Purpose To evaluate intraocular pressure (IOP) change after cataract surgery in nonglaucomatous eyes with narrow and open angles (OAs) and its relation to novel lens parameters measured by anterior segment optical coherence tomography (AS-OCT). Setting University affiliated hospital, Farabi Eye Hospital, Tehran, Iran. Design Prospective interventional case series. Methods In this prospective study, 85 nonglaucomatous eyes underwent phacoemulsification and lens implantation. Thirty-nine eyes had OAs and 46 eyes had narrow angles (NAs). IOP and biometric parameters were measured by AS-OCT preoperatively and 3 months after surgery. Change in IOP and its relation to biometric parameters, including lens vault (LV), anterior vault (AV), defined as the sum of the LV and the ACD, and relative LV (rLV), defined as the ratio of the LV to the AV, were evaluated. The main outcome measure was degree of IOP change after phacoemulsification. Results Of the 85 patients included in the analysis, 35 were male and 50 were female with an overall mean age of 62.2 ± 8.9 years. The average IOP reduction was − 4.95 ± 2.26 mm Hg, from a preoperative mean of 17.12 ± 2.47 mm Hg, at 3 months after cataract surgery. The amount of IOP reduction was significantly greater in the NA compared with the OA group. In multivariate linear regression analysis, preoperative IOP and AV were significantly associated with IOP decrease (all ≤ 0.03). Conclusion Cataract surgery results in IOP reduction in both OA and NA eyes. The amount of IOP reduction is related to AV.