USF Research Advances Understanding of Eye Pressure in Glaucoma

These studies, recently published in Investigative Ophthalmology & Visual Science, utilize a pioneering wireless eye-pressure monitoring system developed in Passaglia's lab. The system continuously measures eye pressure in rats, which exhibit eye-pressure rhythms similar to those found in humans. Alexandra Zamitalo, a USF alumna, served as lead author of the research.

Using the monitoring technology, the team explored how the body's circadian rhythm influences eye pressure regulation. This internal clock is known to govern various functions such as sleep and hormone production, with light as a crucial synchronization signal. Passaglia stated, "No one was continuously measuring eye pressure until we figured out a way. It was then that we started seeing patterns that had largely been invisible before, providing one of the most detailed looks yet at the biological mechanisms that control eye pressure."

Typically, eye pressure is assessed as a single measurement during annual exams. However, Passaglia emphasized that eye pressure fluctuates continuously throughout the day, often rising at night and potentially leading to glaucoma. The new monitoring device, which employs a miniature pressure sensor connected to the rat's eye through a small tube, allows for continuous data collection, revealing patterns not captured during standard clinical assessments.

The research indicates that while eye pressure does increase at night, the rats do not develop glaucoma for reasons that remain unclear. The nighttime increase appears to be driven by neural signals from the brain, suggesting that eye pressure is influenced by the body’s biological systems rather than being solely regulated within the eye itself.

To investigate the impact of circadian rhythms on eye pressure, researchers adjusted the rats' light exposure, immersing them in constant light. The results were surprising; the normal pressure rhythm vanished, and average pressure levels began to rise significantly. Passaglia remarked on the unexpected strength of this effect, highlighting the potential for light to play a more substantial role in eye pressure regulation than previously thought. While these findings stem from rodent studies and do not imply that artificial light exposure causes glaucoma directly, they raise important questions about the effects of disrupted light cycles on overall eye health.

Though immediate changes to glaucoma treatment are not anticipated, the identification of the neural pathways and chemical messengers that regulate eye pressure enhances researchers' understanding of this complex system. The knowledge gained may also illuminate why some treatments are more effective at certain times of day and guide future therapeutic approaches. Passaglia concluded, "What we're really trying to understand is the fundamental biology. Once you understand the mechanism, then you can start thinking about better ways to intervene."