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Certainly an optic nerve that has been visually observed by the eye doctor to be 80 percent damaged is more fragile than on optic nerve with less damage. However, an estimate of glaucoma damage looks at more than optic nerve damage.
Usually, an eye doctor will estimate the extent of damage to vision by evaluating the amount of damage to both the visual field and the optic nerve. This is determined by eye examinations.
Learn more about glaucoma eye examinations.
Learn more about the optic nerve.
Last reviewed on August 27, 2012