Impaired dark adaptation could indicate AMD
Age-related macular degeneration (AMD) affects 1.8 million age 50 years and older, and another 7.3 million are at substantial risk of vision loss from AMD, according to the Centers for Disease Control and Prevention.
Alabama Study on Early Age-Related Macular Degeneration (ALSTAR) found impaired dark adaptation was apparent at least three years before AMD can be seen with standard clinical methods. ALSTAR showed individuals with impaired dark adaptation were twice as likely to develop clinically evident AMD and eight times as likely to advance beyond the earliest stage of AMD.
A rod in the retina of the eye can intercept in less than 6.5 minutes, while a rod intercept time greater than 6.5 minutes is an early indicator of retinal disease. In the earlier stages of AMD, a patient can take three times longer to adapt than a patient without AMD. Patients in the later stages of AMD can take 10 times longer.
Impaired dark adaptation is not a risk factor for AMD; instead it is the earliest manifestation of AMD. Optometrists, also known as eye doctors, educate patients about ways to reduce their risk for developing AMD, help diagnose patients before they experience severe vision loss, and refer patients for treatments.
Excerpts taken from Optometric Office, May 2018
