Macular Telangiectasia Type 2

A 55-year-old woman with type 2 diabetes presents with paracentral blur and reading difficulty. On dilated fundoscopy, both maculae show a faint greyish sheen and loss of transparency just temporal to the fovea (marked **A** in the diagram), with right-angled venules dipping into the fovea and tiny refractile crystalline deposits. Spectral-domain OCT reveals hyporeflective cavities in the inner and outer retina temporal to the fovea without retinal thickening, and disruption of the ellipsoid zone. Fluorescein angiography demonstrates dilated telangiectatic capillaries in the deep capillary plexus with late staining but no significant leakage. What is the most likely diagnosis?