Changes in fusional vergence amplitudes after laser refractive surgery for moderate myopia

Abstract

To analyze the effect of bilateral laser refractive surgery on fusional vergence amplitude and near point convergence in normal orthotropic myopic patients. Cornea and refractive private practice, Seoul, South Korea. Prospective observational study. Moderately myopic patients (2.0 to 6.0 diopters [D]) had bilateral laser refractive surgery with postoperative follow-ups at 1 week and 1 and 3 months. Patients with manifest strabismus, previous strabismus surgery, amblyopia, absent or impaired binocularity, or planned monovision were excluded. The preoperative and postoperative examinations included uncorrected and corrected visual acuities; a prism cover test; evaluation of the convergence, divergence, and vertical fusion amplitude using a rotary prism; and near point convergence. The mean age of the 30 patients was 29 years ± 4 (SD). The mean preoperative refractive error was -4.10 ± 1.32 D in right eyes and -4.14 ± 1.37 D in left eyes. The convergence amplitude at near decreased 1 week and 1 month postoperatively, after which it progressively stabilized to near preoperative values. The convergence amplitude at far (break point) was not changed postoperatively; however, the convergence amplitude at far (recovery point) was increased at 1 month and 3 months (P=.008 and P=.003, respectively). There was a slight increase in near point convergence at 3 months (P<.001). Although fusional vergence amplitudes at near and near point convergence changed after laser refractive surgery, the changes observed were small or transient. However, patients with latent phoria or strabismus should be warned before having refractive surgery. No author has a financial or proprietary interest in any material or method mentioned.