Spectral Domain OCT Doppler Assesses Aqueous Outflow
Co-Principal InvestigatorsLarry Kagemann, M.S., Gadi Wollstein, M.D., Hiroshi Ishikawa, MD University of Pittsburgh
The most important factor to consider in glaucoma is the pressure of the eye, which is controlled by the slow outflow of fluid within a drainage system in the front of the eye. We have developed a way to visualize and measure how fast this drainage occurs without touching the eye, and without any bright lights. This project is vital in two ways: 1- in order to validate the new measurement in a controlled environment designed to be nearly identical to that of the clinic, and 2- in order to finally visualize, for the first time, the entire system as it functions.
When this study is complete, glaucoma doctors will be able, for the first time, to actually measure how an eye responds to a glaucoma medication. Glaucoma surgeons will be able, for the first time, to actually know before the operation, where the best place to implant a drainage device would be. The field of glaucoma medicine will know, for the first time, how much of the drainage system is actually used under normal conditions. This may allow glaucoma doctors to detect the conditions that could lead up to pressure elevation and eye damage long before they actually occur.
This study will use eyes generously donated for medical research. The first aim of the study involves setting up drainage in an eye at a known rate, and measuring the size of and location of all key components of the drainage system. This will be the first time that anyone has documented the entire functioning drainage system as it operates. Data from this experiment will give us the best clue as to where it is important to make similar measurements in our patients.
One of our collaborators has studied the drainage system and has found that eye pressure might squeeze some components of the drainage system shut, but was only able to observe it in slices on a microscope. The second component of the experiment will change eye pressure and observe first-hand the effect of pressure on the size of those components. We will examine whether the components are able to rebound back to their original shape after an attack of high pressure, or if damage is permanent. This information could fundamentally change how glaucoma doctors respond to various levels of pressure in their patients, and help to prioritize their responses.
The final aim of the study involves combining measurements of fluid speed and "tube" size to calculate total observable flow. If the flow that we measure leaving through the drainage system matches the flow that we observe going into the eye, we will have validated the first non-contact technique capable of providing doctors immediate data on eye pressure regulation.
No one else is currently capable of making these measurements, and the information provided is at the very core of the processes that result in eye damage in glaucoma. We are incredibly excited to be part of their development, and cannot sufficiently express our gratitude to those willing to support this work.