Question

Describe tests used in assessing the pupillary reflex and cite the possible causes of abnormal pupillary reflexes.

Answer 1

A patient's pupillary reflex are assessed to have a check on the patiet's brain stem function. These assesments usually take lesser time, are noninvasive and are important for the health of our eye and nervous system. Our pupil is responsible for regulating the amount of light coming inside the eyes, prevents the irregular refraction and allows the passage of aqueous humor.

Generally there are three type of tests used in assessing the pupillary reflex which are as follows -

Light-reflex test

This test is for checking the integrity of the pupillary light reflex pathway. During the test, the doctor dims the surrounding light of the patient and ask them to fix their vison onto a distant object. Then the doctor will shine light on both the side of patient's eye to check if the pupils constrict in response to the light and note down the size and shape of the pupil.

Near-reflex test

This test is for checking pupil's response to a near target. During the test, the doctor dims the surrounding light of the patient and ask them to fix their vison onto a distant object. Then the doctor will bring an object near the eyes of the patient and assess pupillary reflex while the patient fixation changes from far to near.

Swinging flashlight test

This test is for checking afferent papillary defect or Marcus Gunn pupil. During the test, the doctor dims the surrounding light of the patient and ask them to fix their vison onto a distant object. Then the doctor will swing the light alternatively from one eye to the another, and check on the response of each pupil during the swing.

The possible causes of abnormal pupillary reflexes are orbital tumours, dysthyroid eye disease, oculomotor nerve damage, brain stem death, brain stem lesion, ischaemic optic neuropathy, optic nerve injury, optic neuritis, asymmetric glaucoma, trauma or depressant drug.