The Influence of Biomechanical Ocular Properties and Ocular Pulse Amplitude in Glaucoma. (Roberts, Weber, Fleming, and Sawchyn) Work will continue on the hypothesis proposed previously, describing the influence of the variation in intraocular pressure caused by the heart beat (ocular pulse amplitude or OPA), in combination with ocular rigidity, on the development and progression of glaucoma. To determine the relationship between ocular pressure waves, arterial pressure waves, and venous pressure waves, a protocol has been approved and 3 subjects enrolled to record natural variation in systemic blood pressure and heart rate during general surgical cases. All three waveforms will be recorded simultaneously, and signal analysis will be performed to investigate the determinants of the ocular pulse waveform. After additional subjects are recruited, these data will be used with our previously described electrical analog model to determine a methodology to estimate ocular blood flow and ocular rigidity in various forms of glaucoma. In addition, the difference in Goldmann Applanation Tonometry (GAT) and Dynamic Contour Tonometry provide an indication of the “stiffness” or “softness” of the cornea. It was determined that this difference was greater in glaucoma subjects treated with Prostaglandins than in normal subjects matched for central corneal thickness, indicating that the glaucomatous corneas are softer than normal, and therefore GAT may be more inaccurate in patients with glaucoma. This was presented at ARVO.
Bryan R. Costin, Gloria P. Fleming, Paul A. Weber, Ashraf M. Mahmoud, Cynthia J. Roberts “Corneal Biomechanical Properties and Intraocular Pressure Measurement in Primary Open Angle Glaucoma versus Normal Control Subjects.” ARVO 2011, E-Abstract 5178.