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S. Dremmel, B. Wagels, D. Betschart, R. North, F. Barker; Biomechanical and Light Scattering Properties of the Human Cornea. Invest. Ophthalmol. Vis. Sci. 2008;49(13):659. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
The Ocular Response Analyzer (ORA) uses an air pulse to measure corneal resistance to deformation (Corneal Resistance Factor (CRF)). CRF has been suggested, but not demonstrated, to correlate with age-related corneal structural changes noted on post-mortem examination. Corneal scatter (haze) has also been reported to increase with age and may be related to these same structural changes that disrupt the normal organization of the cornea. This is a study in which a potential surrogate for corneal structural change, increased corneal scatter measured by Scheimpflug photography, was compared to CRF.
This was a population study of the right eyes of 101 normal local Caucasian individuals ranging in age from 13 to 66 years, mean 38 years (SD 12.98). Pachycham measures of corneal density (scatter) from Bowman’s layer (DB) and the Stroma level (DS). Corneal Resistance Factor (CRF) was measured using the ORA.
A significant age-related increase in stromal corneal light scatter (DS), but not DB, was noted at 4 of 5 corneal eccentricities 0.0, 0.5, 1.5, 2.0 mm (Pearson Correlation r= 0.225, p=0.023; r= 0.205, p=0.040; r= 0.208, p=0.036; r= 0.232, p= 0.019). A significant negative correlation was found between CRF and DS for the corneal eccentricities 0.0, 0.5, and 1.0 mm (Pearson Correlation r= -0.244, p=0.014; r= -0.242, p=0.015; r= -0.203, p=0.041).
The age-related increase in Stromal Density (DS) is consistent with other reports of higher scattering in the corneal with age. Combining this with the noted decrease in CRF with increasing DS indicates that the age-related changes in the stroma that affect corneal biomechanics may also be related to the creation of light scatter within this optical tissue.
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