis (r = 0.76 [P <.001] and r = 0.30 [P = .08], respectively). There was no relations hip in change in visual acuity or initial mean deviation and change in mean dev iation in either analysis. However, the variance of the distribution of change in total analysis was significantly high er in the effect analysis (P <.001). Conclusion: While there was an improvement in best-corrected visual acuity after cataract surgery, the changes in the visu al field as a group were negligible.