Why retinal ganglion cells are important in glaucoma?
The retina is a thin tissue in the back of the eye containing different kinds of nerve cells. Among these are retinal ganglion cells (RGCs) — and they are particularly important in glaucoma because they are the cells that are damaged primarily by the disease.
What triggers apoptosis of retinal ganglion cells in glaucoma?
An established theory is that elevated IOP induces physical changes at the ONH, visualized clinically as optic disc cupping, which causes optic nerve axonal compression at the lamina cribrosa, blockage of axoplasmic flow, and interference in retrograde neurotrophin transport to RGCs, leading to cell death.
What cells are affected by glaucoma?
1 2 Glaucoma patients have characteristic fields of visual loss which enlarge as the disease progresses. Thus, glaucomatous optic neuropathy may not be a chronic degeneration of the whole of the optic nerve and ganglion cell somata but rather a series of acute losses of individual, or groups of, ganglion cells.
What is glaucoma retinal ganglion cells?
Retinal ganglion cell (RGC) loss is the hallmark of optic neuropathies, including glaucoma, where damage to RGC axons occurs at the level of the optic nerve head. In experimental glaucoma, damage is assessed at the axon level (in the retinal nerve fibre layer and optic nerve head) or at the soma level (in the retina).
What do retinal ganglion cells respond to?
In a popular view of retinal function, each ganglion cell responds to a small region of interest in the visual image, known as its receptive field, and is specialized for certain image features within that window. When a cell encounters that image feature, the neuron responds by firing one or more spikes.
Can glaucoma cause brain damage?
Elevated intraocular pressure in glaucoma can injure retinal ganglion cells and trigger the spread of disease to connected target vision structures of the brain. Glaucomatous degeneration has been observed in retrobulbar and intracranial optic nerve, lateral geniculate nucleus, and visual cortex of the brain.
Does glaucoma affect the retina?
Glaucoma damages the retinal ganglion cells and eventually causes them to die. Also, glaucoma typically damages the retinal ganglion cells in a pattern in which the peripheral (side) vision is affected first. These changes to vision typically go unnoticed because one eye can compensate for the other.
What are bipolar cells in eye?
Bipolar cells are the only neurons that connect the outer retina to the inner retina. They implement an ‘extra’ layer of processing that is not typically found in other sensory organs.
How are retinal ganglion cells affected by glaucoma?
Retinal ganglion cells are specialized neurons that send visual information from the eye’s retina to the brain. Increased pressure within the eye can contribute to retinal ganglion cell damage, leading to glaucoma. Even with pressure-lowering drugs, these cells eventually die, leading to vision loss.
Why does RNFL decrease as glaucoma progresses?
As glaucoma advances, RNFL measurement continues to decrease but it doesn’t go to zero, which is known as the “floor effect.” This is because the architectural support made up by Müller cells, astroglia, microglia and blood vessels doesn’t degenerate completely with retinal ganglion cell axons.
What causes thinning of the macula in glaucoma?
Glaucoma can cause thinning of the macula early in the disease, especially the inferior macula, from which the retinal ganglion cells project to the inferotemporal region of the disc. Previous histology studies have shown that thinning of the macula, due to selective loss of retinal ganglion cells, occurs in glaucoma.
Why do retinal ganglion cell axons fail to regenerate?
There is some evidence, however, that retinal ganglion cell axons fail to regenerate not only because of CNS glial or other inhibition, but also undergo intrinsic changes during embryonic development that render them refractory to regeneration. As in the spinal cord, these axons can regenerate early in development, but lose this ability later.