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Cherie B. Nau, Daniel J. Repp, Jay W. McLaren, Katrina M. Kittleson, Sanjay V. Patel; Relationship between Central and Peripheral Corneal Thickness in Long-Term Contact Lens Wearers. Invest. Ophthalmol. Vis. Sci. 2012;53(14):4699.
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In recent studies, the relationship between central corneal thickness (CCT) and peripheral corneal thickness (PCT) has been examined as a metric of central corneal function. In this study, we determined if the relationship between CCT and PCT in long-term contact lens wearers differed from that in non-contact lens wearers.
Corneal thickness was measured in 74 corneas of 37 soft contact lens wearers (ages 20-63 years; duration of lens wear, 10-35 years), 22 corneas of 11 rigid gas permeable contact lens wearers (ages 35-63 years; duration of lens wear, 10-40 years), and 267 normal corneas of 142 non-contact lens wearers (ages 24-88 years). Contact lenses were not worn for 2 weeks prior to examination. CCT was determined by ultrasonic pachometry (DGH 1000) and PCT was determined by scanning-slit pachometry (Orbscan) as the mean of measurements at 4 mm superior, inferior, nasal, and temporal to the center of the cornea. The central-to-peripheral-thickness-ratio (CPTR) was calculated by dividing CCT (by scanning-slit pachometry) by PCT. Relationships between age and CCT, PCT, and CPTR were assessed by Pearson correlation coefficients, and significances were determined by using generalized estimating equation (GEE) models to account for possible correlation between fellow eyes of the same subject. Comparisons of CCT, PCT, and the CPTR between contact lens wearers and non-contact lens wearers were assessed by using GEE models, and minimum detectable differences (MDDs) were calculated for non-significant differences (α=0.05, β=0.20).
In non-contact lens wearers, CCT was not correlated with age (r= -0.10, p=0.28, n=267), whereas PCT decreased with age (r= -0.33, p<0.0001, n=254), and the CPTR increased with age (r=0.59, p<0.0001, n=254). CCT did not differ between non-contact lens wearers (562 ± 30 μm, mean ± SD) and either soft lens wearers (561 ± 33 μm, p=0.56, MDD=11 μm) or rigid lens wearers (553 ± 28 μm, p=0.23, MDD= 19 μm). After adjusting for age, PCT did not differ between non-contact lens wearers (643 ± 43 μm) and soft lens wearers (652 ± 32 μm, p=0.26, MDD=15 μm) or rigid lens wearers (652 ± 31μm, p=0.80, MDD=27 μm), and the CPTR also did not differ between non-contact lens wearers (0.87 ± 0.05 μm) and soft lens wearers (0.85 ± 0.03, p=0.07) or rigid lens wearers (0.84 ± 0.02, p=0.31).
Long-term soft or rigid gas permeable contact lens wear is not associated with clinically significant changes in corneal thickness. Long-term contact lens wearers can be considered a normal control group when using the CPTR to assess corneal disease.
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