An analysis of clinical correlations one, three, six and 12 months after excimer laser photorefractive keratectomy

Background: The excimer laser has been shown to be safe and effective for the treatment of myopia. Examination of clinical correlations one, three, six and 12 months following photorefractive keratectomy (PRK) or photo-astigmatic refractive keratectomy (PARK), and evaluation of the progression of patients with initially poorer outcomes may enable the more effective management of patients. Methods: All eyes undergoing excimer laser surgery to correct myopia were assessed one, three, six and 12 months postoperatively. Visual acuity, spherical equivalent (SEQ), corneal clarity,and adverse reactions were evaluated at each visit. Chi-square tests were employed to assess associations between categorical variables and correlations were employed to assess associations among continuous variables. Results: Complete 12-month follow-up data were available on 150 eyes that underwent photorefractive or photo-astigmatic refractive keratectomy with a VisX 20/20 laser. Epithelial healing occurred faster in females and in eyes with more severe myopia. Poorer best corrected and uncorrected visual acuities were positively associated with age and prior acuities, and inversely associated with SEQ. The best predictor of corneal clarity at any postoperative time point was prior corneal clarity. Initial adverse reactions (corneal haze ≥ 2.0, loss of ≥ 2 lines best corrected vision, and overcorrection ≥ 1.00 D SEQ at one month) improved dramatically between one and three months postsurgery, and had cleared entirely in nearly all eyes by 12 months. Conclusions: These data should be useful to ophthalmologists in counselling their patients before and after excimer laser surgery. First of all, the type of procedure (PRK versus PARK) and a patient's age do not predict adverse reactions or delayed healing time. Secondly, patient data at any one time point are the best predictors of subsequent outcome. Finally, patients should be advised to be tolerant of less than satisfactory results initially as our data demonstrate that improvement is highly likely within three months, and usually by 12 months.