Revealing the retina: Graphene corneal contact lens provides robust, irritation-free topographic electroretinography

phys.org | 8/15/2018 | Staff
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Our vision can be damaged or lost by damage to the retina—a sensory membrane lining the back of the eye that senses light, converting the image formed into electrochemical neuronal signals—resulting from two classes of medical conditions: a number of inherited degenerative conditions—including retinitis pigmentosa, Leber's congenital amaurosis, cone dystrophy, and Usher Syndrome—as well as diabetic retinopathy, central retinal vein occlusion, sickle cell retinopathy, toxic an autoimmune retinopathies, retinal detachment, and other ocular disorders. To be properly diagnosed and treated (especially when a cataract compromises ophthalmoscopy, 2-D fundus photography, 3-D optical coherence tomography, and other retinal imagery tools), such medical conditions rely on electroretinography—a sensitive technique that detects and measures electrical potential changes at the eye's corneal surface produced in response to a light stimulus by neuronal and non-neuronal retinal cells. Nevertheless, electroretinography has historically faced challenges in the ocular interface electrodes needed to detect an electroretinogram (ERG), these being patient discomfort due to hard electrodes, limited types of electroretinograms with a single type of electrode, reduced signal amplitudes and stability, and excessive eye movement. Recently, however, scientists at Peking University, Beijing, have demonstrated soft, transparent GRAphene Contact lens Electrodes (GRACEs) for conformal full-cornea electroretinogram signal recording in rabbits and cynomolgus monkeys, showing that their soft graphene contact lens electrodes address these limitations.

Prof. Xiaojie Duan discussed the paper that she, graduate students and lead authors Rongkang Yin and Zheng Xu, and their co-authors published in Nature Communications. The biggest challenge in fabricating soft graphene contact lens electrodes with broad-spectrum optical transparency, Dr. Duan told Phys.org, was fabricating wrinkle-free contact lens electrodes, explaining that wrinkles can cause optical inhomogeneity across the electrode, thereby affecting ocular refraction and the accuracy of the light stimulus pattern on the retina. "This in turn undercuts retinopathy diagnosis efficacy," Dr. Duan added. "Graphene obtained from conventional...
(Excerpt) Read more at: phys.org
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