Chapter 153. Eye Examination

Emergency Physicians often approach the eye examination with some degree of apprehension. Eye complaints comprise up to 10% of Emergency Department visits. A systematic approach to the eye examination can alleviate any discomfort and provide the basis for an accurate diagnosis and treatment.1–14 The most common ophthalmologic problems that present to an Emergency Department are injuries, inflammation, infections, and visual disturbances.

A careful history will help to guide the differential diagnosis and the physical examination. It must include a history of the presenting complaint, the mechanism of any injury, exposures to chemicals or infectious agents, baseline visual acuity, known ophthalmologic problems, baseline medical problems, current medications, and any known allergies. The eye examination progresses from the outside and works inward, beginning with the visual acuity to assess the function of the eye. It is important to routinely inspect all anatomic structures of the eye regardless of the presenting eye complaint. Secondary problems, such as corneal lesions associated with conjunctivitis, may be missed if a complete examination is not performed on all patients.

The bony orbit is pyramidal in shape and surrounds the eyeball and its associated neurovascular structures. The blood supply to the structures of the orbit originates from the ophthalmic artery. The anatomy of the eyeball and its surrounding soft tissue structures is demonstrated in Figure 153-1. A detailed discussion of the complex anatomy of the eye is beyond the scope of this chapter. The anatomy relevant to the eye examination will be discussed throughout this chapter.

Visual acuity is referred to as the vital sign of the eyes. It provides a means for the functional assessment of this delicate sensory apparatus. Documentation of the visual acuity is essential when approaching a patient with eye complaints. Assess the patient's visual acuity as soon as possible, preferably as part of the triage assessment. Test and document the patient's visual acuity before the physical examination begins. There are few exceptions to this rule. Chemical exposures to the eye require immediate irrigation to avoid potentially irreversible visual loss. In these cases, irrigation should not be delayed for visual acuity testing. In all other cases, visual acuity testing should be the primary component of the ophthalmologic exam. Failure to document visual acuity is a common omission and may have medicolegal ramifications.

Always test each eye individually and then both simultaneously. Test and document the visual acuity with the respective annotation to the right eye (OD), the left eye (OS), and both eyes (OU). Test the problematic eye first. Completely cover the eye not being tested. Light shining into the opposite eye may adversely affect the results of visual acuity testing. A list of commonly used abbreviations in the measurement of visual acuity is presented in Table 153-1. Inquire as to the patient's baseline visual acuity and whether they wear corrective lenses for reference. Test the visual acuity using corrective lenses whenever possible. When corrective lens are unavailable, use of the pinhole device will help to correct any refractory errors. The abbreviations for the documentation of with and without correction are cc and sc, respectively.

Use caution when allowing contact lenses to be used as a visual aid in patients with eye pain, an eye injury, or an eye discharge. Their application may worsen the ocular condition. Remove all contact lenses before the slit lamp examination and fluorescein staining. Fluorescein will permanently stain soft contact lenses and may stain hard contact lenses.

An accurate assessment of visual acuity is essential and this cannot be overemphasized. It is not uncommon for a Physician to miss a secondary ophthalmologic diagnosis when they do not recognize a change in visual acuity. As a rule of thumb, a patient with previously normal (20/20) vision with or without correction that has an acute deterioration to 20/50 or less suggests a serious ophthalmologic condition. These cases require emergent consultation and prompt referral to an Ophthalmologist.

Visual Acuity Charts

The Snellen eye chart is the most commonly used tool for assessing visual acuity (Figure 153-2). Place the Snellen chart on a flat wall in a well-lit room without obstructions. Place the patient standing 20 feet from the chart. With one eye completely covered, instruct the patient to read each line of the chart beginning at the top and proceeding to the bottom or until they are unable to correctly and consistently read the letters. The visual acuity is the fraction corresponding to the last line that the patient identifies at least half of the letters correctly (i.e., 20/40). The numerator corresponds to what the patient is able to see at 20 feet. The denominator corresponds to the distance where a patient with normal vision would be able to read the same line accurately. For example, a patient with a visual acuity of 20/40 sees at 20 feet what a patient with normal vision would see at 40 feet. Document the fraction corresponding to the line minus the number of letters missed if the patient is able to accurately identify more than half of the letters on that line (i.e., 20/40-3).

When a patient is unable to read the Snellen chart at 20 feet, move the patient closer and reevaluate the visual acuity. Test the patient 10 feet from the chart. The test is the same at 10 feet as it is at 20 feet only the documentation changes. Recall that the numerator corresponds to the patient's distance from the chart. If starting at the 10 foot mark and the patient is able to read the letter at the line designated 20/200 then document 10/200. The test can also be performed at 5 feet or closer if necessary, with the appropriate change in the numerator.

The Snellen chart is the most effective tool for documenting an accurate and reproducible visual acuity. There are circumstances that render this tool less effective and inaccurate. The chart utilizes the English alphabet and effective use requires that the patient can identify all letters. This is difficult, if not impossible, in patients who are illiterate or do not speak and/or read English. The illiterate E chart is an alternative (Figure 153-3). Instruct the patient to identify the direction that each “E” is facing. An alternative is to use a pediatric visual acuity chart (Figure 153-4). Instruct the patient to identify the objects on each line. Both of these visual acuity charts are assessed and documented like that of the Snellen chart.

There are a few circumstances where the standard eye chart may give falsely low and inaccurate readings. Patients with eye pain or photophobia may have difficulty reading the chart in bright light secondary to excessive lacrimation, blepharospasm, or pain. There are several options to provide a more optimal assessment of visual acuity. A Rosenbaum card is the handheld equivalent of the Snellen chart (Figure 153-5). It is viewed at a distance of 14 inches. Its advantages are that it can be used in the patient's room with less-offensive lighting and it can adjust for refractory errors in near-sighted patients who present without correction. A clever idea that some use is to attach a 14 inch string to the Rosenbaum card so that it can be accurately tested at the exact distance each time. A near vision test for children may also be used to assess visual acuity (Figure 153-6).

Photophobia or eye pain, particularly that which results from corneal injuries or lesions, may prevent the patient from complying with the visual examination. They may often have difficulty opening the eye at all. The instillation of a topical ophthalmic anesthetic agent may be remarkably helpful as an adjunct to the visual acuity evaluation as well as for the remainder of the eye examination.

Pinhole Device

The pinhole device can filter out excessive light (Figure 153-7). It allows direct light rays to pass through the holes while blocking divergent light rays. This results in a sharper, but dimmer, image on the retina. The pinhole device may correct refractory errors to 20/30. An index card punctured multiple times with an 18 gauge needle can substitute if the pinhole device is not available. The pinhole device should be used in a well-lit room because it results in a dimmer image on the retina. Instruct the patient to place the pinhole device over the eye being tested and close the other eye. Instruct the patient to read the visual acuity chart. Record the patient's visual acuity in each eye. Make a notation in the record that the pinhole device (PH) was used in the measurement of the visual acuity.

Finger Counting

Another means of visual acuity assessment must be utilized if the patient is unable to identify the letter or object in the 20/200 position, the first and largest letter in the visual acuity chart. The next level of visual acuity that is traditionally accepted is the ability to count fingers (CF). It is important for documentation that the examiner note at what distance from the eye the patient is able to consistently count the examiner's fingers (e.g., OD CF at 12 inches). The distance used for counting fingers is the distance where the patient is first able to accurately complete the test. Test one eye at a time and then both eyes simultaneously.

Documentation of “CF at 2 feet” means that the patient can accurately count fingers starting at 2 feet. This implies that the patient cannot accurately count fingers if they were held at a distance greater than 2 feet. It is thus very important to determine the distance where the patient can accurately count fingers and measure this distance with a tape measure and not estimate.

Hand Movements

The next test of visual acuity to perform is hand movements if the patient cannot count fingers. Move or wave a hand back and forth in front of the eye being examined. Document hand movement positive (HM+) or hand movement negative (HM−). Note the distance from the eye that hand movement is first visible (i.e., how close to the eye must the hand be positioned) in the medical record (e.g., HM+ at 12 inches). Test one eye at a time and then both eyes simultaneously.

Light Perception

If the patient is unable to perceive hand movement, the next determination of visual acuity is light perception. Use a penlight or ophthalmoscope to determine the presence or absence of light perception. Shine the light directly into one eye while the opposite eye is covered. Document the patient's ability to correctly identify when the light is on and off. This is noted as light perception positive (LP+) or light perception negative (LP−). Test one eye at a time and then both eyes simultaneously. True blindness is present when the patient has no light perception.

Uncooperative or Unresponsive Patients

Unresponsive patients are a challenge for the evaluation of visual acuity. First shine a light into each of the patient's eyes to test for pupillary reactivity. Move the light slowly through all of the cardinal positions to identify if the patient is able to track the light movement. Refer to the evaluation of extraocular movements section below. Perform the doll's eyes maneuver if the patient is unable to track the light.

A difficult situation occurs in the patient whose visual acuity is “no light perception or LP–” but has normal pupillary responses and normal responses to the doll's eyes maneuver. This suggests that the visual loss is not anatomic or physiologic, but rather has a psychologic component. Test the optokinetic reflex using either a spinning device or a scintoscope in order to narrow the differential diagnosis. A patient who can see movement will not be able to resist the normal tracking response to the rotating cylinder. A positive response will appear as nystagmus upon examination.

Pediatric Visual Acuity Testing

It is important to evaluate the vision of infants. There is a critical time during which visual problems must be corrected to avoid permanent visual disturbances. This is optimally before 4 months of age. The eyes continue to develop quickly up to 2 years of age. Refer any questionable visual disturbances to a Pediatric Ophthalmologist.

Infants from term delivery to 3 to 4 months of age are not able to consistently follow and track objects. An infant's eyes may not move in perfect alignment until the age of approximately 3 to 4 months. Infants begin to focus on faces and follow them at approximately 6 weeks of age. They should consistently focus on and follow objects at 4 months of age.

Testing an infant's vision can be quite difficult. Place the infant with their parent holding them in the feeding position. Cover one of the infant's eyes. Ask the parent to move their head from side to side. Note whether the infant's uncovered eye tracks the parent's face. Repeat this with the opposite eye covered. The inability to track objects suggests that the visual acuity is 20/200 or less.

Children who cannot yet read or identify the letters of the alphabet are at a disadvantage when using the Snellen chart (Figure 153-2). Use the illiterate E chart (Figure 153-3), the pediatric visual acuity chart (Figure 153-4), the pediatric near vision test (Figure 153-6), or the Allen chart (Figure 153-8) to test their visual acuity. The illiterate E chart requires the patient to identify the direction that each variably rotated letter E faces (i.e., up, down, right, and left). Some clinicians find it helpful to describe the E as a table and ask which way the legs are facing. The procedure and documentation is otherwise the same as with the Snellen chart. The pediatric charts use shapes of common objects in the place of letters and apply the same corresponding fractions for determining visual acuity. Have the child identify each of the pictures before beginning the examination to ensure that the child knows what the picture represents. Children may use unexpected words to identify the objects, which may complicate the interpretation of the exam.

The examination of the eye proceeds from the outside and works inward. Begin with inspecting the external structures. Note the presence of any enophthalmos or exophthalmos. This is best accomplished by viewing the eyes from above and behind the patient. The normal globe position is just within the orbital rim. Enophthalmos is a recession of the globe within the bony orbit. It is an important clue for the presence of a blow-out or orbital floor fracture. Exophthalmos is a protrusion of the globe from the bony orbit. It may be an important clue to the presence of a retrobulbar hemorrhage or an orbital cellulitis. Esotropia refers to an inward or nasal deviation of the globe. Exotropia refers to an outward or temporal deviation of the globe.

Evaluate the eyes and eyelids for symmetry, lid position, obvious injuries, lesions, discoloration, and/or swelling. Ptosis suggests a Horner's syndrome or a third cranial nerve abnormality. Any evidence of facial trauma or eye trauma raises the possibility of a ruptured globe. Avoid placing pressure directly on the globe if there is any possibility of a ruptured globe. Inadvertent tactile pressure placed on a ruptured globe may result in extrusion of intraocular structures. This can result in an otherwise avoidable visual loss that is typically not reparable. Manipulate the eyelids by applying pressure over the bony orbit instead of directly on the globe (Figure 153-9).

Extraocular movements are easily assessed in the cooperative patient. Instruct the patient to keep their head still and directed toward the examiner. Instruct the patient to follow the motions of a finger with only their eyes as it follows the pattern of an H (Figure 153-10). This is referred to as the six cardinal positions for testing extraocular muscle movements. It may be helpful to retract the patient's eyelids to better visualize the eye movements. Observe the eyes for symmetric or conjugate gaze as each position is reached. Note whether the patient sees one finger clearly at each position. Ask the patient to describe the orientation of the images (i.e., side to side) if more than one image is noted. Assess the far lateral positions by paying careful attention for evidence of nystagmus. A few beats of nystagmus that quickly extinguishes is within normal limits. Keep in mind that the nose may obstruct the view at extreme points. Move the examining hand into a plane that is a few inches closer to the examiner if this occurs (i.e., a few inches away from the patient), and repeat the testing.

It is helpful to use a penlight directed toward the patient's eyes during the examination when a question of subtle disconjugate gaze is entertained, particularly in the position where the patient complains of diplopia. Look into the patient's pupils to see the reflection of the light (Figure 153-11). The reflection of the light is symmetrical, located in the same position in each pupil, if the gaze is conjugate (Figure 153-11A). Asymmetrical light reflection is noted in cases of disconjugate gaze (Figure 153-11B).

Consider the innervation of the extraocular muscles in order to narrow the differential diagnosis when abnormal extraocular movements are identified. The lateral rectus muscle is innervated by the sixth cranial nerve (CN VI). The superior oblique muscle is innervated by the fourth cranial nerve (CN IV). The remaining extraocular muscles are innervated by the third cranial nerve (CN III). An isolated sixth cranial nerve palsy, particularly in a child, strongly suggests an intracranial neoplasm. A complete third cranial nerve palsy suggests an intracranial aneurysm pressing on the oculomotor nerve, particularly when the pupil is involved. A physical obstruction originating in the retrobulbar region manifests as restricted extraocular movements in one eye. Consider the presence of an orbital cellulitis or a retrobulbar hemorrhage in the appropriate clinical setting.

Consider the presence of an orbital floor or blow-out fracture if the patient is unable to elevate one of the eyes. The etiology of the restricted movement may be physical entrapment of the inferior rectus and/or inferior oblique muscles within the orbital floor fracture or a contusion of the nerve innervating the inferior oblique muscle. The two must be distinguished by an Ophthalmologist as the management, treatment, and follow-up are different. Place two drops of a topical ophthalmic anesthetic agent into the affected eye. Grasp the bulbar conjunctiva with forceps and attempt to gently elevate the eye. A physical cause is ruled out if the eye is able to be elevated and a nerve contusion is likely.

Place the patient with their head looking directly forward while retracting the upper eyelid. Complete the pupillary examination and a cursory evaluation of the cornea and anterior chamber simultaneously. Clinicians commonly use the abbreviation “PERRLA” as documentation for the pupillary examination. “PERRLA” means the pupils are equal, round, and reactive to light with normal accommodation. Be sure that you assess accommodation if you use this acronym. In any case, this abbreviation is typically inadequate when a patient has emergent eye complaints.

When dealing with emergent eye complaints it is important to document a detailed pupillary exam. Darken the room as much as possible. Instruct the patient to focus on a distant object. The normal response is symmetric dilation of the pupils. Note the size, in millimeters, of each pupil. Shine a focused beam of light into one eye to test reactivity, or the direct pupillary response to light. The normal pupil will constrict immediately and briskly. Document the direct response to light in millimeters at maximal constriction (e.g., OD = 4 mm → 2 mm). Note if the pupil is not briskly reactive (e.g., OS = 5 mm → 3 mm, sluggish) or if it dilates (e.g., OS = 3 mm → 6 mm). Repeat this test with the contralateral eye.

The consensual pupillary response is the reaction of the contralateral eye to light shined into the opposite eye. The normal consensual pupillary response is constriction of the contralateral pupil when light is shined into the opposite eye. This occurs because some of the efferent optic nerve fibers cross the midbrain to the contralateral optic tract and result in constriction of the contralateral pupil. Be careful to document a normal consensual response if it is present.

When assessing an inflamed eye, the consensual pupillary response can be used as a diagnostic tool. Close and cover the affected eye and shine the light in the opposite eye. With the cornea protected by the lid on the affected side, if the consensual pupillary response causes pain in the affected eye it suggests deep inflammation or a uveitis.

A common example of an abnormal pupillary examination illustrates the importance of paying specific attention to the consensual pupillary response. The relative afferent pupillary defect (RAPD) results from the tested eye not perceiving the light. There is no perception of light (LP−) transmitted to the optic tracts. The tested pupil will not constrict to direct light. The pupil may, in fact, inappropriately dilate in response to direct light. There will be no consensual response in the contralateral pupil. The contralateral pupil will constrict appropriately to direct light and the previously unresponsive pupil will demonstrate a normal consensual response. The “swinging flashlight test” is used to test for a RAPD. Shine the light into one eye. Note the direct and consensual responses. Swing the light over to test the opposite eye. Note the direct and consensual responses.

A common problem for the Emergency Physician is the patient with unequal pupils. In the appropriate context, the primary consideration is typically a “blown pupil” suggesting an uncal brain herniation from a mass lesion. This would be very unusual in a patient who is awake, alert, and cooperating with the eye examination. In this case, physiologic anisocoria is the most common cause. Patients with physiologic anisocoria will have a normal response to light and typically the difference in pupillary size will be no more than 2 to 3 mm. If the response is abnormal, the Emergency Physician must determine which of the two pupils is problematic. The normal response to a darkened room is dilation. The pupil that does not dilate is abnormally miotic. The appropriate response to bright light is constriction. The pupil that does not constrict is abnormally mydriatic.

It is important to note and document the shape of each pupil. They should be round and regular. Irregularly shaped pupils may give important clues to otherwise undiagnosed injuries. A “D-shaped” pupil suggests a disruption of the ciliary muscles in the region adjacent to the flat part of the “D”. A teardrop-shaped pupil suggests a ruptured globe, with the point of the teardrop directed toward the point of penetration. A quivering and dilated pupil that does not react appropriately to light suggests a lens dislocation partially obstructing the visual axis. An irregularly shaped pupil may be an important diagnostic clue, but do not be misled. The most common cause of an irregularly shaped pupil is a postoperative change. Always inquire about previous eye surgery or old injuries, especially if an abnormality is noted.

A new device, the NeurOptics® NPi™-100 pupillometer, has been developed to accurately measure pupil size and reactivity (NeurOptics, Irvine, CA). This handheld device is easy to use, takes over 30 pictures a second, analyzes the pictures, and prints via infrared to a portable printer. It can display values over time numerically or graphically. While not for routine daily use, it has a role in the evaluation of critically ill or injured patients.

The examination should proceed from the outside and work inward following an anatomic checklist. Examine the eyelids, lash line, and tarsal plates. Examine them for symmetry, normal position of the eyelashes, injury, infection, or inflammation. Examine the puncta of the lacrimal apparatus for signs of inflammation and obstruction. Examine the bulbar conjunctiva and vasculature for injection, ciliary flush, chemosis, discharge, and foreign bodies. Examine the cornea for clarity, evidence of injury, lesions, or foreign bodies. Examine the palpebral conjunctiva and cul-de-sac for injection, foreign bodies, discharge, and lymphatic (follicular) enlargement. Examine the anterior chamber for clarity, depth, and particulate matter.

Expose the structures of the inner aspect of the upper eyelid. Evert the eyelids (Figures 153-12 & 153-13) or retract the eyelids (Figures 153-14 & 153-15). Place the patient facing forward with their eyes focused downward to evert the upper eyelid (Figure 153-12). The patient's eyes must remain directed downward during the entirety of the exam as looking up or forward will cause the eyelids to return to their natural position. This process requires the use of a cotton-tipped applicator. An assistant may be required to aim and focus a light source during the examination as it may require two hands to evert and hold the eyelids in position.

Grasp the midpoint of the upper eyelash line or the tarsal plate between the index finger and thumb (Figure 153-12A). Place a cotton-tipped applicator 0.5 to 1.0 cm superior to the tarsal plate, with the cotton tip in the midplane of the upper eyelid (Figure 153-12A). Apply gentle pressure directed slightly downward against the upper eyelid with the cotton-tipped applicator. Use the other hand to pull the eyelid upward and evert it (Figure 153-12B). The upper eyelid may not completely evert. Sweep the cotton-tipped applicator from left to right while still holding the lash line in one hand and simultaneously applying gentle downward pressure with the applicator within the false pocket to completely evert the upper eyelid (Figure 153-12C). Gently and slowly remove the cotton-tipped applicator.

Eversion of the lower eyelid is much simpler (Figure 153-13). Instruct the patient to look upward. Place the index finger on the patient's lower eyelid. Apply downward traction to evert the lower eyelid.

The use of a Desmarres eyelid retractor is an alternative option, if available, to retract the eyelids. It is very difficult to manually evert the eyelids when they are swollen. Manual eyelid eversion can result in excessive pressure being placed on the potentially injured globe. An eyelid retractor can be used to avoid placing pressure on the globe (Figure 153-14). Place the patient facing forward with their eyes directed downward. Place the eyelid retractor approximately 5 mm above the tarsal plate on the outer surface of the eyelid (Figure 153-14A). Grasp the midpoint of the upper eyelash line or the tarsal plate between the index finger and thumb. Slightly retract the upper eyelid away from the globe. Elevate and retract the tarsal plate upward to evert the eyelid onto the retractor (Figure 153-14B). Lift the retractor upward to fully expose the undersurface of the eyelid (Figure 153-14C).

This technique allows the eyelid to be retracted with one hand while directing the light with the other hand. It also prevents any pressure from being placed on the globe if a rupture is suspected. It may be necessary to slide the retractor 0.5 cm to the left and to the right of midline to fully visualize the ocular structures. Use the same technique to retract the lower eyelids. Instruct the patient to direct their gaze and focus upward when retracting the lower eyelid.

A simple method to retract, but not evert, the eyelid with the Desmarres retractor is shown in Figure 153-15. Place the eyelid retractor in front of the upper eyelid (Figure 153-15A). Gently insert the retractor under the upper eyelid (Figure 153-15B). Apply slight outward traction on the retractor to securely grasp the tarsal plate. Rotate the retractor upward to retract the upper eyelid (Figure 153-15B). Elevate the retractor upward to open the eyelid (Figure 153-15C). Use the same technique to retract the lower eyelid. Never use this technique if a foreign body or ruptured globe is suspected. It may cause secondary injury by embedding a foreign body, perforating the globe with the foreign body, or expressing the ocular contents if the globe is ruptured.

Eyelid retractors are not uniformly available in all Emergency Departments. They should be part of an “eye kit” (Table 153-2). An alternative used by some is to unfold a paper clip and bend it into shape with a hemostat (Figure 153-16). This is not recommended by the editor as the metal coating on the paper clip flakes off and can result in corneal abrasions and foreign bodies. Plastic-coated paper clips, if available, might be a safer alternative to metal paper clips.

The slit lamp is an essential piece of machinery for a thorough eye examination (Figure 153-17). It is an invaluable resource that can be used to identify and aid in the treatment of ophthalmologic problems that might otherwise go unrecognized. It provides an adjustable light source with variable magnification. The eyes remain in a fixed position while the light and microscope are independently adjusted. The result of these attributes is that it can focus precisely on the structures of the eye and provide a three-dimensional image. The slit lamp provides valuable information, particularly when examining the cornea and the anterior chamber. The three-dimensional microscopic capability is best demonstrated when examining the intricate topography of the iris.

It may be helpful to set up the slit lamp before the patient is in the room until one feels comfortable using the slit lamp. Place one hand against the middle of the forehead bar in the examination plane to help become familiar with the capabilities of the machine and the joystick. Practice focusing the slit lamp on the details of the skin on your hand. Adjust the focus and depth of vision by sliding the joystick to move the entire slit lamp apparatus forward and backward. Slide the joystick side to side to scan across and examine the entire width of the hand. Rotate the joystick clockwise and counterclockwise to move the line of vision up and down.

Place the slit lamp in the standard position. It takes very few adjustments of the slit lamp to complete the entire examination. The slit lamp can be focused and locked in position with the knob located on the table base for procedures that require the Emergency Physician's hands to be free (e.g., foreign bodies embedded within the cornea). This allows one hand to hold the eyelids open while using the appropriate tool in the other hand.

Setting Up the Slit Lamp

The slit lamp has many parts, most of which are capable of movement. The slit lamp components are often moved into a complete disarray by previous users. The position should be checked when the Emergency Physician sits down to use the slit lamp. It is important to start by readjusting the slit lamp to a “standard operating position.”

The body of the slit lamp has three rotating arms. The examiner's neutral position is designated as 0° and the center of the chin rest is designated 180°. The lower arm rotates the binocular microscope. It is rarely, if ever, necessary to move the rotating binocular microscope from the 0° position for the purposes of an Emergency Department examination. The next two arms are moved as a unit. The lower arm rotates the light 90° in either direction. The light source remains directed toward the structure that is being focused upon. The angle of the light is changed when the arm is rotated up to 90° in either direction. The standard position for the light is to rotate it 45° to the examiner's left to examine the patient's right eye and 45° to the examiner's right to examine the patient's left eye. Rotation of the upper arm independently rotates the slit of light in the coronal plane. It is unnecessary to rotate the two upper arms independently during the Emergency Department examination.

The eyepieces of the binocular microscope can be adjusted and focused independently in accordance to the Emergency Physician's needs. The standard starting position is in the 0 and 0 position. The eyepieces can be adjusted to compensate for refractory errors and to correct for the interpupillary distance of the Emergency Physician.

Two levels of magnification are typically available (10× and 16×). The switch to change magnification is located just below the eyepieces. The standard beginning position is low magnification. The higher power may be helpful when examining the details of the cornea or looking for cellular or inflammatory material within the anterior chamber.

The next step is to find the on–off switch. It is typically located just under the table base and on the left. Place one hand in the examination plane against the headband where it should pick up a focused beam of light to ensure that the light source is functional. Observe the top of the slit lamp to determine whether light shines through the casing that houses the light source. The bulb will periodically need to be replaced. Remove the casing and replace the bulb as needed. The correct position for the bulb is obvious as it has a notch that fits into a corresponding notch in the housing.

The focused light can be adjusted in intensity, color, vertical width, and horizontal width. The standard position is for the light to be at its maximum size with a circular beam of white light at a moderate intensity. This position is used for scanning the eye and examining the external structures. Three independent adjustment mechanisms interact to create the most appropriate illumination to meet examination needs.

The color of the light and the intensity of the light originate from the same mechanism. Most of the positions represent variations in intensity of a white light. There are two other options for color. The cobalt blue light is used for emphasizing corneal lesions that pick up fluorescein stain. The green light or red filter is helpful for patients who cannot tolerate the white light secondary to photophobia. This green light will cause red structures to appear darker or black.

The horizontal width of the light can be adjusted with the knob located at the base of the middle arm. The light can be narrowed to 1 to 2 mm or a “slit” for evaluating the depth of corneal lesions (Figure 153-18A). The vertical control is used in conjunction with the horizontal control. Narrow the horizontal width to 2 to 3 mm and the vertical width to 2 mm when examining the anterior chamber. This creates a small focused beam. Rotate the light 30° to 60° in order to illuminate the depth of the anterior chamber (Figure 153-18B). This orientation is most beneficial when attempting to identify cellular or inflammatory material within the anterior chamber.

Patient Positioning

Cleanse the chin rest and the forehead bar before the slit lamp is used to examine a patient. The patient must be able to tolerate a seated position, leaning slightly forward with their head placed in the chin rest and their forehead pressed against the bar to use the slit lamp (Figure 153-19). The slit lamp examination cannot be completed in a patient who cannot remain in a seated position. Patients will often need to be reminded to keep their head in the chin rest and their forehead against the bar. Subtle movements from this position will change the viewing plane and disrupt the focus on the structures of the eye. Always check the patient's position if you are having difficulty focusing the slit lamp.

A motorized chair with the ability to move up and down is optimal for this examination. The slit lamp can be adjusted to match the height of a chair or stretcher if necessary by pressing the release bar located below the slit lamp table to move the entire table up and down. When the table height is properly positioned, release the bar to lock the table at this new height. The level of the chin bar can be adjusted to account for the subtle differences in the length of individual patient faces. Rotate the knob located at the base of the chin rest apparatus to move it up and down. Raise or lower the chin bar so that the reference mark located below the forehead bar is at the patient's eye level.

Use the joystick to move the slit lamp and scan the patient's eye. The patient must keep their eye in a fixed position while the Emergency Physician uses the joystick to move the slit lamp and scan the eye. Instruct the patient to focus their eye on your shoulder or earlobe. It is very difficult for the Emergency Physician to focus and complete a thorough examination if the patient's eyes wander.

The Slit Lamp Examination

The slit lamp examination begins with an overall microscope-enhanced evaluation of the external structures of the eye including the lash line, the bulbar conjunctiva, the palpebral conjunctiva, and the lacrimal puncta. The cornea is best evaluated primarily with a wide beam and the fine details are evaluated with the slit. Do not focus the light into the pupil for an extended period of time. It is very uncomfortable for the patient and may result in injury. The normal cornea is perfectly clear and homogeneous. Note any deviation from this if applicable. Specific abnormalities are best documented in writing in addition to a basic schematic diagram.

The anterior chamber should be clear and without particulate matter. It may be difficult initially to identify cells floating in the anterior chamber. They appear like “dust in a sunbeam.” The cells, if not clumped, are barely visible with the microscope at the lowest magnification. They do, however, often reflect the light slightly, and this may catch the Emergency Physician's eye. Take care to pay special attention to the lower one-fourth of the anterior chamber because, in an upright position, cells and inflammatory products tend to settle and may form a meniscus. Flare is the noncellular inflammatory material in the anterior chamber that makes the aqueous humor appear hazy, or gelatinous, and obscure the details of the iris. Use the high-power magnification to identify particulate matter after scanning the anterior chamber with the low-power magnification.

Administration of Fluorescein

Repeat the corneal examination with the aid of fluorescein stain after the slit lamp examination is completed without stain. Fluorescein is a hydrophilic substance that stains and illuminates any portion of the cornea where there is a breech in the epithelium. The addition of fluorescein helps to illuminate corneal lesions that might otherwise go unrecognized. This includes corneal abrasions or keratopathy associated with viral infections. Fluorescein is most commonly packaged as individual single-use strips. There is the potential for infectious agents to be transmitted when one fluorescein strip is used for both eyes or when a multidose vial of fluorescein solution is used. Take care to avoid iatrogenically transmitted infections.

Remove all contact lenses before the slit lamp examination and fluorescein staining. Accidental application of fluorescein without their removal will permanently stain contact lenses. Place a small drop of saline or topical ophthalmic anesthetic solution onto the tip of the fluorescein strip. Retract the lower eyelid by placing pressure on the skin overlying the inferior orbital rim and distracting it downward. Ask the patient to look upward to facilitate the administration of the stain and to avoid inadvertent corneal injuries caused by the strip itself. Touch the fluorescein strip lightly against the palpebral conjunctiva of the inferior eyelid (Figure 153-20A). Remove the fluorescein strip. Ask the patient to gently open and close their eyelids to distribute the fluorescein across the entire eye.

Aqueous fluorescein solution can be used as an alternative to the paper strips. Retract the lower eyelid and instill two drops of fluorescein into the cul-de-sac of the lower eyelid (Figure 153-20B). Take special care when using fluorescein to avoid accidentally staining the patient's skin, clothing, or contact lenses. Most Emergency Departments use fluorescein strips rather than liquid solution. The liquid solution, or the tip of the applicator, can become contaminated and transmit infection.

A small amount of fluorescein is required to adequately stain the cornea. A common mistake is to apply an excessive amount of fluorescein stain. This illuminates the entire tear film and makes it difficult to evaluate subtle lesions on the cornea. Ask the patient to blink several times to remove the excess fluorescein from the cornea. This maneuver will not remove the fluorescein adhering to any corneal defects. If blinking does not remove the excess fluorescein, place one or two drops of sterile saline or eyewash onto the eye. Avoid the use of excessive fluorescein as it is likely to obscure exam and potentially stain the patient's skin.

The underlying cell layers of the cornea will hold the fluorescein stain if the corneal epithelium is injured. This allows corneal lesions to be visualized. Use the cobalt blue light, preferably in conjunction with the slit lamp, to identify and evaluate any corneal lesions that become apparent. The regions that stain with fluorescein and are visible with the cobalt blue light will appear bright yellow to yellow-green. The green light on the ophthalmoscope and the slit lamp are not intended to be used to illuminate the fluorescein stain. The green light will enhance the stain in some circumstances but is not as reliable as the cobalt blue light source.

Traditional Methods

Topical ophthalmologic medications are used for examining and treating the eyes. Eyedrops and ophthalmologic ointments are most effectively and accurately instilled within the lower eyelid (Figure 153-21). Instruct the patient to direct their head toward the examiner with their eyes looking upward (Figure 153-21A). Patients often close their eyes at this point. Retract the lower eyelid, without placing pressure on the globe, and expose the inferior cul-de-sac (Figure 153-21B). Apply the drops, or ointment, in the cul-de-sac (Figure 153-21C). Close the eyelid and apply thumb pressure over the lacrimal duct (Figure 153-21D). This prevents the liquid medicine from immediately draining through the nasolacrimal duct and into the nose. Instruct the patient to blink once or twice to quickly distribute the medication across the globe. This last step, applying pressure on the lacrimal duct, is unnecessary if instilling an ophthalmic ointment.

Uncooperative Patients

Some patients require but do not want medication in their eyes. The best examples of these challenging patients are infants, small children, and patients with altered mental status. Prying the eyes of these patients open and applying the drops is difficult for both the physician and the patient. Forcefully opening the eyelids is potentially dangerous because secondary injuries may occur. The majority of medication is typically applied to the physician's hand or the stretcher, as anyone who has tried this approach knows. An alternative approach in this situation is advisable.

The problem is that the uncooperative patient squeezes their eyes closed tightly. Place the patient supine with an assistant holding the head in a fixed upright position with the eyes facing the ceiling in order to overcome this challenge (Figure 153-22). Note the small anatomic depression created over the medial canthus of each eye when they are closed tightly. Place the eyedrops in this anatomic depression to create a shallow pool (Figure 153-22). Firmly maintain the patient's head in this position until they spontaneously open their eyes and allow the medication to spread across the globe.

Ophthalmic Anesthetic Agents

Two types of eye medications are required in drop form for most routine ophthalmologic examinations, a topical ophthalmic anesthetic agent, and a dilating agent. Topical ophthalmic anesthetic agents provide relief from eye pain and photophobia. This may help the patient to cooperate with the necessary examination. Topical ophthalmic anesthetic agents may be used as adjuncts to fluorescein application and to facilitate the placement of eyelid retractors. They may at times be used as an adjunctive diagnostic tool. There are several possible causes of eye pain and photophobia that must be differentiated, some of which may coexist. Complete symptom relief with a topical ophthalmic anesthetic agent suggests that the etiology of the pain is the conjunctiva or cornea.

Tetracaine hydrochloride and proparacaine hydrochloride are the most commonly available agents. Their onset of action and duration of action are similar. The onset is within 1 minute and lasts approximately 10 to 20 minutes. Tetracaine hydrochloride (Pontocaine) instillation often results in a transient stinging sensation that lasts 3 to 10 seconds before dissipating. Proparacaine hydrochloride (Ophthetic or Ophthaine) does not result in the stinging sensation.

Topical ophthalmic anesthetic agents are toxic to corneal epithelial cells and can delay corneal healing.15 They are currently used in the Emergency Department only to aid in the diagnosis and evaluation of an eye problem. They should not be prescribed for treatment outside the Emergency Department except by an Ophthalmologist. These agents are currently being used for up to 4 days on an outpatient basis after photorefractive keratectomy surgery.16 Several small studies suggest these agents are safe to use for a few days without adverse effects.17,18 With additional studies, the Emergency Department practice of not prescribing topical ophthalmic anesthetic agents for outpatient use may change.

Pupillary Dilating Agents

Dilating agents are used as an adjunct to the fundoscopic examination. Always perform and document a complete pupillary examination before instilling dilating agents. It is important to document the use of dilating agents and the time of administration. Avoid using dilating agents in patients who require serial pupillary examinations to follow their neurologic status. Dilating agents are contraindicated in patients with a known or suspected narrow iridocorneal angle. Dilating the pupil may result in acute angle-closure glaucoma. Some intraocular lens implants may become dislodged if the pupils are pharmacologically dilated. Inquire about ocular surgery, known narrow angles, and glaucoma prior to dilating any pupils.

Dilating agents are categorized as mydriatics and cycloplegics. All dilating agents are stocked with red caps. Mydriatic agents directly dilate the pupil while cycloplegics paralyze the ciliary muscles. Cycloplegic agents should not be used in patients who require serial neurologic examinations. Choose a noncycloplegic mydriatic agent such as phenylephrine to dilate the pupils of a patient requiring serial examinations. The duration of action is significantly shorter than that of a cycloplegic agent. Phenylephrine is systemically absorbed and may be inappropriate for patients with hypertension or cardiac conditions. A combination of a mydriatic agent (e.g., phenylephrine) and a shorter-acting cycloplegic agent (e.g., cyclopentolate) is optimal when maximal dilation is necessary or when a single agent is ineffective.

Most Emergency Departments stock or have access to five dilating agents. The choice of agents depends upon the length of time required for dilation, the need for a cycloplegic agent, and the need for a mydriatic agent. Atropine (Isopto Atropine) produces cycloplegia lasting 5 to 10 days and mydriasis lasting 7 to 14 days. Cyclopentolate (Cyclogyl, AK-Pentolate, Pentolair) produces cycloplegia lasting 6 to 24 hours and mydriasis lasting 24 hours. Homatropine (Isopto Homatropine) produces cycloplegia and mydriasis lasting 1 to 3 days. Phenylephrine (Neo-Synephrine, Mydrin, Relief) produces mydriasis lasting 5 hours. Tropicamide (Mydriacyl) produces mydriasis lasting 4 to 6 hours.

A fundoscopic examination is an essential part of every eye evaluation. It is particularly helpful when the patient complains of visual disturbances or visual loss. Examine the patient's right eye first. Hold the ophthalmoscope in the right hand and use the right eye to examine the patient's right eye. Remember “right eye to right eye and left eye to left eye” or the Emergency Physician may otherwise find themself in an awkward nose-to-nose position with the patient. Instruct the patient to focus the eye not being examined on a fixed object over the Emergency Physician's shoulder and approximately 6 to 8 feet away. It is important that the patient maintain their focus on the object throughout the complete examination of the eye.

Set the ophthalmoscope initially at 0. Adjust the dial as the examination begins to adjust for refractory errors. Moving the dial into the red numbers moves the point of focus forward toward the red retina. Moving the dial into the black numbers moves the point of focus closer to you. Approach the eye from a slightly lateral position to quickly identify the medial position of the optic disk. Position the ophthalmoscope as close as possible to the patient's eye without making contact. Imagine looking at the fundus through a peephole. The closer you get, the wider the view on the other side. By the same analogy, the larger the peephole the better the view on the other side. Thus, dilate the patient's pupils to obtain the best results from the ophthalmoscope examination.

Adjust the diameter of the light down to the size of the patient's pupil in order to avoid the bright reflection off of the iris if dilation is not possible. This bright reflection is a common reason for inadequate visualization of the fundus. The patient's eyes are often moving if the structures seem to move in and out of focus. Remind the patient to focus on one point in the distance.

Inspect the eye grounds for uniformity. The normal color of the fundus is creamy peach to pink, but may be pigmented in darker skinned people. A pale fundus with a small cherry-red spot in the region of the macula suggests an infarction generally associated with a retinal artery occlusion. The optic disk is located on the nasal aspect of the fundus. If the optic disk does not come into view, follow the blood vessels that extend from the disk to the periphery of the retina. The disk margin should be sharp with the exception of the nasal aspect that may appear slightly blurred in a normal eye. Papilledema appears as diffusely blurred disk margins. Papilledema may be the result of localized inflammation of the optic nerve or may be the result of elevated intracranial pressure.

The veins will appear darker and wider than the arteries. Evaluate the blood vessels for evidence of hemorrhages and irregularities. Acute hemorrhages may be helpful in the diagnosis of a variety of problems such as a hypertensive emergency or the shaken baby syndrome. Give careful consideration to the clinical setting. A helpful finding in the patient suspected of having increased intracranial pressure is the presence or absence of venous pulsations. Venous pulsations are best seen as the veins cross into the optic cup. The presence of venous pulsations is a normal finding. The first sign as the intracranial pressure rises is a loss of venous pulsations followed later by papilledema. The green light or red filter helps to provide a sharper image when evaluating the retinal vessels in detail.

Examine the fovea and the surrounding macula. This area is located approximately two to three disk diameters (DD) lateral to the optic disk. Instruct the patient to look directly into the light to bring the fovea and macula into view. The target setting on the ophthalmoscope is helpful for this purpose. Look into the patient's eye with the ophthalmoscope turned to the target. Instruct the patient to look directly into the center of the target. The fovea will be found at the center of the target in your view as well.

Examine the vitreous chamber for evidence of a vitreous hemorrhage when a retinal detachment is suspected or when the patient complains of floaters. The fluid within the vitreous chamber is gelatinous so blood within it does not dissipate quickly. Blood within this chamber appears as clouds, spots, or veils to the patient and the examiner. Their color is typically described as black or red. Set the ophthalmoscope to +10 to move the point of focus anteriorly toward the examiner's eye to evaluate the vitreous. Dial the ophthalmoscope down as the examination proceeds. Each click results in focusing a little deeper within the vitreous chamber until the point of focus is upon the retina at the posterior aspect of the chamber.

The measurement of intraocular pressure should be included in the eye examination. It is particularly important in patients with eye pain and visual loss. Refer to Chapter 156 regarding the complete details of ocular tonometry.

Approach all eye complaints with a detailed history that includes a chief complaint, the duration of symptoms, and the natural history of their evolution. It is important to inquire about exposures and trauma. The past medical history must include the patient's baseline visual acuity and any history of eye problems. Perform a complete examination on all patients with eye complaints. Always document an accurate visual acuity and carefully inspect all of the eye structures. A thorough approach in all patients with eye complaints improves diagnostic accuracy. The end result is decreased morbidity and long-term complications in this vital sensory apparatus.