Combined confocal scanning laser ophthalmoscopy and spectral-domain optical coherence tomography imaging of reticular drusen associated with age-related macular degeneration

Purpose: To determine microstructural retinal alterations associated with reticular drusen in patients with age-related macular degeneration (AMD) using high-resolution in vivo imaging techniques.

Design: Retrospective case series.

Participants: A total of 116 eyes of 78 AMD patients with reticular drusen were examined.

Methods: Simultaneous spectral-domain optical coherence tomography (SD OCT; 870 nm, 40,000 A-scans/sec) and near-infrared confocal scanning laser ophthalmoscopy (cSLO; 830 nm) were performed using a combined imaging instrument (Spectralis HRA+OCT, Heidelberg Engineering, Heidelberg, Germany). Individual anatomic layers in SD OCT were evaluated and correlated to en face cSLO fundus imaging.

Main outcome measures: Description of corresponding structural changes in areas of reticular drusen.

Results: Reticular drusen appeared as an interlacing network of round or oval irregularities by near-infrared cSLO reflectance imaging. On SD OCT, reticular drusen corresponded to marked changes at a level anterior to the retinal pigment epithelium (RPE) and Bruch's membrane complex to the interface of inner and outer photoreceptor segment layer (IPRL). Individual reticular drusen correlated to focal elevations of the IPRL, accumulation of highly reflective material below the IPRL, and an increased distance between the IPRL and RPE.

Conclusions: The findings indicate that the morphologic substrate of reticular drusen is the accumulation of highly reflective material within outer retinal layers anterior to the RPE. This is in contrast to previous assumptions pointing toward a localization of abnormal material at the level of the inner choroid. Although the origin of the material is unknown, the results may indicate a role for primary abnormalities in the neurosensory retina. Because reticular drusen represent high-risk markers for the progression of AMD, their ready identification is relevant both for natural history studies as well as for interventional trials.