Purpose:
To assess the prevalence and characteristics of Slovenian patients with Usher syndrome and to evaluate their fundus autofluorescence (FAF) patterns.
Methods:
Forty-six patients (22 men, 24 women, mean age 36 years, range, 15-68) with Usher syndrome were reviewed. Three pairs were siblings. FAF images (N=23) of 30°×30° field of view were obtained with confocal scanning laser ophthalmoscope (HRA, Spectralis; Heidelberg Engineering, Germany). Argon blue laser light (488 nm) was used for excitation and a wide band-pass filter with cut-off at 521 nm. Images were categorized depending on presence or absence of high density parafoveal ring, and on normal or abnormal central FAF. Ring width was measured using HRA software.
Results:
Based on records from 1996-2010, we estimated prevalence of 2,6-3,0 per 100 000 for Slovenian population. Average visual acuity was 0.52, and it negatively correlated with age (p<0,01). Color vision correlated well with VA, although 5/10 eyes with normal VA of 1.0 showed color vision loss. On FAF imaging, 9 (40%) patients exhibited high density parafoveal ring with normal central FAF signal and 7 (30%) had abnormal FAF signal inside the ring. 30% of patients did not have the ring; 3 (13%) had normal, and 4 (17%) abnormal central FAF signal. Among all patients with FAF imaging, 48% (11/23) exhibited abnormal central signal. Average horizontal ring width was 0,9 mm (range, 0,3-2,0). Fig. 1 shows four different FAF patterns: parafoveal ring with normal central FAF (A), parafoveal ring with abnormal central FAF, normally apearing FAF (C) and abnormal central FAF without the ring (D).
Conclusions:
Prevalence of Usher syndrome in Slovenia is comparable to published figures elsewhere. Fundus autofluorescence images show several different patterns. High density parafoveal ring was seen in approximately 70% of all patients, and out of these, 44% had abnormal central FAF, attributed to macular involvement and RPE atrophy. Parafoveal ring was not seen in 30% of patients. Relatively high proportion of phenotypes with affected retina inside the ring is noted in our population.
Keywords: retinal degenerations: hereditary • imaging/image analysis: clinical • ipofuscin