Indocyanine green angiography for identifying telangiectatic capillaries in diabetic macular oedema

Abstract

AimsDuring diabetic macular oedema (DME), a spectrum of capillary abnormalities is commonly observed, ranging from microaneurysms to large microvascular abnormalities. Clinical evidence suggests that targeted photocoagulation of large microvascular abnormalities may be beneficial, but their detection is not done in a routine fashion. It was reported that they are better identified by indocyanine green angiography (ICGA) than by fluorescein angiography. Here, we investigated the prevalence and ICGA and optical coherence tomography (OCT) features of retinal microvascular abnormalities in a group of patients with DME.MethodsObservational study. The fundus photographs, ICGA and structural and angiographic OCT charts of 35 eyes from 25 consecutive patients with DME were reviewed.Results22 eyes (63%) had at least one focal area of microvascular abnormalities showing prolonged indocyanine green (ICG) staining (ie, beyond 10 mins after injection). In particular, all eyes (n=9) with circinate hard exudates showed foci of late ICG staining. These areas were either isolated globular capillary ecstasies or a cluster of ill-defined capillary abnormalities. They were located at a median distance of 2708 µm from the fovea (range: 1064–4583 µm). Their diameter ranged from 153 to 307 µm. During ICGA, 91% showed increased their contrast and apparent size in late frames, whereas 79% of microaneurysms showed reduced contrast on late frames. OCT angiography was not contributive for the detection of these lesions.ConclusionLate ICG staining revealing large microvascular abnormalities is commonly observed during DME. Because of their specific angiographic and OCT features relative to microaneurysms, we propose to name them telangiectatic capillaries (TelCaps).

Detection rate of diabetic macular microaneurysms comparing dye-based angiography and optical coherence tomography angiography

“…They adjudged ICGA to be helpful in finding leaking spots in CSME and probably even in diffuse edema 23 . Farias et al recently investigated the feasibility of ICGA in DR and distinguished between MAs smaller than 150 µm and telangiectatic capillaries 24 . They concluded that early phases were more helpful for the detection of MAs while later staining revealed larger telangiectatic vessels.…”

Infrared reflectance image-guided laser photocoagulation of telangiectatic capillaries in persistent diabetic macular edema

“…A previous study reported that TelCap was associated with chronic macular edema refractory to intravitreal treatment 10 . ICGA is known to be useful in the diagnosis of TelCap, showing delayed staining with limited leakage in the late phase 12 . However, the clinical use of ICGA could be challenging in real-world practice because it is invasive, costly, and time-consuming.…”

“…They also described the intraluminal clotting with the extracellular matrix and lipid-containing macrophages within microaneurysms 20 . Castro-Farías et al suggested that hydrophobic intraluminal materials in TelCap may induce incomplete and delayed filling in ICGA 12 . Hyperreflectivity in a blood vessel on IR imaging indicates a defect of red blood cell flow.…”

“…OCT (SPECTRALIS, Heidelberg Engineering, Heidelberg, Germany) was performed using the scan protocol of 6 mm radial scans of 30° intervals, in addition to a horizontal raster scan that transected the center of each TelCaps. OCT showed that the TelCap had a round or ovoid structure, presenting a thick hyperreflective wall surrounding a hyporeflective lumen 10 – 12 . On the IR image, which was provided as default OCT imaging, the TelCap appeared as a hyporeflective spherical lesion with or without central hyperreflectivity.…”

“…A pilot study reported that leakage from capillary macroaneurysms was associated with persistent DME refractory to intravitreal treatment 10 . Castro-Farías et al recently proposed the name ‘telangiectatic capillaries’ (TelCaps) to describe capillary abnormalities larger than 150 μm to avoid confusion with the term ‘retinal arterial macroaneurysm’ 12 .…”