Abstract
Purpose :
To further characterize specific spectral-domain optical coherence tomography (SD-OCT) signs in cases of intermediate age-related macular degeneration (iAMD) suggestive of abnormal choroidal vascular complexes (ACVC), identified on OCT angiography (OCTA). The presence of ACVC may be associated with a greater risk of progression to exudative neovascular AMD, warranting more regular monitoring.
Methods :
ACVC has previously been associated with shallow, irregular retinal pigment epithelium (RPE) elevations (SIRE) above Bruch’s membrane using OCT, commonly called the “double layer” sign. We investigated a cohort of AMD eyes with large drusen in cross-section with SD-OCT and swept-source OCTA, graded independently in a masked fashion for SIRE and CNV respectively, to determine common characteristics of SIRE in predicting subclinical CNV.
Results :
Four eyes with known OCTA-defined ACVC and SIRE on SD-OCT were used to define the common features of the RPE elevation; >1000μm long, a consistent, flat profile predominantly <100μm high, an irregular RPE contour, and moderate, non-homogenous reflectivity of the sub-RPE space.
233 eyes of 132 participants with large drusen (>125 micrometres) were then assessed, with 24 (10.3%) graded to have SIRE on SD-OCT. On OCTA, six eyes had definite ACVC. All six (100%) of these had SIRE, conferring a sensitivity of 100% (54.1-100%) and a specificity of 92.1% (87.8-95.2%). The positive predictive value (PPV) was 25% (9.77-46.7%) and the negative predictive value (NPV) was 100% (98.3-100%) in eyes with large drusen. In participants with bilateral large drusen (iAMD), the PPV reduced to 16.7% (11%-24.6%).
Conclusions :
Our results indicate that all iAMD eyes with asymptomatic OCTA-defined ACVC will demonstrate SIRE on SD-OCT, but SIRE can also be present without identifiable vascular changes by current imaging techniques. Therefore, the presence of SIRE should raise suspicion of ACVC, which may increase the risk of exudative disease. Further follow-up of SIRE cases will determine their risk of progression to exudative CNV, a complication that threatens central vison. Closer monitoring with earlier identification would ensure appropriate treatment can commence before irreversible vision loss occurs.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.