| Abstract |
History of contact lens wear is frequent in refractive surgery candidates. Patients may have been wearing lenses for many years. It has been reported that contact lens wear can temporarily distort corneal surface shape and physiology. There is supporting evidence for permanent contact lens induced changes in corneal topography, transient changes in the refractive error, and transient corneal edema (leading to increased corneal thickness). Moreover, there have been reports of permanent decrease in corneal pachymetry possibly due to the long-term hypoxia, leading to keratocyte loss and suppression of the collagen production function. Prior refractive surgery, it is important to discontinue lens wear and allow the cornea to reach a stable state in order to exclude transient changes from the preoperative measurements. The purpose of the study is to evaluate the transient changes in corneal geometry following the discontinuation of soft contact lens wear. Eighteen normal eyes and eighteen eyes that used soft contact lenses as primary means for refractive error correction were enrolled in this study. Refractive error, corneal topography, monochromatic aberrations and central corneal thickness measurements were performed immediately after discontinuation (day 1) and at each visit on days 2, 4, 8, 11 and 15. We found changes in the pachymetry of the cornea and in the high order aberrations over time between the two groups (p < 0.05). Corneal thickness was stabilized between the 4th and the 8th day after discontinuation. The dioptric range for the two main keratometric axes in the contact lens wearers group was slightly lower than in the noncontact lens wearers group (p < 0.05). It is suggested that a time interval of approximately 8 days is required for cornea in order to reach a stable condition following contact lens wear discontinuation. In refractive surgery candidates, preoperative measurements -and specifically refraction and pachymetry- should be performed after this time interval. Future studies enrolling more subjects, and associating the transient changes with different soft contact lens types and materials could provide could provide more reliable results on the temporal characteristics of these transient changes and moreover provide insight into the physiological mechanisms involved.
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