Abstract
Purpose: :
To characterize the structural changes observed for several types of macular dystrophies using Spectral-Domain Optical Coherence Tomography (SD-OCT) instrument.
Methods: :
In a retrospective study a total of twenty-five patients (48 eyes) with inherited retinal degeneration were included: 6 patients (12 eyes) with Stargardt disease, 8 patients (14 eyes) with retinitis pigmentosa, 7 patients (14 eyes) with cone dystrophy and 4 patients (8 eyes) with cone-rod degeneration. Ocular examination included visual acuity (VA), biomicroscopy, applanation tonometry and fundoscopy. Full-field electroretinogram was performed in all patients to confirm diagnosis. For SD-OCT the Spectralis HRA+OCT (Heidelberg Engineering, Heidelberg, Germany) was used including vertical and horizontal scans for every patient. The best scan of each patient was chosen and analyzed. The thickness of the fovea was measured in all groups.
Results: :
Mean visual acuity of the better-seeing eye was 1.14 logMAR in Stargardt disease, 0.45 logMAR in retinitis pigmentosa, 1.0 logMAR in cone dystrophy and 1.0 logMAR in cone-rod degeneration. The main features of Stargardt disease by SD-OCT was loss of inner segments (IS) and outer segments (OS) of photoreceptors and the underlying retinal pigment epithelium (RPE) at the fovea. In cases of retinitis pigmentosa, OCT images revealed generalized thinning of parafoveal area with normal aspects of fovea in patients with better VA (<0.6 logMAR) and diffuse loss of thickness with internal disorganization in those with worse VA (> 0.9 logMAR). Some similarities were found between the cone dystrophy and cone-rod degeneration: a remarkable damage characterized by focal loss of OS of the photoreceptors in foveal center and normal RPE layer, images similar to external lamellar hole. The mean fovea thickness in Stargardt disease, retinitis pigmentosa, cone dystrophy and cone-rod degeneration was respectively 84.0±36, 188.6±55, 139.7±42 and 106.0±47 micra.
Conclusions: :
The SD-OCT presents is a useful non-invasive diagnostic tool to analyze structural changes in retinal dystrophies contributing to early diagnosis in these potentially blinding diseases.
Keywords: degenerations/dystrophies • clinical (human) or epidemiologic studies: systems/equipment/techniques • photoreceptors