OBJECTIVE: To evaluate the influence of cataract extraction on the results of visual field testing in chronic open-angle glaucoma. DESIGN: We performed automated perimetry within 6 months before and after phacoemulsification and combined trabeculectomy in 24 consecutive patients with chronic open-angle glaucoma. Eyes were pharmacologically dilated and were tested with their best corrected refraction for each visual field performed. RESULTS: After surgery, the average mean defect, pattern SD, and total decibel loss within any visual field cluster (as determined by the Glaucoma Hemifield Test, Humphrey Field Analyzer, Humphrey Instruments, San Leandro, Calif) did not change significantly (P > .05, paired t test). These findings did not vary on the basis of the amount of preoperative damage in the visual field. The power of this study to exclude a 4-dB change in the mean defect after surgery was 86.5%. CONCLUSION: This study suggests that cataract extraction in patients with chronic open-angle glaucoma has minimal effect on the visual field test results after surgery.