Central Retinal Vein Occlusion gets a By-Pass.
Central retinal vein occlusion (CRVO) affects one to four
percent of Americans older than 40 and very often causes severe
vision loss, including "legal blindness" (20/200 vision).
While current treatments reduce CRVO symptoms such as macular
edema-swelling of the center of the eye's light-sensitive
retina-none address the underlying problem, the blocked retinal
vein.
Ian L. McAllister, MD, Lions Eye Institute, Australia, and his
research team took direct aim at the problem, using lasers to
create a "bypass" around the constricted retinal vein with the aim
of restoring near-normal blood flow to the retina.
Perth grandmother Lorraine Hillier was one of the first to
benefit. A few years ago, she was legally blind. Now she's driving
a car, has thrown away her glasses and is living life to the full
after her sight was restored.
"It's a miracle; it really is," she told The Australian. "I
can't thank him enough."
Professor McAllister and his team from the Lions Eye Institute
in Perth spent 15 years developing the treatment, which creates a
bypass around blockages in the retinal vein that cause progressive
blindness, particularly in the elderly.
Mrs Hillier was headed for total blindness after losing the
sight in her left eye, and then discovered the same problem
emerging in her right eye.
"I panicked a bit," she said. "If I lost the second eye, I'd be
completely blind. It affects everything; you lose all of your
independence."
By the time she saw Professor McAllister, the prognosis was
grim. "She was legally blind when I saw her. Her vision was at the
stage where she'd have been eligible for a blind pension," he
said.
But three months after treatment, the vision in her right eye
was restored. The damage to her left eye had been left too
long.
Professor McAllister said other treatments were focused on
managing the end-stage complications of the vein obstruction rather
than tackling the obstruction itself so that vision could be
restored. Some patients even endured painful injections into their
eyes each month to help manage the condition. "This treatment
represents a cure for many patients afflicted by this otherwise
blinding eye condition," he said.
Professor McAllister -- who was a state finalist in this year's
Australian of the Year awards -- said an 18-month human trial of
his procedure, funded by the National Health and Medical Research
Council, recorded that in three-quarters of the eyes treated the
"bypass" was successful, and patients achieved significant vision
gains by the 18 month follow-up. This study was also the first
prospective, randomized trial to compare the bypass approach,
called laser-induced chorioretinal venous anastomosis (L-CRA), with
conventional treatment.
L-CRAs were successfully created in 76.4 percent of the 58
patients in whom the procedure was attempted. Overall,
bypass-treated patients achieved significantly better visual acuity
and were more likely to gain 20/40 vision (the legal standard for
drivers in many countries) than were control group patients.
Bypass patients were significantly less likely to have moderate
or severe vision loss. While about 18 percent of L-CRA-treated
patients developed a significant complication-abnormal blood vessel
growth at the surgery site-the researchers report that due to close
monitoring and effective management, negative consequences from
this and other complications were minimal.
"The risk of complications from L-CRA should be weighed against
the substantial vision loss faced by CRVO patients with standard
treatments," Dr. McAllister said. "In future studies of L-CRA,
optical coherence tomography (not widely available when our study
began) would be another useful outcome measure for L-CRA
effectiveness," he added.