Association between cystoid spaces on indocyanine green hyperfluorescence and optical coherence tomography after vitrectomy for diabetic macular oedema.

Purpose: To study retrospectively the characteristics of residual indocyanine green (ICG) fluorescence after ICG-assisted vitrectomy and the association with spectral-domain optical coherence tomography (SD-OCT) findings in diabetic macular oedema (DMO).

Methods: Thirteen consecutive eyes of 12 patients for whom fundus near-infrared fluorescence and 20° retinal sectional images were obtained using HRA2 and Spectralis OCT, respectively, 5 days after vitrectomy combined with ICG-assisted inner limiting membrane peeling for DMO. The relationship between the characteristics of the ICG hyperfluorescence and the cystoid spaces in the outer plexiform layer (OPL) on SD-OCT images was evaluated.

Results: A total of 390 well-demarcated areas of ICG hyperfluorescence were delineated on 20° radial OCT scans dissecting the fovea 5 days after vitrectomy. The areas of ICG hyperfluorescence in the parafovea or perifovea were significantly smaller than those at the fovea. Most areas of hyperfluorescence were irregularly shaped in the parafovea and perifovea, whereas 18 of 38 areas of hyperfluorescence were round or oval at the fovea (P<0.001). SD-OCT delineated the cystoid spaces in the OPL in 73 areas of hyperfluorescence that were round or oval and accompanied by dark spots more frequently than that without cystoid spaces on OCT images (P<0.001 and P=0.002). Of the 123 cystoid spaces in the OPL on OCT images, 44 did not have ICG hyperfluorescence, had lower OCT reflectivity, and contained fewer hyperreflective foci than those with ICG hyperfluorescence (P<0.001 and P=0.020).

Conclusion: The results provided novel interpretations of the ICG hyperfluorescence and its association with OCT characteristics of the cystoid spaces in DMO.