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Optic nerve

Pupil constriction -- Facts, Info, and Encyclopedia article   (Site not responding. Last check: 2007-10-21) In (The branches of medical science that deal with nonsurgical techniques) medicine, pupil constriction (also known as the pupillary reflex) is reduction of (Contractile aperture in the iris of the eye) pupil size. It is the normal response of the pupil of the eye to ((physics) electromagnetic radiation that can produce a visual sensation) light and dependent on the function of the (The cranial nerve that serves the retina) optic nerves and (Supplies extrinsic muscles of the eye) oculomotor nerves. Dependent on how the pupils constrict or do not constrict one can determine which of the (Any of the 12 paired nerves that originate in the brain stem) cranial nerves is damaged. www.absoluteastronomy.com /encyclopedia/p/pu/pupil_constriction.htm   (433 words)

Pupillary reflex - Wikipedia, the free encyclopedia Pupillary constriction may be induced pharmacologically by parasympathomimetics and is also seen in accommodation (when the eyes focus on something close). The oculomotor nerve is responsible for the efferent limb of the pupillary reflex; in other words, it drives the muscles that constrict the pupil. Dependent on how the pupils constrict or do not constrict one can determine which of the cranial nerves is damaged. en.wikipedia.org /wiki/Pupil_constriction   (366 words)

Segmento anteriore   (Site not responding. Last check: 2007-10-21) The pupil alterations are miosis, mydriasis, Argyll Robertson pupil, tonic pupil and anisocoria. Pupil reflexes are: the photomotor direct reflex and the consensual light reflex, the reflex for close vision and that for the emotional and/or sensorial stimuli. The pupil contraction at the lightening, as it has been proved by pupillography, includes a quick primary phase, which is parasympathetic, and a secondary and tertiary one, which are slower and depend on the sympathetic system. www.sifi.it /archivio/EN132/rubri08.htm   (2929 words)

Human Biology Final Year Project   (Site not responding. Last check: 2007-10-21) Pupil size varies with changing ambient light conditions to try and ensure that a constant amount of light hits the retina. The correlations between age and constriction amplitude, constriction velocity, % redilation O.9s after minimum diameter, and pupil sizes were not statistically significant although trends were found suggesting that a relationship was present. This suggests that techniques using pupil responses to investigate the health of the eye, which at the moment do not take age into account, are probably justified. www.lboro.ac.uk /departments/hu/projects/abstracts/91hb0115.htm   (336 words)

The Iris When too much light is entering the eye, the iris sphincter muscle (which encircles the pupil) pulls toward the center, causing the pupil to “constrict” and allowing less light to reach the retina. Constriction of the pupil also occurs when the crystalline lens accommodates (changes focus) to a near distance; this reaction is known as the “near reflex.” A representation of parasympathic pathways in the pupillary light reflex can be seen here: parasympathic response. With a uniform background light present in the room, causing the pupils to slightly constricted, there is less variance in the size of the pupil as the television illumination changes, and the muscles controlling the pupil size become less tired. www.tedmontgomery.com /the_eye/iris.html   (1034 words)

Pupillary autonomic denervation with increasing duration of diabetes mellitus -- Cahill et al. 85 (10): 1225 -- British ... Pupil size was calculated from the pupillographs as the average of its vertical and horizontal diameters. of the pupil constriction, and prolonged redilatation in the dark. Cholinergic supersensitivity of the iris sphincter in Adie's tonic pupil. bjo.bmjjournals.com /cgi/content/full/85/10/1225   (3481 words)

absbook Purpose The tonic pupil is characterized primarily by pupillary abnormalities. Pupil diameter was monitored with a binocular infrared television pupillometer before and after the administration of treatment for 4 h at 20 min intervals. Pupil diameter was increased by yohimbine and clonidine + yohimbine and tended to be reduced by clonidine. www-staff.lboro.ac.uk /~huph/absbook.htm   (11727 words)

Oculomotor nerve   (Site not responding. Last check: 2007-10-21) The fibers of the oculomotor nerve arise from a nucleus in the midbrain, which lies in the gray substance of the floor of the cerebral aqueduct and extends in front of the aqueduct for a short distance into the floor of the third ventricle. A nearby nucleus, the Edinger-Westphal nucleus, is responsible for the autonomic functions of the oculomotor nerve, including pupillary constriction and lens accommodation. Both pupils should constrict at the same time, independent of what eye the light is actually shone on. www.1bx.com /en/Occulomotor_nerve.htm   (856 words)

Using Pupillometry to Measure Sleepiness: The Reproducibility, Ultradian Sensitivity and Validity of Outcome Measures Pupillometry is a convenient, easily repeatable clinical technique for measuring pupil constriction and oscillation, signs that have been observed to occur concurrent with behavioral indicators of sleepiness. The ALT was conducted with 11 normal subjects every 2 hours for 4 times on one day to determine if this test demonstrated significant pupil constriction and oscillation in the afternoon when an increase in sleepiness is expected and demonstrated on polygrahic daytime nap studies. Linear regression of pupil diameter data for the 4 time periods demonstrated that the estimated slope of the line for the 2 PM period was significantly greater than each of the other 3 time periods (10 AM - p.005, 12N - p.005, 4 PM - p.02). stti.confex.com /stti/sos13/techprogram/paper_11403.htm   (635 words)

Researchers identify 'light meter' that controls pupil constriction This new study complements earlier work that had demonstrated the pupils of blind mice still respond to light. In these experiments, however, Van Gelder, and his research team demonstrated that the constriction of the pupil in the chick eye seems to be regulated by cryptochrome rather than melanopsin, Melanopsin is part of the family of proteins, called opsins, that mediate normal visual function. In a series of experiments led by first author Daniel C. Tu, a graduate student in Van Gelder's lab, the researchers looked at the chick eye under various kinds of light and treated it with drugs that disrupt normal, opsin-mediated visual pathways in insects and mammals. www.medicalnewstoday.com /medicalnews.php?newsid=14265   (799 words)

Researchers identify 'light meter' that controls pupil constriction Working with embryonic chicken eyes, Washington University ophthalmology researchers found that cryptochrome allows the pupil to react independently from light-sensitive photoreceptor cells at the back of the eye. In that nonvisual pathway, melanopsin is thought to play the dominant role in synchronizing the mouse's internal circadian clock to external light and dark cycles. In the mouse, the meter is located in the retina and primarily uses melanopsin to do its work with cryptochrome proteins amplifying the signal. www.eurekalert.org /pub_releases/2004-09/wuso-ri092904.php   (764 words)

[No title]   (Site not responding. Last check: 2007-10-21) Miotics facilitate the outflow of aqueous humor from the anterior chamber of the eye by stimulating miosis (pupil constriction). The parasympathetic nervous system is responsible for actions such as pupil constriction, heart rate decrease, and increased glandular secretion. As an example, in order for the pupil to constrict, a message has to be transmitted via nerve fibers (facilitated by the neurotransmitter acetylcholine) from the brain to the iris. dev.pitchsmartclassroom.com /myriad/l1_c2/2_4_B5.html   (243 words)

The eyes of suckermouth armoured catfish (Loricariidae, subfamily Hypostomus): pupil response, lenticular longitudinal ... Pupil response of a Liposarcus pardalis individual during 60 min exposure to different intensities of white light. Pupil response of a Liposarcus pardalis individual to 60 min exposure to white light at an intensity of 5.6 Illumination resulted both in a decrease of pupil diameter and the outgrowth of an iris flap, such that overall pupil area following illumination in this example is 34% of the dark-adapted value. jeb.biologists.org /cgi/content/full/205/22/3425   (4373 words)

Friedman Veterinary Service: Eye Aftercare Most eye problems in the horse involve pain, inflammation, pupil constriction (which is also very painful), and occasionally ulcers with bacterial or fungal infection. These signs are linked together in a cascade: inflammation causes pain which causes more inflammation, both of which lead to pupil constriction which leads to more pain and so on. Treatment is based on eliminating the infection with antibiotics, allowing the ulcer (if present) to heal, dilating the pupil to relieve pain, relieving inflammation, and giving pain relief all in an attempt to stop the cascade. www.oregonequine.com /eyeaftercare.htm   (297 words)

Pupil response components: studies in patients with Parinaud's syndrome -- Wilhelm et al. 125 (10): 2296 -- Brain Pupil response components: studies in patients with Parinaud's syndrome -- Wilhelm et al. Pupil response triggered by the onset of coherent motion. Differential pupillary constriction and awareness in the absence of striate cortex. brain.oxfordjournals.org /cgi/content/full/125/10/2296?...   (4954 words)

Signs and Symptoms of Drug and Alcohol Use, pupil constriction, dilation charts, definition of addiction, pictures and ...   (Site not responding. Last check: 2007-10-21) A 6mm, 7mm, or 8mm pupil size could indicate that a person is under the influence of cocaine, crack, meth., hallucinogens, crystal, ecstasy, or other stimulant. This pupil is close to pinpoint and could indicate use. Pinpoint pupils are indicative of heroin, opiate, depressant use. www.ni-cor.com /ni-corsignsandsymptomsofalcoholismanddrugaddiction.html   (3222 words)

Distler - Vis.Neurosci. 1989 - Allgemeine Zoologie und Neurobiologie RUB   (Site not responding. Last check: 2007-10-21) Neurons in the nucleus praetectalis olivaris (NPO) were antidromically identified by electrical stimulation of the nucleus of Edinger-Westphal (EW), the location of preganglionic pupilloconstrictor motoneurons. Single neurons recorded in the NPO respond tonically to light stimuli, and their discharge frequency increases linearly with logarithmic increase in light intensity. the increase of pupil constriction during binocular illumination when compared to monocular illumination is less than in normal animals. www.ruhr-uni-bochum.de /neurobiol/abstract/distler_vn1989a.htm   (316 words)

Pupil Diameter Changes Associated with Blinking   (Site not responding. Last check: 2007-10-21) We had expected to see either or both pupil diameter increases associated with the loss of visual input and pupil constriction associated with the reopening phase of the blink. We are currently investigating this issue by using brief flashes of darkness (to simulate the loss of light input to the eyes during a blink) as well as blinks in response to stimulus presentation (voluntary blink) and normal "involuntary" or "spontaneous" blinks. This research is being supported by a grant from the American Trucking Association and the Department of Transportation to John A. Stern. www.artsci.wustl.edu /~psycphys/pupil.html   (246 words)

FAQ's Adie's pupil responds poorly or not at all to light because of damage to the parasympathetic nerves (not muscarinic receptors). The Pilocarpine test is just to see that the pupil will constrict and is not by itself diagnostic for Adie's pupil. It could have been that an atropine-like agent (muscarinic blocker) was present and was responsible for the lack of response to light. www.courses.vcu.edu /ptxed/pmc537/faq.htm   (4777 words)

Pupil constriction Normally it is difficult to make the pupil constrict arbitrarily, i.e., at a person's will, without a natural reason (lighting or viewed distance change). However it is possible, after an appropriate practice. Some hypnotizerss use the knack of quick constriction/dilation of their pupils in their trade. www.brainyencyclopedia.com /encyclopedia/p/pu/pupil_constriction.html   (417 words)

There's more to vision than meets the eye In a study published earlier this year in the journal Science, his team reported that a family of proteins called cyptochromes are important in the pupil's response to light in blind mice. Although the mice could not see, their pupils of their eyes changed size in response to light. It took about 10 times more light to make pupils constrict in blind mice with cryptochrome than in mice that could see. news-info.wustl.edu /tips/page/normal/506.html   (1354 words)

Researchers Identify 'Light Meter' That Controls Pupil Constriction   (Site not responding. Last check: 2007-10-21) Molecule Helps Pupils Respond To Light (January 10, 2003) -- Researchers are reporting progress in understanding whether a second light-sensing pathway in mammals indeed contributes to the detection of ambient light for controlling body... Doctors Focus on Pupil Size for Safety of Laser Vision Correction (May 8, 2003) -- Exactly how a person's eyes respond to low levels of light is even more crucial than doctors have thought in deciding who is and who isn't a good candidate to have laser vision correction... Molecular Motor Shuttles Key Protein In Response To Light (July 19, 2004) -- In experiments with fruit flies, Johns Hopkins researchers have discovered how a key light-detecting molecule in the eye moves in response to changes in light... www.sciencedaily.com /releases/2004/10/041001092706.htm   (973 words)

Vision Secreted by the ciliary epithelium into the posterior chamber of the eye, it diffuses forward through the pupil and into the anterior chamber. Glaucoma is the raised intraocular pressure that arises from an imbalance of secretion and drainage, usually due to blocked outflow. In bright light, the parasympathetic nervous system causes the circular sphincter muscle of the iris to contract and pupil constriction occurs. www.cf.ac.uk /biosi/staff/jacob/teaching/sensory/vision.html   (1196 words)

biology - Oculomotor nerve   (Site not responding. Last check: 2007-10-21) The muscles it controls are the ciliary muscle (affecting accommodation), and all extrinsic eye muscles except for the superior oblique muscle and the lateral rectus muscle. In addition, it supplies parasympathetic fibres to the eye via the ciliary ganglion, and thus controls pupil constriction. By moving a finger towards a person's face, as well as them going cross-eyed, their pupils should constrict. www.biologydaily.com /biology/Oculomotor_nerve   (757 words)

Peripheral opioid analgesia in experimental human pain models -- Tegeder et al. 126 (5): 1092 -- Brain M6G potency for pupil constriction in carriers of the mutated The pupil diameter was assessed to monitor the absence or presence The pupil diameter was determined as the mean of five measurements (30 s rest period). brain.oxfordjournals.org /cgi/content/full/126/5/1092   (5192 words)

Ask Lasik Doctors   (Site not responding. Last check: 2007-10-21) I don't use either medicine for pupil constriction post LASIK, and I'm not sure how much additional effect to expect with the alpha2 blocker effect of the medicine. I heard that since the development of so many excellent new POAG drops, that formulation of Pilo is difficult to obtain. I'm using ALPHAGAN P for pupil constriction and I simply love it. www.asklasikdocs.com /forum/Pupil/64.html   (408 words)

UW Department of Ophthalmology: NEURO-OPHTHALMOLOGY SERVICE The optic nerve carries the axons from the back of the eye, across the back part of the eye socket, through a small hole in the skull, where it meets the optic nerve from the other eye in the optic chiasm. Variations in light level produce changes in the size of the pupils in the eyes. Examination of the pupil is an integral part of the neuro-ophthalmic examination. depts.washington.edu /ophthweb/neuro.html   (1010 words)

Relative Potency of levo-alpha -Acetylmethadol and Methadone in Humans under Acute Dosing Conditions -- Eissenberg et ... all physiologic measures except for pupil diameter and respiration. naloxone-induced reversal of pupillary constriction at 24 h. The measures are the "Do you like the drug" VAS, "Do you feel any drug effect" VAS, pupil diameter, and observer-rated magnitude of drug effect. jpet.aspetjournals.org /cgi/content/full/289/2/936   (5836 words)

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