Abstract
Purpose: :
Fundus Autofluorescence (AF) is an indicator of retinal pigment epithelium (RPE) activity, with Hypo-AF indicating loss of RPE cells, and hyper-AF indicating RPE stress. Ultra-Widefield (Panoramic) AF (PAF) imaging with Optos 200Tx captures a 200 degree image in a minimally invasive, time-effective, manner. This study utilizes PAF in patients with reduced visual acuity (VA) (a) to determine whether PAF images correspond with color optomap® images and (b) to determine the scope and symmetry of retinal degeneration.
Methods: :
A retrospective review of 100 PAF and color optomap images from 50 patients with either reduced VA or unusual visual symptoms was conducted in an ocular disease clinic. Based on patterns of AF, the images were categorized as normal (N) or abnormal, further designated by location: Abnormal centrally (AC), abnormal peripherally (AP), or abnormal centrally & peripherally (ACP). The central region was defined as the posterior pole, within 1 DD anterior to sup/inf arcades and around optic nerve. The images were analyzed for (a) PAF/color optomap correspondence and (b) OD/OS PAF pattern symmetry within each patient. Spectral domain optical coherence tomography (SDOCT) was used to confirm retinal abnormalities in all cases.
Results: :
61 of the 100 PAF images reviewed had AF abnormalities: 18(29.5%) were AC only, 10(16.4%) were AP only, and 33(54.1%) were ACP. 5 patients had AP in 1 eye with ACP in the fellow eye. Of the 61 abnormal PAF images: (a)44(72.1%) did not match the appearance of corresponding color optomap image. (b)48(78.7%) had symmetric patterns OD and OS, suggesting retinal degeneration. Bilateral, previously undetected bull’s-eye maculopathy was discovered in 12 of the 61 images. SDOCT confirmed RPE defects in the posterior pole via evaluation of the outer retina (i.e. Photoreceptor integrity line (PIL) and RPE) in all AC and ACP eyes.
Conclusions: :
1)PAF is a fast, non-invasive procedure that can effectively detect outer retinal pathology in patients with vision defects. 2)Pan-retinal AF abnormalities are more common than those isolated to the central or peripheral retina. However, isolated AP may precede ACP, as several asymmetric cases suggest. 3)PAF reveals abnormalities throughout the retina that may be invisible to binocular indirect ophthalmoscopy, fundus photography or similar imaging modalities. 4)Abnormality in PAF is more extensive than in color images when the changes are in the outer retina. 5)PAF may be used in the early detection of bull’s-eye maculopathy, which is known to occur in Retinitis Pigmentosa, cone-rod dystrophy, and drug toxicity (e.g. Plaquenil, Accutane). 6)SDOCT analysis of the outer retina confirms RPE involvement in areas of hyper/hypo AF.
Keywords: imaging/image analysis: clinical • retina: distal (photoreceptors, horizontal cells, bipolar cells) • retinal degenerations: hereditary