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H.A. Swarbrick, J. Jayakumar, W. Co, D. He, C. Siu, B. Yau; Overnight Corneal Edema Can Modulate the Short–Term Clinical Response to Orthokeratology Lens Wear . Invest. Ophthalmol. Vis. Sci. 2005;46(13):2056.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: To investigate the influence of overnight corneal edema on the clinical response to overnight orthokeratology lens wear. Methods: Twelve young adult subjects (age 20 to 25 years) were fitted with reverse–geometry lenses for orthokeratology (BE; UltraVision, Brisbane, Australia) in both eyes. Matched design lenses in Boston ES (nominal Dk/t = 8) and Boston XO materials (nominal Dk/t = 45) were worn in the two eyes for eight hours overnight. A separate overnight trial was conducted to examine corneal changes in the absence of lens wear in the contralateral eye. LogMAR visual acuity, apical corneal radius (ro, mm; Medmont E–300 topographer) and corneal eccentricity (e; Medmont) were measured before and immediately after overnight lens wear. The overnight corneal edema response was monitored using optical pachometry. Changes from baseline were examined using ANOVA and post hoc protected t–tests, with a critical p–value of 0.05. Results: Overnight central corneal edema averaged 11.5 ± 5.8% and 3.3 ± 3.7% in the ES and XO lens–wearing eyes respectively (ES > XO; p < 0.001), compared to 2.4 ± 2.1% with no lens wear. Despite the matched reverse–geometry lens designs, changes in unaided visual acuity and corneal topography were much less evident in the ES lens–wearing eyes compared to those wearing the XO material (change in logMAR VA: –0.09 ± 0.25 vs. –0.33 ± 0.16, p < 0.001; change in ro: 0.02 ± 0.06 vs. 0.18 ± 0.11 mm, p < 0.001; change in e: 0.00 ± 0.09 vs. –0.19 ± 0.13; p < 0.001). No significant differences in these clinical outcomes were found between ES lenses and no lens wear. Conclusions: High levels of overnight corneal edema appear to limit the clinical effects of overnight reverse–geometry lens wear, at least in the short term. This suggests that the use of high Dk materials for overnight orthokeratology not only provides physiological advantages, but may also optimize clinical outcomes.
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