Elisa Castaldi1, Guido Marco Cicchini2, Benedetto Falsini3, Paola Binda2,4, Maria Concetta Morrone4,5. 1. Department of Neuroscience, Psychology, Pharmacology and Child Health, University of Florence, Florence, Italy. 2. Institute of Neuroscience CNR, Pisa, Italy. 3. Department of Ophthalmology, Policlinico Gemelli, Università Cattolica del Sacro Cuore, Rome, Italy. 4. Department of Translational Research and New technologies in Medicine and Surgery, University of Pisa, Pisa, Italy. 5. IRCCS Stella Maris, Calambrone, Pisa, Italy.
Abstract
PURPOSE: We evaluated the potential of magnetic resonance imaging in identifying signs of cortical visual processing with greater sensitivity than standard ophthalmological measures in patients with retinitis pigmentosa (RP) at advanced stages. METHODS: Eight patients affected with RP with only bare light perception and weak or absent visual evoked potential (VEP) or electroretinogram (ERG) responses to flashes of light were tested. Visual impairment was evaluated by means of psychophysical testing, where patients were asked to discriminate the drifting direction of a contrast modulated grating. Patients underwent magnetic resonance imaging scanning, and the behavioral performance was correlated with both blood oxygenation level-dependent (BOLD) signal elicited by flashes of lights and cortical thickness measured in primary visual area. RESULTS: Contrast sensitivity to drifting gratings of very low spatial and temporal frequency was greatly impaired, yet measurable in all patients. Weak luminance flashes elicited significant BOLD responses in the striate and extrastriate cortex, despite that the stimuli were not perceived during scanning. Importantly, patients with less severe impairment of contrast sensitivity showed stronger V1 BOLD responses. Striate cortical thickness did not correlate with visual sensitivity. CONCLUSIONS: BOLD responses provide a sensitive and reliable index of visual sparing more than VEPs or ERGs, which are often absent in RP patients. The minimal residual vision can be assessed by optimal visual stimulation in two alternative forced choice discrimination tasks and by BOLD responses. Imaging techniques provide useful information to monitor progressive vision loss. TRANSLATIONAL RELEVANCE: Functional magnetic resonance imaging might be a practical tool for assessing visual sparing, as it is more feasible and sensitive than psychophysical or ophthalmological testing. Copyright 2019 The Authors.
PURPOSE: We evaluated the potential of magnetic resonance imaging in identifying signs of cortical visual processing with greater sensitivity than standard ophthalmological measures in patients with retinitis pigmentosa (RP) at advanced stages. METHODS: Eight patients affected with RP with only bare light perception and weak or absent visual evoked potential (VEP) or electroretinogram (ERG) responses to flashes of light were tested. Visual impairment was evaluated by means of psychophysical testing, where patients were asked to discriminate the drifting direction of a contrast modulated grating. Patients underwent magnetic resonance imaging scanning, and the behavioral performance was correlated with both blood oxygenation level-dependent (BOLD) signal elicited by flashes of lights and cortical thickness measured in primary visual area. RESULTS: Contrast sensitivity to drifting gratings of very low spatial and temporal frequency was greatly impaired, yet measurable in all patients. Weak luminance flashes elicited significant BOLD responses in the striate and extrastriate cortex, despite that the stimuli were not perceived during scanning. Importantly, patients with less severe impairment of contrast sensitivity showed stronger V1 BOLD responses. Striate cortical thickness did not correlate with visual sensitivity. CONCLUSIONS: BOLD responses provide a sensitive and reliable index of visual sparing more than VEPs or ERGs, which are often absent in RP patients. The minimal residual vision can be assessed by optimal visual stimulation in two alternative forced choice discrimination tasks and by BOLD responses. Imaging techniques provide useful information to monitor progressive vision loss. TRANSLATIONAL RELEVANCE: Functional magnetic resonance imaging might be a practical tool for assessing visual sparing, as it is more feasible and sensitive than psychophysical or ophthalmological testing. Copyright 2019 The Authors.
Authors: Samantha I Cunningham; Yonggang Shi; James D Weiland; Paulo Falabella; Lisa C Olmos de Koo; David N Zacks; Bosco S Tjan Journal: Transl Vis Sci Technol Date: 2015-12-08 Impact factor: 3.283
Authors: Geoffrey K Aguirre; Ritobrato Datta; Noah C Benson; Sashank Prasad; Samuel G Jacobson; Artur V Cideciyan; Holly Bridge; Kate E Watkins; Omar H Butt; Aleksandra S Dain; Lauren Brandes; Efstathios D Gennatas Journal: PLoS One Date: 2016-11-03 Impact factor: 3.240
Authors: Markus Ritter; Allan Hummer; Anna A Ledolter; Graham E Holder; Christian Windischberger; Ursula M Schmidt-Erfurth Journal: Br J Ophthalmol Date: 2018-04-26 Impact factor: 4.638
Authors: Piotr Bogorodzki; Ewa Piątkowska-Janko; Jerzy Szaflik; Jacek Paweł Szaflik; Mira Gacek; Paweł Grieb Journal: PLoS One Date: 2014-04-07 Impact factor: 3.240
Authors: Artur V Cideciyan; Samuel G Jacobson; Allen C Ho; Arun K Krishnan; Alejandro J Roman; Alexandra V Garafalo; Vivian Wu; Malgorzata Swider; Alexander Sumaroka; Caroline Van Cauwenbergh; Stephen R Russell; Arlene V Drack; Bart P Leroy; Michael R Schwartz; Aniz Girach Journal: Ophthalmol Sci Date: 2022-03-02