[PO1] Pupil

Pupil assessment

holds paramount significance in clinical practice as a valuable window into the neurological and ophthalmic status of an individual.

pupillary pathway

neuroanatomical and physiological system responsible for regulating the size of the pupils in the eyes.

involves a complex interaction between the sympathetic and parasympathetic divisions of the autonomic nervous system, allowing for precise control of pupil diameter in response to changes in light intensity and other stimuli.

Retina

Pretectal Nucleus

Edinger Westphal Nucleus

Oculomotor Nerve

Ciliary Ganglion

Sphincter Pupillae

Contriction

Pupillary Light Reflex Pathway

1. Measurement of the Pupil Size

2. Measurement of Direct, consensual and near reflexes

3. Swinging flashlight test

TESTS OF PUPILLARY FUNCTION

Direct Reflex

the constriction of the pupil of the illuminated eye

Indirect Reflex

the constriction of the pupil of the unilluminated eye

Near Reflex

observing the constriction of the pupil as the patient change fixation from distance to near.

Swinging Flashlight Test

it is used to detect a relative afferent pupil defect (RAPD)

Pupil Size

the size of the pupil which is measured using a millimeter ruler

Pupil Equal Responding to Light and Accommodation

PERLA

Adie’s Tonic Pupil

unilaterally dilated pupil with little or no reaction to light but with sluggish reaction to near stimulation.

due to the lesion of ciliary ganglion and requires no treatment

slow redilation of the affected pupil

results from a disorder of the parasympathetic innervation of the constrictor pupillae muscle.

it can be tested by looking for its hypersensitivity to cholinergic agents, like using 2.5% methacholine or 0.1 % Pilocarpine (It should constrict)

methacholine

Pilocarpine

cholinergic agents (adie's tonic pupil)

Adie's tonic Pupil

Amaurotic Pupil

Marcus Gunn Pupil

Horner’s Syndrome

Argyll Robertson Pupil

Pupillary Anomalies

Amaurotic Pupil

an eye will have no direct pupillary reflex but will contract consensually when the normal eye is stimulated by light.

the near reflex is PRESENT on both

Blind eye = no reaction to its own light, but still reacts when the other eye sees light, and near works.

Marcus Gunn Pupil

also called afferent pupillary defect, detected by means of swinging flashlight test.

due to a conduction defect of the optic nerve, stimulation of the affected pupil

results in slightly less constriction of both pupils than that occurring when the normal pupil is stimulated.

among the causes are multiple Sclerosis which may be accompanied by optic neuritis or by retrobulbar neuritis

Sclerosis

optic neuritis

retrobulbar neuritis

Among the causes of Marcus Gunn Pupil

Horner’s Syndrome

consist of miosis, ptosis, apparent enophthalmos, vasodilation of skin arterioles and a possible decrease in facial sweating on the affected side.

caused by the paralysis of the ocular sympathetic fibers responsible for pupillary dilation.

the Lesion can be anywhere in the long, complicated sympathetic pathway (midbrain, pons, upper spinal cord, middle cranial fossa, and orbit)

Miosis

small pupil

Ptosis

droopy eyelid

Apparent enophthalmos

eye looks sunken

Vasodilation

skin looks a bit red/warm

first neuron defect (central HS)

contralateral hyperesthesia of the body and loss of sweating of the entire half of the body

opposite side of the body becomes abnormally sensitive to stimuli.

(BIG problem)

second neuron defect (preganglionic HS)

loss of sweating limited to face and neck, presence of flushing of the Face

(MEDIUM problem)

third neuron defect (postganglionic HS)

include facial pain or ear, nose or throat disease

Postganglionic (SMALL/local problem (eye and nearby area)

Argyll Robertson Pupil

characterized by a small pupil, which is of fixed size and does not react to light but contracts to accommodation.

usually found in cases of neurosyphilis (neurosyphilitic lesion interrupting fibers that run from pretectal nucleus to parasympathetic nuclei (Edinger Westphal nuclei) of the oculomotor nerve of both sides.

Pretectal Nucleus

middleman between the eye (retina) and the pupil control center (Edinger–Westphal nucleus).

Edinger–Westphal Nucleus

small group of nerve cells in the midbrain

controls the parasympathetic pathway to the eye.

sympathetic pathway

Responsible for dilation (mydriasis).

parasympathetic pathway

Responsible for constriction (miosis).

Hyperesthesia

means your skin or body feels extra sensitive.

increased sensitivity to touch, pain, or sensory stimuli.

Direct Reflex

Shine light in one eye → that same pupil shrinks.

Consensual Reflex

Shine light in one eye → the other pupil also shrinks.