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Mydriasis is frequently induced by drugs for certain ophthalmic examinations and procedures, particularly those requiring visual access to the retina. Fixed, unilateral mydriasis could be a symptom of raised intracranial pressure. The opposite, constriction of the pupil, is referred to as miosis. Both mydriasis and miosis can be physiological.
Miosis caused by high doses of opiates. The person also shows ptosis of both eyelids and an inattentive look at the camera, a sign of altered level of consciousness caused by the sedative effect of the drug.
Lethality of cyclopentolate has been studied in rodents. The LD50 (the dose at which 50% of animals die from the drug) is approximately 4000 mg/kg in rats and 960 mg/kg in mice. Readily recognizable symptoms of overdose include tachycardia, dizziness, dry mouth, behavioral disturbances, uncoordination, and drowsiness.
A constriction response , [2] is the narrowing of the pupil, which may be caused by scleral buckles or drugs such as opiates/opioids or anti-hypertension medications. Constriction of the pupil occurs when the circular muscle , controlled by the parasympathetic nervous system (PSNS), contracts, and also to an extent when the radial muscle relaxes.
Topical atropine is used as a cycloplegic, to temporarily paralyze the accommodation reflex, and as a mydriatic, to dilate the pupils. [15] Atropine degrades slowly, typically wearing off in 7 to 14 days, so it is generally used as a therapeutic mydriatic, whereas tropicamide (a shorter-acting cholinergic antagonist) or phenylephrine (an α-adrenergic agonist) is preferred as an aid to ...
When cycloplegic drugs are used as a mydriatic to dilate the pupil, the pupil in the normal eye regains its function when the drugs are metabolized or carried away. Some cycloplegic drugs can cause dilation of the pupil for several days.
Anticholinergic drugs are used to treat a variety of conditions: Dizziness (including vertigo and motion sickness-related symptoms) Extrapyramidal symptoms, a potential side-effect of antipsychotic medications; Gastrointestinal disorders (e.g., peptic ulcers, diarrhea, pyloro spasm, diverticulitis, ulcerative colitis, nausea, and vomiting)
Tropicamide is an antimuscarinic drug that produces short acting mydriasis (dilation of the pupil) and cycloplegia [7] when applied as eye drops. It is used to allow better examination of the lens, vitreous humor, and retina.