Contrast visual acuity (CVA) was used to analyze the binocular visual spatial resolution and visual perception quality after strabismus surgery.

Consecutive patients with strabismus 42 cases (84 eyes) who underwent surgery in Shenzhen Eye Hospital from December 2018 to June 2019. Among of them, there were 18 males (36 eyes) and 24 females (48 eyes); age 18 to 48 years-old with an average age of (25.8±5.8) years-old. The monocular and binocular visual acuity of the patients was measured at 4 contrast levels (100%, 25%, 10%, 5%) , 1 day before and 1 week after surgery. The age, neardistant squint and CVA of the patients were described by mean±standard deviation. The percentage of patients with different types of strabismus and the rate of postoperative CVA improvement were described by cases and percentages. The paired t-test was used to compare the CVA of strabismus patients before and after operation and the chi-square test was used to compare the increase rate of CVA in patients with different strabismus types and different degrees of impaired binocular monocular function. The paired chi-square test and Kappa consistency test were used to compare the results of binocular monocular function test and binocular CVA test 1 week after strabismus surgery. LogMAR contrast visual acuity and reaction times were detected at 4 contrast levels (100%, 25%, 10%, 5%) with standard high background before and 1 week after strabismus surgery.

The postoperative CVA on binoculus at 4 contrast levels (100%, 25%, 10%, 5%) were higher than the preoperative CVA , and there was statistically significant difference between them (t=3.655, 2.086, 2.216, 3.699; P<0.05). The postoperative CVA in dominant eye at 100% and 25% contrast were higher than the preoperative CVA , and there was were statistically significant difference between them (t=2.742, 2.400; P<0.05), but there were no significant differences between them (t=2.021, 1.773; P>0.05) at 10% and 5% contrast levels. The patients with postoperative CVA in dominant eye had 5 cases (5 eyes), accouting for 11.90%; 8 cases (8 eyes), accouting for 19.04%; 11 cases (11 eyes), accouting for 26.19%; 13 cases (13 eyes), accouting for 30.95% were lower compared with the preoperative CVA at 4 contrast levels (100%, 25%, 10%, 5%). When the postoperative CVA in deviated eye at 4 contrast levels (100%, 25%, 10%, 5%) were compared with the preoperative CVA, there were no significant differences among them (t=0.415, 0.471, 0.659, 0.639; P>0.05). The patients with the increase of postoperative CVA on binoculus had 24 cases (48 eyes), accouting for 80.00%; 5 cases (10 eyes), accouting for 41.67%; 23 cases (46 eyes), accouting for 74.19% and 4 cases (8 eyes), accouting for 36.36% among the patients with concomitant strabismus, non-concomitant strabismus, exotropia and esotropia. The increase rate of the postoperative CVA were higher compared between non-concomitant strabismus and concomitant strabismus; between exotropia and esotropia; between grade Ⅱ binocular function before operation and their deficient function, and there were statistically significant differences among them(χ²=4.60, 5.52, 5.35; P<0.05). The increase rate of the postoperative CVA accouting for 69.0% was higher than binocular vision accouting for 50.0% examined with a synoptophore at 1 week after surgery; and there were statistically significant differences between them (χ²=4.08, P<0.05).

CVA was a sensitive detection method for visual function. Strabismus surgery could improve the contrast sensitive visual quality on binoculus and dominant eye at the medium and high frequencies. The close relationship suggests that the detection of CVA may provide foresight for the recovery of binocular function after strabismus surgery.