Ophthalmologic Procedures

Indications

Visual acuity should be assessed as soon as practicable and before the patient is examined with bright lights. In the event of blepharospasm from an injury (e.g., abrasion, chemical exposure), a topical anesthetic may facilitate the examination. Patients with eye complaints often say that they “can't see.” In these instances, emergency visual acuity assessment should be performed first, beginning with evaluation of light perception, then hand motion, and finally counting fingers at 3 ft ( Fig. 62.1 ). If the patient succeeds in performing these assessments, a near vision card may then be used or distant visual acuity assessed. In emergency circumstances, detailed formal vision testing is not essential; however, some form of visual acuity assessment is needed. In this situation, the ability to count fingers or read newsprint gives some indication of gross visual function. Formal visual acuity testing should never delay critical therapeutic interventions such as eye irrigation in the case of eye exposures.

Distant Visual Acuity Procedure

For formal vision testing, ask the patient to face a well-lit standard Snellen or similar eye chart from a premeasured distance of 20 ft. Use a card or the palm of the hand to occlude one eye at a time. If possible, examine all patients while wearing their current lens correction to obtain the best corrected distant visual acuity. If not available, measure visual acuity first without correction and then with a pinhole device, and note any improvement in visual acuity. The pinhole device functions as a corrective lens by eliminating divergent light rays and allowing light only through the center of the lens, thus reducing corneal refractive error. In general, visual acuity is improved with the pinhole device. Decreased visual acuity that is not improved with this device suggests that corneal refractive error is not the cause. Construct a pinhole device by punching one to several holes in the center of a card (3 × 5 inch index card) with an 18-gauge needle. Devices with one or more pinholes drilled into an eye cover are available commercially ( Fig. 62.2 A and B ) or can be constructed from readily available material in the ED, such as the index card with holes just mentioned ( Fig. 62.3 ). Fig. 62.2 C presents a chart for testing visual acuity while the patient is on a stretcher or in a chair. The chart can be used directly from this text if held 14 inches from the eye. Begin by testing the affected eye or the one presumed to have the worst visual acuity. First, instruct the patient to read the smallest letters on the chart that can easily be seen. Then ask the patient to read letters that can just barely be made out (i.e., they do not have to be clear). If the patient is unable to read the largest letter on the chart, move the patient to half the distance from the chart (10 ft), or if using the figure in this text, move it 7 inches closer to the eye and repeat the procedure. Record the results reflecting the change in distance (e.g., 10/200). The numerator in the vision ratio is the distance of the patient from the chart and the denominator is the distance at which a patient with normal vision can read the line of letters. For patients who still cannot read the letters on the chart, test vision progressively as follows: the ability to count fingers, detect hand motion, and perceive light (with or without projection; i.e., the ability to perceive the direction of light), and finally, the inability to perceive light.

Near Visual Acuity Procedure

Perform near visual acuity assessment in the ED at the bedside or at triage. Hold a pocket near vision card (see Fig. 62.2 C ) or any printed material in good light at a distance of approximately 14 inches in front of the patient and occlude each eye alternately as described earlier. Alternately, an “app” may be used from a smart phone device, but directions vary and not all apps measure near distance. When using available printed material in lieu of a near vision card, measure the size of the letters that are discerned by the patient. At a later time compare these letters with the size of the letters on the near vision card to deduce the patient's actual visual acuity. When near vision is decreased, it is usually caused by either loss of visual function or poor accommodation as a result of advancing age (presbyopia). Less commonly, it is caused by traumatic mydriasis. Thus, examine patients with presbyopia with their reading correction in place to obtain the best corrected near visual acuity.

For patients who cannot communicate or in whom factitious blindness or malingering is suspected, check for optokinetic nystagmus (OKN) to determine whether the visual pathway is intact. To test for OKN, pass a regularly sequenced pattern in front of the eyes. If an optokinetic drum is available, rotate the drum in front of the patient ( Fig. 62.4 ). This is not available in many EDs, however multiple apps are available for use with an iPhone or smart phone which show a moving stripe which elicits nystagmus. Some apps have the ability to record the nystagmus in a video format (Optokinetic Drum Proversion 1.0, Bluestone Publishing, Inc, updated Sept 18, 2015). In place of the drum, substitute a printed piece of paper such as newsprint (without photographs or large areas with no print) or a standard tape measure. Pass it in front of the patient's eyes at reading distance while instructing the patient to look at it as it moves rapidly by. Evaluate for tracking as demonstrated by involuntary nystagmus-like eye movements seen when the test object is moved from side to side in front of the patient. Such movement indicates an intact visual pathway. Finally, another effective method is to hold a mirror in front of the patient and slowly rotate the mirror to either side of the patient. Patients with an intact visual pathway will maintain eye contact with themselves as demonstrated by eye movement as the mirror is moved. A large mirror that reflects the patient's entire face is most effective for this purpose.

All patients with decreased visual acuity from baseline require routine referral for further ophthalmologic follow-up; however, patients with moderately or severely decreased visual acuity not explained by refractive error require ophthalmologic consultation in the ED.

Indications and Contraindications

Application of topical anesthetic agents can be both diagnostic and therapeutic. Relief of discomfort with a topical anesthetic strongly suggests, but does not ensure, a conjunctival or corneal injury. An ocular irritant may also be masked by the use of these agents. Classic teaching is that patients should not self-administer anesthetic preparations. It is thought that they delay wound healing by disrupting surface microvilli and causing a decrease in the tear film layer and tear break-up time. Although self-administered topical anesthetic agents are now routinely used after photorefractive keratectomy for the first 3 or 4 postoperative days, this likely safe technique has not yet become a common ED practice.

As evident from Table 62.1 , the anesthetic solutions commonly used have a duration of action of less than 20 minutes, though tetracaine may have a slightly longer clinical effect. Patients with a large corneal lesion may need a more extended period of pain relief and may require bed rest, opioid analgesics, and/or appropriate sedatives.

A final word of caution should be added regarding the use of ophthalmic solutions. Guaiac solutions are commonly supplied in dropper bottles similar in size and appearance to those containing ophthalmic solutions. Well-intentioned ED personnel may store the guaiac reagent bottles with the ophthalmic bottles. One should encourage both color coding of the bottles and examination of them and their labels before each use to avoid corneal injury from inadvertently instilling guaiac reagent into the eye.

Procedure

Instillation of anesthetic or analgesic agents is similar to the administration of other eye solutions as described later. Forewarn the patient that the medication will sting transiently on instillation but will quickly offer relief. Repeat instillation in one minute to ensure maximum effect. Instruct the patient not to rub the insensate eyes to avoid causing or worsening an abrasion. Provide the patient material to blot the eyes gently, if needed, as tearing occurs.

Complications

Open bottles can harbor bacteria and introduce infection. Out-of-date medication may not be effective and result in inadequate anesthesia. The absence of protective reflexes while the patient is under the effect of the medication may encourage use of the eye and result in further corneal injury from the foreign body (FB) or corneal infection.

A systemic review of the safety of topical anesthetics in the treatment of corneal abrasions found corneal erosions, edema, or iritis reported when agents were used for prolonged periods of time (up to 10 weeks), too often (up to every 15 minutes), and with higher concentrations. Delayed corneal healing has been long taught as a significant complication of topical anesthetic and analgesic agents, but several well-designed randomized clinical trials in the ED-based and ophthalmology (PRK surgery) literature report no adverse events from topical anesthetic use and corneal re-epithelialization occurring by 72 hours, indicating that any delay in healing does not appear to be clinically significant. Thus, though not currently used for routine outpatient treatment, topical anesthetic drops can be considered for use safely for 2 to 3 days without documented adverse effects in selected patients.

Indications and Contraindications

There are several diagnostic and therapeutic indications for dilating the pupil. Dilation is indicated for diagnosis when the fundus cannot be examined adequately through an undilated pupil. An elderly patient with miotic pupils and cataracts is an example of a patient in whom dilation may facilitate funduscopic examination. Dilation is therapeutically useful for many ophthalmic conditions, including inflammation of the eye. In the emergency setting, corneal injury with secondary traumatic iritis is a common example. Dilation helps the inflamed eye in two ways. First, it may help to prevent adhesions (synechiae) from forming between the iris and other ocular structures. Such adhesions eventually limit movement of the pupil and may precipitate glaucoma. Second, cycloplegic dilating agents relax the ciliary muscle spasm that often accompanies an inflamed eye and thus may reduce the pain associated with inflammation. Though traditionally used for these purposes, both benefits are largely theoretical with little formal evidence to support or refute their use in the ED.

Dilation is discouraged in patients with head injury who are at risk for herniation when it is necessary to monitor pupil findings. Dilation is contraindicated in the presence of narrow anterior chamber angles. Patients predisposed to having narrow angles may be unaware of this condition. Evaluate the depth of the anterior chamber before this procedure, and do not dilate the eye if there is any question of a narrow angle.

To estimate the depth of the anterior chamber, shine a penlight tangentially from the lateral side of the eye. When the depth of the anterior chamber is normal, uniform illumination of the iris is seen. However, when the iris has a forward convexity as in the case of a narrow anterior chamber, only a sector of iris is illuminated and there will be a shadow on the medial (nasal) side of the iris ( Fig. 62.5 ). With a slit lamp, the depth of the anterior chamber angle can be assessed directly. The definitive test for assessing the anterior chamber angle is gonioscopy, in which the anterior chamber angle structures are viewed directly by means of a special mirrored contact lens and a slit lamp. Gonioscopy is not a technique normally performed by emergency clinicians.

Systemic effects can develop after the application of eye drops. Review the following sections on agents and complications before using these drugs in patients with compromised cardiovascular function.

Agents

Only two dilating agents are really needed in the ED. Phenylephrine (Neo-Synephrine, Hospira, Inc., Lake Forest, IL) 2.5%, a potent sympathomimetic, is used for diagnostic dilation of the pupil and visualization of the fundus. The drug is short acting, and because accommodation is not affected, the patient's vision is not altered. Phenylephrine 10% should not be used routinely because it can be absorbed systemically and, in rare cases, has caused hypertensive crisis, myocardial infarction, and death.

For therapeutic cycloplegia in patients with iritis, 5% homatropine works well. Even though Table 62.2 indicates a maximum duration of 3 days, 24 hours is more common. Therefore 5% homatropine is a useful therapeutic agent for traumatic iritis. Atropine itself should not be used for traumatic iritis because the undesirable effects of pupillary dilation and blurred vision persist for a week or longer after the associated corneal abrasions have healed. Atropine drops may be prescribed as part of the therapy for nontraumatic iritis after appropriate ophthalmologic consultation. Individuals with lightly pigmented irides tend to have greater sensitivity to cycloplegic agents than do individuals with greater pigmentation; the cycloplegic effect might therefore be more prolonged in people with light eyes. It might be difficult to dilate some patients with deeply pigmented irides, however, and numerous applications of drops might be required.

Malingerers may use mydriatic agents to dilate a pupil unilaterally for the purpose of feigning neurologic disease. Normally, the pupillary dilation caused by intracranial compression of the third cranial nerve will constrict with 2% pilocarpine eye drops. A mydriatic-treated eye can be identified by full motor function of the third cranial nerve and absence of miosis after the instillation of pilocarpine. A fixed and dilated pupil in an awake and alert patient cannot be secondary to brain herniation. Although other neurologic problems may be present, in a normal-appearing patient with a fixed and dilated pupil, a pharmacologic cause is highly likely. It should be noted that legitimate patients may not recall the name of an eye medicine that they used but will usually recall whether the bottle had a red cap, as is found on all cycloplegic solutions marketed in the United States, though these agents are marketed in some countries (e.g., Greece, Turkey, India) with different colored caps. An unexpected mydriasis in a trusted patient may be the result of such an agent. Medications that constrict the pupil, such as pilocarpine, generally have a green cap. Pressure-lowering drops for glaucoma may be yellow or blue topped (β-blockers), purple topped (adrenergic agents), or orange topped (topical carbonic anhydrase inhibitors).

A fixed and dilated pupil from a pharmacologic cause may be encountered after both nasotracheal and orotracheal intubation ( Fig. 62.6 ). In such ill or injured patients, cerebral herniation must be considered. When phenylephrine is used to constrict the nasal mucosa before nasal intubation (endotracheal tube, nasogastric tube), inadvertent spread to the eye can result in a fixed and dilated pupil. The same scenario may occur during resuscitation when endotracheal epinephrine has been instilled into the lungs and cardiopulmonary resuscitation has expelled epinephrine into the eye. In such scenarios, the affected pupil will not constrict after intraocular pilocarpine administration. Finally, a fixed and dilated pupil might occur as a result of inadvertent contamination of the eye with scopolamine after the application of a scopolamine patch.

Procedure

Instillation of mydriatic agents is similar to the administration of other eye solutions. For medicolegal purposes, note the patient's visual acuity before instillation of the medicine. This documents that any decreased vision is not the result of the mydriatic agent. Whenever dilation is performed, note on the patient's chart the dose and time that agents have been given to avoid confusion during subsequent neurologic evaluation.

Place the patient in a supine or a comfortable semirecumbent position. Instruct the patient to gaze at an object in the upper visual field, such as a fixture on the ceiling. Gently depress the lower lid with a finger on the epidermis. Instill a single drop of the solution into the lower lid fornix, and ask the patient to blink to spread the medication. Do not use more than a single drop because it produces reflex tearing and reduces the concentration in contact with the conjunctiva. Forewarn the patient that the medication is uncomfortable when it goes into the eyes. After the medication has been instilled, the patient may blot the eye when it is closed but should not rub it with a tissue. If the desired effect is not noted in 15 to 20 minutes, repeat the dose, but this is seldom required.

Complications

Any dilator can precipitate an attack of angle-closure glaucoma in susceptible patients. In the case of angle-closure glaucoma, it may take several hours before symptoms become evident. The patient often complains of smoky vision with “halos” around lights, as well as an aching pain that at times can be quite severe. Nausea and vomiting may occur. If the affected eye becomes infected in association with a hazy cornea, elevated pressure on tonometry, and an oval, fixed pupil, consult an ophthalmologist immediately. Place the patient supine and administer analgesics and antiemetics. Treatment usually includes the agents suggested in Box 62.1 , and later, definitive laser or surgical procedures.

Be aware that if contaminated, an eye medication can introduce infection. Most solutions contain bactericidal ingredients, but contamination of the tips of droppers can still occur ( Fig. 62.7 A ). Use only newly opened bottles of eye medication or single-use vials, particularly if the patient has a deep corneal injury or has recently undergone eye surgery. Promptly discard out-of-date drops and those in which crust or other material is found around the nozzle.

Forewarn the patient that any cycloplegic (in contrast to a sympathomimetic) will blur a patient's near vision. Vision will be less blurred in adults older than 45 years, who generally have a reduced ability to focus for near vision. Although most adults will be able to drive safely, even with both eyes affected, it is advisable to have someone else drive whenever feasible. Light sensitivity caused by pupillary dilation may also be bothersome; sunglasses are sufficient for this problem.

Systemic reactions may rarely be induced by sympathomimetic and cycloplegic eye drops. In one report of 33 cases of adverse reactions associated with 10% phenylephrine, there were 15 myocardial infarctions (11 deaths), 7 cases of precipitation of angle-closure glaucoma, and a variety of systemic cardiovascular or neurologic reactions.

After instillation of eye drops into the conjunctival sac, systemic absorption can occur through the conjunctival capillaries, as well as by way of the nasal mucosa, the oral pharynx, and the gastrointestinal tract after passage through the lacrimal drainage system. Mucosal hyperemia enhances absorption. Symptoms can often be avoided by maintaining digital pressure on the nasal canthus to occlude the puncta for several minutes after administration (see Fig. 62.7 B ).

Indications and Contraindications

Fluorescein staining is indicated for the evaluation of suspected abrasions, FBs, and infections of the eye, including “simple” cases of conjunctivitis, which may actually be herpetic keratitis. Exposure of the face to pepper spray has been associated with corneal abrasions, and such patients should undergo fluorescein staining and be evaluated with a slit lamp or Wood's lamp. Corneal defects may be seen after even a few seconds of unprotected viewing of a welder's arc flame.

Fluorescein permanently stains soft contact lenses. Therefore when fluorescein is used, remove soft contact lenses before instilling the fluorescein and caution the patient to not put the lenses back into the eye for several hours. Topically administered fluorescein is considered nontoxic, although reactions to a fluorescein-containing solution (not impregnated strips) have been described. These reports, which consist of vagal reactions and generalized convulsions, are rare, not rigorously supported, and believed to be caused by agents other than fluorescein in the solution. If using one of these fluorescein-containing solutions rather than the fluorescein-impregnated strips, be aware of these potential, yet scientifically suspect idiosyncratic reactions.

In addition, be aware that fluorescein dye may enter the anterior chamber of the eye in patients with deep corneal defects. This form of intraocular fluorescein accumulation is nontoxic. When the anterior chamber is viewed under the blue filter of the slit lamp, a fluorescein “flare” is visible and should not be confused with the flare reaction noted with iritis.

Procedure

Theoretically, one should not use topical anesthetics before fluorescein staining because a superficial punctate keratitis may develop in some patients from the anesthetic, which can confuse the diagnosis. However, in patients who are tearing profusely and squeezing their eyes shut from an abrasion or an FB, the examination is often impossible if a topical anesthetic is not first used. Thus, it is practical to apply a local anesthetic before instilling fluorescein.

Grasp the fluorescein strip by the non-orange end and wet the orange end with 1 drop of saline. Several convenient forms are available, including a small bottle of artificial tears or a 5-mL “bullet” or “fish” of normal saline commonly used for nebulizer treatments. Alternatively, wet the strip with tap water or the recently used local anesthetic drops. Once the strip is moistened, place it gently on the inside of the patient's lower lid ( Fig. 62.8 , step 1 ). Withdraw the strip and ask the patient to blink, which spreads the fluorescein over the surface of the eye. The key to a good examination is to have a thin layer of fluorescein over the corneal and conjunctival surfaces. If the strip is too heavily moistened before placing it in the lower fornix, the eye may become flooded with the solution, which makes evaluation difficult. If too much dye accumulates, the patient can remove the excess dye by blotting the closed eye with a tissue. Conversely, placing a dry strip in an unanesthetized eye may be irritating. Next, use a Wood's lamp (4× magnification), the blue filter of a slit lamp, or simply a penlight with a blue filter to examine the eye in a darkened room (see Fig. 62.8 , step 2 ). Check for areas of bright green fluorescence on the corneal and conjunctival surfaces. The naked eye may not be able to see small defects. Ideally, use a slit lamp with 10× or 25× magnification to examine the stained cornea before ruling out a pathologic process. A new handheld magnification device, the Eidolon Bluminator ophthalmic illuminator (Eidolon Optical, LLC of Natick, MA), produces an intense blue light from a light-emitting diode with 7× magnification (see Fig. 62.8 , step 3 ). After completion of the fluorescein examination, irrigate excess dye from the eye to minimize damage to the patient's clothing from dye-stained tears.

The Seidel test uses fluorescein to detect perforation of the eye. To perform this test, instill a large amount of fluorescein onto the eye by profusely wetting the strip. Examine the eye for a small stream of fluid leaking from the globe (see Fig. 62.8 , plate 4 ). This stream will fluoresce blue or green, in contrast to the orange appearance of the rest of the globe flooded with fluorescein.

Interpretation

Fluorescein is used mainly for evaluation of corneal injuries. Although conjunctival abrasions pick up the stain, most of the staining on the conjunctiva represents patches of mucus rather than a real pathologic condition. Corneal staining is more specific for injury, and the pattern of injury often reflects the original insult.

Corneal staining patterns are illustrated in Figs. 62.8 and 62.9 . Abrasions usually occur in the central part of the cornea because of the limited protection of closure of the patient's eyelids. The margins of the abrasions are usually sharp and linear if seen in the first 24 hours (see Fig. 62.8 , plate 6 ). Circular defects are seen about embedded FBs and may persist for up to 48 hours after removal of a superficial foreign object. Deeply embedded objects may be associated with defects persisting for longer than 48 hours. Objects under the upper lid (including some chalazia) often produce vertical linear lesions on the upper surface of the cornea (see Fig. 62.8 , plate 7 ). When vertical lesions are noted, search diligently for a retained FB under the upper lid. Overuse of hard contact lenses diminishes the nutrient supply to the cornea. The central part of the cornea sustains the most injury and thus fluoresces brightly when stained. Excessive exposure to ultraviolet light as a result of sunlamp abuse, snow blindness, or welding flashes produces a superficial punctate keratitis, which in its mildest form may not be visible without a slit lamp (see Fig. 62.8 , plate 8 ). The central part of the cornea is the least protected by the lids, and a central, horizontal band–like keratitis can result. Herpetic lesions may develop anywhere on the cornea. Classically, these lesions are dendritic, although ulcers may also be punctate or stellate (see Fig. 62.8 , plate 9 ).

Any area of corneal staining with an infiltrate or opacification beneath or around the lesion should alert the practitioner to the possibility of a viral, bacterial, or fungal keratitis. Obtain urgent ophthalmologic consultation so that cultures of the possible etiologic agents can be procured and appropriate treatment initiated.

Many Pseudomonas organisms fluoresce when exposed to ultraviolet light ; therefore the presence of fluorescence before the instillation of fluorescein in a red eye should suggest the possibility of infection with this organism.

Summary

Fluorescein staining is a quick and easy diagnostic procedure that should be part of every eye evaluation. The extra time that the examination takes provides a wealth of diagnostic information on patients with eye trauma or infection. No complications are associated with the procedure with the exception of the reactions noted with the fluorescein solution, possible discoloration of soft contact lenses, and the potential for infection when premixed solutions rather than fluorescein-impregnated paper strips are used.

Indications and Contraindications

Irrigation is indicated for all acute chemical injuries involving the eyes. Irrigation may also be therapeutic in patients with an FB sensation but no visible FB. Small, unseen foreign material in the conjunctival tissues may be flushed out with irrigation. There is no contraindication to eye irrigation, but in patients with a possible perforating injury, perform the irrigation especially gently and carefully.

Equipment

The following equipment is necessary for eye irrigation:

• Topical anesthetic, such as 0.5% proparacaine

• Sterile irrigating solution (warmed intravenous saline or lactated Ringer's [LR] solution in a bag with tubing) *

  * A balanced salt solution designed for eye irrigation is preferred by some (when available) and may produce less corneal edema with chemical injuries. Readily available normal saline and lactated Ringer's solution are equally well tolerated.

• A basin to catch the fluid

• Cotton-tipped applicators

• Gauze pads to help hold the patient's lids open

• Lid retractors

• Irrigating device (e.g., Morgan Therapeutic Lens [MorTan Inc., Missoula, MT], modified central venous catheter, or Eye Irrigator) for prolonged irrigation

• Optimal: 10 mL of 1% lidocaine added to a liter of irrigating fluid

Procedure

Basic Technique

First, instill a topical anesthetic into the eye ( Fig. 62.10 , step 1 ). Evert the eyelid and sweep out any particulate matter in the conjunctival fornices with a moistened, cotton-tipped applicator (see later section on Ocular FB Removal and Fig. 62.10 , step 2 ). Hold the eyelids open during irrigation (see Fig. 62.10 , step 3 ). The easiest method is to use gauze pads to grasp the wet, slippery lids and hold them open. If the patient has severe blepharospasm, consider using lid retractors (Desmarres [Sklar Surgical Instruments, West Chester, PA] or paper clip retractors; Fig. 62.11 ). When lid retractors are used, be certain that the eye is well anesthetized, that the retractors do not injure the globe or the lids, and that chemicals are not harbored under the retractors. Be aware that simple retractors fashioned from metal paper clips (especially those that are nickel plated and shiny) may have surface chipping, which can create an ocular FB. Exercise caution to avoid ocular injury when using such a makeshift retractor.

Deutsch and Feller recommended an ipsilateral facial nerve block for severe blepharospasm ( Fig. 62.12 ). To avoid swelling of periorbital tissue, block the facial nerve just anterior to the condyloid process of the ipsilateral mandible. Place a subcutaneous line of anesthetic (2% lidocaine) to temporarily paralyze the orbicularis muscle.

Irrigate with normal saline or LR solution directed over the globe and into the upper and lower fornices (see Fig. 62.10 , step 4 ). The choice of fluid initially is less important than initiating irrigation as rapidly as possible. If tap water is available at the scene of the injury, begin irrigation immediately with copious amounts of fluid before transporting the patient to the hospital. Teach out-of-hospital care providers to irrigate all acid injuries of the eye for at least 5 minutes at the scene and to irrigate all alkali injuries for at least 15 minutes. LR or normal saline solution is preferred over tap water or 5% dextrose in water for eye irrigation because these solutions are isotonic and do not contain dextrose. Dextrose can be quite sticky if spilled and might serve as a nutrient for an opportunistic bacterial infection. Although one clinical trial found a balanced salt solution less painful in patients with a chemical eye injury, another volunteer study on uninjured eyes found that LR solution is better tolerated than normal saline and balanced saline solution when used with a Morgan lens. Warmed fluids are also better tolerated than fluids at room temperature. Warmed LR solution should be considered when both it and normal saline are available for eye irrigation.

Be careful to direct the irrigating stream onto the conjunctiva and then across the cornea without letting the stream splash directly onto the cornea because striking the eye with the solution can in itself be harmful and cause mechanical injury (see Fig. 62.10 , step 5 ). Direct irrigation of the cornea can result in the development of a superficial punctate epithelial keratopathy.

Before irrigation, instill anesthetic eye drops, such as 0.5% tetracaine. Adding 10 mL of 1% lidocaine to a liter of irrigating fluid can decrease the patient's discomfort during prolonged irrigation.

Prolonged Irrigation

Alkaline burns may require prolonged irrigation, and it is essential to consult ophthalmology in such cases. The Morgan Therapeutic Lens is a contact lens–type irrigation device that can provide slow, continuous irrigation once the more vigorous initial irrigation has been completed ( Fig. 62.13 and Video 62.3 ). First, anesthetize the eye with topical anesthetic drops. Then place the device carefully on the surface of the eye with the lids closed around the intravenous tubing adaptor. Attach the intravenous tubing to the adaptor and provide continuous flow through the device onto the cornea and into the fornices. As the local anesthetic agents wash out during the irrigation process, the device can become uncomfortable, so reapply the anesthetic drops frequently during irrigation for patient comfort. Such short-term use of local anesthetics will not inhibit healing of the cornea.

Complications

The only significant complication from irrigation is abrasion of the cornea or the conjunctiva. This can be a mechanical injury from trying to keep the lids open in an uncooperative patient, a small corneal epithelial defect from a Morgan irrigating lens, or fine punctate keratitis from the irrigation itself. For this reason, do not direct the stream directly onto the cornea. If a superficial corneal defect occurs, treat it in the usual manner. Deep or penetrating corneal injuries are likely to be a result of the caustic chemical and require emergency ophthalmologic consultation. Continue to provide slow continuous irrigation pending arrival of the ophthalmologist. Some experimental evidence suggests that massive parenteral or oral ascorbic acid supplementation may prevent the development of deep corneal injury, but such treatment has not gained universal acceptance.

Summary

Eye irrigation is easy, and complications associated with the technique are usually minimal. At times the clinician may be unsure whether a chemical injury is toxic enough to warrant irrigation. If any doubt exists, err on the side of irrigating the eye rather than omitting this vital procedure and risking progression of the eye injury.

Indications and Contraindications

Bedside ED ocular ultrasonography may be appropriately used as an adjunct in the evaluation of altered vision, suspected FB, ocular pain, headache, eye trauma, head injury, or altered mental status. Conditions that are reliably diagnosed include globe rupture, intraocular FB, vitreous hemorrhage, lens dislocation, retinal detachment, and elevated intraocular pressure.

There are no absolute contraindications for bedside ED ocular ultrasound, given proper equipment, an experienced sonographer, and a cooperative patient. The evaluation of a potential open globe deserves special mention. Whereas it is generally true that the eye should be protected from further manipulation after suspecting an open globe, evaluation with bedside ED ocular ultrasound is the exception. It is imperative that the EP performing the bedside ultrasound be mindful of the possibility of an open globe and utilizes the no pressure technique described later. An immediate benefit is gained when the EP carefully uses this technique to avoid a delay in diagnosis and treatment. Any delay incurs an increased risk of adverse outcome. In general, the benefit obtained from the use of bedside ED ocular ultrasound outweighs the risk of further examination of the eye in this setting. That said, if the physical exam obviously suggests open globe pathology, the clinician is discouraged from this procedure, as it carries the risk of vitreous extrusion (even with minimal globe compression) with little benefit to the diagnostic evaluation.

Equipment

Appropriate ultrasound machine with linear array transducer, 7.5 to 10 mhz or higher.

Procedure

Ensure ultrasound equipment is clean and disinfected. Adjust setting on machine for ocular ultrasound. Place the patient in a recumbent or semi-reclined position to minimize runoff of gel. Instruct the patient to keep eyes closed, but not clenched, to look straight ahead, and not to move the eyes. It is suggested that the closed eye be covered with a large piece of clear Tegaderm dressing (3M, St. Paul, MN) to facilitate the ultrasound examination without contaminating it with gel or the probe. Place a copious amount of gel over the Tegaderm dressing or closed eyelid to be examined, enough to completely fill the sulcus formed by the eye so that the transducer can touch the gel in a transverse plane without touching the eyelid and without breaking contact of the transducer with the gel ( Fig. 62.16 ). Hold the transducer in such a way so that the examiner's hand can stabilize the probe against movement by resting the hand on the patient's forehead, bridge of the nose, or maxilla ( Fig. 62.17 ). Barely touch the probe to the gel without applying pressure to the eyelid (no-pressure technique) ( Fig. 62.18 ). Maintain this contact throughout the examination. As soon as the probe touches the gel, the ocular structures should immediately come into view. Adjust probe position to obtain a clear cross section of the eye showing anatomic structures (anterior chamber, iris, lens, vitreous, retina, nerve sheath). Adjust gain for a clear image, starting with maximal settings and reducing it until structures come into view again. Position the optic nerve in the middle of the screen and adjust the depth to view approximately 1 cm of the optic nerve. Identify the optic structures ( Fig. 62.19 A ). Identify abnormal findings (see Figs. 62.19 B and C ), and describe abnormal findings in the caption. Use multiple planes to clarify normal and abnormal findings. A direct and consensual pupillary light reflex can be observed by viewing the pupillary response to light via ultrasound.

To measure optic nerve sheath diameter, ask the patient to adjust the gaze of the examined eye, approximately 10 degrees laterally. When viewed at this angle, the optic nerve is aligned with the ultrasound beam and decreases the possibility of obtaining a falsely widened measurement. This can occur if the optic nerve is imaged at an angle. Measure the width of the optic nerve sheath 3-mm deep to the retina ( Fig. 62.20 ). Obtain at least two measurements and average for a final measurement. A diameter of greater than 5 mm is considered to be widened and suggests increased intracranial pressure.

Complications

Inadvertent pressure applied to an eye with a ruptured globe could result in further damage to the globe. Excessive scan times could exceed exposure limit guidelines.