Hypertransmission defect phenotypes and functional associations in eyes with neovascular age-related macular degeneration

Abstract

Purpose : To characterize hypertransmission defect (hyperTD) on en face optical coherence tomography (OCT) images in neovascular age-related macular degeneration (nAMD) and to examine its functional associations.

Methods : In this cross-sectional study, 97-line OCT volumes (Heidelberg Spectralis) from 118 treated nAMD eyes (mean treatment duration: 3.1 yrs) were collected. Reflectivity projection of a slab located 64 to 400 um below Bruch's membrane was manually inspected to identify regions of higher reflectivity (HyperTD). For eyes with hyperTD involving the foveal center, the reflectivity quality was classified into focal, diffuse or incipient (Fig. 1A). The corresponding foveal B scan was graded for the presence of the following 5 fovea center atrophic features (FCAF): outer nuclear layer thinning (ONLT), external limiting membrane disruption (ELMD), ellipsoid zone disruption (EZD), retinal pigment epithelium disruption (RPED), and hypertransmission into choroid (HTC). We analyzed the association of hyperTD phenotypes with presence of FCAFs and best corrected visual acuity (BCVA).

Results : HyperTD was not reproducibly gradable with sufficient confidence in 34 (28.8%) eyes due to large pigment epithelial detachment (PED) or subretinal hyperreflective material (SHRM). In the remaining 84 eyes, foveal-involving hyperTD was present in 56 (66.7%) eyes, which were classified as 8 (9.5%) focal, 25 (29.8%) diffuse and 23 (27.4%) incipient. Compared to incipient hyperTD, diffuse hyperTD were associated with more FCAFs (Fig. 1B) and lower BCVA (Fig. 1C), suggesting that diffuse hyperTD is associated with more advanced stages of macular atrophy.
Among the 5 FCAFs, HTC (61%) and EZD (62%) were the most, while RPED (24%) was the least observed. Each individual FCAF was significantly associated with worse BCVA (Fig. 2A). ONLT, ELMD, EZD and HTC correlated well with each other; Conversely, RPE disruption was less correlated with the other 4 (Fig. 2B). Presence of ≥3 FCAFs started to show a significant association with worse BCVA compared to absence of any FCAF (Fig. 2C).

Conclusions : HyperTD was commonly observed in nAMD eyes. Diffuse hyperTD was associated with more FCAFs and poorer BCVA, suggesting more advanced stages of macular atrophy. However, hyperTD assessment was limited when large PED or SHRM was present, which was seen in more than a quarter of the eyes.

This abstract was presented at the 2024 ARVO Imaging in the Eye Conference, held in Seattle, WA, May 4, 2024.