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D. Z. Savitsky, R. Want, C. Koonapareddy, V. Fan, T. Du, D. Chen, P. Asbell; Fluorophotometry to Evaluate the Cornea in Patients Utilizing Corneal Refractive Therapy (CRT) yo Correct Myopia. Invest. Ophthalmol. Vis. Sci. 2007;48(13):5418.
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Corneal Refractive Therapy (CRT), is an alternative to surgery developed to correct mild to moderate myopia. This non-surgical technique utilizes gas permeable contact lenses worn at night. CRT was approved by the FDA in 2002, and only a few studies have been conducted in relation to the evaluation of corneal health.To evaluate corneal health, we monitored the cornea before and after the fitting with CRT utilizing fluorophotometry to measure corneal epithelial permeability.
After obtaining IRB approval and consent, we enrolled 18 patients in the study whose refractive error was between -0.5 to -4.0 diopters sphere and up to 1.75 diopters astigmatism. After the initial screening, the patients received a full eye exam before using the CRT lenses to ensure healthy eyes other than refractive error. On the day of the fitting (day 0), two baseline fluorometric scans of the right eye were taken using the Fluorotron Master. 15 µL 0.75% fluorescein was then instilled in the lower conjunctival sac. Twenty minutes after the instillation of fluorescein, the eye was rinsed using standard eyewash solution. Peak corneal florescence values (PCFV) was measured by Fluorophotometry, which is an indicator of corneal epithelial permeability. After CRT fitting and consistent nightly use, fluorophotometry was repeated on day 1 and day 7 after the fitting. Patients’ baseline corneal fluorescein levels and post-rinse were compared to pre-fitting values to determine changes in corneal epithelial permeability.
Post-CRT uncorrected visual acuity was 20/20 or better in 15/18 patients by day 7. There were no adverse events seen in patients utilizing CRT, and eye exams for these patients continued to be within normal limits. After the fitting and nightly use of CRT, baseline fluorescence of the cornea (13.38 ± 2.11) remained stable, and the post-wash peak corneal florescence values did not show significant changes from the pre-fitting (84.57 ± 67.49) after use of CRT, on day 1 (76.55 ± 61.36, p>0.05) and day 7 (98.98 ± 95.17, p>0.05).
CRT is effective in correcting myopic refractive errors. The results in the current study have shown that the use of CRT lenses does not have adverse effects on corneal health as evaluated by changes in corneal epithelial permeability and regular eye-exam. This study is ongoing and longer follow-up data will be analyzed.
Mount Sinai Institutional Review Board
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