Orthoptic Changes Following Photorefractive Keratectomy

Purpose: To detect orthoptic changes in patients undergoing photorefractive keratectomy (PRK). Method: This interventional case series was performed on 297 eyes of 150 patients who were candidates for PRK. Complete ophthalmic evaluations focusing on orthoptic examinations were performed before and 3 months after PRK. Results: Before PRK, two (1.3%) patients had esotropia that remained unchanged postoperatively. However, 3 (2%) patients had distance exotropia preoperatively which improved after PRK. Of 12 cases (8%) with preoperative exotropia at near, 3 (2%) cases became orthophoric. Six patients (4%) developed postoperative near exotropia. A significant reduction in means of convergence and divergence amplitudes (P<0.001) and a meaningful increase in mean of near point of convergence (NPC) (P<0.006) were noticed after PRK. A reduction of ≥10 PD in convergence amplitude and ≥5 PD in divergence amplitude were detected in 10 and 5 patients, respectively. Four patients had an preoperative NPC>10 cm which was not changed by the surgery. Out of 9 (6%) patients with baseline stereopsis >60 seconds of arc, 2 (1.33%) cases showed an improvement in stereopsis following PRK. None of the patients complained of postoperative diplopia. Conclusion: Eye deviation in patients undergoing PRK may improve or remain unchanged after operation and postoperative deviations can develop following this surgery. Diminishing of fusional amplitude and increasing of NPC as well as improving of stereopsis may also happen after PRK. Therefore, a preoperative orthoptic examination in patients with any concerning histories and/or motility issues on routine exam is recommended before performing PRK.