Healthy Rods, Healthy Macula

AMD Clinical Insights: Optometric Management July 2016 

The macula is a relatively large area, 6 mm in diameter, or 21.5° of visual angle, centered on the fovea.1 The small, cone-dominated fovea is only 0.8 mm in diameter (2.75°). The central 300 µm of the fovea, or foveola, is totally rod-free. So why do rods matter in AMD?

First, the cone-rich fovea is surrounded by a rod-dominated parafovea (1- 3 mm from the fovea or 3.5–10° from fixation).2 In healthy, young adults, rods outnumber cones in the macula by 9:1. Therefore, the macula may be described as cone-enriched but rod-dominated. In the entire retina, rods outnumber cones 20:1. Rods are responsible for our most sensitive motion detection, peripheral vision, and night vision.2,3

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