The Effect of Surgical Treatment of Horizontal Strabismus on Refractive Changes in Adult Patients

Abstract

Concomitant strabismus and refractive anomalies are often common pathological conditions in adult patients. The patient’s desire to get rid of both problems poses a question to the surgeon about the order of surgical interventions. With non-accommodative concomitant strabismus, the question is not so unambiguous. Despite a significant number of studies devoted to this topic, there is still no unequivocal opinion on the significance of refractive error after strabismus surgery. Thus, it remains an urgent task to study of possible surgically induced refractive changes after interventions on extraocular muscles and their assessment during the observation period.Purpose. Evaluation of the effect of surgical treatment of horizontal strabismus in adults on refractive and astigmatic status.Patients and methods. A prospective study of 30 patients with concomitant convergent or divergent strabismus. Each patient underwent surgery for horizontal strabismus, which consisted in recession and resection of the extraocular muscles of one eye. The spheroequivalent (SE) and cylinder (Cyl) values were determined before surgery, 1, 3, and 6 months after surgery. Refractive changes were calculated in the postoperative period, both for the spheroequivalent and for the cylinder, after 1 month (SIRC1), 3 months (SIRC2) and 6 months (SIRC3). In addition, the difference (d) between SIRC1 and SIRC3 was calculated to determine if they were temporary or permanent. Analysis of the induced changes in the magnitude and direction of astigmatism was performed using vector analysis.Results. The dynamics of SE values within 6 months after surgery shifted to insignificant myopia, however, no significant static difference in this parameter was found (p = 0.17). The mean change in spherical equivalent (SE) refraction was 0.22 ± 0.47 diopters in SIRC1, 0.15 ± 0.44 diopters in SIRC2, and 0.12 ± 0.51 diopters in SIRC3. There was no statistically significant difference between changes in surgically induced refraction at different times after surgery (p = 0.34). The difference (SIRC d) between SIRC1 and SIRC3 for the spheroequivalent was 0.096 ± 0.480 and can be interpreted as a decrease in surgically induced refraction error within 6 months after surgery. Surgically induced astigmatism at different times after surgery was: SIRC1 = 0.44 ± 0.39, SIRC2 = 0.47 ± 0.41, SIRC3 = 0.43 ± 0.29. There was no statistically significant difference in this parameter during the study period (p = 0.1). The difference (SIRC d) between SIRC1 and SIRC3 for astigmatism was 0.0001 ± 0.3200, which indicates stable values of astigmatism. According to the vector analysis, the magnitude and axis of preoperative astigmatism was 1.131 ± 0.410 ax172 and is close to the actual postoperative values of 1.17 ± 0.50 ax172. The vector of surgically induced astigmatism was 0.43 ± 0.10 ax84. These changes were not statistically or clinically significant.Conclusion. In general, the refractive and astigmatic status does not change after surgical treatment of horizontal strabismus. However, in this study, there was a myopic refraction shift during the first 3–6 months after surgery. In this connection, it is possible to recommend refractive operations to adult patients 3–6 months after strabismus surgery.