Haze following photorefractive and photoastigmatic refractive keratectomy with the Nidek EC5000 and the Summit ExciMed UV200

Purpose: To determine the prevalence of moderate to severe subepithelial haze following photorefractive keratectomy for myopia and to compare the prevalence in eyes treated with the Summit ExciMed UV 200 and the Nidek EC5000. Setting: The Wellington Ophthalmic Laser Clinic, Dublin, Ireland. Methods: A retrospective study of 726 consecutive eyes treated with the Summit system and 494 consecutive eyes treated with the Nidek system with similar mean preoperative refractive errors and outcome was carried out. In the group treated with the Summit system, data were available on 692 eyes at 3 months, 612 at 6 months, and 402 at 1 year. In the group treated with the Nidek system, equivalent numbers were 456 at 3 months, 379 at 6 months, and 242 at 1 year. The degree of haze was assessed at these times by two observers using an established six point scale. Results: At 3 months, 82 eyes (11.8%) in the Summit group and 15 (3.3%) in the Nidek group had grade 1 or 2 haze (P = .0000006). At 6 months, 58 (9.5%) and 6 (1.6%), respectively, had grade 1 or 2 (P = .0000017). At 1 year, 28 (7.0%) in the Summit group had grade 1, 2, or 3, whereas only 3 (1.2%) in the Nidek group were in this category (all with grade 1) (P = .0019). Conclusion: In the first postoperative year, moderate and more severe haze was significantly less prevalent in eyes treated with the Nidek EC5000 than in those treated with the Summit ExciMed UV200.