Introduction: PAMM, recently emerged retinal pathology involving preferentially deep retinal capillary system (ICP and DCP) where impaired blood flow occurs, and particularly anatomical and physiological watershed zone is affected (INL and OPL). Resultant ischemia is presented clinically with sudden drop of vision and manifested as band like hyperreflective lesions on SS OCT B scans. SS OCTA with Enface and Retinal flow maps have delineated ischemic lesions within middle retina and exhibited characteristic findings that may help in understanding the pathophysiology behind this entity.
Purpose: To highlight PAMM diagnostic features on Optical Coherence Tomography Angiography and Enface, and to emphasize on their major role in detecting and assessing this condition.
Methods: This is a retrospective study reviewing two clinical cases presented to our facility with sudden decrease in vision in one eye. DRI OCT Triton (Topcon Corporation, Tokyo, Japan) was employed. In addition to generating high quality conventional cross sectional B scan images, Enface C scans and three dimensional angiography images were obtained at different retinal levels. High-resolution color fundus imaging, Fluorescein Angiography (FA) and Fundus Auto fluorescence (FAF), and Enface in conjunction with OCTA were all used in the two cases. Detailed history, full comprehensive Eye exam was done, appropriate thorough systemic workup was performed; baseline blood tests (CBC, KFT, LFT, UA), coagulation profile (INR, APTT, D Dimer) with blood test for sickle cell (SC), and autoimmune profile.
Results: In both cases, OCTA and Enface revealed multiple findings of PAMM during the acute phase of presentation. OCTA provided evidence of DCP ischemia by showing perfusion defects, or capillary dropout. Enface C scans visualized fern-like ischemic distribution at the level of DCP.
Discussion: The use of OCTA in conjunction with Enface OCT has proved superior to other imaging modalities in identifying and diagnosing PAMM. It is anticipated that such imaging techniques may provide new insights for middle and deep retinal ischemic pathologies including PAMM which may have a constellation of imaging findings in the near future for its detection, diagnosis, classification, and perhaps management!