To evaluate the 4 year refractive outcome of multizone photorefractive keratectomy (PRK) in eyes with high myopia.

SSK Okmeydanı Education Hospital, Eye Clinic, Türkiye Hospital, Okmeydanı, İstanbul.

Three ablation zones were used in 92 eyes of 48 patients whose refractive errors were between −6.0 and −10.0 diopters (D) (mean spherical equivalent −7.42 D ± 1.25 [SD]). The zones were between 4.5 and 6.0 mm based on the thickness of the cornea and the refractive correction. After the epithelium healed, dexamethasone was applied 4 times a day during the first postoperative week and then fluorometholone was applied 4 times a day for a minimum of 4 weeks. If hyperopia was found post-PRK, the steroid dose was gradually tapered. The patients were examined 1 and 3 days postoperatively, 1, 2, and 4 weeks, every 3 months for the first year, and then every 6 months.

All patients were overcorrected in the first postoperative week. At 2 and 3 weeks, the mean manifest refraction was closer to emmetropia. At 6 months, the refraction was stable. The mean spherical equivalent was −0.10 D at the end of the first year, and stabilization continued for 4 years. After the third month, the haze regressed gradually without requiring treatment. In 1 patient, herpes simplex keratitis developed and healed in a short time with topical antiviral therapy. Nineteen eyes regressed more than −1.0 D, 4 eyes were overcorrected, 4 eyes had central islands (at 6 months), and 2 eyes were undercorrected. Two eyes were retreated for regression; 1 eye was retreated for undercorrection and 1 eye, for central island. An uncorrected visual acuity of 20/40 or better was achieved in 79.2% of eyes, and 73.9% were within ±1.0 D of the intended correction.

Photorefractive keratectomy was effective in treating high myopia between −6.0 and −10.0 D. The induced refractive changes stabilized between 6 and 9 months. In most patients, no significant regression was found after this period.