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Pathologic Pupillary EyeSigns and Significance

When assessing the pupil, we frequently look atsize, shape, and reaction to light. All too often theassessment stops there. If one has an adequateknowledge base, the eye can give much insightinto the patient’s pathologic process. Some typicalabnormalities seen include nystagmus, deviationsin conjugate eye movement, and pupillary abnor-malities.

Nystagmus is a repetitive, involuntary oscillationof one or both eyes. Not all nystagmus is patholog-ic. There are three planes of movement: horizontal,vertical, and rotary (Figure 1). Horizontal nystag-mus may be normal with extreme lateral gaze andoften is associated with fatigue. It is also seenwith certain drugs, such as phenytoin, alcohol, bar-biturates, and residual effects of anesthesia. It canalso be associated with cerebellar pathology(Figure 2).

Vertical nystagmus, however, is never normal! Italways has some disorder associated with it.Usually, it is associated with problems in the pos-terior fossa or upper cervical spine. Examplesinclude Arnold-Chiari malformation andsyringomyelia. Wernicke encephalopathy or drugintoxication should also be considered. Magneticresonance imaging (MRI) is usually needed as partof this patient’s work-up (Figure 3).

Rotary nystagmus, when the eyes characteristi-cally move in a circular motion, is associated withlesions in the posterior fossa. Commonly, it isseen with multiple sclerosis (Figure 4).

Conjugate movements of the eye are integratedat several different areas of the brain. There is thefrontal gaze center (Brodmann area 8), occipital gazecenter (Brodmann areas 18 and 19), and medial lon-gitudinal fasciculus (MLF) located in the midbrainand pons. Thus, eye movement abnormalities canresult from injuries in many different parts of thebrain. Ophthalmoplegia and strabismus are probablythe more common problems seen in practice.Ophthalmoplegia is a dysconjugate eye movement

caused by a paralysis of one or more eye muscles.Examples of this are internuclear ophthalmoplegia(INO) and Parinaud syndrome.

INO is due to an injury of the MLF. Commoncauses include vascular occlusive disease or multi-ple sclerosis. INO is the inability of the eye tocross midline with lateral gaze. Convergence isusually retained.

Parinaud syndrome is a dysfunction of verticalgaze. There is paralysis of upward gaze and loss ofpupillary constriction. It is most commonly associ-ated with pineal tumors.

Another type of dysconjugate gaze is strabismus,defined as deviation of eyes from their normallyconjugate position; dysconjugate eye movementresults from weakness of the extraocular eye mus-cle. The patient will complain of diplopia becauseimages fall on two different spots on the retina.

Pupillary abnormalities occur in shape, size, andreactivity. Sometimes these variables are com-bined. Irregularly shaped pupils can include key-hole, ovoid, and irregular shape. Keyhole shapecan be caused by an iridectomy. Ovoid shape maybe seen in early herniation syndrome. Irregularlyshaped pupils are often associated with Argyll-Robinson pupils or traumatic orbital injuries.

Anisocoria is a condition in which the pupils areunequal in size. This is nonpathologic in 17% ofthe population. Both eyes will react to light andaccommodation. Anisocoria that is pathologicmay be associated with early herniation syn-drome as a result from head trauma or brainlesion, Horner’s syndrome, Adie’s pupil, or oculo-motor nerve paralysis.

DIAGNOSTIC TIPS

Barbara Bishop

JNP

May 2006340 The Journal for Nurse Practitioners - JNP

The Argyll-Robertson pupil is a condition ofbilaterally small (miotic) irregularly shapedpupils. It will accommodate but not react. It isassociated with neurosyphillis, diabetes, andpineal tumor.

Horner’s syndrome is due to an ipsilateral sym-pathetic dysfunction. It presents with a triad ofptosis, miosis, and anhydrosis. The pupil reacts todirect and consensual light and to accommoda-tion. Clinically, it may be associated with aPancoast tumor, brainstem lesion, spinal cordlesion, or trauma that interrupts the sympatheticnerve supply (Figure 5).

Adie’s pupil is also referred to as tonic pupil.This is due to an ipsilateral parasympathetic dys-function. It presents with a unilateral, large, regu-lar-shaped pupil. There are no other cranial nerveIII findings (as opposed to Horner’s syndrome).The pupil reacts poorly or has an absent responseto light and accommodation. The problem may becongenital or related to viral infection (Figure 6).

The miotic pupil is a constricted pupil, often pin-point to 2 mm. Parasympathetic innervation resultsin pupillary constriction. Pontine lesions result inpinpoint lesions. Pontine lesions destroy sympa-

Figure 1. Nystagmus Movements

Figure 2. Horizontal Nystagmus

Characteristically, the eye moves slowly to one side and thenquickly returns to a position of rest. Horizontal nystagmus isnormally seen on extreme lateral gaze frequently associatedwith fatigue. It can be associated with certain drugs(anticonvulsants, barbiturates, alcohol, residual anesthesia)and with cerebellar dysfunction.

Figure 4. Rotary Nystagmus

Characteristically, the eyes move in a circular motion. It isoften seen with multiple sclerosis, lesions of the posteriorfossa, or cerebellar tumor.

What are the usual movements Associated with Nystagmus?

There are three planes of movement:

rotary

horizontal

vertical

Horner syndrome is defined as ipsilateral sympatheticdysfunction. It results in the following triad: (a) ptosis, (b)miosis, and (c) anhydrosis. The pupil reacts to direct andconsensual light and accommodation. Clinical significance isthat it is usually a result of a brainstem lesion, spinal cordlesion (syringomyelia, tumor), or trauma that interrupts thesympathetic nerve supply; hypothalamic damage.

Figure 5. Horner’s Syndrome

Adie pupil is defined as ipsilateral parasympatheticdysfunction. It results in unilateral, large, regular-shapedpupil; it is unaccompanied by other cranial nerve III findings(as opposed to Horner syndrome). The pupil reacts poorly orhas absent response to light and accommodation. Clinicalsignificance is that it can be congenital or related to viralinfection.

Figure 6. Adie’s PupilFigure 3. Vertical Nystagmus

Characteristically, the eye is classified as upbeat ordownward. Upbeat nystagmus is associated with drugintoxication, disease of the posterior fossa, Wernickeencephalopathy, and cerebellar or medullary disease.Downward nystagmus is associated with Arnold-Chiarimalformation, syringomyelia, and arachnoiditis. It is alwayspathologic.

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thetic pathways. Other causes to consider includeArgyll-Robertson pupil, ophthalmic miotic drug(such as acetylcholine and pilocarpine), opiates(such as heroin and morphine), and metabolicencephalopathies.

The mydriatic pupil is the opposite of the mioticpupil. It is a dilatation of the pupil, often greaterthan 6 mm. Sympathetic innervation results in dila-tion of the pupil. Ipsilateral mydriasis that is notresponsive to light is often associated with cranialnerve III compression. It can be seen in rapidlyincreasing intracranial pressure.

Bilateral mydriasis that is unresponsive to lightcan be seen with high doses of dopamine (30mcg/kg per minute) in the absence of cerebraldamage and in the presence of shock. It can beseen with midbrain compression, causing bilateral-ly unresponsive and dilated pupils in the midposi-tion. Drugs such as amphetamines, cocaine,atropine, and scopolamine can cause bilateralmydriasis. Severe anoxia is also associated withthis finding.

Hippus is a state of physiologic unrest. Thepupil constricts to direct light stimulus but cannotmaintain constriction and dilates. Each eye hasdual innervation of both sympathetic andparasympathetic systems. The normal restingpupil size is not constant. Slight fluctuation maybe seen bilaterally. Nonpathologic hippus maydiminish in the dark and is more prevalent in the

younger population. Course fluctuation in one orboth eyes is pathologic.

Pathologic hippus, if unilateral, may be signifi-cant for compression of cranial nerve III that isoften seen in herniation syndrome. If bilateral,consider meningitis, seizures, or hysteria as pos-sible causes.

Afferent pupillary defect, also known as MarcusGunn syndrome, results in an absent directresponse but a normal consensual response. Thisis often associated with an optic nerve lesion(Figure 7).

Although certainly not complete, these aresome of the more common pupillary abnormali-ties that are encountered in the primary care andtriage situations. This overview may give a betteridea into a differential diagnosis just by evaluat-ing the eyes.

Portions of this article were initially published by thisauthor in Critical Care Nurse. 1991;11:6-8.

1555-4155/06/$ see front matter© 2006 Elsevier Inc. All rights reserved.doi:10.1016/j.nurpra.2006.03.008

Barbara Bishop, MS, ANP-C, CNRN, MSCN, works atVirginia Beach Neurology in Virginia Beach, VA. She canbe reached at bsb@vbn-vb.com.

Marcus Gunn syndrome is defined as afferent pupillarydefect. It results in an absent direct response but a normalconsensual response. If a direct light stimulus is applied tothe affected eye immediately after a consensual stimulus hascaused constriction, the affected eye will appear to dilatebecause it has no direct response.

Figure 7. Marcus Gunn Syndrome.