Abstract
Abstract: :
Purpose: Ocular Coherence Tomography (OCT) enables high resolution imaging of the retina, including the outer nuclear layer (ONL). Previous OCT studies have revealed reduced foveal thickness in Stargardts maculopathy together with loss of the neurosensory retina. Reduction of the p50 component of the pattern ERG (PERG) is usually the only abnormal electrophysiological finding in Stargardts, and reflects reduced macular function. This study compares PERG and OCT findings in Stargardts maculopathy in order to compare structural and functional changes in this condition. Methods: Twenty five patients with a clinical diagnosis of Stargardts (15 males,10 females (age range 17–46 years), underwent OCT3 analysis of the fovea, and central 1, 3, and 6 mm. Measurements of foveal thickness, and mean ONL thickness were made. Each patient also underwent flash and pattern ERG according to International standardised (ISCEV) protocols. All parameters were compared to an age/sex matched Control group of 20 healthy volunteers, and results analysed using analysis of variance (ANOVA). Results: The group mean foveal thickness was significantly (p<0.001) reduced in those with Stargardts compared to Controls (88.93 µm; s.d. 12.6, compared to 210.4 µm; s.d 31.5, ). The group mean ONL thickness was also significantly reduced (p<0.001 in all cases) in Stargardts compared to Controls at 1mm (45.62µm; s.d. 6.32, compared to 182.2 µm; s.d. 21.6, ), 3mm (48.5µV: s.d.6.20, compared to 127.6µm; s.d. 16.5) , and 6mm (52.43µm; s.d. 7.11, compared to 102.5 µm, s.d. 11.4) from the foveal centre. Flash ERGs (Standard Flash Scotopic, Single Flash Photopic and 30 Hz) were normal and similar between Controls and the Stargardts group. The group mean amplitude of the p50 component of the PERG was significantly reduced in Stargardts at 1.63 µV; s.d. 0.25, compared to 3.23 µV; s.d. 0.27 in Controls (p<0.001). In Stargardts there was a significant correlation between p50 amplitude and ONL thickness (r 2 = 0.85 at 1 mm, 0.71 at 3 mm, and 0.79 at 6 mm ). Conclusions: This study confirms the findings of previous studies in showing a marked reduction in foveal thickness in Stargardts. Furthermore, there appears to be a significant reduction in macular ONL thickness in this condition, particularly within 1 mm from the foveal centre, which correlates closely with PERG p50 amplitude. The OCT therefore provides in–vivo outer retinal structural information which correlates directly with macular function as determined electrophysiologically. This can give important diagnostic and prognostic information in heredo–macular disease.
Keywords: imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • electroretinography: clinical • retinal degenerations: hereditary