Age-related macular degeneration (AMD) is a progressive vision impairment resulting from the deterioration of the retina, a thin layer of light-sensitive cells at the back of the eyeball that triggers nerve impulses to the brain.
AMD is the most common cause of blindness in people over 50. Most of these patients experience the "wet" form of the condition characterized by the overgrowth of leaky blood vessels around the retina. Injections of a drug called anti-vascular endothelial growth factor (VEGF) directly into the eye gradually abate blood vessel growth and protect the remaining vision.
Keeping up with the regular injection schedule has been challenging for patients with wet AMD. These need to be given by a physician on a bimonthly or monthly cadence, and it's typical for patients to sometimes miss treatments, ultimately resulting in a deterioration of their already limited vision.
Professor of ophthalmology at Johns Hopkins University School of Medicine, Akrit Sodhi, has been taking a closer look at AMD patients' treatment outcomes to improve their clinical outcomes.
Sodhi and the team published their findings in the Journal of Clinical Investigation, which saw them tracking over 100 patients receiving anti-VEGF injections. How the patient responded to the therapy was carefully analyzed to determine the levels of fluid accumulation in the eye or worsening vision.
Should their conditions appear to have stabilized, clinicians could pause their treatments. If the physicians detected signs of AMD reactivation at subsequent check-ins, the treatment regime resumed.
Sodhi and colleagues found that once vision loss plateaued, the patients (who were monitored for just over two years) could safely stop anti-VEGF treatments. Of course, not all the AMD patients responded similarly. After a year, 31 percent of eyes no longer needed injections, and a subset of patients still required less frequent treatments, coming in between one and three months.
"Across the board, the patients who could enter a treatment pause did the best even though they were receiving no anti-VEGF drugs. They had better visual acuity, better gain of vision, and less fluid in their retina," commented Sodhi.
Following up on these observations, Sodhi and colleagues collected tiny volumes of fluid from the eyes of both patients who had been weaned off anti-VEGF and those requiring continued care.
The scientists found that those who no longer needed the injections had higher levels of a molecule called apolipoprotein B100. Subsequent investigations in animal models of AMD further confirmed that apolipoprotein B100 protected against AMD.
These observations help lay the foundations of improved strategies to identify patients most likely to respond to anti-VEGF treatments. First, randomized clinical trials in patients need to be conducted to understand better the complex mechanisms involved in AMD progression and resolution.