Visual outcome of cataract surgery and its influencing factors in China

Objective: To explore the visual outcome of cataract surgery and its influencing factors in China. Methods: A case-control study. The information of 2 078 479 patients who underwent cataract extraction of 31 provinces (municipalities and autonomous regions) recorded in the National Cataract Surgery Information Reporting System during January to December, 2017 were analyzed. The postoperative visual outcomes of 3 days after surgery and 3 months after surgery were analyzed. The effects of age, gender, preoperative corrected visual acuity, past medical history, and surgical methods on the results of cataract surgery were analyzed. Surgery effect was divided into ideal effect, moderate effect and poor effect according to the best corrected visual acuity after operation. Wilcoxon rank sum test and multinomial logistic regression model were used for statistical analysis. Results: There were 1 197 942 female patients (57.64%) and 880 537 male patients (42.36%) in all 2 078 479 cases. The average age was (69±11) years old. The main type of cataract was age-related (1 928 440 cases; 92.78%). There were 1 608 385 cases, 1 126 961 cases and 389 020 cases with complete corrected visual acuity before surgery, 3 days after surgery and 3 months after surgery, respectively. The median difference of corrected visual acuity of preoperative versus three days after surgery, and preoperative versus three months after surgery were -0.48, -0.52 respectively (after logarithm of the minimum angle of resolution conversion). The interquartile ranges were 0.60 and 0.73 respectively. The differences were statistically significant (Z=551 599.30, 206 815.35; both P<0.01). Multivariate analysis showed that postoperative complications (moderate effect: OR=0.50, 95%CI: 0.46 to 0.55; ideal effect: OR=0.31, 95%CI: 0.28 to 0.33), preoperative pupil abnormal (moderate effect: OR=0.52, 95%CI: 0.44 to 0.61; ideal effect: OR=0.55, 95%CI: 0.47 to 0.63), preoperative intraocular pressure abnormalities (moderate effect: OR=0.86, 95%CI: 0.79 to 0.93; ideal effect: OR=0.45, 95%CI: 0.42 to 0.49), history of hypertension (moderate effect: OR=0.90, 95%CI: 0.85 to 0.95; ideal effect: OR=0.88, 95%CI: 0.83 to 0.93) and history of diabetes (moderate effect: OR=0.86, 95%CI: 0.80 to 0.93; ideal effect: OR=0.92, 95%CI: 0.86 to 0.99) were predictors of worse outcome. Good preoperative corrected visual acuity (0.2 to 0.4 for moderate effect: OR=2.20, 95%CI: 2.06 to 2.34; for ideal effect: OR=5.25, 95%CI: 4.94 to 5.59; 0.5 to 0.7 for moderate effect: OR=1.08, 95%CI: 0.96 to 1.21; for ideal effect: OR=6.35, 95%CI: 5.69 to 7.08; above 0.8 for moderate effect: OR=0.73, 95%CI: 0.60 to 0.89; for ideal effect: OR=6.58, 95%CI: 5.51 to 7.86), small incision extracapsular extraction (moderate effect: OR=3.19, 95%CI: 2.35 to 4.33; ideal effect: OR=6.79, 95%CI: 5.13 to 8.97) and phacoemulsification (moderate effect: OR=2.12, 95%CI: 1.60 to 2.81; ideal effect: OR=3.34, 95%CI: 2.59 to 4.32) were predictors of better outcome. Conclusions: Visual acuity of patients in China improve significantly after cataract surgery. However, some patients still suffer moderate visual impairment. The effect of surgery can be affected by many factors, such as preoperative corrected visual acuity, preoperative intraocular pressure, preoperative pupil status, surgical approach and postoperative complications, etc. (Chin J Ophthalmol, 2021, 57: 63-70).