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Dr. Passaglia Tackles Glaucoma with Novel Technology

Christopher Passaglia

Christopher Passaglia, PhD, Professor in the Department of Medical Engineering.

In late 2023, Dr. Passaglia and his lab published two papers related to intraocular pressure. "Characterization of intraocular pressure variability in conscious rats" and "Simulation of gravity- and pump-driven perfusion techniques for measuring outflow facility of ex vivo and in vivo eyes." Dr. Passaglia has put himself at the forefront of innovation between the two. He and his team have developed novel devices to measure and manipulate eye pressure continually. His lab focuses on understanding the mechanisms involved with human and animal vision and diagnosing the conditions that lead to vision loss in glaucoma and other ocular diseases.

The basic research side of the lab uses visual electrophysiological tests, computer modeling, and animal behavior to understand what animals see in response to light stimuli. Electrodes record the electrical activity of visual neuron cells when rats are presented with visual stimuli, which are analyzed with computer models to help understand how neurons relay information to the brain and compared against behavioral studies that define the limits of what rats can and cannot see.

The applied research side of the lab studies the causes of glaucoma using novel technologies, which Dr. Passaglia was enthusiastic about talking about. As it stands, Dr. Passaglia and his lab are the only people with the capability to continually measure eye pressure and manipulate eye pressure with any desired waveform in alert, free-moving animals as small as rats. They have developed a device that rats wear like a backpack, which monitors intraocular pressure every second round-the-clock. The device connects to a small piece mounted to the rat's head that feeds a tiny tube into the rat's eye. The head mount also keeps the tube from moving—this tube couples intraocular pressure to the pressure sensor electronics in the backpack.

They have uncovered a significant impact: intraocular eye pressure varies throughout the day. For instance, sleeping subjects exhibit intraocular pressures well above what would be considered in the range of glaucoma. When the same subjects wake up, the eye pressure returns to normal. Dr. Passaglia believes there is an association between circadian rhythm and eye pressure. He points out that glaucoma medications are often prescribed to be taken at night, which is when pressure levels are elevated. Additionally, there are findings that subjects undergo stresses that elevate eye pressure. These findings show that continuous eye pressure monitoring is critical in diagnosing and treating glaucoma accurately.

The lab has also created a portable pump to inject fluid into the eye to set intraocular pressure to any desired level. This device is presently too big for rats to wear but instead attaches to the side of their cage. Dr. Passaglia hopes to use the device to determine what causes cell death in the eye that typically leads to glaucoma. He noted that eye pressure is not the only factor, as some subjects may have pressure elevated to glaucoma levels without showing signs of glaucoma, while others may have glaucoma and normal eye pressure. His lab has demonstrated that intracranial pressure may play a role. They showed that eye pressure increases with intracranial pressure elevation, and these changes can be blocked by applying neurotoxins to the cornea, meaning the brain sends signals to modulate intraocular pressure actively.

Dr. Passaglia's ultimate goal is to seamlessly merge the basic and applied research labs that complement each other. He hopes to continue trailblazing research on the causes of glaucoma. There are many factors that Dr. Passaglia and his team wish to study, including the circadian effect and intracranial pressure. Understanding these mechanisms that can cause glaucoma will lead to better treatment options and may save patients money.

Visit Dr. Passaglia's lab website here.

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