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Giulia Torregrossa, leonardo colombo, giovanni montesano, fabio patelli, Luca Mario Rossetti; Retinal structure evaluation using spectral domain optical coherence tomography in patients with Syndromic and Non-Syndromic forms of Retinitis Pigmentosa due to USH2A gene mutations. Invest. Ophthalmol. Vis. Sci. 2017;58(8):3248.
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To evaluate morphological macular changes using spectral domain optical coherence tomography (SD- OCT) and their relationships with visual function, comparing patients affected by syndromic and non-syndromic forms of RP due to USH2A gene mutations.
27 patients (54 eyes) with clinical signs and genetic diagnosis of Usher syndrome type IIa and 27 (54 eyes) with nonsyndromic RP with USH2A mutations were recruited. Data on clinical characteristics and best corrected visual acuity (BCVA) were extracted from medical charts, while morphological macular changes were evaluated on SD-OCT scans by the analysis of the following structures: extension of ellipsoid zone (EZ), extension of external limiting membrane (ELM), central macular thickness (CMT), presence or absence of epiretinal membrane (ERM), presence or absence of cystoid macular edema (CME).
All analyses were age corrected using multivariate mixed models. Usher patients were significantly younger compared to non syndromic patients (44.4±13.21 vs 55.7±12, p<0.01). Only male non syndromic patients had higher BCVA with respect to Usher subjects (0.77±0.07 vs 0.3±0.08, decimals). We found a significant difference in the extension of the EZ between non syndromic RP and Usher patients in both male and female (estimated difference 1648±380 μm, p<0.0001), while the difference in the extension of the ELM was significant for male subjects only (2584±55 μm, p<0.0001). Non syndromic patients had a higher CMT (estimated difference 53.61±19.4 μm, p 0.008). CMT was significantly affected by CME in males only (p<0.0001). Male Usher patients had a higher incidence on ERM compared to female Usher (OR 2.5, p=0.04).
Despite the younger age, Usher patients showed generally a more advanced stage of retinal degeneration, both in functional and in morphological aspects, with male subjects usually more impaired than females. The significant difference in CMT related to CME in male patients but not in females suggests a more important edema in male subjects. OCT data should be considered as markers of disease progression for future clinical trials evaluating RP therapies.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.
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