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Ieva Sliesoraityte, Saddek Mohand-Saïd, Dorothée Dagostinoz, Konstantin E Kotliar, Shahira Miloudi, Jose Alain Sahel; Cones structure and function related patterns in Usher syndrome patients. Invest. Ophthalmol. Vis. Sci. 2014;55(13):339.
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© ARVO (1962-2015); The Authors (2016-present)
Structure and function related cone measures are needed to be standardized for efficacy assessment in gene therapy trials. We aim to investigate cone mosaic changes in association to cone functional patterns in Usher syndrome (USH) patients.
High-resolution macular images were obtained by en-face adaptive optics imaging (AO, Imagine Eyes, Orsay, France) and spectral domain optical coherence tomography (SD-OCT, Spectralis, Heidelberg, Germany) from 15 eyes of fifteen USH patients with confirmed gene mutations. Cone density and spatial organization of the cone mosaic was evaluated in 50x50microns rectangles at 0.1 mm, 0.5mm and 1.0 mm from the center of the fovea. Functional cone patterns were obtained using custom-made chromatic pupillometer (AMTech, Dosenheim, Germany), while pupil diameter response to the red light (640 nm) was recorded. Correlation between cones mosaic spatial organization changes and cone function was performed using MATLAB software. Age-matched healthy subjects’ eyes data served as a norm for comparison purposes.
All patients (mean age 35 years, mean visual acuity 0.40 logarithm of the minimum angle of resolution (logMAR)) demonstrated abnormal and irregular cone mosaic patterns with significantly decreased cone density at 0.1 mm, 0.5mm and 1.0 mm from the center of the fovea as 30%, 20% and 20%, respectively (p=0.001). In addition, greater decrease in cone density was related to disruption of the photoreceptor inner segment ellipsoid band on SD-OCT images, i.e. 30% compared to 48% for the vulnerable region (p=0.03). The significant reduction of chromatic pupil responses were determined in all Usher syndrome patients (15% reduction, p=0.01). Decreased cone density was significantly associated with diminished cones functional activity (r=0.39, p=0.015). Cone mosaic patterns having less regular and large dark regions were related with highly significant cones function attenuation (r=0.89, p=0.012).
Decreased cone density and irregularity of the cone mosaic alongside with diminished cones function was observed in eyes with Usher syndrome. Chromatic pupillometry and adaptive optics imaging potentially could be implemented as objective and sensitive tools in gene therapy trials for cones structure and function related changes quantification in Usher syndrome.
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