Hippus is the normal rhythmic pupillary oscillation commonly seen when light stimulates either eye. This balance is in constant flux, so that pupil sizes change symmetrically from moment to moment. The size of the pupils at any one moment is determined by the balance of the parasympathetic tone of the iris sphincter and the sympathetic tone of the iris dilator. Light directed into either eye normally produces bilateral pupillary constriction.Įach pupil receives both sympathetic (dilator muscle: active dilation) and parasympathetic (sphincter muscle: active constriction) innervation. The pupillary response in the eye that is not being illuminated is called the consensual response.ġ2.2 Clinical Anatomy and Physiology of the Pupils The pupillary response in the illuminated eye is called the direct response. Shining a light in one eye of a normal subject causes both pupils to constrict equally. When pupillary reactions are abnormal, slit lamp examination of the anterior segment and the iris may demonstrate abnormalities that may affect pupillary size and shape, such as synechiae, uveitis, iris tear, segmental contraction of the iris, iris tumor, and lens subluxation (▶Fig. Presence of a relative afferent pupillary defect (RAPD).Response to light (direct and consensual response).When examining the pupils, you should record the following: Pupils should be tested in the dark with a bright light and with the patient fixating at distance. Pupils are usually symmetrical in size, although physiologic anisocoria (the difference in size between the two pupils) of 0.4mm or greater is seen in about 20% of individuals. The normal pupil varies in size, depending on the ambient illumination. If not, do they react to a near target?.Do the pupils react to a light stimulus?.Are the pupils round or irregularly shaped?.The mnemonic PERRLA (pupils equal, round, reactive to light, and accommodation)reminds us of the four questions we should ask in evaluating the pupils: Pupillary function is an important objective clinical sign in patients with visual loss and neurologic disease. The information below is from Neuro-ophthalmology Illustrated-2nd Edition. Pharmacological testing in Horner’s syndrome – a new paradigm. Because the afferent pathways serving the light reflex and the near reflex are anatomically distinct, patients with severe optic neuropathies will still have intact, brisk pupillary responses to near stimuli, while their pupils will not, or will only poorly, react to light. If a patient with a suspected optic neuropathy has no relative afferent pupillary defect, either the patient does not have an optic neuropathy or the optic neuropathy is bilateral. A relative afferent pupillary defect does not cause anisocoria. Presence of a relative afferent pupillary defect (RAPD) Response to light (direct and consensual response) If a patient has severe bilateral optic neuropathy will the pupils respond to near stimuli? If there is no relative afferent pupillary defect in a patient is suspected of having optic neuropathy (regardless of the cause) does that rule-out this diagnosis?Ĥ.

Does a relative afferent pupillary defect cause anisocoria?ģ. When examining the pupils, what 6 items should be recorded?Ģ.

Hippus pupil