An early symptom of retinitis pigmentosa (RP) is night blindness caused by the loss of rod photoreceptors. Years later, in the virtual absence of rods, many cones may still survive and are responsible for “tunnel vision”—the remaining central vision that often is reduced to a visual acuity of 20/200 or worse and a visual field of less than 20°. This limited and deteriorating sight may continue for many more years. The protracted clinical course of diminishing cone function speaks to the resilience of the cones, which gives hope to finding therapeutic interventions that might halt their degeneration and thus preserve functional vision for patients with RP. What causes the decline and eventual demise of the cones? Recent discoveries suggest that the residual cones are starving and that increasing glucose uptake by these cells might be the key to improving their health and extending their longevity.1,2
Wong F, Kwok SY. The Survival of Cone Photoreceptors in Retinitis Pigmentosa. JAMA Ophthalmol. 2016;134(3):249–250. doi:10.1001/jamaophthalmol.2015.5490
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