Purpose of review: To describe the novel spectral-domain optical coherence tomography (SD-OCT) finding of paracentral acute middle maculopathy (PAMM) that can be associated with acute macular neuroretinopathy (AMN) or retinal vasculopathy, and that may indicate an underlying pathogenesis related to ischemia of the retinal deep capillary plexus (DCP).
Recent findings: With the advent of high-definition SD-OCT imaging, we are now able to detect deep capillary ischemia. Although cotton wool spots are caused by ischemia of the superficial capillary plexus, PAMM is caused by ischemia of the DCP, and appears as hyper-reflective, band-like lesions in the middle retina, extending from the inner nuclear layer (INL)/outer plexiform layer junction to involve the full-thickness INL. Over time, these lesions resolve with atrophy of the INL, resulting in persistent paracentral scotomas for the patient. Originally, PAMM was identified in isolation and thus classified into a subcategory of AMN. Subsequent reports have demonstrated PAMM lesions in the setting of coexisting retinal vascular disease, notably nonproliferative diabetic retinopathy and central retinal vein occlusion.
Summary: PAMM refers to a recently described class of characteristic SD-OCT lesions involving the middle layers of the retina at the level of the INL. If a patient presenting with PAMM is young and healthy without any other vascular disease, this may represent a novel variant of AMN. However, if the patient has an underlying retinal vascular disease, such as diabetic retinopathy or retinal vascular occlusion, one would refer to the lesion as PAMM complicating the underlying retinal vascular disease.