En face localization of retinal telangiectatic capillaries using OCT compared with ICG angiography in chronic
Lucas Unger1,2, Bénédicte Dupas3,4,5, Mohamed Bennani6
1Univ Bordeaux, INSERM, BPH, U1219, Bordeaux, France.
Purpose:
Retinal telangiectatic capillaries (TelCaps) are microvascular abnormalities associated with chronic vascular macular oedema and suboptimal response to intravitreal therapy. Targeted laser photocoagulation is beneficial but requires precise localization using indocyanine green angiography (ICG-A), the reference standard. However, ICG-A is invasive and not easily repeatable. This study evaluated OCT performance for TelCaps identification and en face localization versus ICG-A.
Methods:
ICG-A and OCT images from 62 patients with TelCaps secondary to diabetic retinopathy or vein occlusion were analysed in a masked fashion. TelCaps were identified on OCT cube B-scans using predefined structural criteria and subsequently localized on co-registered infrared en face images. Sensitivity, positive predictive value (PPV) and subgroup analyses were used to assess OCT accuracy for lesion localization versus ICG-A and to evaluate the influence of anatomical factors.
Results:
ICG-A identified 148 TelCaps, whereas OCT detected 157 lesions. ICG-stained TelCaps appeared as isolated large lesions or clustered microvascular abnormalities. OCT-identified and en face localized lesions showed 87% sensitivity (95% CI, 81%-92%) and 82% PPV (95% CI, 75%-88%). Sensitivity was higher for isolated lesions (92%) and those adjacent to hard exudates, but lower for clustered lesions (62%) and those distant from exudates. False positives were mainly lesions without retinal thickening or exudates, while false negatives predominantly involved clustered lesions.
Conclusion:
OCT represents a valuable non-invasive tool for identifying and localizing TelCaps on en face images in eyes with macular oedema and hard exudates, supporting its use for guiding focal laser photocoagulation. While it may reduce the need for systematic ICG-A in selected patients, angiography remains essential in complex equivocal cases, particularly for clustered lesions, where OCT may be less effective.
