To describe microvascular abnormalities and capillary density in macular telangiectasia type 1 (MT1) using optical coherence tomography angiography (OCTA), and correlate them with fluorescein angiography (FA).

Observational case series.

Seven patients with MT1 and 12 age-matched controls were included. Focal microvascular dilations were identified on 3 × 3 mm OCTA and early-frame FA images. OCTA images were processed to determine the global capillary density after subtraction of larger vessels and cystoid edema cavities. Local capillary densities were calculated inside 100-μm circles around telangiectasias, projected over superficial (SCP) and deep capillary plexuses (DCP). They were compared to a random sample of 100-μm circles generated in each OCTA image. FA images were processed to measure mean perifoveal intercapillary areas (PIA), inversely reflecting capillary density.

In MT1 eyes, fewer telangiectasias were identified with OCTA than with FA (P = .016), exclusively localized in the DCP (P = .016). Rarefaction of both capillary plexus and abnormal microvascular morphology were better identified by OCTA than by FA. The global capillary density on OCTA was significantly lower in MT1 eyes than in fellow and control eyes, respectively: SCP, 0.347 vs 0.513 (P = .004) and 0.560 (P = .0005); DCP, 0.357 vs 0.682 (P = .016) and 0.672 (P = .0005). Capillary density was significantly reduced around telangiectasias in both SCP (P = .021) and DCP (P = .042). Capillary density of the SCP correlated inversely with the mean PIA on FA (r = −0.94, P = .017). LogMAR visual acuity was inversely correlated with SCP (r = −0.88, P = .012) and DCP capillary densities (r = −0.79, P = .048).

OCTA confirmed that global and focal capillary depletion is associated with MT1.