Retinal Telangiectasis

Abstract: • Twenty-seven healthy adult patients had visual loss in one or both eyes because of exudation from juxtafoveolar retinal capillary telangiectasis of uncertain cause. These patients were subdivided as follows: group 1, men with uniocular involvement, intraretinal lipid exudation, and telangiectasis largely confined to the temporal half of the juxtafoveolar area; group 2, mostly men with symmetric areas of telangiectasis affecting the temporal half of the juxtafoveolar areas and minimal intraretinal exudation; group 3, both sexes with symmetric involvement of all of the parafoveolar capillary bed and minimal exudation; and group 4, one case of telangiectasis with occlusive perifoveolar capillary changes and familial optic disc pallor. The visual acuity prognosis in groups 1 through 3 is relatively good. Photocoagulation may be of some value in the treatment of patients in group 1.

Abstract: Muller cells are the major glia of the retina that serve numerous functions essential to retinal homeostasis, yet the contribution of Muller glial dysfunction to retinal diseases remains largely unknown. We have developed a transgenic model using a portion of the regulatory region of the retinaldehyde binding protein 1 gene for conditional Muller cell ablation and the consequences of primary Muller cell dysfunction have been studied in adult mice. We found that selective ablation of Muller cells led to photoreceptor apoptosis, vascular telangiectasis, blood–retinal barrier breakdown and, later, intraretinal neovascularization. These changes were accompanied by impaired retinal function and an imbalance between vascular endothelial growth factor-A (VEGF-A) and pigment epithelium-derived factor. Intravitreal injection of ciliary neurotrophic factor inhibited photoreceptor injury but had no effect on the vasculopathy. Conversely, inhibition of VEGF-A activity attenuated vascular leak but did not protect photoreceptors. Our findings show that Muller glial deficiency may be an important upstream cause of retinal neuronal and vascular pathologies in retinal diseases. Combined neuroprotective and anti-angiogenic therapies may be required to treat Muller cell deficiency in retinal diseases and in other parts of the CNS associated with glial dysfunction.