Overcorrection after excimer laser treatment of myopia and myopic astigmatism. Melbourne Excimer Laser Group

R. B. Vajpayee, C. A. McCarty, G. Aldred and H. R. Taylor
Department of Ophthalmology, University of Melbourne, Australia.

OBJECTIVE: To study the incidence and associations of overcorrection after excimer laser treatment of myopia and myopic astigmatism. METHODS: The study cohort consisted of 645 patients who had photorefractive or photoastigmatic refractive keratectomy done by an excimer laser during a 2-year period. Patients were assessed 1,3,6, and 12 months postoperatively. The variables evaluated were visual acuity, refraction, keratometry, and corneal clarity. RESULTS: At 1 month, overcorrection of more than +1 diopter spherical equivalent (SEQ) was seen in 22% of the eyes. This progressively regressed so that only 8.6% of the 140 eyes that were overcorrected at 1 month were overcorrected at 1 year. Overall, 2.2% of eyes were overcorrected at 1 year. The magnitude of attempted correction and use of topical nonsteroidal anti-inflammatory drugs disclosed a notable association with occurrence of overcorrection at 1, 3, and 6 months. The use of bandage contact lenses also was associated with overcorrection at 1 and 3 months. After controlling for myopia and use of contact lenses, the odds of overcorrection for use of topical nonsteroidal anti-inflammatory drugs at 1,3, and 6 months were 2.21 (95% confidence limits [CL]=1.49, 3.44), 1.69 (95% CL=0.88, 3.24), and 2.01 (95% CL=0.88, 4.56), respectively. The odds of overcorrection with bandage contact lenses were 1.79 (95% CL=1.05, 3.05) at 1 month and 2.42 (95% CL=1.23, 4.75) at the end of 3 months. No associations were seen between overcorrection and age, gender, surgical technique, or simultaneous astigmatic corrections. CONCLUSIONS: Overcorrection is common during the early postlaser treatment period and is associated with degree of myopia, use of nonsteroidal anti-inflammatory drugs, and bandage contact lens wear.