Cuticular Drusen: Clinical Phenotypes and Natural History Defined Using Multimodal Imaging

Abstract

To define the range and life cycles of cuticular drusen phenotypes using multimodal imaging and to review the histologic characteristics of cuticular drusen. Retrospective, observational cohort study and experimental laboratory study. Two hundred forty eyes of 120 clinic patients with a cuticular drusen phenotype and 4 human donor eyes with cuticular drusen (n= 2), soft drusen (n= 1), and hard drusen (n= 1). We performed a retrospective review of clinical and multimodal imaging data of patients with a cuticular drusen phenotype. Patients had undergone imaging with various combinations of color photography, fluorescein angiography, indocyanine green angiography, near-infrared reflectance, fundus autofluorescence, high-resolution OCT, and ultrawide-field imaging. Human donor eyes underwent processing for high-resolution light and electron microscopy. Appearance of cuticular drusen in multimodal imaging and the topography of a cuticular drusen distribution; age-dependent variations in cuticular drusen phenotypes, including the occurrence of retinal pigment epithelium (RPE) abnormalities, choroidal neovascularization, acquired vitelliform lesions (AVLs), and geographic atrophy (GA); and ultrastructural and staining characteristics of druse subtypes. The mean age of patients at the first visit was 57.9±13.4 years. Drusen and RPE changes were seen in the peripheral retina, anterior to the vortex veins, in 21.8% of eyes. Of eyes with more than 5 years of follow-up, cuticular drusen disappeared from view in 58.3% of eyes, drusen coalescence was seen in 70.8% of eyes, and new RPE pigmentary changes developed in 56.2% of eyes. Retinal pigment epithelium abnormalities, AVLs, neovascularization, and GA occurred at a frequency of 47.5%, 24.2%, 12.5%, and 25%, respectively, and were significantly more common in patients older than 60 years of age (all P < 0.015). Occurrence of GA and neovascularization were important determinants of final visual acuity in eyes with the cuticular drusen phenotype (both P< 0.015). Small cuticular drusen typically demonstrated a homogenous ultrastructural appearance similar to hard drusen, whereas fragmentation of the central and basal contents was seen frequently in larger cuticular drusen. Although the ultrastructural characteristics of cuticular drusen appear more similar to those of hard drusen, their lifecycle and macular complications are more comparable with those of soft drusen. Cuticulardrusen phenotype may confer a unique risk for the development of GA and neovascularization.