Our group studies disease mechanisms in inherited retinal degenerations (IRDs), and evaluates efficacy and safety of potential treatments. IRDs result in vision loss due to mutations in more than 200 different genes and include diagnoses such as Retinitis Pigmentosa, Stargardt Disease, Leber Congenital Amarousis, and others. There are multitudes of different pathological mechanisms resulting from different mutations. Our group uses non-invasive tests to link changes in retinal structure and function to underlying molecular pathology. We also develop and evaluate novel outcome measures for use in clinical trials.
June 1, 2016: Paper published in Investigative Ophthalmology and Visual Science
Most ophthalmic vision testing equipment can present light stimuli over a limited range of intensities. We recently modified a Nidek MP1 microperimeter in order to present stimuli with varied sizes, colors, and patterns over a large range of luminance. For this purpose, the filter bar used in scotopic MP1 was replaced with a custom slide-in tray that introduces light from an external projector driven by an additional computer. MP1 software was modified to provide retinal tracking information to the computer driving the projector. Retinal tracking performance was evaluated by imaging the system input and the output simultaneously with a high-speed video system. Spatial resolution was measured with achromatic and chromatic grating/background combinations over scotopic and photopic ranges. The range of retinal illuminance achievable by the modification was up to 6.8 log photopic Trolands (phot-Td); however, in the current work, only a lower range over -4 to +3 log phot-Td was tested in human subjects. Optical magnification was optimized for low-vision testing with gratings from 4.5 to 0.2 cyc/deg. In normal subjects, spatial resolution driven by rods, short wavelength-sensitive (S-) cones, and long/middle wavelength-sensitive (L/M-) cones was obtained by the choice of adapting conditions and wavelengths of grating and background. Data from a patient with blue cone monochromacy was used to confirm mediation. The modified MP1 can be further developed into an outcome measure for treatments in patients with severe retinal degeneration, very low vision, and abnormal eye movements such as those for whom treatment with optogenetics is planned, as well as for patients with cone disorders such as blue cone monochromacy for whom treatment with gene therapy is planned to improve L/M-cone function above a normal complement of rod and S-cone function.
Cideciyan AV, Roman AJ, Jacobson SG, Yan B, Pascolini M, Charng J, Pajaro S, Nirenberg S. Developing an outcome measure with high luminance for optogenetics treatment of severe retinal degenerations and for gene therapy of cone diseases. Investigative Ophthalmology & Visual Science 57:3211-3221, 2016. [PubMed]
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