Effective drug management of PVR remains unfulfilled goal
The bottom line about pharmaceutical management of proliferative vitreoretinopathy (PVR) is that many different drugs have been tried, but so far nothing has been proven effective for treating PVR or reducing its risk, said Demetrios G. Vavvas, MD, PhD, at the inaugural Retina World Congress.
Introducing a discussion of published studies and case series reporting on pharmaceutical management of PVR, Dr. Vavvas told attendees: “Welcome to the graveyard.” Ending his review, he acknowledged that the picture he painted was “bleak.”
Dr. Vavvas admitted that though he cannot predict the future, he is an optimist by nature and is hopeful that researchers will eventually identify effective pharmacotherapy for PVR management. Success, however, will require better knowledge of PVR pathogenesis and awareness of the probable flaws of previously attempted strategies.
“There are several reasons why we have yet to identify effective pharmaceutical agents for the management of PVR," said Dr. Vavvas, Monte J. Wallace Ophthalmology Chair in Retina and associate professor of ophthalmology, Harvard Medical School, Boston.
"First, we do not fully understand how it develops," he said. "Furthermore, the preclinical models used to investigate potential therapies are imprecise and do not really recapitulate what happens in patients in vivo. Therefore, it is not surprising that an agent that looks promising for treating PVR induced experimentally by a single factor fails in clinical trials."
In addition, available histopathological studies have looked at epiretinal and subretinal membrane specimens, but they overlook the presence and role of intraretinal fibrosis that causes retinal stiffness and shortening, he noted.
“Furthermore, many of the clinical trials of pharmaceutical intervention for PVR did not take into account that PVR develops through a long-term, continuous process that cannot be effectively interrupted by a single or short-term intervention," Dr. Vavvas said. "So, in addition to identifying an appropriate agent, there is a need to figure out the appropriate dosing, timing, and duration of treatment. Likely, there is also a need for combination therapy.”