Discovery Could Improve Treatment of Cataracts

Originally Published MDDI March 2004R&D DIGEST

March 1, 2004

3 Min Read
Discovery Could Improve Treatment of Cataracts

Originally Published MDDI March 2004


Erik Swain

Researchers at the Washington University School of Medicine (St. Louis) have found what may be a significant risk factor for cataracts. 

The discovery could lead to medical products to ward off cataracts, or diagnostic equipment to identify who is at risk.
The team has demonstrated a link between the loss of gel in the eye's vitreous humor and the formation of nuclear cataracts, the most prevalent type of cataracts related to age. The vitreous humor is between the back of the lens and the retina.

The researchers are led by David C. Beebe, PhD, a professor at Washington University. The team had earlier found that the lens is normally oxygen-deprived. Studies in Sweden had shown that patients treated with high levels of oxygen for a long time tend to develop nuclear cataracts. With those findings in mind, the team hypothesized that oxygen might be toxic to the lens.

“And there was another key observation: the high incidence of cataracts in patients who have retinal surgery,” said Beebe. “It's typical for retinal surgeons to remove the vitreous body in order to get access to the retina. Within two years of retinal surgery and vitrectomy, patients develop cataracts at a rate approaching 100%.”

The team decided to investigate whether there was an association between the breakdown of the vitreous humor into a liquefied state, the delivery of oxygen from the retina, and the formation of nuclear cataracts. They studied 171 human eyes from eye banks, measuring how much liquid was in the vitreous humor compared to how much gel and looking for cataracts.

“We found that nuclear cataracts were strongly correlated with high levels of vitreous liquefaction, independent of age,” Beebe said. The team published its findings in the January issue of Investigative Ophthalmology and Visual Science. The study was funded by Research to Prevent Blindness and the National Eye Institute of the National Institutes of Health.

Beebe believes that when the vitreous gel separates from the retina or breaks down and liquefies, fluid flows over the surface of the retina, and that fluid then carries oxygen from the retina to the lens. A key function of the vitreous body may be to keep the oxygen in the retina from moving to the lens and damaging it. 

The Washington University researchers are now working with a team from the University of Virginia to develop advanced ultrasound techniques to measure the breakdown of vitreous gel in living people. That could enable caregivers to identify who is most at risk of developing cataracts. 

Beebe is also trying to apply the findings to surgical patients. With his colleague, Nancy M. Holekamp, MD, he is working on a project involving vitrectomy patients. They are measuring oxygen levels in the vitreous body of patients before a vitrectomy, and in patients who have had a vitrectomy and require a second retinal surgery after one or two years. The data will enable them to compare patients with a gel vitreous humor to ones whose vitreous humor is completely liquid to see if oxygen levels near the lens do in fact increase when the vitreous humor has been liquefied. 
If these studies show that vitreous gel breakdown is in fact a risk factor for cataract development, then there could be development of ways to stop oxygen from migrating from the retina to the lens.

“Perhaps we could replace the vitreous gel with a gel polymer that would keep oxygen away from the lens by replacing the barrier between the retina and the lens,” said Beebe. “Now that we're beginning to get an idea of how the vitreous works, it may be possible to design interventions to protect the lens both in people who have had a vitrectomy and in those whose vitreous is degenerating as a part of normal aging.” 

Copyright ©2004 Medical Device & Diagnostic Industry

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