Relevance of Intraretinal Hyperreflective Foci and Subretinal Drusenoid Deposits in Type 3 Macular Neovascularization

Abstract

Purpose : To describe the role of intraretinal hyperreflective foci (IHRF) and subretinal drusenoid deposits (SDD) in predicting the evolution from intermediate age-related macular degeneration (iAMD) to Type3 macular neovascularization (MNV) using optical coherence tomography (OCT).

Methods : This study includes 20 eyes of 20 patients with iAMD and SDD at baseline. Ten of these eyes developed Type 3 MNV in 24 months and were considered the “Type 3” group. The other 10 eyes remained as stable iAMD over the 24 months and were considered the “control” group. Groups were matched for age and extent of SDD at baseline. OCT scans at baseline, 12, and 24 months were evaluated to assess for the presence of IHRF, IHRF specifically over drusen, and the area of SDD. These characteristics were compared between the Type 3 and the control group. In addition, for the Type 3 group, the OCTs at 18 (i.e. 6 months before MNV onset) and 23 months (i.e. 1 month before MNV onset) from baseline were also evaluated to specifically assess the topographic relationship between the IHRF and the location of MNV development.

Results : IHRF were present in all patients in the Type 3 group from baseline through Month 24. In the control group, IHRF were present in 1 case at baseline, 3 cases at 12 months, and 4 cases at 24 months, which was significantly less frequent than the Type3 group at all time points (p<0.001, P=0.003, P=0.011).
With regards to IHRF over drusen specifically, these were observed in 9 cases at baseline and in all 10 cases at 12 months and 24 months in the Type3 group. The frequency was again significantly lower at all time points in the control group: 0 at baseline, 3 cases at 12 months, and 4 cases at 24 months (p<0.001, P=0.003, P=0.011). In addition, all 10 cases had IHRF over drusen one month before MNV onset in the Type 3 group. Although the baseline SDD area was not significantly different between the two groups (P=0.230), the area of SDD significantly increased over time (P<0.001) in the Type3 group but not the control group (P=0.164).

Conclusions : The presence of IHRF, particularly IHRF over drusen in iAMD patients may identify eyes at high risk for progression to Type 3 MNV over two years, and also define the location of MNV onset. Type 3 MNV onset also appears to be associated with an increase in the area of SDD. These findings may provide insight into the pathophysiology of Type 3 MNV.

This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.