Researchers at the Anglia Ruskin University (ARU) in the U.K. have made significant progress in treating cataracts using a drug compound, paving the way for new treatment methods, a university press release said.
A cataract is a medical condition where the eye's lens becomes clouded over some time and affects vision quality. The clouding is caused by the disorganization of the proteins present in the lens. This eventually leads to their clumping, which scatters light away from the retina, thereby reducing vision. According to estimates from the World Health Organization (WHO), the condition affects approximately 65 million people globally, with moderate to severe vision loss seen in about 80 percent of the cases.
Using a drug as a remedy
Conventionally, surgery has been the only remedy for this condition. Still, a team of researchers led by Professor Barbara Pierscionek at ARU has carried out advanced tests of an oxysterol compound as an anti-cataract drug. An oxysterol is a derivative of cholesterol that plays a role in many cellular functions, including autophagy - conserved cell degradation to remove unnecessary components.
The compound called VP1-001, when used in laboratory-based trials, showed a marked improvement in the refractive index profile for 61 percent of the cases. In comparison, the press release said that lens opacity was found to have been decreased in 46 percent of the cases. A refractive index profile is a crucial parameter in determining the focusing capacity of the eye. The drug is therefore acting to restore the protein organization inside the lens.
"It is the first research of this kind in the world," said Professor Pierscionek in the press release. "The positive effects of the compound have been proposed as an anti-cataract drug but never before tested on the optics of the lens. It is a significant step forward towards treating this extremely common condition with drugs rather than surgery."
However, the studies also showed improvements in only some types of cataracts and not all. This would mean that the treatment would be an option for only specific cataract types, and distinctions need to be made while developing anti-cataract medications in the future, the researchers said.
The study was published in the journal, Ophthalmology and Visual Science.
Purpose: To investigate how cataract-linked mutations affect the gradient refractive index (GRIN) and lens opacification in mouse lenses and whether there is any effect on the optics of the lens from treatment with an oxysterol compound.
Methods: A total of 35 mice including wild-type and knock-in mutants (Cryaa-R49C and Cryab-R120G) were used in these experiments: 26 mice were treated with topical VP1-001, an oxysterol, in one eye and vehicle in the other, and nine mice were untreated controls. Slit lamp biomicroscopy was used to analyze the lens in live animals and to provide apparent cataract grades. Refractive index in the lenses of 64 unfixed whole mouse eyes was calculated from measurements with X-ray phase tomography based on X-ray Talbot interferometry with a synchrotron radiation source.
Results: Heterozygous Cryaa-R49C lenses had slightly irregularly shaped contours in the center of the GRIN and distinct disturbances of the gradient index at the anterior and posterior poles. Contours near the lens surface were denser in homozygous Cryab-R120G lenses. Treatment with topical VP1-001, an oxysterol, showed an improvement in refractive index profiles in 61% of lenses and this was supported by a reduction in apparent lens opacity grade by 1.0 in 46% of live mice.
Conclusions: These results indicate that α-crystallin mutations alter the refractive index gradient of mouse lenses in distinct ways and suggest that topical treatment with VP1-001 may improve lens transparency and refractive index contours in some lenses with mutations.