Analysis of refraction and visual function changes postvitrectomy

Objective To observe the refractive changes and visual function recovery of patients after various types of vitrectomy,and provide the basis for late optical correction.Methods It was a retrospective case-control study.Two hundred and fifty postvitrectomy patients,including 147 males and 103 females,were followed up from January 2009 to February 2011.The patients ranged in age from 3 to 78 years (mean 48.6±16.4 years).They were divided into 3 groups based on the type of surgical technique: including simple vitrectomy,87 patients; vitrectomy combined with silicone oil filling,131 patients; vitrectomy combined with crystal excision and silicone oil filling,32 patients.Refraction and visual function changes were analyzed and subjective sensation was assessed preopertively and one week to one month after the operation,and again a half year to one year after the operation.Data were analyzed with ANOVA.Results The mean refractive error (RE) for the 3 groups was lower one week to one month after the operation compared to preoperative RE.There were no statistically significant preoperative or postoperative differences for the simple vitrectomy patients (P＞0.05).However,there was a statistically significant difference for the patients in the other two groups (F=22.406,18.714,P＜0.05).The degree of astigmatism was higher 1 week to 1 month after the operation than preoperative levels for the 3 groups.These changes were statistically significant (F=4.395,4.81,6.354,P＜0.05).There were no obvious changes in RE or degree of astigmatism a half year to one year after the operation for the 3 groups.And there was no statistically significant difference between the simple vitrectomy group and the other 2 groups (P＞0.05).Best corrected visual acuity (BCVA) improved significantly 1 week to 1 month after the operation compared to preoperative VA and it remained stable a half year to one year after the operation.Visual distortion symptoms occurred in thirty-three patients with a best corrected visual acuity of more than 0.3 one month after the operation and was still present in 13 patients a half year to one year afterthe operation.Conclusion Vitrectomy can significantly improve visual function,reduce total refractive error and increase the degree of astigmatism in patients.Visual distortion occurred in the patients with better BCVA after the operation and gradually improved. Key words: Vitrectomy;  Diopter;  Visual function