Abstract
Purpose: :
To evaluate the clinical findings in age-related macular degeneration (AMD) using near-infrared fundus autofluorescence (NIR-FAF), fundus autofluorescence (FAF) and spectral-domain optical coherence tomography (SD-OCT).
Methods: :
Patients with AMD with both exsudative and dry features were included in this cross-section study. OCT images, FAF, NIR-FAF and simultaneous recording of fluorescein angiography (FA), indocyanine green (ICG) angiography images were obtained using the Heidelberg Retina Angiography 2 (HRA2) and Spectralis OCT (Heidelberg Engineering, Heidelberg, Germany). A masked retina specialist analyzed the images.
Results: :
Early, neovascular and atrophic age-related macular degeneration were imaged, and NIR-FAF images were correlated with the other exams to evaluate the significant findings. A dark halo on NIR-FAF was found in the cases and showed high correspondence to leakage on FA. Surrounding the choroidal neovascularization (CNV) lesions a diffuse hyperautofluorescence was seen on FAF. Higher NIR signaling emanates from hyperpigmentation, from the choroidal pigment (nevi, outer layers) and from the pigment epithelium and stroma of the iris. Low NIR signals are observed in geographic atrophy particularly in subjects with light irides. Abnormal NIR-FAF signals correlated to changes at the outer retinal/retinal pigment epithelial cell layer in high-resolution OCT scans.
Conclusions: :
NIR-FAF may be a useful non-invasive tool to visualize pathologic features of the RPE and the choroid. These provided information may contribute to the diagnosis and treatment of the pathology. Oxidized melanin, or compounds similar to melanin, contributes substantially to NIR-FAF, but other fluorophores cannot be excluded at this stage. We could observe several areas in which NIR-FAF showed unique features unrelated to other exams and these findings might represent increased melanin granules and hyperpigmented deposits. Together with FAF imaging, offers a tool to study biological changes associated with aging of the RPE and pathology. These findings remain to be confirmed in large prospective studies.
Keywords: age-related macular degeneration • imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • macula/fovea