Abstract
Purpose: :
To assess autofluorescence features of drusen in patients with early and intermediate age-related macular degeneration (AMD) using a modified fundus camera (mFC) and Heidelberg confocal scanning laser ophthalmoscopy (cSLO).
Methods: :
Patients (30 eyes of 30 patients) with early and intermediate AMD were imaged with color and monochromatic fundus photography and with mFC and cSLO-modes of fundus autofluorescence (FAF) imaging in the same sitting. The modified Topcon fundus camera was equipped with a black and white digital sensor and used a 580nm excitation filter with a 700nm band pass emission filter. cSLO FAF imaging was performed with a 488nm excitation laser line and a 500nm high-pass emission filter. Drusen were identified on fundus photographs (within the central 1500µm diameter field) and assigned to one of three groups based on size as per the AREDS AMD grading protocol: (1) small: <63 µm, (2) intermediate: 63-124µm (3) large ≥ 125µm. Corresponding FAF features were examined and qualitatively scored for drusen in each category in the mFC and cSLO FAF images. Image analysis was used to compare the autofluorescence patterns and their spatial distribution around individual drusen.
Results: :
Particular FAF patterns were associated with drusen, as revealed on the mFC-based images. Small drusen (<63 µm) are typically correlated with a small central area of decreased FAF. Intermediate drusen (63-124 µm) are often found to have a surround of increased FAF in addition to a central single area of decreased FAF. Large (≥ 125µm) drusen typically contain multiple small pinpoint areas of decreased FAF, which are usually irregular and eccentric, surrounded by an area of increased FAF that correlates well with drusen boundaries. In contrast, FAF patterns revealed on cSLO-based imaging cannot be consistently associated with drusen.
Conclusions: :
FAF patterns in AMD, thought to arise from structural and compositional alterations in the aging RPE, can be correlated to drusen distribution and drusen size, when captured using a modified fundus camera. These patterns may relate to drusen development and AMD progression, and may reveal anatomic changes occurring in the RPE in response to drusen. Although the clinical utility of these findings needs to be further explored, mFC autofluorescence imaging may be a useful tool to monitor patients with drusen and AMD.
Keywords: age-related macular degeneration • drusen • imaging/image analysis: clinical