Direct and Consensual Pupil Light Reflex and Swinging Flashlight Test
A light shined in the pupil elicits rapid and equal constriction in the eye in which the light is shined (direct) and in the opposite eye (consensual). This normal reflex arc depends on an intact afferent visual pathway (CN II) and the efferent CN III pathways. In cases of complete optic nerve impairment, neither pupil will constrict when light is shined on the affected eye, but both pupils will constrict when light is shined on the opposite eye.
A relative afferent pupillary defect, or Marcus Gunn pupil, is observed during the swinging flashlight test: The pupil constricts less (and may appear to dilate) when the light is swung from the unaffected side to the affected side. An afferent pupil defect suggests ipsilateral optic nerve pathology (inflammatory, vascular, or compressive) or, in rare cases, extensive retinal pathology.
Response to Accommodation and Light-Near Dissociation
The pupils normally constrict in near-focus, presumably to improve depth of field. In those with light-near dissociation, the pupil responds to accommodation but not to light.
Unilateral cases are usually associated with Adie syndrome, a peripheral neuropathy affecting the ciliary ganglion. The pupil responds very slowly on near-focus with vermiform movements of the iris constrictor muscle. It demonstrates denervation hypersensitivity with response to dilute 0.125% pilocarpine drops (unlike a normal pupil). The term Argyll-Robertson pupils refers to bilateral light-near dissociation associated with neurosyphilis. Parinaud dorsal midbrain syndrome may be caused by neoplasia or hemorrhage and is associated with upgaze palsy.12
Ocular Examination
Intraocular Pressure
Intraocular pressure (IOP) is measured in millimeters of mercury (mm Hg) by using various tonometers, including the Goldmann applanation, Tono-pen, or air puff. High pressures (>22 mm Hg) may be associated with several orbital conditions, including trauma, hemorrhage, and compartment syndrome (see Chapter 34), elevated episcleral venous pressure from carotid cavernous fistulae or periocular or scleral venular malformations (see Chapters 24 and 26), or in upgaze as a result of restrictive inferior rectus myopathies, including myositis or thyroid orbitopathy. IOP may also rise in response to systemic or topical corticosteroids in or around the eye.
Funduscopy
Vitreous cells in the absence of retinal trauma may indicate intraocular lymphoma, often involving the optic nerve or central nervous system.
Choroidal granulomatous infiltrates may be caused by sympathetic ophthalmia, sarcoidosis, or tuberculosis. Macular pathology should be identified to distinguish visual loss resulting from other causes, including optic nerve or orbital pathology.
The optic nerve examination may reveal optociliary shunt vessels, a sign of optic nerve meningioma, glioma, or cavernous venous lesion (anomaly). Acute or subacute optic nerve pathology tends to produce a congested, hyperemic disk, whereas chronic optic neuropathy from compression or tumor infiltration manifests as optic nerve pallor (see Chapter 18).
Optic disk edema is characterized by elevation and hyperemia of the disk, often with blurred margins and occasionally surrounding retinal folds. Table 3.6 lists the distinguishing features of some of the causes, including papilledema from intracranial masses or idiopathic intracranial hypertension (Fig. 3.2), demyelinating optic neuritis, arteritic anterior ischemic optic neuropathy (from giant cell arteritis, polyarteritis nodosa, granulomatosis with polyangiitis (GPA), Churg-Strauss disease), nonarteritic ischemic optic neuropathy (crowded disk disease), inflammatory diseases (sarcoidosis), infectious disorders (cat scratch disease, Lyme disease, tuberculosis, syphilis), infiltrates (lymphoma), compressive diseases (meningioma, orbital masses, thyroid orbitopathy), toxins, and trauma. Optic nerve pallor, when present, may indicate irreversible vision loss.
Table 3.6
Causes of Optic Disk Edema
| Laterality | Symptoms/Signs | Vision | Visual Field | |
| Papilledema | Bilateral | Headaches, transient visual obscurations | Peripheral loss with central vision spared | Enlarged blind spot; constriction |
| Optic neuritis | Unilateral | Painful ocular movements; other neurologic symptoms (multiple sclerosis) | Sudden visual loss | Focal loss |
| Anterior ischemic optic neuropathy | Unilateral | Crowded disk or systemic vasculitis | Sudden visual loss | Altitudinal visual field defect |
| Infiltrative optic neuropathy | Bilateral | Sequential cranial neuropathies | Rapid visual loss | Generalized depression |
| Compressive optic neuropathy | Unilateral | Optociliary shunts; proptosis | Insidious loss of vision | Generalized depression |
Orbit
General Overview
A general assessment of the orbit prior to detailed measurements helps identify structural deformities, displacement, or asymmetry.
Enlargement of the orbital structures may occur congenitally with facial hemihyperplasia (see Chapter 7) or from acquired conditions such as fibrous dysplasia (see Chapter 16) or neoplasia such as neuroblastoma or meningioma (Fig. 3.3). Enlarging vascular lesions, particularly in infancy, will also produce orbital overgrowth (see Chapter 24). A sphenoid wing meningioma may cause fullness of the temporal fossa.
Orbital hypoplasia may be associated with anophthalmia, microphthalmia, or craniosynostosis or may be acquired after enucleation in young children (Fig. 3.4).
Orbital displacement (dystopia) may be associated with congenital facial clefts, resulting from genetic abnormalities or amniotic bands (Fig. 3.5) (see Chapter 7).13,14 Acquired dystopia is usually caused by severe midface trauma (see Chapter 34).
The intercanthal distance (between the two medial canthi) is measured using a transparent ruler and averages 29 to 32 mm in adults. It usually equals the horizontal length of the palpebral fissure and half the length of the interpupillary distance (average 62 mm in adults). Telecanthus refers to widening of the intercanthal distance without displacement of the orbit, lateral canthus, or eye; telecanthus is often seen in blepharophimosis–epicanthus–ptosis syndrome (see Chapter 8) or nasoethmoidal trauma (see Chapter 34) (Fig. 3.6).
Medial or lateral canthal displacement may signify nasoethmoidal or zygomatic fractures.
Axial Globe Displacement
Various models of exophthalmometer are available to measure the axial displacement of the globe.
The Hertel exophthalmometer helps determine the distance (mm) from the lateral orbital rim to the corneal apex, with the use of split prisms to superimpose a ruler on the side view of the eye, which can be seen while facing the patient (Fig. 3.7A). In general, these instruments are reliable to within 1 mm, and a recent study reported that there was excellent correlation for the same observer and instrument, although interrater reliability was lower, less than that for CT.15
With the Naugle exophthalmometer, the forehead and cheek are used as fixation points to measure the difference in axial position between the two eyes. It is useful in facial fractures if the orbital rims are displaced.
The Luedde exophthalmometer is a rectangular transparent ruler, which is fixed on the lateral orbital rim and the distance to the corneal apex viewed directly from the side (Fig. 3.7B). This inexpensive device has good correlation with the Hertel exophthalmometer.16
A digital caliper attached to the rollers of a slit-lamp biomicroscope allows measurement of the axial distance traveled as focus is adjusted from the lateral rim to the tear film at the corneal apex (Fig. 3.7C).17
Normal exophthalmometry values range from 12 to 21 mm for a white adult but, on average, may be 2 mm lower for those of East Asian ancestry and 2 mm higher for those of African ancestry. Children under age 4 years have a mean exophthalmometry of 12.3 mm, and this increases with age.18 Because of the wide normal range, a comparison between the two eyes or a comparison with old pictures may be more useful in identifying underlying pathology. Asymmetry of greater than 2 mm should prompt further investigation.
Causes of proptosis and enophthalmos are listed in Table 3.7. Pulsatile proptosis may be a sign of a large orbital roof defect resulting from a fracture, neurofibromatosis type 1, previous surgery, meningocele, or encephalocele.
Table 3.7
Proptosis and Enophthalmos
| Displacement | Disease Process | Specific Disorder |
| Proptosis | Inflammatory | Thyroid eye disease, orbital cellulitis |
| Neoplastic | Optic nerve meningioma, glioma, sarcomas, lymphomas, histiocytoses | |
| Traumatic | Retrobulbar hemorrhage, orbital emphysema | |
| Vascular | Lymphatic malformations Venous malformations | |
| Enophthalmos | Structural | Trauma, asymmetry, sphenoid wing dysplasia, silent sinus and cranium syndromes, venous malformations |
| Atrophy | Trauma, post radiation, prostaglandin analogues | |
| Cicatrization | Sclerosing inflammation, metastatic scirrhous breast carcinoma |
Nonaxial Globe Displacement
The eye may be displaced away from a mass lesion such as a neoplasm, vascular malformation, inflammatory mass, or collection of pus or blood. It may shift toward an area of fat atrophy or cicatrization (including sclerosing inflammation or malignancies) or because of widened orbital volume from a displaced fracture or bone destruction (Fig. 3.8). For example, hypoglobus (downward displacement of the globe) may be caused by a superior orbital mass (ethmoidal mucocele, subperiorbital abscess; Fig. 3.9A and B) or by orbital floor excavation (silent sinus syndrome, bone fracture, floor decompression, or other destructive process; Fig. 3.9C and D); see Table 3.8.19
Table 3.8
Nonaxial Globe Displacement
| Direction of Globe Displacement | Etiology |
| Inferior | Frontal sinus mass (mucocele, osteoma, neoplasm or abscess) Intracranial or roof malignancy, inflammation, trauma Superior orbital mass Orbital floor defect (trauma, sinus atelectasis) |
| Superior | Maxillary sinus or lacrimal sac malignancy, infection, inflammation Inferior orbital mass lesion |
| Medial | Lateral orbital or lacrimal gland mass (neoplasia, vascular, inflammation) Extension of temporal fossa pathology Medial wall bony defect (trauma, surgery) |
| Lateral | Medial orbital mass (infection, lymphoma, vascular malformation, neoplasm) Ethmoid sinus or lacrimal sac pathology Lateral wall displaced fracture |
Horizontal displacement can be measured with a transparent ruler centered on a dot between the eyebrows, measuring the distance to each medial limbus. Vertical displacement can be assessed by centering a transparent vertical ruler on the edge of the horizontal ruler and measuring the distance down to each pupil (Fig. 3.10).20
Orbital Palpation and Auscultation
Palpation along the orbital rims may identify discontinuities from displaced fractures, elevated or depressed skeletal lesions, foreign bodies, or areas of tenderness.
Soft tissue masses or the edge of prolapsed lacrimal glands may be identified with gentle exploration over the closed eyelids using the index finger from each hand.
Orbital tension may be assessed by gentle ballotment of the eye through closed lids. Orbital compartment syndrome is a sudden rise in intraorbital tension from a space-occupying hematoma, abscess, or emphysema, with subsequent proptosis, chemosis, raised intraocular pressure, restricted ocular motility, and possible visual compromise. Urgent intervention may be indicated to lower raised ocular or orbital pressure to prevent or reverse vision loss (see Chapters 10 and 34).
Auscultation may identify bruits from carotid cavernous fistulae (see Chapter 26) or arteriovenous malformations (see Chapter 24).
Sensory Deficits
Periocular pain or sensory deficits involving the forehead, temple, eyelids, and midface should be assessed by confirming sensation along the applicable dermatomes, as well as the cornea. Corneal sensation is important in cases of facial paralysis (see Chapter 31) and may be tested by lightly touching the peripheral cornea with a wisp of cotton stretched from a cotton-tipped applicator. Deficits or pain in the distribution of these nerves may localize the disease and also suggest specific pathologic processes (inflammation/infection or neoplasm) (Table 3.9).
Table 3.9
Pain and Sensory Loss
| Disease Process | Pain | Sensory Loss |
| Infection | Bacterial, viral, parasitic infections | Mucormycosis |
| Inflammation | Idiopathic orbital inflammation, thyroid orbitopathy, vasculitis | |
| Orbital compartment syndrome | Hemorrhage, carotid–cavernous fistula | |
| Neoplastic | Adenoid cystic carcinoma Cutaneous malignancy with perineural spread | Cutaneous malignancy with perineural spread |
| Trauma | Acute and subacute pain from fracture, soft tissue damage, foreign body, thermal injury | Orbital floor fracture (infraorbital nerve), lid, forehead, or brow laceration (supraorbital nerve) |
Periorbital Soft Tissue Changes
Periorbital soft tissue changes provide important clues to underlying orbital pathology.
Skin findings may include café-au-lait spots in neurofibroma 1 or Albright syndrome, infiltrates in T-cell lymphoma, or xanthophyllic deposits in xanthogranulomatous disease (Fig. 3.11). Examination of the conjunctiva may reveal sarcoid nodules, lymphoid “salmon patches,” and dermolipomas or orbital fat prolapse. Spontaneous bruising involving the eyelid or orbit suggests spontaneous hemorrhage from a vascular anomaly, metastatic neuroblastoma, or blood dyscrasia.
Isolated eyelid edema without erythema may be a feature of passive congestion, allergy, or lymphatic disorder (Melkersson-Rosenthal syndrome). When combined with erythema, it suggests eyelid inflammation (dermatitis; see Chapter 13) or infection (preseptal cellulitis; see Chapter 10).21
Erythema and edema involving the eyelid and conjunctiva along with orbital findings such as impaired ocular movement or proptosis may have numerous causes, including orbital inflammatory conditions (see Chapter 11), thyroid orbitopathy (see Chapter 12), or infections (see Chapter 10). Congestion from a superior orbital vein or cavernous sinus thrombosis or reversal of venous flow from a dural cavernous fistula may cause proptosis and arteriolization of episcleral vessels, as well as edema and erythema of eyelids and conjunctiva (Fig. 3.12).22
The Clinical Activity Score (CAS) and VISA (vision, inflammation, strabismus, appearance) inflammatory score are methods of grading orbital soft tissue congestive or inflammatory changes in thyroid eye disease (see Chapter 12). The CAS is used as a surrogate marker for disease activity. The VISA inflammatory score is interpreted as a sign of significant muscle inflammation or enlargement, but active thyroid orbitopathy is diagnosed only if there is evidence of worsening of the inflammatory score or other clinical signs.23
Ocular Motility
Ocular motility is the study of the extraocular muscles and disruptions in their normal ability to ensure the eyes work together in a wide range of gazes. A detailed motility examination is indicated if the patient complains of diplopia or if any orbital or neurologic diseases are suspected.
Ocular Deviations (Strabismus)
Definitions.
A manifest ocular deviation (tropia) is present even when both eyes are open. The position of the nonfixing eye is described as being hypertropic (rotated upward), hypotropic (downward), exotropic (outward), or esotropic (inward). An intermittent tropia only occurs sporadically under certain conditions. For example, an intermittent exotropia may only be evident during distant gaze. An alternating horizontal tropia means the patient may fixate equally with either eye.
A concomitant deviation is one that is constant in all directions of gaze, whereas an incomitant deviation varies with gaze. An “A” pattern deviation shows greatest separation of the eyes in downgaze, whereas in a “V” pattern, the reverse is true.
A latent ocular deviation (phoria) is only apparent when the eyes are dissociated (when fusion is disrupted, either by covering the eye or using a Maddox red cylinder occluder). For example, in a right hyperphoria, the right eye deviates upward when it is covered but is aligned when both eyes are open. The ability of the central nervous system to overcome a phoria is called fusional ability, and the amount it can overcome is called fusional amplitude.24,25
The amount of deviation is measured in prism diopters, the unit measuring the deflection of light passing through a prism and is equal to a deflection of 1 cm at a distance of 1 m. Prism bars contain prisms from 1 to 25 prism diopters, and loose prisms to 50 prism diopters are available.
Assessment of Strabismus.
This begins with an overall observation of the patient, often performed while taking the history. A face turn, head side tilt, or chin vertical tilt may indicate an underlying incomitant strabismus with the head positioned to allow best alignment of the eyes. Large deviations may also be observed during this time.
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