The purpose of the proposed study is to investigate the separate effects of corneal stiffness and intraocular pressure (IOP) on corneal deformation characteristics under an applied air pulse. Paired human donor eyes (n=60 pairs; 120 eyes) will be used to allow both IOP and corneal stiffness to be varied in a systematic fashion with one eye of the pair treated with a corneal stiffening procedure, and the fellow eye serving as control, combined with 4 levels of IOP from 10 to 40 mmHg in 10mmHg increments. Stiffness will be modified using incremental changes in gluteraldehyde concentration to generate two stiffness groups. Deformation characteristics will be measured in a series of 140 images captured during a ~30ms air pulse with the CorVis ST, a new device with a high speed speed camera (>4,300 frames/sec) aligned with the horizontal meridian of the cornea using Scheimpflug geometry. ANOVA will be used to determine differences in the 3x4 matrix of data, as well as stepwise regression to determine predictors of IOP and level of stiffness based on deformation parameters including a novel stiffness parameter. A clinical investigation of deformation response in keratoconus (n=50), glaucoma (n=50), ocular hypertension (n=50), diabetes (n=50), and normal individuals (n=200) will be conducted with evaluation of novel stiffness parameter. Expected results include the creation of a comprehensive database of ex vivo and in vivo corneal deformation response parameters as a function of IOP, corneal stiffness parameter, and in vivo ocular disease.
This research will investigate the separate effects of both corneal stiffness and intraocular pressure (IOP) on the shape of the cornea as it deforms under an air puff. Human donor eyes will be used so that IOP and stiffness can be experimentally varied systematically. A new device with a high speed camera will be used to capture a series of images of the cornea deforming under an air puff. Those images will be analyzed to look at deformation shape features, as well as a novel stiffness parameter, both ex vivo and clinically in glaucoma, diabetes, and corneal disease. At the conclusion of this study, we will have created a comprehensive database of ex vivo and in vivo corneal deformation response parameters as a function of IOP, corneal stiffness parameter, and in vivo ocular disease. This database of findings, and our new methods, can be used in future translational studies on clinical biomechanical biomarkers to assess pathology of eye diseases.