Case #63 – Let it Snow: A Case of Retinal Whitening

Ischemia of the Retina Superficial retinal ischemia: CWS Intermediate/Deep retinal ischemia: PAMM Deep/Choroidal retinal ischemia: AMN

History  First described by Sarraf et al. in 2013Described as a superficial variant of acute macular neuroretinopathy

Pathophysiology of PAMM   Ischemia of the middle retinal layers from microvascular damage of the intermediate/deep retinal capillary complex Moura-Coelho N et al. Paracentral acute middle maculopathy – review of the literature. Graefe’s Archive for Clinical and Experimental Ophthalmology. 2020; 258(10).

Diagram of the retinal layers and vascular anatomy. The inner retinal layers are supplied by the central retinal artery via the SCP, ICP, and DCP. The deeper retinal layers are supplied by the choroidal circulation. The watershed area is at the OPL.

Overlay of the previous images showing the retinal vasculature. The superficial capillary plexus is located within the RNFL, the intermediate capillary plexus is located within the IPL-INL junction, and the deep capillary plexus is located within the INL-OPL junction.

Review of Anatomy  Left: normal OCT labeling the different layers of the retina.Right: anatomy of the retinal vasculature that supplies the retina.

Diagnosis  Acute Posterior Vitreous DetachmentRetinal ischemia likely impending CRAO

Differentials:Ischemic: RAO, NPDRInflammatory: SLE, GCA, Polyarteritis Nodosa, MEWDsInfectious: Viral Retinitis, HIV RetinopathyNeoplastic: Leukemia, LymphomaTraumatic: Purtscher Retinopathy

Still images from the OCT of the left eye Top: scan of the superior macula with arrow pointing to a thickened and hyper-reflective area of the RNFL representing a CWS Middle: scan of superior paracentral macula with arrows pointing to hyper-reflective inner retinal layers Bottom: arrow pointing to hyper-reflective inner retinal layers nasal and

  Fundus photo of the right eye with “snowballs” highlighting the areas of retinal whitening