Impact of laser refractive surgery on ocular alignment in myopic patients.

Abstract

PURPOSE: To evaluate the impact of myopic keratorefractive surgery on ocular

alignment. METHODS: This prospective study included 194 eyes of 97 myopic

patients undergoing laser refractive surgery. All patients received a complete

ophthalmic examination with particular attention to ocular alignment before and 3

months after surgery. RESULTS: Patients with a mean age of 26.6 years and a mean

refractive error of -4.83 diopters (D) myopia were treated. Asymptomatic ocular

misalignment was present preoperatively in 46 (47%) patients: a small-angle

heterophoria (1-8 prism diopters, PD) in 36%; and a large-angle heterophoria (>8

PD)/heterotropia in 11%. Postoperatively, the change in angles of 10 PD or

greater occurred in 3% for distance and 6% for near fixation: in 7% of the

patients with orthophoria, in 3% of those with a small-angle heterophoria, and in

18% of those with a large-angle heterophoria/heterotropia. No patient developed

diplopia. The preoperative magnitude of myopia or postoperative refractive status

was not related to the change in ocular alignment. The higher anisometropia was

associated with a decrease in deviation (P=0.041 for distance and P=0.002 for

near fixation), whereas the further near point of convergence tended to be

related with an increase in near deviation (P=0.055). CONCLUSIONS: Myopic

refractive surgery may cause a change in ocular alignment, especially in cases

with a large-angle heterophoria/heterotropia. There is also a chance of

improvement of misalignment in patients with anisometropia.