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The optic nerve contains axons of nerve cells that emerge from the retina, leave the eye at the optic disc, and go to the visual cortex where input from the eye is processed into vision. There are 1.2 million optic nerve fibers that derive from the retinal ganglion cells of the inner retina. [2] Damage to the optic nerve can have different causes:
Patient sitting straight in front of the examiner, is asked look directly at the examiner's eye during the test. The target eye should be the one directly across from the patient's eye. When the patient's right eye is being tested, closing the other eye, patient is instructed to look directly at the examiners left eye.
A tear in the retina can allow fluids from the eye to leak in behind the retina, which causes retinal detachment. When this occurs, blood from the retinal blood vessels can bleed into the vitreous. [4] Retinal tear accounts for 11.4–44% of vitreous hemorrhage cases. [1]
The optic disc is where the axons from the retinal ganglion cells collect into the optic nerve. The optic nerve is the bundle of axons that carry the visual signals from the eye to the brain. This optic nerve must penetrate through the wall of the eye, and the hole to accommodate this is usually 20-30% larger than the nerve diameter.
The pulling forces or traction from this adhesion on the retinal surface can sometimes cause edema within the retina, damage to retinal blood vessels causing bleeding, or damage to the optic nerve causing disruption in the nerve signals sent to the brain for visual processing. It is important to note that while the VMA itself is not dangerous ...
Major symptoms are sudden loss of vision (partial or complete), sudden blurred or "foggy" vision, and; pain on movement of the affected eye. [4] [5] [2]Many patients with optic neuritis may lose some of their color vision in the affected eye (especially red), with colors appearing subtly washed out compared to the other eye.
Retinopathy is diagnosed by an ophthalmologist or an optometrist during eye examination. The clinician will need to examine the retina, at the back of the eye, to make this diagnosis. There are several ways to examine the retina. The clinician can directly view the retina by looking through the pupil with a light.
The retina lines the inside of the eye. It is light-sensitive and communicates visual messages to the brain. If the retina detaches, it moves and shifts from its normal position. This can cause photopsia, but can also cause permanent vision loss. Medical attention is needed to prevent vision loss.