Longitudinal assessments of corneal and tear film characteristics after lasik versus continued contact lens wear
Doctoral thesis, Peer reviewed
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Original versionAakre, B. (2009). Longitudinal assessments of corneal and tear film characteristics after LASIK versus continued contact lens wear. (Doktoravhandling), Glasgow Caledonian University, Glasgow.
Changes in oxygen availability, exerted mechanical force or even surgical manipulation are all factors known to influence corneal characteristics, yet detailed information about the changes such influence may induce is limited in ophthalmic literature. Furthermore, the appearance of the corneal endothelium, which is often used as a presage of structural and functional changes taking place in the cornea, has not been systematically studied over extended periods and information such as endothelial morphometry is hence not available. The purpose of this study was therefore to evaluate the endothelial morphometry over a two-year period in subjects who underwent different types of intervention, either in the form of change in contact lens material, LASIK surgery or by replacing existing contact lenses with a similar type. A group of spectacle wearers served as a control group. Results obtained through the course of the study revealed that subjects who continued wearing conventional contact lenses had substantial amounts of polymegethism compared with the control group. Those who had undergone LASIK surgery had significantly reduced amount of polymegethism three months after surgery and reached a concentration level that was consistent with the control group after 24 months. A similar tendency was found in the subjects who were refitted with silicone-hydrogel (SiH) lenses although the high number of endothelial cells that was found to reverse back to a six-sided shape after LASIK treatment was not apparent in this group of subjects. This may be associated with the sustained inflammatory response, which is arguably present in the corneas of these subjects. LASIK surgery seems to have no detrimental effect on the corneal endothelium and the procedure may even reverse some of the contact lens induced changes in the endothelial mosaic. Pre-ocular tear film evaluation revealed no inferior quality or quantity nor did these subjects report any higher dry eye sensation than the other subjects.