Optical coherence tomography measurements of the fresh porcine eye and response of the outer coats of the eye to volume increase.

Corneal and scleral thickness and anterior chamber dimensions are required for understanding developmental and pathological processes. Parameters of the eyeball are also required to calculate optical and material properties. As the eyeball resembles a pressure vessel, it has been suggested that elasticity of the cornea and sclera could be calculated from the measurements of thickness. Baseline corneal and scleral thicknesses and anterior chamber dimensions and how these change with incremental increases of intraocular fluid are measured in fresh porcine eyes using the Visante OCT (optical coherence tomography). At baseline, corneal thickness is almost constant. Anterior scleral thickness is variable, decreasing from 0.91+/-0.07 mm near the limbus to a minimum of 0.58+/-0.13. Posterior scleral thickness is more constant with an average of 0.78+/-0.09 mm. Near the optic nerve the thickness increases to 1.00+/-0.09 mm. Average baseline anterior chamber angle, diameter, and depth were found to be 33.15+/-4.91 deg, 13.60+/-0.38 mm, and 2.13+/-0.22 mm, respectively. After fluid injections, maximum changes in corneal and scleral thicknesses were 9 to 10 and 1 to 3%, respectively. Anterior chamber angle and depth decreased slightly but significantly. Changes in the eyeball coats with fluid injections, indicate that the pressure vessel model can be applied to the eye to calculate corneal and scleral elasticities.