Abstract
Purpose::
Optical coherence tomography is a recent tool providing morphological information with a very high resolution. We tried to find a relationship between fundus lesions and functional abnormalities in patients with Stargardt disease (STGD) and fundus flavimaculatus (FFM).
Methods::
A complete ophthalmologic examination, including best corrected visual acuity (BCVA), and OCT was performed in 61 eyes of 32 consecutive patients (21 M, 11 F) with FFM/STGD and in 60 eyes of 30 matched healthy control subjects (18 M, 12 F). Fundus-related perimetry (FRP) was also performed in 12 of the affected eyes (6 patients).
Results::
The age ranged from 21 to 71 years (average 43.2 years) in STGD/FFM patients and from 21 to 72 years (average 45.8 years) in controls. BCVA ranged from 20/20 to 20/400 and from 20/20 to 20/32 respectively in STGD/FFM patients and in controls. A foveal thinning was found by OCT Stratus in almost all cases (mean macular thickness ranged between 97 and 238 µm, average 160 µm) compared with controls (mean macular thickness ranged between 167 and 253 µm, average 210 µm; p < 0.001). This finding seems to represent a marker of the possible evolution towards foveal atrophy and probably explains the progressive visual loss. BCVA impairment exactly correlated to the degree of the foveal thinning (mean BCVA/ macular thickness, p = 0,0029; mean macular thickness / BCVA, p = 0,0008) (Linear Regression r^2 = 0,16; p-value = 0,0014). Moreover, in FFM/STGD patients, using OCT, we observed hyperreflective deposits which we classified in two types: type 1 lesions (29/32 eyes) presented as dome-shaped deposits located in the inner part of the retinal pigment epithelium (RPE) layer and type 2 lesions (22/32 eyes) presented as small linear deposits located at the level of the outer nuclear layer. Neither of the two types was correlated with either BCVA impairment or foveal thinning. In addition, FRP, which was performed only in 12 eyes (6 patients), revealed a stable fixation in 8 eyes, that was predominantly central only in 4 eyes. A more stable fixation (P = 0,0108), even if not predominantly central (P value =0,0218), correlated well to a less degree of the foveal thinning.
Conclusions::
In our series, lower visual acuity and instable fixation correlated with a greater transverse foveal thinning. OCT may therefore be an useful tool in the diagnosis and the progression as well as in the analysis of the pathogenesis of FFM/STGD.
Keywords: imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • retinal degenerations: hereditary • photoreceptors: visual performance