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Mydriasis is the dilation of the pupil, usually having a non-physiological cause, [3] or sometimes a physiological pupillary response. [4] Non-physiological causes of mydriasis include disease , trauma , or the use of certain types of drug .
Dilation and constriction of the pupil Pupillary response is a physiological response that varies the size of the pupil , via the optic and oculomotor cranial nerve. A constriction response ( miosis ), [ 1 ] is the narrowing of the pupil, which may be caused by scleral buckles or drugs such as opiates / opioids or anti-hypertension medications.
Segments 3, 4, 5, and 6 are all located within a compact region within the midbrain. Segments 7 and 8 each contains parasympathetic fibers that courses from the Edinger-Westphal nucleus, through the ciliary ganglion, along the oculomotor nerve (cranial nerve #3), to the ciliary sphincter, the muscular structure within the iris.
Adie's pupil is supersensitive to ACh so a muscarinic agonist (e.g. pilocarpine) whose dose would not be able to cause pupillary constriction in a normal patient, would cause it in a patient with Adie's Syndrome. The circuitry for the pupillary constriction does not descend below the upper midbrain, henceforth impaired pupillary constriction is ...
Toggle Causes subsection. 1.1 Age. 1.2 Diseases. 1.3 Drugs. 2 Physiology of the photomotor reflex. ... The opposite condition, mydriasis, is the dilation of the pupil.
Oculomotor nerve palsy or oculomotor neuropathy [1] is an eye condition resulting from damage to the third cranial nerve or a branch thereof. As the name suggests, the oculomotor nerve supplies the majority of the muscles controlling eye movements (four of the six extraocular muscles, excluding only the lateral rectus and superior oblique).
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.
When the test is performed in an eye with an afferent pupillary defect, light directed in the affected eye will cause only mild constriction of both pupils (due to decreased response to light from the afferent defect), while light in the unaffected eye will cause a normal constriction of both pupils (due to an intact efferent path, and an ...