In acupuncture, long, slender needles are inserted in specific areas of the skin and twirled by hand or with an instrument. After about 30 minutes, pain is absent in a given area for up to 8 hours. Where the needles are inserted depends on the location of the pain or intended surgery. Acupuncture is mostly used in the United States to relieve the pain of childbirth as well as for arthritis and a number of common complaints. It is rarely used during surgery in the U.S.
How acupuncture works relates to the functioning of the nervous system. The brain triggers the release of neuromodulators in response to pain; the neuromodulators block the traffic of pain impulses, so the pain is not sensed. Acupuncture triggers the release of pain-blocking neuromodulators, such as enkephalin, that are carried to the locations of pain. It takes up to 30 minutes for the concentrations of neuromodulators to be high enough to sufficiently block the pain. Acupuncture has also been used successfully in patients with spinal cord injuries to help them regain the functions of healthy nerve tissue and the use of their limbs.
Detachment of the retina can occur because of a fall or blow to the head, and can also occur in those who are severely nearsighted. The inner layer of the retina containing the sensory receptors actually becomes separated from the dark-colored vascular layer that nourishes the sensory receptors. When this happens, the sensory receptors are deprived of oxygen and eventually die. To the person whose retina is becoming detached, it appears as though a black sheet were coming down over a portion or all of the field of vision in one eye. When this happens, the person needs to seek medical attention immediately. The retina can be reattached using laser or other surgical means.