Search results
Results from the WOW.Com Content Network
The experience of eye strain when reading in dim light has given rise to the common misconception that such an activity causes permanent eye damage. [3] When concentrating on a visually intense task, such as continuously focusing on a book or computer monitor, the ciliary muscles and the extraocular muscles are strained. This causes discomfort ...
Oculomotor nerve palsy or oculomotor neuropathy [1] is an eye condition resulting from damage to the third cranial nerve or a branch thereof. As the name suggests, the oculomotor nerve supplies the majority of the muscles controlling eye movements (four of the six extraocular muscles, excluding only the lateral rectus and superior oblique).
The symptoms and signs associated with convergence insufficiency are related to prolonged, visually demanding, near-centered tasks. They may include, but are not limited to, diplopia (double vision), asthenopia (eye strain), transient blurred vision, difficulty sustaining near-visual function, abnormal fatigue, headache, and abnormal postural adaptation, among others.
Normally, muscle contraction is a result of electrical signals sent from the central nervous system to muscle fibers via nerve impulses.At the neuromuscular junction, this electrical message is converted into a chemical message as acetylcholine is released from nerve fibers and attaches to corresponding receptors on the muscle fiber.
The ciliary muscles that control the lens shape and the iris muscles are often unaffected by CPEO. [ citation needed ] Additional symptoms are variable, and may include exercise intolerance, cataracts , hearing loss, sensory axonal neuropathy, ataxia , clinical depression, hypogonadism , and parkinsonism .
The symptoms may be temporarily alleviated by sensory tricks (geste antagoniste) including stretching or rubbing the eyebrows, eyelids, or forehead, [19] and singing, talking, or humming. [20] Blepharospasm is aggravated by fatigue, stress, and environmental factors such as wind or air pollution.
Torticollis can be caused by damage to the trochlear nerve (fourth cranial nerve), which supplies the superior oblique muscle of the eye. The superior oblique muscle is involved in depression, abduction, and intorsion of the eye. When the trochlear nerve is damaged, the eye is extorted because the superior oblique is not functioning.
Myelitis causes spinal cord dysfunction, which can result in muscle weakness, paralysis in the limbs, lost or reduced sensation, spasms, loss of bladder and bowel control, or erectile dysfunction. [1] [4] [2] [7] [8] [9] The myelitis can be transverse, affecting an entire cross-section of the spinal cord, and showing bilateral symptoms.