Neuro-ophthalmology
If the human eye works like a camera, we can imagine that the "processing of the film" into what we see as visual images is transmitted by the optic nerves from the globe of the eye, to their visual pathways in the brain and finally towards the visual processing centers at the back part of the brain. This is the realm of a Neuro-ophthalmologist, i.e., an eye specialist with special interest in the eye manifestations of diseases or injuries of the optic nerves and visual pathways (everything behind the eye involved in the visual process). Included in this field are brain pathways and processes involved in the control of eye movements. Several neuro-ophthalmic symptoms are also manifestations of systemic conditions like hypertension, diabetes, stroke, cardiovascular diseases, multiple sclerosis, brain tumor, and many others.
Some common neuro-ophthalmic conditions affecting vision include optic neuritis and toxic optic neuropathy (from intake of anti-TB medications); while examples of those affecting eye movements are cranial nerve strokes and thyroid disease. Patients with eye problems secondary to brain tumors or strokes, as well as migraines are also commonly seen in the neuro-ophthalmologist's clinic. As vast areas of the brain are involved in the overall function of the visual system, injuries from strokes or brain tumors affect vision and eye movements in various ways depending on the extent and location of the lesion. These include loss of vision (often described as loss of a particular field of vision, say, peripheral areas or one-half of the visual field), and "muscle imbalance" with inability to move the eye to a particular position, leading to double vision. Several post-stroke patients may also have visual perception difficulties, meaning the visual pathway may be intact, but the processing of the information is affected (the patient may not "understand' what he sees). Occasionally, patients with neuro-ophthalmic signs and symptoms from brain tumors are initially seen by the ophthalmologist, who then makes the crucial primary diagnosis and subsequent referral to a neurosurgeon. Ideally, the neuro-ophthalmologist, neurologist, and neurosurgeon should all be involved in the long term management and care of these patients (as well as in many other neuro-ophthalmic conditions). |
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