Objective: To analyze the health-related quality of life (HRQOL) in adults with strabismus, and to identify the factors that affect the HRQOL in strabismus patients. Methods: In this investigation study, 202 adults with strabismus and 110 healthy control adults were recruited. Participants were asked to complete the Chinese Adult Strabismus 20 scale (CAS-20) HRQOL assessment. The following individual information was recorded: type and degree of strabismus, diplopia, age, sex, and marital status. Independent samplest-tests, ANOVA, Pearson correlation analyses, multiple linear regression analyses were used to analyze the effects of strabismus on HRQOL in adults based on the CAS-20 score. Results: The mean CAS-20 score for strabismus adults was 56.8±16.7, while the score in the control group was 98.0±4.3 (t=-35.2,P<0.001). The CAS-20 function score of patients with diplopia was significantly lower than that for patients without it (t=-1.987, P=0.047). The CAS-20 mean scores were all significantly lower in patients with amblyopia (t=-2.122, P=0.004). The psychosocial score of patients with a large horizontal strabismus(>25△) was significantly lower than those with a small horizontal strabismus (≤25△) (t=2.523, P=0.007).There were no significant differences among the different types of strabismus. Age and the course of strabismus were negatively correlated with the HRQOL in strabismus adults (r=-0.260, P < 0.001; r=
-0.142, P=0.035). Married strabismus subjects had lower scores than unmarried subjects (t=2.981, P=0.004). Patients who were students had higher scores (t=-2.084, P=0.038). A multifactor retrospective analysis showed that age and the course of the strabismus, with or without amblyopia, were the main factors affecting the HRQOL for strabismic adults. Conclusions: The HRQOL of adults with strabismus is worse than that for healthy adults. The CAS-20 function scores of patients with diplopia or amblyopia are significantly lower than for patients without diplopia or amblyopia. The course of strabismus, age and with or without amblyopia are important factors in HRQOL.