That is, pupils will change their size in an effort to control how much light enters the eyes. The primary and most well-known factor is brightness. There are several factors that control pupil size. Although pupil size is only a modest sign, and may not be a reliable indicator in all cases, it is still known as one of the more visible effects caused by certain drugs. Learning the signs of drug use can be helpful for people concerned about a loved one struggling with substance abuse. In clinical terms, this is known as eye miosis, sometimes spelled myosis. This effect is often referred to as ‘pinpoint pupils’. On the opposite end, there are some drugs - most notably, narcotics - that can cause the pupils to constrict, or become smaller. Many drugs can also affect eye movement and sometimes eye color. Several drugs are known to cause dilation of the pupils, resulting in your pupils (black dots) to become larger than normal size. One of the more visible signs that can indicate the use of certain drugs is a change in pupil size. Some side effects can also be more visible than others. Some side effects may result in discomfort, while others may pose potential harm. Many illicit and prescription drugs have a long list of side effects on the brain and body. Does ObamaCare (Affordable Care Act) Cover Rehab?.Drug Abuse Hotlines – 100% Confidential – 24/7.Visceromotor nerve axons (which constitute a portion of cranial nerve III, along with the somatomotor portion derived from the Edinger-Westphal nucleus) synapse on ciliary ganglion neurons, whose parasympathetic axons innervate the iris sphincter muscle, producing miosis. From the pretectal nucleus neurons send axons to neurons of the Edinger-Westphal nucleus whose visceromotor axons run along both the left and right oculomotor nerves. Nerves involved in the resizing of the pupil connect to the pretectal nucleus of the high midbrain, bypassing the lateral geniculate nucleus and the primary visual cortex. The retinal photoceptors convert light stimuli into electric impulses. Signals from photosensitive ganglion cells have multiple functions including acute suppression of the hormone melatonin, entrainment of the body's circadian rhythms and regulation of the size of the pupil. The ganglion cells give information about ambient light levels, and react sluggishly compared to the rods and cones.
Light entering the eye strikes three different photoreceptors in the retina: the familiar rods and cones used in image forming and the more newly discovered photosensitive ganglion cells. In some rare cases, when exposed to mustard gas.
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