Illegal drugs such as heroin are also opioids. Such is the case for hydrocodone, oxycodone, codeine and morphine.ĭespite these drugs being legal if obtained by the regular protocol involving a physician and a pharmaceutical distributor, there has been reported misuse of these legal drugs due to its dependence-inducing effects. Some opioid derivate drugs are used among clinicians to treat different diseases such as chronic pain or palliative treatment of pain for cancer patients. Opioids are substances that act like opioid receptors in order to induce morphine-like effects both in the spinal cord and the central nervous system in order to reduce the intensity of pain-signal perception (). However, bilateral pinpoint pupils are the most frequent form presentations, and this might be attributed to many causes, such as: Furthermore, strictly unilateral miosis might respond to malignant and serious causes such as tumors or acute ophthalmic nerve compression by some extrinsic cause. First, if the miotic or pinpoint pupil is non-reactive, minimally reactive or normally reactive. The assessment of probable causes of miotic pupils depends on a variety of criteria. If a person’s pupils do not change sizes after an alteration of environmental lighting, it means that the regulatory iris mechanism for pupil diameter control is altered in one way or another, mainly because of central nervous system alterations.Ĭonstant miosis is not normal and it is a sign of neurological abnormalities. However, pupils should go back to its normal or usual diameter after the direct source of light is removed or once the person enters a dim room. It is also frequent to find newborns and the elder have smaller pupils than usual, with a slowest PLR time.
Like it was stated in the previous point, it is completely normal to have small pupils while out on the daylight or while being exposed to a direct source of light. Pinpoint pupils with no PLR are usually a translation of a neurological abnormality. Pinpoint pupils are pupils with a fixed diameter smaller than 2mm that do not respond accordingly to changes in lighting. These fluctuations in pupil diameter when exposed to different lighting is normal and called Photopupillary Reflex or Pupilary Light Reflex (PLR). That is why pupils get wider during the night or while the person is in a dark room with dim lights, and they get small when exposed to a direct source of light like the one on the environment during daytime, or the one coming from the doctor’s flashlight. According to the intensity and quality of the light that is passing through the eye, the muscle fibers of the iris will either relax or contract in order to keep the posterior chamber, and particularly the retina, safe from photogenic harm. Whenever a ray of light hits the eye, it passes through the cornea all the way into the anterior chamber. This structure is made of small smooth muscle fibers and these fibers are responsible for the size of the pupil. What is popularly known as “eye color” is actually called iris. The pupil is located at the exact center of the eye and it is perceived as a black circle. When a patient’s pupil holds a diameter smaller than 2mm, clinicians might diagnose that patient with miosis or pinpoint pupils. The regular diameter of pupils ranges from 2mm to 4mm. Intoxication by organophosphates and other chemicals.
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