Document Type

Theses, Ph.D


Available under a Creative Commons Attribution Non-Commercial Share Alike 4.0 International Licence



Publication Details

Successfully submitted for the award of Doctor of Philosophy (Ph.D) to the Technological University Dublin in 2016.


Introduction: Soft CL (SCL) wear can alter the cornea and have significant effects on vision quality (Hardten and Gosavi, 2009; Pflugfelder et al., 2002; Ryan and Jacob, 1996; Tseng et al., 2007). This may have implications for visual outcomes following corneal refractive surgery (CRS) (Tang et al., 2005). The time required for resolution of these SCL-induced changes can vary (González-Méijome et al., 2003a; Hashemi et al., 2008; Ng et al., 2007; Nourouzi et al., 2006; Schornack, 2003; Wang et al., 2002b). Despite this, current guidelines relating to cessation of SCL wear prior to CRS vary greatly, and are lacking in relation to the criteria required to achieve stability of measurements (FDA, 2014; Royal College of Ophthalmologists, 2011).

Purpose: To examine the influence of SCL wear on cornea structure, the corneal epithelium and endothelium and the outcomes of CRS. Methodology: The cornea and CRS outcomes were compared between patients who wore SCLs (n = 179) against a non-CL wearing control group (NCL) (n= 148).

Results and conclusion: SCL wear had a significant effect on corneal curvature (mean anterior inferior tangential radii SCL 7.77mm, NCL 7.90mm, p = 0.04). Peripheral endothelial cell density (SCL = 3109 cells/mm2, NCL = 2935.08 cells/mm2, p = 0.03), mean endothelial cell area (SCL = 322.25 cells/mm2, NCL = 346.92 cells/mm2, p = 0.00) and coefficient of variation of cell size (SCL = 29.13, NCL = 25.63, p = 0.00) were significantly affected by SCL wear. Six weeks following LASIK central epithelial thickness was significantly thicker in the SCL group (59.65 ±6.20μm) compared with the NCL group (54.42 ±8.12μm, p = 0.04) whereas the epithelial thickness in the nasal periphery was significantly thinner in the SCL group (59.52 ±7.01μm) compared with the NCL group (65.83 ±9.16μm, p = 0.03). Although 24 hours was insufficient for resolution of these changes, 2 weeks SCL cessation was sufficient. Previous SCL wear had no negative impact on visual outcomes following CRS compared with a NCL control group, regardless of previous SCL cessation time prior to CRS (all p values > 0.05).


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