Clinicians may need to take a more holistic approach with patients with age-related macular degeneration (AMD) to help them protect their ability to see at night, new research suggests. In studying 78 patients with AMD, researchers found certain systemic conditions and lifestyle choices can impair dark adaptation (DA).1
Using multivariate assessments, they noted body mass index (BMI), taking Age-Related Eye Disease Study (AREDS) vitamins and family history of AMD were each significantly associated with worse rod intercept times, measured with AdaptDx (MacuLogix). Abnormal dark adaptation, defined as a rod intercept time ≥ 6.5 minutes, was significantly associated with family history of AMD, taking AREDS supplements and alcohol intake.1
Studies suggest impaired dark adaptation is one of the first detectable consequences of AMD, and measuring the impairment may be a new method for identifying subclinical disease.2
The researchers admit the links found in the study are challenging to explain, particularly the association between higher BMI and impaired DA. “To our knowledge, no previous clinical studies have reported similar findings,” they said. Obesity is considered a chronic inflammatory condition, and “there is an association between inflammatory conditions and impaired nutritional status of vitamin A.” Deficiency of vitamin A can cause dysfunction and photoreceptor death, which might help explain, in part, the newfound link between higher BMI and impaired dark adaptation.
“Family history of AMD also seem to play a role, but the influence of genetic profiles, as well as of dietary patterns, remains to be established,” the researchers concluded. “There is increasing evidence that DA is a valuable functional outcome for AMD. Therefore, it is crucial to understand what risk factors affect it and how these might influence its interpretation.”
1. Laíns I, Miller JB, Mukai R, et al. Health conditions linked to age-related macular degeneration associated with dark adaptation. Retina. 2018;38(6):1145-55.|
2. Liu L, White J. Early age-related macular degeneration impairs tolerance to stimulus degradation. Optom Vis Sci. 2010 Aug;87(8):532-42.