The physical examination typically proceeds in a sequential fashion unless the circumstances require otherwise (i.e., chemical ocular injuries require intervention prior to assessment of visual acuity). The glossary of terms and abbreviations below is useful in documenting the findings. The typical eye examination sequence is as follows.
VISUAL ACUITY An attempt should be made to obtain an assessment of visual acuity in each eye in all consciously alert patients. Each eye should be tested individually. If the patient uses glasses or contacts but the glasses are not available, pinhole testing can be performed to obtain an estimate of corrected visual acuity. Distance charts are preferable but are not practical with patients confined to a stretcher. Nearsighted patients and those under age 45 can use a near card to test their visual acuity. Patients in their midforties or older may require reading glasses or bifocals to read a near card because of presbyopia. If these patients do not have their glasses available, a pinhole occluder, again, can be used with a near card. The patient with a corneal abrasion or foreign body is frequently experiencing significant photophobia, pain, and tearing; here, a drop of a topical anesthetic will often reduce the patient's discomfort sufficiently to allow a more accurate assessment of visual acuity. Documentation of best acuity in each eye and whether prosthetic devices were used (glasses, pinhole) should be noted. If the patient cannot read the chart or near card, try asking him or her to count how many fingers you are holding up and record the furthest distance at which the fingers can be counted correctly (e.g., at 4 ft). If the patient is unable to count fingers, assess his or her ability to detect hand motion 1 to 2 ft in front of the eye. If the patient is unable to detect hand motion, turn off all the lights in the room, fully occlude the contralateral eye, and test for light perception. In recording the results of visual acuity testing, refer to the glossary of abbreviations, terms, and notations below.
EXTERNAL EYE Examine the periorbital skin and lids for trauma, infection, dysfunction, or deformity. Proptosis should be recognized and recorded. Subcutaneous emphysema can be found with blowout fractures of the medial orbital wall (ethmoid). The orbital rims should be palpated for step-off deformities in trauma cases.
CONFRONTATION VISUAL FIELDS Testing of the gross confrontation visual field of each eye can provide additional supportive diagnostic information if the history suggests a process that typically causes a field loss [i.e., bitemporal hemianopia in pituitary adenoma, homonymous hemianopia associated with some cerebrovascular accidents (CvAs), and monocular field cuts sometimes seen with significant retinal detachments].
PUPILS Pupil assessment should be performed under slightly dim lighting conditions in testing for an afferent pupillary defect ( Fig 230-3). A positive afferent pupillary defect (APD) is indicative of an optic nerve disorder, and it is important to note that the pupils will be equal in size prior to testing because of the consensual light response. Therefore an APD does not cause a baseline anisocoria and will be discovered only if it is specifically tested for. Causes of unequal pupils (anisocoria) can range from an acute emergency [posterior communicating artery (PCA) aneurysm], to chronic baseline conditions such as previous intraocular trauma or surgery. A careful history is important to determine whether the anisocoria is preexistent. Ocular medications such as pilocarpine can cause extreme miosis, resulting in small, nonreactive pupils. Some patients with uveitis will be using a cycloplegic agent (scopolamine, cyclopentolate, or atropine) and have a chemically dilated, unreactive pupil. It is not worthwhile to attempt to "reverse" a chemically altered pupil in the ED, as the results are variable and unreliable.
FIG. 230-3. "Swinging flashlight test" revealing an afferent pupillary defect (Marcus-Gunn pupil) of the left eye. B. The test is positive when the affected pupil dilates in response to light.
OCULAR MOTILITY Eye movements are controlled by the six extraocular muscles attached to each eye (Fig.230-4 and Fig 230-5). These muscles are innervated by cranial nerves III, IV, and VI. Cranial nerve IV controls the superior oblique muscle, cranial nerve VI controls the lateral rectus muscle, all other extraocular muscles are controlled by cranial nerve III. Ocular motility can be impaired by restriction, interrupted or decreased innervation, or trauma. Examples of restriction include thyroid orbitopathy, myositis, and mechanical entrapment of a muscle secondary to an orbital blowout fracture. Cranial nerve palsies or paresis may be caused by cVAs, myasthenia gravis, diabetes, hypertension, tumors, aneurysms, infections, and trauma. Penetrating or blunt traumatic injury to an extraocular muscle can also result in motility disturbance. Diplopia may develop, especially when the patient is attempting to look in the direction of the malfunctioning muscle. Ocular alignment should be evaluated in primary gaze initially (looking straight ahead), followed by testing in all fields of gaze.
FIG. 230-5. Cranial nerve IV, superior oblique muscle; cranial nerve VI, lateral rectus muscle; cranial nerve III, superior rectus, inferior rectus, inferior oblique, and medial rectus muscles.
ANTERIOR SEGMENT The conjunctiva, cornea, anterior chamber, iris, lens, and ciliary body make up the anterior segment. All of these structures except the ciliary body can be inspected directly on slit-lamp examination. A slit lamp is a biomicroscope that affords an excellent view of these structures and should be used whenever possible. The conjunctiva should be inspected for hemorrhages, discharge, inflammation, trauma, and foreign bodies. The upper lid should always be everted anytime a foreign-body sensation or abrasion is present. The cornea should be assessed by narrowing the light source to produce a slit beam and optically sectioning the cornea (Fig.230-6), which allows an oblique section to be seen and facilitates evaluation of the entire corneal thickness. This is a particularly important technique when one is trying to determine if a corneal foreign body has caused a full-thickness penetration. Fluorescein dye should be instilled and the cobalt-blue filter used to identify corneal abrasions, dendrites, and perforations. The modified Seidel test is useful in identifying corneal perforations. The eye is anesthetized and held open and the cobalt-blue filter is used to observe the eye while a moistened fluorescein strip is "painted" across the suspicious site. Leakage of aqueous through a penetrating wound will appear as a lime-green fluid oozing onto the dark violet corneal surface ( Hg...230i-Z, P]a.t.e 9). The anterior chamber should be checked for clarity and the presence of a hyphema (Fig, 2.3.0:8, .Pla.t.e 1Q) or hypopyon (Fig 230-9, .Pia.te 1..1). Cell and flare may be present in acute injuries or in chronic uveitis/iritis conditions and should be checked for as follows: The slit beam should be shortened to about 1 mm and all of the room lights should be out. The high-magnification position should be selected. The incident light source should create an angle of 45 to 60° with the objective (similar to optical sectioning). The light beam should be focused on the pupillary margin, then pull back on the joy stick to focus on the cornea, then move the focus inward halfway between the iris and cornea, with the pupillary aperture as a dark backdrop. This will place your focus in the center of the aqueous, and the light beam will illuminate cells slowly drifting up and down in the aqueous convection currents. Flare is typically described as the appearance of "headlights in a fog" and represents the ability to see the course of the normally transparent light beam through the aqueous. This is caused by increased aqueous protein content, which is commonly seen with inflammatory conditions. The iris should be inspected for tears and foreign bodies if trauma occurred. The lens should likewise be inspected for injury, subluxation, and foreign bodies.
FIG. 230-6. Optical sectioning: By creating an angle of 45 to 60° between the slit-beam light source and the observer's biomicroscope objective, the cornea can be optically "sectioned" obliquely. This allows a cross-sectional view of the cornea and is helpful in ascertaining depth of penetration of corneal foreign bodies and injuries.
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