Purpose
To investigate the impact of subretinal drusenoid deposits (SDD) on the structure of underlying retinal pigment epithelium (RPE) cells, using multimodal imaging.
Methods
Twenty-six (n=26) eyes of 15 patients with AMD (AREDS grade 5-8) were evaluated with color fundus photography, infrared reflectance, blue reflectance, autofluorescence images, optical coherence tomography (OCT), and high resolution adaptive optics scanning laser ophthalmoscopy (AOSLO). SDD were detected by multimodal imaging and classified using an OCT-based 3-stage grading system. The photoreceptor mosaic overlying the SDD was assessed with AOSLO. Subfoveal choroidal and retinal thickness, choroidal thickness (ChT) and photoreceptor length (PL) at sites that are 1 mm and 2 mm superior, inferior, temporal and nasal to the fovea were measured in the OCT b-scans.
Results
OCT disclosed increased light penetration patterns beneath stage 3 SDD in 8 eyes (Fig.1). AOSLO revealed the en face microstructure of the overlying photoreceptors. The abnormal light penetration was not associated with the SDD size (Repeated measures ANOVA, F=0.838, P=0.372). The ChT at most sites in eyes with hyperreflective light stripes were significantly thinner than those at the corresponding locations in eyes without the abnormal light penetration (independent samples t-test, t=2.210-2.922, P=0.010-0.042). There was no significant difference between the PL measured in these eyes. Significant positive correlation was found between ChT and PL in most sites (Pearson’s r = 0.457-0.636, P =0.005-0.049).
Conclusions
The abnormally increased light penetration is not an imaging artifact. It may indicate RPE degeneration associated with the overlying SDD development.