83. The Turtle Sign
A 54-year-old with rheumatoid arthritis and visual loss:
Here the inner retinal layers are well within normal limits. The outer left and right of the image show an intact retina. The middle third of the image shows RPE elevation centrally and atrophy in the immediate peri-foveal area. With this atrophy, there is shadowing present. Because there is a loss of RPE in the area immediately surrounding the fovea, the outer nuclear layer (black) appears somewhat elevated. It sort of looks like a small turtle. So we can call this the “turtle” sign. This patient had signs of chloroquine retinopathy and had a “bull's eye” picture of atrophy.
If you see the “turtle” sign, toxic causes need to be ruled out.
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