The learning curve in myopic photorefractive keratectomy

The aim of this study was to assess the role of surgeons' skill on the final results of photorefractive keratectomy (PRK) in the correction of myopia.

We evaluated the results of 160 consecutive unilateral treatments performed by four surgeons in a multicenter study group, with a one year follow up. Eighty-eight patients were males (55%) and 72 females (45%). Mean age was 33.7 years (median = 33, standard deviation = 10.22, range 18-65). Attempted correction ranged between -1.50 and -15.00 D. All the eyes received topical corticosteroid therapy postoperatively. At the one year follow up, we evaluated the following: uncorrected visual acuity lines gained and refractive error (spherical equivalent) as parameters of efficacy and predictability; best spectacle corrected visual acuity loss and corneal clarity as safety parameters. We also examined the centration or decentration of the ablation zone. In order to draw up a kind of learning curve, the mean values for each parameter were calculated by arbitrarily grouping the first 10 cases of each surgeon in the first group (40 patients), the second 10 cases in the second group (40 patients) and so on.

We found that increase in uncorrected visual acuity, final refractive error and corneal clarity appeared to improve as the surgeon became more experienced, while loss of best spectacle corrected visual acuity was not significantly influenced by increased surgical experience.

We think experience with photorefractive keratectomy in at least 40 eyes is necessary to obtain best results.