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J.H. Wang, T. Simpson, D. Fonn; Objective Measurements of Corneal Light Backscatter During Corneal Swelling Using Optical Coherence Tomography . Invest. Ophthalmol. Vis. Sci. 2003;44(13):3666.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: To demonstrate that corneal light scattering can be measured objectively during corneal swelling using optical coherence tomography (OCT). Methods: One eye (randomly selected) of twenty non contact lens wearers (10 males and 10 females, age 35.6 ± 9.6 years) was patched during 3 hours of soft contact lens (SCL) wear and the contralateral eye acted as control. Corneal images were captured before and after SCL wear at 20-minute intervals over 100 minutes using optical coherence tomography (OCT) to obtain corneal thickness and light backscatter profiles. OCT backscattered light of the epithelial layer (decided by the thickness measurements) and 10 equally divided layers of the remaining were analyzed using a custom software program. Two baseline measurements were taken at different visits before lens wear to test the repeatability of lightscatter measurements. Results: From two baseline measurements, repeated measurements showed good repeatability of normalized lightscatter results. Immediately after contact lens removal, total corneal thickness increased significantly by 13.8 ± 2.3% (Mean ± SD) compared to baseline (p<0.0001, paired t-test) then decreased during deswelling course. Corneal light backscatter changed significantly (Re-ANOVA: F(50, 950)=2.22, p <0.0001) after lens wear and a significant light scatter increase was found in the epithelial layer (36.4%) and last posterior layer (35.6%) immediately after lens removal (post hoc tests, p<0.005). There was a strong correlation (r=0.9375, p<0.05) between the change of light scatter and corneal swelling during the deswelling period. The light scatter recovery rate was approximately the same for both epithelial and posterior layers after lens removal. Conclusions: Lightscatter analysis with OCT seems to be a promising method to objectively estimate corneal light scattering property with good repeatability. Corneal light scatter increases in the anterior and posterior layers of the cornea during corneal swelling induced by contact lens wear and eye closure.
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