Corneal changes and wavefront analysis after orthokeratology fitting test.

PURPOSE: To evaluate corneal changes and ocular aberrations during an orthokeratology test. DESIGN: A prospective, nonrandomized cohort study. METHODS: Fourteen myopic patients (26 eyes) underwent an orthokeratology fitting test with the BE contact lens (Ultravision Pty, Ltd, Brisbane, Australia). Best spectacle-corrected visual acuity (BSCVA), uncorrected (Ultravision Pty, Ltd, Brisbane, Australia) visual acuity (UCVA), subjective cycloplegic refraction, biomicroscopy, corneal topography, optical pachymetry, and aberrometry were performed at baseline and one and eight nights orthokeratology. The short-term effect of orthokeratology using corneal topography, tomography, and ocular aberrations was evaluated. RESULTS: The mean spherical equivalent changed from -2.24 +/- 0.98 diopters (D) at baseline to 0.15 +/- 0.76 D after the eight nights of lens wear (P = .001). All patients had an UCVA of 20/30, 69.2% with 20/20. Changes in central corneal pachymetry were not observed. There was a statistically significant increase in the temporal corneal thickness from night one, without any difference between nights one and eight (P > .001). A significant increase of higher-order root mean square values was observed from baseline (0.42 +/- 0.16 mum), night one (0.81 +/- 0.24 mum), and night eight (1.04 +/- 0.24 mum). Increases in coma (Z7+Z8) and spherical aberration (Z12) were observed. Positive horizontal (Z8) coma increased in right eyes, and negative horizontal (Z8) coma increased in left eyes (P < .001). CONCLUSIONS: Myopia reduction resulting from rapid central corneal flattening and improvement of UCVA occurred after orthokeratology. Higher-order aberrations (HOAs), particularly spherical aberration and coma, increased significantly during the orthokeratology test. An increase of temporal pachymetry and differences in coma direction induced between the eyes may be related to the subclinical lens decentration temporally.

Laser in situ keratomileusis with the Nidek EC-5000 excimer laser for astigmatism greater than 4.00 D.

PURPOSE: To evaluate laser in situ keratomileusis (LASIK) performed with the Nidek EC-5000 excimer laser in 66 astigmatic eyes with cylinder from 4.00 to 8.00 D. METHODS: LASIK was performed with the Nidek EC-5000 excimer laser in 66 astigmatic eyes with cylinder from 4.00 to 8.00 D. Based on Chayet's nomogram, ablation zone diameters were 5.5 mm (steep meridian ablation) to 7.5 mm (flat meridian ablation). In eyes with simple myopic astigmatism, mixed astigmatism, and compound myopic astigmatism (low sphere), ablation was performed in both meridians. In eyes with simple hyperopic astigmatism, ablation was performed in the flat meridian alone. In eyes with compound hyperopic astigmatism, ablation zone diameter was 5.5 mm and the transition zone was 7.5 mm. RESULTS: Uncorrected visual acuity was 20/40 or better in 89% of eyes and was equal to preoperative best spectacle-corrected visual acuity in 62% of eyes. No eyes lost lines of best spectacle-corrected visual acuity. CONCLUSIONS: Using the Nidek EC-5000 excimer laser, we had satisfactory results in the treatment of astigmatic eyes with cylinder from 4.00 to 8.00 D, based on Chayet's nomogram.

Complications of photorefractive keratectomy and laser in situ keratomileusis.

PURPOSE: To analyze the safety of photorefractive keratectomy (PRK) and laser in situ keratomileusis (LASIK) with the Nidek EC-5000 excimer laser for surgery performed from Jan 1999 to Dec 2001. METHODS: Retrospective study of excimer laser in 683 eyes: PRK was performed in 103 eyes and LASIK was performed in 580 eyes using the Nidek EC-5000 excimer laser and Moria Carriazo Barraquer microkeratome. We classified complications as intraoperative, early postoperative (30 days) and late postoperative complications. All patients were followed for at least 6 months. RESULTS: There were 15 (2.19%) intraoperative microkeratome-related flap complications, 5 thin flaps (0.73%), 4 free caps (0.58%), 3 buttonholes (0.43%), and 3 small flaps (0.43%). The most frequent early postoperative complication was dry eye with pain in 42 eyes. There were 30 cases of microwrinkled flaps (4.39%), 14 cases of dislocated flaps or flap striae that necessitated lifting and irrigating the flap (2.04%), 8 interface epithelial ingrowth (1.17%), 4 interface debris (0.58%), 3 haze (0.43%), 3 glare (0.43%), 2 decentered ablations (0.29%), and 2 cases of toxic keratitis (0.29%). Late postoperative complications were 98 cases of spherical equivalent refraction more than or equal to 1.00 D (14.3%) with 6 months follow-up. Reoperation was necessary in 33 eyes (4.83%). Five eyes lost 1 or more lines of preoperative best spectacle-corrected visual acuity (0.73%), and 2 eyes had keratoconus (0.29%). CONCLUSION: Refractive surgery with the Nidek EC-5000 excimer laser was safe, with few complications.