Analysis Of Convergence And Accommodative Function Of Myopia And Changes After Small Incision Lenticule Extraction

PurposeTo study the prevalence of convergence and accommodative dysfunction in myopes.To analyze the changes of binocular and accommodative function after small incision lenticule extraction and association with asthenopia.MethodsFirstly,It's an observational study.Eighty-one myopic patients were included.The values of parameters of convergence and accommodationwere measured and symptoms scores were examined.According to Morgan normal values and Sheard criteria,the prevalence of convergence and accommodative dysfunction was analyzed.The Chisquared test was used to evaluate different prevalence in different groups by refractive error or symptoms scores and the independent T-test was used to analyze the difference of parameters between groups.Then the serial cases-observational was performed.Twenty-five myopic patients underwent small incision lenticule extraction(SMILE)surgery were included in this study.The values of parameters of convergence and accommodation were measured at preoperative,1 week,1 month and 3 months postoperatively.The patients were grouped by the preoperative symptoms scores.The comparisons among different follow-up periods were conducted by the repeated measures analysis of variance and comparison between every two periods by the LSD test.The comparison between two groups was conducted by the independent t-test.The Pearson correlation coefficient(r)was used to evaluate the linear fit of the relationship between variables.Multiple linear regressions were used to analyze the relationship between asthenopia and parameters of binocular and accommodative function.Results1.The prevalence of non-strabismic anomalies of binocular vision and accommodative dysfunction in myopes was found to be 35.80% and 13.58%,respectively.2.Distance heterophoria,near heterophoria,negative related accommodation and the recover point of positive fusional vergence showed significant difference in different diopter groups(P<0.05).3.Twenty-six percent of myopes has the visual symptoms and the prevalence of the convergence anomalies showed significant difference between symptoms and nonsymptoms groups(P<0.05).There was significant differences in the monocular accommodative amplitude(P<0.05)between two groups.4.The distance heterophoria,near point of convergence,near heterophoria,MAA,MAF,PRA and AC/A after SMILE procedure showed significant difference among each observed period postoperatively and preoperatively(P<0.05).5.For symptom group,the visual symptom scores were positively correlated with ?1w near heterophira(?1w =1-week postoperative value-preoperative value),and were negatively correlated with recovery point of near positive fusional vergence(P<0.05).Conclusion1.There was a high prevalence of non-strabismic anomalies of binocular vision and accommodative dysfunction in myopic population.Clinicians should pay attention to them and give them appropriate description and treatment;High myopes showed larger exophoria and lower negative related accommodation compare to low and moderate myopes;High prevalence of asthenopes was found in myopes,in which the prevalence of convergence and accommodative dysfunction was higher than that in non-symptoms myopes;2.The distance heterophoria,NPC,MAA and AC/A ratio significantly decreased at 1 week after SMILE,however,they remained stable in 3 months postoperatively.Thus,SMILE surgery wouldn't influence the binocular vision and accommodation in the long term;From the aspect of decreased near heterophoria and increased MFF and PRA in 3 months postoperatively,SMILE surgery may benefit the binocular vision and accommodation function;Factors of asthenopia in early period of SMILE sugery should be further studied.