J. Crawford Downs, Ph.D., vice chair of Research in the University of Alabama at Birmingham Department of Ophthalmology, was awarded a three-year, $1.23 million grant from the National Eye Institute to explore intraocular pressure fluctuation as it relates to the development and progression of glaucoma, a potentially blinding disease that affects more than 2.2 million Americans.Downs, a leading ocular biomechanics expert, is director of the UAB Ocular Biomechanics and Biotransport Program, and studies the eye using principles traditionally associated with mechanical engineering. He is exploring the underlying reasons that the elderly and people of African descent are more likely to develop glaucoma.
“It is well-known that IOP and age are the most consistent independent risk factors for glaucoma,” Downs said. “Despite this, many people who present with these risk factors will not develop glaucoma, while others develop glaucoma or worsen rapidly at clinically measured normal levels of mean IOP. This illustrates the need for further research into the underlying causes of this complex, multifactorial disease.”
Lowering mean IOP is the only clinical treatment that has been shown to slow the progression of glaucoma, but little is known about IOP variations. In earlier research, Downs developed a system to monitor IOP continuously. He demonstrated that IOP does not stay at a consistent level as previously thought, but instead continually fluctuates, with about 7,000 large IOP spikes occurring per hour during waking hours.
“Our research shows that IOP spikes account for up to 15 percent of the total IOP energy the eye must absorb,” Downs said. “This is extraordinary in that IOP spikes represent a previously unknown component of the IOP insult that has yet to be characterized or considered in previous studies. We had no idea that the eye is constantly subjected to these pressure spikes, and this could be a significant contributor to the optic nerve head damage typical in glaucoma. Our biomechanics work has shown that IOP spikes are likely to be much larger in the elderly and persons of African descent, which may explain their increased susceptibility to glaucoma.”
Downs suspects that there are poorly understood disease-related components of IOP that independently contribute to the onset and progression of glaucoma. His studies will further explore how IOP fluctuations affect the development and progression of glaucoma, especially for high-risk populations.