By Charnicia E. Huggins
NEW YORK, Jun 01 (Reuters Health) - Most people have heard that the drug
Viagra (sildenafil) can be used to treat impotence in men. However, new research
shows that in addition to enhancing one's sex life, the drug may one day help
those suffering from vision problems such as macular degeneration--a common
cause of blindness in the elderly.
In a small study, 10 men and 2 women experienced an almost 30% increase of
blood flow to the eyes less than 2 hours after administration of sildenafil. In
addition, the investigators noted a 34% increase in the study participants'
contrast sensitivity--their degree of sensitivity to light, according to
findings published in the June 1st issue of The New England Journal of Medicine.
In macular degeneration, blood flow in the eye is diminished. Patients lose
vision in the center of the eye--which is used in reading, writing, driving and
other activities--but maintain peripheral vision.
Although the 12 study subjects were healthy, the findings suggest that the
drug might also be helpful in people with vision problems.
"Visual function--that which is closest to the center of (the) reading and
color vision area--seems to increase with the use of oral sildenafil," said lead
author Dr. William E. Sponsel, director of clinical research at the department
of ophthalmology at the University of Texas Health Science Center in San
Antonio. Sponsel and colleagues conducted the study because about 3% of men who
take Viagra experience mild changes in their vision.
In one case, a patient with "very serious loss of vision in the central area
of his vision field" had been given a prescription for Viagra from his general
practitioner, Sponsel told Reuters Health. "One of the four most central parts
of the patient's visual field had dropped from a threshold of 26 down to 14--a
10,000-fold drop in visual light sensitivity," he said. After taking Viagra,
however, he had a dramatic increase in each of his visual fields, with the
lowest threshold rising from 14 to 23, he said.
"This class of drugs has great potential, and certainly we want to proceed
with an open mind," said Sponsel. "These drugs may be able to help us treat a
variety of conditions that even go beyond those that have a fundamental
circulatory basis."
Circulation to the eye, like that to the brain, is difficult to control,
Sponsel told Reuters Health. However, the ophthalmologist speculated, if we are
"able to find ways to treat macular disease--the number one cause of acquired
blindness in North America and Europe--we might also find ways to treat brain
disorders."
However, Sponsel acknowledged that more research is needed, and his results
should be viewed with "guarded" optimism.
