Objective To observe the changes in peripapillary vessel perfusion after uncomplicated phacoemulsification surgery in patients with cataract and primary open-angle glaucoma (POAG). Methods A case-control study. From November 2017 to April 2019, 17 eyes of 17 cases of POAG complicated with cataract (observation group) and 17 eyes of 17 cases of simple senile cataract (control group) were included in the study. All the affected eyes underwent best corrected visual acuity (BCVA), intraocular pressure (IOP), visual field, optical coherence tomography angiography (OCTA) examination, and measurement of axial length (AL) and central corneal thickness (CCT). All eyes underwent conventional phacoemulsification surgery for cataract. After the operation, the same equipment and methods as before the operation were used for related inspections. The VD, the thickness of the retinal nerve fiber layer (RNFL), and the IOP were observed before the operation, at the end of the operation, and 1 d, 1 week, 1 month and 3 months after the operation, mean visual field defect (MD) changes 3 months after surgery. Data comparisons within groups used repeated measures analysis of variance; data comparisons between groups used independent samples t test. Results The average age of patients in the observation group and control group was 68.18±6.13 and 65.82±6.95 years, respectively, and the difference was not statistically significant (t=1.912, P=0.072). There was no significant difference in AL (t=1.436), CCT (t=−1.557) and phacoemulsification (t=1.602) between the two groups (P>0.05). The difference of the mean IOP was statistically significant between the two groups (t=4.139, P<0.05). Before surgery, the VD (t=−6.560) and RNFL thickness (t=−7.320) of the observation group were lower than those of the control group, and the difference was statistically significant (P＜0.05). Compared with before the operation, the VD around the disc of the eye in both groups increased at the end of the operation and at different time points after the operation. Among them, the observation group had a statistically significant difference at 1 month after the operation of the eye (F=3.108, P=0.042); the control group had no significant difference at different time points after the operation (F=1.981, P＞0.05). The results of each quadrant analysis showed that only the observation group had a statistically significant difference in the temporal side of the eye one month after surgery (F=5.414, P=0.017). After surgery, the observation group and the control group had thicker RNFL thickness around the disc of the eye, and the difference was statistically significant (F=22.670, 23.080; P=0.002, 0.001). Before the operation and 3 months after the operation, the average MD of the eyes of the observation group and the control group were 14.90±7.15, 1.12±0.93 dB and 12.10±7.70, 0.88±0.66 dB, respectively. The average MD before and 3 months after the operation was compared, and the difference was statistically significant (t=14.414, 13.225; P=0.000, 0.000). Compared with before surgery, there was no statistically significant difference in the average MD of the two groups of eyes at 3 months after surgery (t=0.938, 0.817; P=0.082, 0.103). At the end of the operation, the intraocular pressure of the observation group and the control group were 10.84±3.39 and 11.46±3.79 mm Hg (1 mm Hg=0.133 kPa), respectively; they were both lower than before the operation, and the difference was statistically significant (t=−2.211, −2.310; P＜0.05). Conclusions The thickness of VD and RNFL in eyes with POAG combined with cataract is lower than that in patients with senile cataract alone. The high perfusion pressure during conventional phacoemulsification surgery can cause a transient increase in VD, but it will not cause further damage to the visual field of POAG patients.