Abstract
Purpose: :
To investigate foveal changes in patients with autosomal recessive achromatopsia.
Methods: :
Optical coherence tomography and fundus autofluorescence (SD-OCT and FAF; Spectralis, Heidelberg Engineering, Germany) were obtained from 10 patients (one aged 79, the remaining aged 6 to 34, median 20 years). Homozygous or compound heterozygous mutations were identified in CNGB3 in 6 patients, and in CNGA3 and GNAT2 in 2 patients, each. Clinical data including visual acuity, color vision and ERG were consistent with the diagnosis of achromatopsia. Ethic committee approval and written informed consent were obtained.
Results: :
Despite nystagmus, SD-OCT of the fovea was obtained in 9 of 10 patients. Even at young age, 5 patients showed small subfoveal gaps at the level of the connecting cilium of the photoreceptors with a median diameter of 265 µm. Six patients had a more or less distinct ring of increased FAF with a median diameter of 1300 µm surrounding a central region with reduced signal with a median diameter of 300 µm. For the 2 patients with GNAT2 mutations no gaps were detected with either SD-OCT or FAF - instead, the SD-OCT of one of these patients showed an enhanced signal in the corresponding layer.
Conclusions: :
Achromatopsia has recently been suggested to show signs of progressive cone disease although stable regarding rod function. Small foveal gaps as found in our study appear to be a frequent feature in cases with mutations in CNGB3 and CNGA3, thus confirming OCT-findings by Thiadens et al. (2010, IOVS 51:5952-7), but possibly not in mutations of GNAT2.
Keywords: imaging/image analysis: clinical • macula/fovea • genetics