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Cord R H Huchzermeyer, Francesca Pasutto, André Reis, Jan J Kremers; L- and M-cone driven temporal contrast sensitivity is reduced at low frequencies in patients with Stargardt’s disease. Invest. Ophthalmol. Vis. Sci. 2017;58(8):4299. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
To measure perifoveal temporal contrast sensitivity functions (tCSFs) for L-, M-, S-cone- and rod-isolating stimuli based on the silent substitution paradigm in patients with Stargardt’s disease.
Stimuli were created using an LED stimulator with a 2° diameter central circular field and a 13° outer diameter annular surround field, each driven by four independent primaries. Sine-wave modulated stimuli were presented in the white surround field (mean luminance 2.7 log phot Td) while subjects fixated the darker, steady central field (2.3 log phot Td).Isolating stimuli were created based on the triple silent substitution paradigm using the 10° cone fundamentals and scotopic luminous efficiency. For each condition, the critical flicker fusion frequency (CFF) was determined at the maximal available contrast. The tCSFs were measured at 1, 2, 4, 6, 8, 10, 12, 16, 20, and 28 Hz, but only up to the frequency just above the CFF.In total, the tCSFs were measured in 11 patients diagnosed with Stargardt’s disease. Mutations screening in ABCA4 gene by Sanger sequencing and MLPA analysis were used to confirm the clinical diagnosis. Patients’data were compared the data of 24 healthy subjects.
According to the recessive model of Stargardt’s disease inheritance, the mutations screening revealed compound heterozygous disease-causing variants in all but one patient analyzed. The spectrum of identified mutations includes missense and nonsense mutations, splice mutations and deletion of few exons. Compared with the healthy subjects, the tCSFs of patients were more variable, and several patients showed generally reduced tCSFs. Systematic sensitivity decreases were especially pronounced at low frequencies for L- and M-cone stimuli. S-cone- and rod-driven tCSFs differed only slightly between patients and healthy subjects.
Measurements of tCSFs of the photoreceptor classes is feasible in patients with Stargardt’s disease using our protocol. In contrast to tCSFs of RP patients from an earlier study, where rod sensitivities at 10-12 Hz were best suited to separate patients from normal subjects, differences were most pronounced at low temporal frequencies for L- and M-cone isolating stimuli. In the future, our paradigm may allow more accurate genotype-phenotype correlations and offer advantages in the monitoring of progression of Stargardt’s disease.
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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