Cynthia Owsley, PhD, MSPHResearchers at the University of Alabama at Birmingham discovered that night vision tests at a specific location in the retina will be suitable for assessing treatments and preventions for age-related macular degeneration (AMD), a common cause of vision loss in older persons.

Cynthia Owsley PhD and Christine Curcio PhD (UAB) lead the Alabama Study on Early Age-related Macular Degeneration (ALSTAR2). This NEI-funded project prospectively assesses >500 persons over 3 years to determine the best vision test for signaling disease onset and worsening. The study is notable for its large size and focus on early disease.

AMD is currently treatable with injections into the eye that reduce leakage from abnormal blood vessels behind and in the retina. Recently, a new drug has been approved to slow the advance of atrophy, an AMD end-stage. For earlier disease stages, when tissue damage is minimal, diet modification and smoking cessation are recommended. Lack of tests to assess whether a new treatment works is a major roadblock to new preventions or treatments targeting early stages. Finding such tests is the mission of ALSTAR2.

Christine Curcio, PhDThe retina is a layer of nerve cells in the back of the eye that act as a light-sensing chip for the brain. Reading and other bright-light visual tasks require cone photoreceptors concentrated in the fovea, a retinal region that lacks rod photoreceptors, which sense dim light. A new study from ALSTAR2 (link) shows that rod photoreceptors next to the fovea are few in number but are stronger indicators than the more numerous rods further away.

After a bright flash of light, rods take time to recover their sensitivity. This time lengthens in aging and much more so in AMD. Learning that slowing is worse near the fovea links vision changes to specific cellular mechanisms. The researchers think that a lifetime of maintaining high-energy cones has degraded supporting tissues that affect the nearby rods. Whether dark adaptation slowing predicts disease progression will be learned from the ongoing 3-year follow-up visit of ALSTAR2.

These findings are published in "Biologically Guided Optimization of Test Target Location for Rod-mediated Dark Adaptation in Age-related Macular Degeneration: Alabama Study on Early Age-related Macular Degeneration 2 Baseline" in the June 2023 issue of Ophthalmology Science.