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MH Awan, JT Whitson, JP McCulley, RW Bowman, HD Cavanagh, J Song, L Hertzog; Effect of Betaxolol on Optic Nerve Head Topography and Retinal Nerve Fiber Layer Thickness During LASIK . Invest. Ophthalmol. Vis. Sci. 2002;43(13):2100.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: To determine if LASIK produces significant changes in optic nerve head (ONH) topography and retinal nerve fiber layer (NFL) thickness as measured by the Heidelberg Retina Tomograph (HRT) and to evaluate the potential neuroprotective effect of betaxolol on these changes. Methods: This was a double-masked, randomized, prospective study in which patients undergoing primary LASIK were selected. Those with age less than 21, history of glaucoma, ocular hypertension or retinal disorders, or previous keratorefractive procedures were excluded. Patients underwent a preoperative HRT evaluation and were randomly selected to receive either betaxolol hydrochloride 1/2% solution (BT) or placebo (PL) twice daily for two days prior to LASIK. The drops were continued for seven days after the procedure. All LASIK procedures were done using the Hansatome microkeratome. Postoperative HRT's were performed at one week, one month, and three months. Mean image (3 consecutive images) having less than 30 microns of the measurement reproducibility were used for analysis. All images were read in a masked fashion with regards to patient group using the HRT II progression analysis software, version 1.6.1. Rim area (RA), rim volume (RV), mean retinal NFL thickness (mRNFL), and cup shape measure (CSM) were evaluated. A student's t-test was used for statistical analysis. Results:59 eyes of 34 patients were included. Mean age was 46.2 years (range: 29-71 years). There were 16 males and 18 females. Suction times during the LASIK procedure averaged 50.1 seconds (range: 45-58 seconds). 32 eyes received BT and 27 eyes received PL. Mean preoperative HRT values for all patients were: RA = 1.397+/-0.266mm², RV = 0.408+/-0.182mm³, mRNFL = 0.273+/-0.126mm, and CSM = -0.187+/-0.073. Mean final postoperative values were RA = 1.411+/-0.252mm², RV = 0.422+/-0.17mm³, mRNFL = 0.267+/-0.085mm, and CSM = -0.191+/-0.079. No significant differences occurred in any of these parameters. When the data were analyzed with respect to patient group (BT or PL), no significant differences were found between preoperative and final exams. Conclusion:For suction times of less than 60 seconds, no significant changes were found in ONH topography or NFL thickness following LASIK as measured by the HRT. Since no neural damage occurred, we were unable to assess any potential neuroprotective effects of betaxolol.
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