Photoreceptor deflection around subretinal drusenoid deposits (SDD) revealed by adaptive optics scanning laser ophthalmoscopy (AOSLO)

Abstract

 

Purpose

 

To use a novel imaging technique to reveal microscopic structure of photoreceptors around SDD, a lesion recently recognized in eyes with age-related macular degeneration (AMD).

 

Methods

 

Patients with various stages of AMD (n=33) and age-similar participants in normal macular health (n=7) underwent best-corrected visual acuity as measured by the EVA and digital color fundus photography. En-face infrared, red-free, and autofluorescence (AF) images were acquired with confocal SLO. Retinal cross-sections were imaged with SD-OCT. AOSLO was performed to image the maculae of the participants. SDD were determined by a reticular pattern discernible in color fundus photo, IR reflectance, AF, and red-free images. A subset of solitary lesions with complete rings of hypo-reflectance in IR was further examined in detail. Photoreceptor structure around these specific SDD formations was examined en-face by AOSLO and by SD-OCT scans that crossed them.

 

Results

 

AOSLO produced high-magnification, high-resolution, and high-contrast images in 13 eyes of 8 patients with bilateral SDD, revealing a distinct en-face structure (Fig.1 A): a hyporeflective ring surrounding an area with indistinct photoreceptors. SD-OCT revealed that SDD was an accumulation of highly reflective material in the subretinal space internal to the retinal pigment epithelium (RPE) and Bruch’s membrane complex (Fig.1 B, C).

 

Conclusions

 

AOSLO may be an effective method for imaging SDDs. The findings indicate that solitary SDD can deflect surrounding photoreceptors, thus supporting histological studies describing SDD as solid, space filling lesions in the subretinal space; accordingly, photoreceptor function is expected to be negatively impacted by this perturbation.

 

 

Fig.1 SDD perturbation of photoreceptors, revealed by AOSLO and SD-OCT. 73 year old man with non-neovascular AMD OS (AREDS grade 6, VA 20/25). A. AOSLO image. Cone photoreceptors are represented by evenly spaced spots of hyper-reflectivity (bright). SDD is indicated by a wide hypo-reflective ring with indistinct borders. B-C. SD-OCT scans through SDD center (B) and off-center (C) reveal a gap in the photoreceptor ellipsoid zone (EZ) on either side of the SDD. The gap corresponds to the hypo-reflective ring in the AOSLO image, strengthening the association between the reflectivity sources in these 2 imaging modalities.

 

Keywords: 504 drusen • 552 imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • 648 photoreceptors