Abnormal Vision, Pupils, and Eye Movements
Ashley Norse
CLINICAL CHALLENGE
Eye complaints can be a sign of minor irritation or significant neurologic or systemic diseases such as stroke, multiple sclerosis, or myasthenia gravis. Eye complaints can be the presenting symptom of disease from multiple organ systems ranging from the sequela of uncontrolled hypertension and diabetes to infectious disease and food borne pathogens. Approximately 2% of all emergency department (ED) visits each year are for eye-related complaints, and although life-threatening diagnoses are rare, a disproportionate percentage of serious neurologic diagnoses are made in patients who present to the ED compared to ambulatory clinics.1,2
ANATOMY AND PATHOPHYSIOLOGY
To understand the pathology that can affect the eye, it helps to understand eye anatomy and the visual pathway. Light enters the eye through the dome-shaped cornea and traverses the aqueous humor in the anterior chamber. To maintain a constant eye pressure, the eye is continuously producing and draining aqueous humor. Muscles in the iris (the colored part of the eye) dilate or constrict the pupil to control the amount of light entering the posterior chamber of the eye. The lens sits behind the pupil and changes shape to allow the eye to focus on objects that are up close or far away.
The light then enters the posterior chamber and traverses the vitreous, hitting the retina. Photoreceptors in the retina generate signals, rods for dim light (black and white) vision and cones for color and bright light vision. The macula, in the center of the retina, contains the fovea, with the highest concentration of cones, and thus is responsible for our detailed, central vision. The remainder of the retina provides peripheral vision.
The retina sends electrical impulses through the optic nerve to the brain. The visual signals exit via the optic nerve and travel to the optic chiasm where the impulses decussate. Information from the nasal portion of each retina decussate and are interpreted by the opposite side of the brain. The signals continue from the optic chiasm to the lateral geniculate bodies, and on to the occipital lobe via the optic radiations. The Edinger-Westphal nuclei, or oculomotor complexes, are parasympathetic fibers located in the midbrain and responsible for extraocular movements of the eye, accommodation, pupillary constriction, and convergence.
APPROACH
History
The emergency clinician must use key findings in the history to help localize the pathology and direct the physical examination and workup of the patient. Critical components of the history include onset of symptoms, history of trauma, progression of the symptoms, relieving of exacerbating symptoms, whether the symptoms are unilateral or bilateral, and the presence or absence of other neurologic symptoms. Other important associated symptoms include eye redness, photophobia, floaters, sensation of flashes of light (photopsias), and the presence of pain at rest or with eye movement. In the absence of trauma, the presence of pain suggests an inflammatory or infectious process and narrows the differential diagnosis. A history of progressive symptoms raises concern for a compressive lesion, whereas intermittent symptoms, especially if associated with diplopia and ptosis, is concerning for a neuromuscular junction disorder such as myasthenia gravis. Systemic symptoms such as generalized weakness and neurologic symptoms, such as vertigo, dizziness, ataxia, or aphasia, are red flags for critical conditions, for example, stroke, bleed, or other brainstem lesions.
Past medical history should focus on diseases known to cause eye pathology including hypertension and diabetes, and conditions associated with immunocompromise including human immunodeficiency virus (HIV). Hematologic disorders such as sickle cell anemia or multiple myeloma can cause a hyperviscosity syndrome and eye complaints. Family history should include questions about migraine headaches, multiple sclerosis, lupus, and vascular disease.
Abnormal Vision
Abnormal vision complaints will commonly be blurry vision, in actuality, which may result from a simple refractory issue, but can also be due to a corneal abrasion, hyphema, iritis, uveitis, glaucoma, lens dislocation, or stroke. Blurry vision must also be differentiated from floaters that are often due to posterior chamber pathology such as retinal detachment or retinal hemorrhage. Retinal detachment can also present with the complaint of the sensation of a curtain falling over the eye, which results from the retinal pulling away from the choroid and sclera.
Central retinal artery occlusion (CRAO) or central retinal venous occlusion (CRVO) can present with sudden complete unilateral vision loss. In sudden vision loss, it must be determined whether the vision loss is monocular or binocular, and whether it involves the entire visual field or an isolated visual field cut. Important associated visual symptoms include floaters, flashing lights, halos, and distorted color vision. A review of systems should seek extraocular symptoms including jaw or tongue claudication, temporal headache, proximal muscle pain or stiffness (giant cell arteritis), and headaches (ocular migraine).
Diplopia
The differential for diplopia is extensive, and key features of the history are critical to determining the cause (see Table 3.7 later in this chapter). It must be determined whether the diplopia is monocular or binocular. Monocular diplopia is defined as double vision that does not correct when one eye is closed or occluded. Monocular diplopia is usually caused by intraocular pathology, with the most common cause being a refractive error. Lens dislocations (spontaneous or traumatic) can also be a cause of monocular diplopia. Binocular diplopia is double vision that resolves when one eye is closed and is caused by misalignment of the visual axes.
In addition to onset of the diplopia (sudden versus gradual), and the presence or absence of pain, another important question in a patient with diplopia is the directionality of the diplopia. Diplopia can be horizontal with side-by-side images, vertical with the images above and below each other, or torsional. The directionality of the diplopia is equally important as the type of diplopia. Horizontal diplopia, without vertical separation, is often indicative of medial or lateral rectus muscle pathology, whereas torsional or oblique diplopia is more commonly caused by superior or inferior oblique muscle dysfunction or lateral medullary syndrome. Vertical diplopia is often a sign of brainstem pathology; it is also seen in isolated cranial nerve (CN) IV pathology.
The most common cause of diplopia is an isolated CN VI palsy, often from trauma or compression. A sudden onset of binocular diplopia suggests ischemia, whereas a gradual onset suggests a compressive lesion or systemic disease. A fluctuation in symptoms may suggest transient ischemic attacks (TIAs), but neuromuscular disease must be ruled out as well.
Physical Examination
The physical examination should include a complete neurologic examination in addition to the eye examination. The provider should focus on any subtle findings including head positioning, facial asymmetry, CN abnormalities, extremity weakness, and sensory deficits. In patients with complaints of headache and vision changes, the physical examination should also include palpation of the temples for tenderness or nodularity over the course of the temporal artery.
The eye examination typically has nine components (Table 3.1): the external eye examination, a visual acuity and visual field examination, a pupil examination, the extraocular muscle examination, a funduscopic examination to view the posterior chamber, a slit lamp examination to look at the anterior chamber, a fluorescein examination, as well as intraocular pressure (IOP) measurements. In addition to these eight components, bedside ultrasound (US) is a valued adjunct that can diagnose papilledema/increased IOP, vitreous hemorrhage, and retinal detachment.
The External Eye Examination
The external eye examination includes an examination of the orbital and periorbital structures, the lids and lashes, as well as the ductal and lacrimal systems. By just looking at the patient, critical physical examination findings such as proptosis, ptosis, lid lag, anisocoria, and head position can be identified.
If there is a history of trauma, inspection for periorbital edema or ecchymosis is important. Subtle finding of proptosis or a sunken orbit may be missed if the provider does not have a high index of suspicion. Shining a light in the unaffected eye can cause pain in the traumatized eye by stimulating a consensual response, indicating traumatic iritis. A patient presenting after trauma to the eye can also have orbital fractures with extraocular muscle entrapment causing diplopia. Trauma patients may also present with a sunken eye due to a complete blowout fracture of the orbit or with a proptotic eye secondary to a retrobulbar hematoma. Patients with retrobulbar hematoma may also have vision loss, a dilated and nonreactive pupil, and elevated ocular pressure. In the absence of trauma, proptosis can be a sign of space-occupying lesions of the orbit or systemic disease, such as thyroid disease.
Erythema and edema of the orbital and periorbital structures are a sign of infection. The conjunctiva should be examined for any signs of infection, inflammation, chemosis, or hemorrhage. A red eye can be a sign of acute iritis, glaucoma, infection, or trauma (Table 3.3). Patients with iritis and acute glaucoma will usually have findings of decreased visual acuity and may have abnormal pupillary examinations in addition to a red eye. A hyphema, which is blood in the anterior chamber of the eye (Figure 3.1), or a hypopyon, which is pus in the anterior chamber resulting from infection or corneal ulceration (Figure 3.2), can often be seen on an external eye examination as well.
TABLE 3.1 Nine Components of the Eye Examination | ||||||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| ||||||||||||||||||||||
 Figure 3.1: Hyphema. |
 Figure 3.2: Hypopyon. |
Visual Acuity and Visual Field Examinations
Testing for visual acuity and visual field deficits are key components of the eye examination. Visual acuity is ideally measured using a Snellen chart at 20 ft; a handheld chart is an alternative. Each eye is measured separately with and without the patient’s glasses. If the patient does not have their glasses, a pinhole refractor can be used. If visual acuity corrects with glasses or a pinhole refractor, the problem is a refractory error. If the patient cannot read the eye chart at all, perception of hand motion and light should be assessed.
A test for red desaturation is helpful to assess optic nerve function: If color plates are not available, a quick assessment can be performed by asking the patient to cover each eye alternately while looking at a red object and report any relative dullness of the color in one eye. Many patients with optic neuritis will lose some of their color vision in the affected eye, especially red, and are not aware of the loss until tested.
Peripheral visual fields are assessed by confrontation, and central visual fields (eg, in suspected macular degeneration) are assessed using an Amsler grid. Bilateral field cuts localize pathology posterior to the retina and should always be investigated with either computed tomography (CT) or magnetic resonance imaging (MRI). Causes of bilateral field cuts include space-occupying lesions, stroke, bleeds, abscess, encephalitis, migraine, and arteriovenous malformations (Figure 3.3).
Pupil Examination
The pupillary examination includes looking for signs of asymmetry or irregularity. Direct and consensual pupillary light responses are examined (Figure 3.4) by shining a light in the first eye, which should cause both pupils to constrict equally. The pupillary reaction in the illuminated eye is called the direct response, and the reaction in the other eye is the consensual response. The afferent pupillomotor fibers from the optic nerve undergo hemidecussation in the chiasm, with a second hemidecussation of the pupillomotor fibers in the brainstem, so direct and consensual responses of
the eyes should be equal. The test should be repeated on the opposite eye. To test for an afferent pupillary defect, the light is again shone in the first eye and then swung to the other eye (swinging flashlight test). If the pupils respond differently to the light stimuli, a retinal or optic nerve disease process is suspected.
the eyes should be equal. The test should be repeated on the opposite eye. To test for an afferent pupillary defect, the light is again shone in the first eye and then swung to the other eye (swinging flashlight test). If the pupils respond differently to the light stimuli, a retinal or optic nerve disease process is suspected.
 Figure 3.3: The visual pathway from the retina to the visual cortex showing visual field defects. (1) Ipsilateral blindness. (2) Binasal hemianopia. (3) Bitemporal hemianopia. (4) Right hemianopia. (5) Right upper quadrantanopia. (6) Right lower quadrantanopia. (7) Right hemianopia with macular sparing. From Gould DJ, Brueckner-Collins JK, Fix JD, eds. In: Visual system. High-YieldTM: Neuroanatomy (Figure 14.1). 5th ed. Wolters Kluwer; 2016:108-115. |
 Figure 3.4: Abnormal and normal eye positions in cranial nerve (CN) palsies. |
A tonic pupil (Adie pupil) has parasympathetic denervation and will not constrict well to light, but typically reacts better to accommodation. It is a common, benign cause of anisocoria, seen more often in females (70% of cases). About 20% of the population has pupil asymmetry of up to 1 mm; however, anisocoria can also be a sign of pathology. Patients who present with a dilated pupil along with a CN III palsy may have an aneurysm at the junction of the posterior communicating artery and the middle cerebral artery. Horner syndrome presents with a constellation of symptoms including a dilated pupil, ptosis, oculosympathetic paralysis, and ipsilateral anhydrosis.
Extraocular Muscle Examination
There are six extraocular muscles of the eye that attach to the sclera. The lateral rectus is innervated by the abducens nerve (CN VI) and is responsible for outward gaze. The superior oblique is innervated by the trochlear nerve (CN IV) and moves the eyes up and outward. The inferior, superior, and medial rectus muscles are all innervated by the oculomotor nerve (CN III) and move the eye in and up. Examination of the extraocular muscles should be performed in the H pattern while holding the head steady, with close observation of both eyes through the full range of motion.
Injury to the lateral rectus muscle or a palsy of CN VI will cause the affected eye to turn inward, and patients will have limited abduction of the affected eye with horizontal diplopia that is worse when looking toward the affected side. Injury to the superior oblique or palsy of CN IV will cause the affected eye to be displaced slightly upward and have vertical or oblique/torsional diplopia. Patients may compensate with a head tilt to the side of the palsy, making an isolated CN IV palsy difficult to diagnosis. Palsy of CN III results in the affected eye turning down and outward. Patients are unable to supraduct, infraduct, or adduct the affected eye. Patients with a complete CN III palsy will also have ptosis and may have a dilated pupil (Figure 3.5).
The diplopia that results during range of motion in patients with an ocular myositis or trauma is different from the diplopia seen with a CN palsy. Ocular myositis can be distinguished from CN pathology in that it abruptly restricts eye movement away from the muscle, whereas a CN palsy smoothly and progressively impairs movement toward the weakened muscle. Entrapment of the inferior rectus muscle after trauma to the eye or face prevents the affected eye from tracking with the nonaffected eye, especially on upward gaze.
Funduscopic Examination (Posterior Chamber Examination)
Funduscopy is performed to look for signs of retinal pathology and papilledema (Figure 3.6). More details, for example, hemorrhage, exudate, and abnormalities of the optic disc, are visible if the eyes are dilated. Structures of the posterior chamber include the retina, macula, fovea, optic nerve, optic disk, the central retinal artery, the retinal veins, and the vitreous.
 Figure 3.5: Abnormal and normal cranial nerve (CN) palsies. |
 Figure 3.6: Papilledema—note the obscured optic disk margins and hyperemia due to dilated capillaries. |
Patients presenting with acute sudden vision loss most often have pathology in the posterior chamber: CRAO, CRVO, retinal detachment, or vitreous hemorrhage. Patients with a CRAO may also have a relative afferent pupillary defect regardless of their visual acuity. Classic ophthalmoscopy signs include retinal edema (ischemic retinal whitening) and a cherry red spot due to underlying normal choroidal circulation (Figure 3.7). In the acute phase, segmentation of blood in retinal arterioles, known as box-cars may also be seen. A retinal embolus may be visible in up to 40% of patients.
Patients with a CRVO will have findings of a blurred optic disk margin and areas of ischemia and hemorrhage in the retina (Figure 3.8). Patients with a retinal detachment and hemorrhage may present with complaints of floaters or vision loss. A retinal detachment will appear as marked elevation or separation from the surrounding retinal (retinal fold or flap) (Figure 3.9). The detachment may appear gray, with dark blood vessels in the folds. The vitreous should also be examined for signs of pigment that looks like dust the color of tobacco (Shafer sign), which is suggestive of a retinal detachment. In retinal hemorrhage that is dispersed, red blood cells can be seen posterior to the lens in the vitreous. In localized retinal hemorrhages, the bleeding will be seen within the area of the retinal involved.
Bedside point-of-care ultrasonography of the eye has become a valuable adjunct in the physical examination of patients with eye complaints, especially in cases of posterior chamber pathology. Retinal detachments and retinal hemorrhage can be rapidly and accurately visualized on ultrasonography of the eye (see “Ocular Ultrasound” section).
Findings in optic nerve pathology will vary on direct ophthalmoscopy. Patients with glaucoma will present with a large optic cup. Patients with optic neuritis frequently will have a normal examination, although the optic nerve may be swollen in some patients (more extensive optic neuritis).
Bilateral optic disc swelling is seen in intracranial hypertension, from idiopathic intracranial hypertension (see Figure 3.6), cerebral venous sinus thrombosis, or intracranial hemorrhage. Unilateral papilledema is extremely rare and suggests a disease in the eye itself such as a mass/tumor.
Bilateral optic disc swelling is seen in intracranial hypertension, from idiopathic intracranial hypertension (see Figure 3.6), cerebral venous sinus thrombosis, or intracranial hemorrhage. Unilateral papilledema is extremely rare and suggests a disease in the eye itself such as a mass/tumor.
 Figure 3.7: Central retinal artery occlusion—retinal edema (ischemic retinal whitening) and a cherry red spot due to underlying normal choroidal circulation. |
 Figure 3.8: Central retinal venous occlusion—note the blurred optic disk margin as well as areas of ischemia and hemorrhage in the retina. |
Slit Lamp Examination (Anterior Chamber Examination)
The slit lamp examination allows for visualization of the structures of the anterior chamber of the eye including the sclera, conjunctiva, cornea, iris, pupil, lens, and the aqueous humor. Signs of inflammation or infection in the structures of the anterior chamber, known as cell and flares, are a critical physical examination finding of iritis (traumatic or infectious) or uveitis. The cornea should be examined for injection, chemosis, opacification, discharge, and foreign bodies. The lens should be examined for opacification (cataract) and for positional changes. Subluxation of the lens can occur spontaneously or after trauma, causing vision loss or monocular diplopia. The abnormal lens is apparent on direct visualization or ultrasonography. If a foreign body is suspected, the eyelids should be everted to rule out a retained foreign body under the eyelid. A small hyphema or hypopyon, not seen on external examination, should be visualized on slit lamp.
Patients presenting with painful vision loss, whether sudden or gradual, should have a thorough anterior chamber examination to look for signs of acute narrow-angle glaucoma, iritis, temporal arteritis, optic neuritis, and lens dislocation or subluxation. Patients with acute narrow-angle glaucoma will present with varying complaints ranging from a sudden-onset headache and vomiting to eye pain and sudden painful vision loss. Physical examination usually reveals a red eye with
perilimbal injection, conjunctival edema, and increased IOP (>50 mm Hg). Patients may also have a dilated, poorly reactive pupil (Table 3.2). Experienced providers may be able to see a shallow anterior chamber depth on slit lamp examination or ocular US.
perilimbal injection, conjunctival edema, and increased IOP (>50 mm Hg). Patients may also have a dilated, poorly reactive pupil (Table 3.2). Experienced providers may be able to see a shallow anterior chamber depth on slit lamp examination or ocular US.
 Figure 3.9: Retinal detachment that appears as marked elevation or separation from the surrounding retinal (retinal fold or flap in top right quarter of the retina). |
TABLE 3.2 Treatment of Acute Angle-Closure Glaucoma/Increased Intraocular Pressure | ||||||
|---|---|---|---|---|---|---|
| ||||||
Iritis (anterior uveitis) may be infectious, traumatic, or the result of a systemic disease or an autoimmune process. It classically presents with eye pain, blurry or decreased vision, and photophobia. Patients may also have a small, constricted pupil on the affected side. Physical examination classically reveals perilimbal redness (“ciliary flush”) and cells and flares on slit lamp examination (Table 3.3).
Fluorescein Examination
The fluorescein examination involves staining the eye with fluorescein and examining the eye under a cobalt-blue light to look for abnormalities in the cornea, including corneal abrasions, ulcerations, and foreign bodies. The pattern of fluorescence uptake can also diagnose retained foreign bodies and inflammatory and infectious processes such as ultraviolet (UV) keratitis and herpes zoster. A retained foreign body under the upper eyelid may present with the “ice-rink sign” (multiple linear, superficial abrasions with the appearance of skate marks on ice). In cases of a retained foreign body, the slit lamp can also be used to provide magnified visualization and aid in removal. Herpes zoster is diagnosed by the presence of a dendritic lesion on fluorescein examination. UV keratitis, classically seen in welders or in UV exposures, is the most common cause of radiation injury to the eye, and fluorescein staining will show superficial punctate epithelial surface irregularities covering the entire surface of the cornea. Seidel sign, streaming of the aqueous humor through the fluorescein stain, is indicative of a ruptured or perforated globe.
Related posts:
Stay updated, free articles. Join our Telegram channel
Full access? Get Clinical Tree
