Abstract
Purpose: :
To conduct a proof of concept study to examine if the structural parameters derived from the AOSLO on AMD patients are related to participants’ AMD disease severity.
Methods: :
Patients with various degrees of AMD and age-matched subjects in normal retinal health were recruited. AOSLO was performed to image the maculae of the participants. Photoreceptor (cones) visibility, packing structure, and density as well as spacing were measured. Best-corrected visual acuity (BCVA) was tested using the ETDRS protocol. Digital fundus photography, high-resolution spectral-domain OCT, infrared, red-free, and autofluorescence (AF) retinal images were taken in all participants’ eyes. AMD presence and severity were determined by the AREDS 11-step fundus grading system. The micro-structural parameters obtained from the AOSLO were examined in light of functional (i.e., visual acuity) and macro-structural (stage of disease by fundus photography and grading) variables.
Results: :
AOSLO was able to produce high-resolution images in most patients. In patients with early to intermediate stage of AMD (AREDS grade 2~6), the cone photoreceptors overlaying on drusens showed reduced reflectivity and moderately increased cell spacing, whereas in patients with advanced stage of disease(AREDS grade 9), cones mosaic were severely disrupted, cone density and reflectivity were significantly decreased compared to that of normal subjects.
Conclusions: :
This study demonstrated that cone photoreceptors structure can be studied in various stages of AMD with the AOSLO. With further investigation of larger number of subjects, the relationship between the statistical structural parameters of the photoreceptors derived from the AOSLO and disease severity will be explored more fully, which may provide quantitative measures of disease severity, progression, and the treatment efficacy at the cellular level.
Keywords: age-related macular degeneration • imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • photoreceptors