Changes

<p><strong>Miosis</strong> is a medical term for constriction of the <a title="Pupil" href="http://en.wikipedia.org/wiki/Pupil">pupil</a>. It is the opposite of <a title="Mydriasis" href="http://en.wikipedia.org/wiki/Mydriasis">mydriasis</a>. It is seen in a variety of medical conditions, and can also be caused by certain drugs and chemicals. Eye drops used to intentionally cause miosis are known as &quot;miotics&quot;. Extreme miosis is commonly called &quot;pinpoint pupils&quot;, a situation that can be caused by use of opiates.</p> 

<p>Visual stimuli enters the eye, and through the retinal photoceptors is converted into an electric impulse, carried through the optic nerve (<a title="Cranial nerve" href="http://en.wikipedia.org/wiki/Cranial_nerve">cranial nerve</a> II) to the brain, where it connects to the pretectal nucleus of the high midbrain. It bypasses the lateral geniculate nucleus and the primary visual cortex. From the pretectal nucleus neurons send axons to neurons of the <a title="Edinger-Westphal nucleus" href="http://en.wikipedia.org/wiki/Edinger-Westphal_nucleus">Edinger-Westphal nucleus</a> whose visceromotor axons run along both the left and right oculomotor nerves. Visceromotor nerve axons (which constitute a portion of the III <a title="Cranial nerve" href="http://en.wikipedia.org/wiki/Cranial_nerve">cranial nerve</a>, along with the somatomotor portion derived from the Edinger-Westphal nucleus) synapse on ciliary ganglion neurons, whose <a title="Parasympathetic" href="http://en.wikipedia.org/wiki/Parasympathetic">parasympathetic</a> axons innervate the constrictor muscle of the iris, producing <strong><strong class="selflink">miosis</strong></strong>. <a class="external autonumber" title="http://www.coldbacon.com/mdtruth/pics/netter/fn-oculomotor.jpg" rel="nofollow" href="http://www.coldbacon.com/mdtruth/pics/netter/fn-oculomotor.jpg">[1]</a></p>

<li><a title="Horner syndrome" href="http://en.wikipedia.org/wiki/Horner_syndrome">Horner syndrome</a> (a set of abnormalities in the nervous supply of the face due to damage to the <a title="Sympathetic nervous system" href="http://en.wikipedia.org/wiki/Sympathetic_nervous_system">sympathetic nervous system</a>). </li> <li><a title="Pancoast tumor" href="http://en.wikipedia.org/wiki/Pancoast_tumor">Pancoast tumor</a> (a <a title="Lung cancer" href="http://en.wikipedia.org/wiki/Lung_cancer">tumor</a> of the apical <a title="Lung" href="http://en.wikipedia.org/wiki/Lung">lung</a>), due to damage to the ascending sympathetic tract that would normally cause the pupil to dilate. </li> <li><a title="Hemorrhage" href="http://en.wikipedia.org/wiki/Hemorrhage">Hemorrhage</a> into <a title="Pons" href="http://en.wikipedia.org/wiki/Pons">pons</a> (<a title="Intracranial hemorrhage" href="http://en.wikipedia.org/wiki/Intracranial_hemorrhage">intracranial hemorrhage</a>) </li>

<li><a title="Opioid" href="http://en.wikipedia.org/wiki/Opioid">Opioids</a> such as <a title="Codeine" href="http://en.wikipedia.org/wiki/Codeine">codeine</a>, <a title="Morphine" href="http://en.wikipedia.org/wiki/Morphine">morphine</a>, <a title="Heroin" href="http://en.wikipedia.org/wiki/Heroin">heroin</a> and <a title="Methadone" href="http://en.wikipedia.org/wiki/Methadone">methadone</a> </li> <li><a title="Antipsychotics" href="http://en.wikipedia.org/wiki/Antipsychotics">Antipsychotics</a>, including <a title="Haloperidol" href="http://en.wikipedia.org/wiki/Haloperidol">haloperidol</a>, <a title="Thorazine" href="http://en.wikipedia.org/wiki/Thorazine">thorazine</a>, <a title="Olanzapine" href="http://en.wikipedia.org/wiki/Olanzapine">olanzapine</a>, <a title="Quetiapine" href="http://en.wikipedia.org/wiki/Quetiapine">quetiapine</a> and others </li> <li><a title="Cholinergic" href="http://en.wikipedia.org/wiki/Cholinergic">Cholinergic</a> agents such as those used to treat <a title="Alzheimer's disease" href="http://en.wikipedia.org/wiki/Alzheimer%27s_disease">Alzheimer's disease</a> and <a title="Nerve gas" href="http://en.wikipedia.org/wiki/Nerve_gas">nerve gases</a>; cholinergic drugs such as <a title="Carbachol" href="http://en.wikipedia.org/wiki/Carbachol">carbachol</a> (Miostat) and <a title="Neostigmine" href="http://en.wikipedia.org/wiki/Neostigmine">neostigmine</a> </li> <li>Some cancer <a title="Chemotherapy" href="http://en.wikipedia.org/wiki/Chemotherapy">chemotherapy</a> drugs, including <a title="Camptothecin" href="http://en.wikipedia.org/wiki/Camptothecin">camptothecin</a> derivatives </li> <li><a title="Mirtazapine" href="http://en.wikipedia.org/wiki/Mirtazapine">Mirtazapine</a>, a <a title="Noradrenergic and specific serotonergic antidepressant" href="http://en.wikipedia.org/wiki/Noradrenergic_and_specific_serotonergic_antidepressant">noradrenergic and specific serotonergic antidepressant</a> (<a title="NaSSA" href="http://en.wikipedia.org/wiki/NaSSA">NaSSA</a>) </li> <li><a title="Trazadone" href="http://en.wikipedia.org/wiki/Trazadone">Trazadone</a> </li> <li><a title="Alcohol" href="http://en.wikipedia.org/wiki/Alcohol">Alcohol</a> </li>

<p>A <strong>miotic</strong> substance causes the constriction of the <a title="Pupil" href="http://en.wikipedia.org/wiki/Pupil">pupil</a> of the eye (or <strong class="selflink">miosis</strong>). It is the opposite of a <a title="Mydriatic" href="http://en.wikipedia.org/wiki/Mydriatic">Mydriatic</a> substance, which causes <a title="Dilation" href="http://en.wikipedia.org/wiki/Dilation">dilation</a> of the pupil.</p>