PURPOSE
To present a method that determines the efficacy of flap creation using a microkeratome.
METHODS
Thirty-six eyes of 18 patients were included in the study, operated by two experienced surgeons using the Moria LSK-One microkeratome. Very high-frequency (VHF) digital ultrasound arc-scanning using Artemis technology was used to measure the Reinstein Flap Thickness Profile created by addition of the preoperative epithelial thickness profile to the postoperative stromal component of the flap. Descriptive statistics revealed central flap thickness accuracy and reproducibility. Univariate and multivariate regression analysis was used to determine correlations between central flap thickness and preoperative clinical parameters. Three-dimensional flap thickness maps demonstrated the mean, median, standard deviation, and range of thickness.
RESULTS
Intended flap thickness was 160 µm. Mean central flap thickness was 161 µm in the right eye and 166 µm in the left eye. Central reproducibility (standard deviation of the mean) was 30.3 µm, with a range of 106 to 228 µm. Central flap thickness correlated to preoperative corneal thickness measured by VHF digital ultrasound but not by Orbscan. On qualitative analysis, no consistency among eyes was observed in the three-dimensional flap thickness map. Flaps were on average thinner in the center, but not in all cases.
CONCLUSIONS
A systematic qualitative and quantitative statistical evaluation of microkeratome accuracy and reproducibility can be performed by measuring corneal flap thickness with arc-scanning VHF digital ultrasound. [J Refract Surg. 2006;22:431-440.]
AUTHORS
From Margaret M. Dyson Vision Research Institute, Department of Ophthalmology, Weill Medical College of Cornell University, New York, NY (Reinstein, Sutton, Silverman, Coleman); the Department of Ophthalmology, University of British Columbia, Vancouver, British Columbia, Canada (Reinstein, Sutton, Srivannaboon); Faculté de Médecine St. Antoine, Université Paris VI - Centre Hospitalier National d’Ophtalmologie des Quinze-Vingts, Paris, France (Reinstein); London Vision Clinic, London, United Kingdom (Reinstein, Archer).
Certain aspects of the ultrasound technology described in this report are protected by US and international patents. Patents are administered by the Cornell Research Foundation, Ithaca, NY, and licensed to Ultralink LLC, St Petersburg, Fla.
Supported in part by NIH grant EY01212, the Dyson Foundation, the St Giles Foundation, and Research to Prevent Blindness Inc.
Drs Reinstein, Silverman, Sutton, and Coleman have a proprietary interest in the materials presented herein. The remaining authors have no proprietary interest in the materials presented herein.
Preparation in partial fulfillment of the requirements for the doctoral thesis, University of Cambridge, for Dr Reinstein.
Presented in part at the Association for Research in Vision and Ophthalmology Annual Meeting, May 11, 1998, Ft Lauderdale, Fla; and the International Society of Refractive Surgery Meeting, November 6, 1998, New Orleans, La.
Correspondence: Dan Z. Reinstein, MD, MA(Cantab), FRCSC, London Vision Clinic, 8 Devonshire Place, London W1G 6HP, United Kingdom. Tel: 44 20 7224 1005; Fax: 44 20 7224 1055; E-mail: dzr@londonvisionclinic.com
Received: March 20, 2002
Accepted: March 8, 2006
