title: Angle kappa changes after photorefractive keratectomy for myopia.
abstract: The goal of this study was to compare differences in the mean angle kappa and its intercepts before and after photorefractive keratectomy (PRK) for myopia. In a prospective controlled study, myopic patients were treated with aspheric wavefront-guided (personalized) PRK with a Bausch & Lomb Technolas 217z excimer laser. The manifest refraction, visual acuity, and angle kappa were evaluated preoperatively and at 1 and 6 months postoperatively. The same operator performed all angle kappa measurements using Orbscan IIz. A total of 48 cases (96 eyes, 68.75 % female) with a mean age of 26.70 ± 4.89 years (18-34 years) were treated. The preoperative and postoperative mean angle kappa values were not significantly different (4.97 ± 1.24 vs 4.99 ± 1.10 at 6 months). The average horizontal distance (x-intercept) between the visual axis and pupillary axis intersection on the corneal surface measured before surgery (-0.562 ± 0.074 mm) did not significantly differ from the values measured at 1 and 6 months after surgery (-0.559 ± 0.048 and -0.554 ± 0.055 mm, respectively). Similarly, the average vertical distance (y-intercept) values did not differ before and at 1 and 6 months after surgery (0.156 ± 0.225, 0.142 ± 0.040, and 0.149 ± 0.33 mm, respectively). No differences in the angle kappa or its corneal intercepts were observed between pre- and post-PRK. This finding implies that PRK does not change the corneal vertex locations.
authors.affiliation: Eye Research Center, Mashhad University of Medical Sciences, Mashhad, Iran.
authors.forename: Siamak
authors.initials: S
authors.lastname: Zarei-Ghanavati
authors.forename: Hamid
authors.initials: H
authors.lastname: Gharaee
authors.forename: Alireza
authors.initials: A
authors.lastname: Eslampour
authors.forename: Mojtaba
authors.initials: M
authors.lastname: Abrishami
authors.forename: Soamaye
authors.initials: S
authors.lastname: Ghasemi-Moghadam
mesh_terms: D000293:Adolescent; D000328:Adult; D016022:Case-Control Studies; D019781:Corneal Topography / Q000379:methods; D003941:Diagnostic Techniques, Ophthalmological; D005260:Female; D006801:Humans; D054018:Lasers, Excimer; D008297:Male; D009216:Myopia / Q000503:physiopathology / Q000601:surgery*; D018903:Photorefractive Keratectomy; D011446:Prospective Studies; D011680:Pupil / Q000502:physiology; D012029:Refraction, Ocular / Q000502:physiology; D014792:Visual Acuity / Q000502:physiology; D055815:Young Adult