Optical coherence tomographic angiography of choroidal neovascularization ill-defined with fluorescein angiography

Purpose To evaluate the morphological structure of illdefined choroidal neovascularisation (CNV) with traditional fluorescein angiography (FA) compared with optical coherence tomographic angiography (OCTA). Methods A retrospective case series study of 11 eyes with ill-defined CNV on FA was performed. Eyes were scanned with commercially available spectral-domain optical coherence tomography (OCT) (70 000 A-scans/s). The split-spectrum amplitude-decorrelation angiography (SSADA) algorithm was used to distinguish blood flow from static tissue. En face OCT angiograms were compared with FA. Results Eleven cases of ill-defined CNV on FA were identified from 10 study participants. Mean age of the participants was 74.5±6.8 years. Six cases had late leakage from undetermined source (LLUS) and five had fibrovascular pigment epithelial detachment (FVPED). Combining cross-sectional structural OCT with OCT angiograms, all cases were found to have type 1 CNV that corresponded to occult CNV with FA. In all cases of occult CNV on FA, distinct vascular structures were visible with OCTA in the outer retinal/retinal pigment epithelium slab. The mean CNV vessel area was 2.61 ±3.65 mm². The mean CNV vessel area in cases with FVPED was larger than that in cases with LLUS (4.69 ±4.72 mm² compared with 0.85±0.90 mm², Mann- Whitney p value=0.04). Conclusions Although the sample size is small to draw conclusions and the nature of work is retrospective and descriptive, OCTA has the potential to improve visualisation of ill-defined CNV with dye-based angiography, including occult CNV.