Ординатура / Офтальмология / Английские материалы / Practical Ophthalmology A Manual for the Beginning Ophthalmology Residents 4th edition_Wilson_1996

356 Chapter 14: Ophthalmic Emergencies

Use a papoose board to restrain an uncooperative child during the examination. If the globe is open, however, the papoose board should not be used; it may provoke straining and elevated intraocular pressure, which could lead to extrusion of ocular contents. Alternatively, swaddle a small child or infant tightly (see Chapter 9), or ask a nurse or parent to help restrain an uncooperative child. Consider sedation only as a last resort. If it is necessary, sedate the child under controlled conditions with strict monitoring to avoid complications. You may need to consult an anesthesiologist. If the child is a surgical candidate, some of the evaluations that are particularly difficult to perform may be deferred until the child is under general anesthesia.

Complete examination of the anterior segment and fundus may be facilitated by the use of a pediatric lid speculum and, for small children and infants who cannot be placed at the slit lamp, a portable slit lamp.

Ocular Trauma in the Emergency Setting

Patients seen in the emergency room with ocular trauma may have other, nonocular injuries. Priority must be given to treatment of lifethreatening conditions, and communication among the various physicians involved is helpful in establishing the best sequence of treating the multiple injuries. A protective eye shield should be taped in place until the patient is stabilized. Attention can then be turned to the ocular trauma. The most common traumatic ocular disorders and their treatments are detailed below.

Corneal Abrasion

It is critical to distinguish between a typical corneal abrasion and a corneal ulcer. In patients with abrasions, you must rule out a foreign body embedded in the tarsal conjunctiva of the upper or lower lid by examining the everted lid with the biomicroscope and sweeping the fornices with a moistened cotton swab. Complete instructions lor lid eversion are presented in Clinical Protocol 9.6; instructions lor sweeping the conjunctival sac and fornices appear in Clinical Protocol 11.1. Tarsal conjunctival foreign bodies will cause vertical corneal abrasions, produced as the foreign body rubs up and down the corneal epithelium with blinking.

Treatment

The treatment of a typical corneal abrasion is as follows:

1. Instill a drop of topical anesthetic into the affected eye.

2.Rule out a foreign body in the affected eye. Inspect the fornices thoroughly.

3.Instill a drop of intermediate-acting cycloplegic agent (eg, cyclopentolate 1%) to relieve the discomfort caused by ciliary spasm.

4.Apply a pressure patch over the closed lids to reduce discomfort caused by the lids moving against the cornea. This technique is described in Clinical Protocol 14.1, "Applying Pressure Patches and Shields."

a.Allow the patch to remain until reexamination. It is not necessary to patch patients with abrasions smaller than 3-4 mm in diameter. Also, the need to patch patients with clean abrasions less than 10 mm in diameter has been called into question recently.

b.Never patch an eye if bacterial or fungal infection (eg, conjunctivitis or blepharitis) is present.

c.Because of the probability of an infection, patients with abrasions related to contact lens wear should not be patched.

5.Alternatively, apply a bandage soft contact lens. This is especially good for patients with bilateral abrasions.

6.Reexamine within 24 hours and discontinue patching if the abrasion is mostly healed. The need for antibiotic drops or ointment at this time is controversial.

For abrasions associated with contact lens wear, remove the contact lens and inspect both it and the cornea for defects with the slit lamp. If the patient wears hard lenses, treat the abrasion as described above for a typical abrasion. If the patient wears soft lenses, you may need to

358 Chapter 14: Ophthalmic Emergencies

rule out a potential microbial keratitis (eg, Pseudomonas) bv culturing the cornea and contact lens case if the clinical appearance wan-ants. If you suspect strongly the presence of microbial keratitis, the patient should be given appropriate antibiotics until the culture results become available.

Corneal Foreign Body

the possibility of foreign bodies in the tarsal conjunctiva or the fornices. If there is any suspicion of associated microbial keratitis, the cornea should be scraped, stained, and cultured as for a corneal ulcer.

Treatment

Treatment depends on the nature, location, and depth of the corneal foreign body. Superficial foreign bodies that appear to have penetrated no deeper than the superficial stroma mav be removed in the clinic or emergency room, as described in Clinical Protocol 14.2. If the foreign body is very deep or if corneal perforation is suspected, treat the patient

Figure 14.1 A metallic corneal foreign body, si and grayish cornea! edema.

in the sterile setting of an operating room equipped to handle corneal perforations. The patient should wear a rigid fenestrated aluminum (Fox) shield until it is time for surgery (see Clinical Protocol 14.1).

Globe Laceration

Because some lacerated globes may appear normal, you should maintain a high index of suspicion in cases that have a suggestive history. Symptoms and signs of ocular perforation include significantly decreased vision; hypotony; shallow or flat anterior chamber; altered size, shape, or position of pupil; visible tracks through the crystalline lens or vitreous tracing the line of passage of a foreign body; and marked conjunctival chemosis (clear fluid under the conjunctiva) or subconjunctival hemorrhage. Another sign of likely laceration of the globe is total (or large) hyphema with low or normal intraocular pressure; total hyphemas in intact globes are nearly always associated with elevated pressure.

A Seidel test can detect ocular perforation or a wound leak. In this simple test, a moistened fluorescein strip is applied directly over the suspected site of perforation while the examiner observes the site through the biomicroscope using the cobalt-blue light. If a leak exists, the dye will be diluted by the aqueous and will appear as a green stream within the dark-orange concentrated dye. It is important to recognize the presence of vitreous or uveal tissue on the ocular surface. Do not mistake vitreous for mucus and try to wipe it away vigorously; if in doubt, defer the determination to someone more experienced or until the patient is in the operating room.

Avoid the following actions during the evaluation of a patient with a potentially ruptured globe:

•Applying pressure on the globe during the examination (eg, tonometry, scleral depression, gonioscopy).

•Placing ointment or drops (eg, miotics or cycloplegics) on the globe.

•Ordering magnetic resonance imaging studies in patients with potential metallic intraocular foreign bodies. Computed tomography (CT) is the proper imaging modality in this setting. A protective aluminum Fox shield should be left in place over the affected globe during the CT scan.

Measure the visual acuity as the first step in the examination, then perform the rest of the examination as described earlier in this chapter. Gently obtain cultures from the cul-de-sac if needed. Keep the riafid shield over the »lobe when it is not bein<j examined.

t

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Treatment

In the emergency setting, consider the administration of antiemetics to suppress nausea and vomiting. Sedatives and analgesics may be administered judiciously. Tetanus prophylaxis should be administered if needed. A rigid shield should be placed over the eye. A light patch in addition to the shield is optional and, depending on the circumstances, may even be inadvisable (to avoid undue pressure on die globe). Give appropriate prophylactic parenteral antibiotics. Definitive repair is then performed in the operating room. In cases of massive disrupting injury to the globe, informed consent for possible primary enucleation should be obtained from the patient or the family after thorough explanation and counseling. However, every attempt should be made to preserve the eye if there is even a remote chance of any vision.

Eyelid Laceration

All patients with eyelid lacerations should be meticulously evaluated for the possibility of concurrent injuries, such as canalicular lacerations, occult trauma to the globe, orbital wall fracture, extraocular muscle laceration, and embedded foreign body. Inquire about the object causing die laceration, the time and severity of the injury, and any associated symptoms and signs.

Blunt Ocular Trauma

Blunt ocular trauma results from a direct blow to the eye by a blunt -•...-" object. Ophthalmic sequelae include subconjunctival hemorrhage, hyphema (see below), lens dislocation, globe rupture, orbital wall fractures (see below), iridodialysis, angle recession and subsequent glaucoma, iris sphincter rupture, traumatic iritis, posterior segment alterations

(commotio retinae, retinal hemorrhages, choroidal rupture, vitreous hemorrhage, retinal detachment), and traumatic optic neuropathy.

The first three questions to answer when evaluating a patient writh blunt trauma are

1.Is the globe ruptured?

2.Is there a hyphema?

3.Is there a retained foreign body?

The physician should always consider the possibility of a retained foreign body in any patient with a traumatic ocular injury, even though the history does not directly suggest it and no obvious entrance wound exists. Appropriate imaging studies should be obtained in patients with suspected retained foreign bodies. Magnetic resonance imaging is contraindicated if the suspected foreign body is metallic with a magnetic nature. Ultrasound may be helpful. Indicate on the radiology order slip the nature of the trauma and any suspicion of a foreign body; this helps the radiologist design an appropriate imaging study as well as interpret its results.

Crepitus on palpation supports the diagnosis of an orbital wall or orbital floor fracture. Gently retract the eyelids manually or with an eyelid retractor to expose the globe. Measure the visual acuity, if possible. Inspect the ocular surface for signs of perforation. Check the pupil for traumatic mydriasis with sphincter rupture, miosis associated with traumatic iritis, iridocyclitis, and afferent pupillary defect indicative of traumatic optic neuropathy. Evaluate the anterior segment with the slit lamp, looking for hyphema, traumatic iridocyclitis, and subluxation of the lens. Although acute swelling of the eyelids may preclude it, gonioscopy should be performed at an appropriate time to rule out angle recession, which places the patient at risk for glaucoma in the future. Perform a motility examination. An isolated elevation deficit suggests inferior orbital blowout fracture; mild to moderate generalized limitation of eye movements may accompany orbital edema or hematoma.

Applanation tonometry is difficult if the orbit is swollen and the eyelids are tightly closed (Figure 14.2), and intraocular pressure can be artificially elevated from forced opening of the eyelids to obtain the measurement. A pressure in the low teens or less than 10 mm Hg in a setting of blunt ocular trauma suggests the possibility of a ruptured globe. A thorough fundus examination is required, but scleral depression should be deferred in patients with hyphema or suspected scleral rupture. Typical posterior segment disorders associated with blunt ocular trauma include commotio retinae, retinal hemorrhages, choroidal rupture, vitreous hemorrhage, and traumatic retinal detachment.

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Figure 14.2 Marked orbital swelling after blunt trauma can make the ocular examination difficult or impossible.

Treatment

Treatment of blunt ocular injuries depends on the nature of the findings, as detailed throughout this chapter. The physician may recommend supportive measures such as ice packs to the orbit for the first 1 to 2 days (if the globe is intact), elevation of the head of the bed, and medical pain management. The patient should avoid anticoagulants and aspirin.

Traumatic Hyphema

Hyphema denotes blood in the anterior chamber (Figure 14.3). The bleeding may occur spontaneously (eg, in patients with retinoblastoma, iris neovascularization, or juvenile xanthogranuloma), after intraocular surgery (eg, cataract surgery, lensectomy, and vitrectomy), or after traumatic injury, particularly blunt ocular trauma. Traumatic hyphemas vary in clinical manifestations and potential complications. Ranging in size from microscopic to complete, hyphemas may subside spontaneously or with medical management, or they may require surgical evacuation. I lyphemas can be graded by the height of layered blood (in mm). They are frequently associated with other signs of blunt ocular trauma, including corneal abrasions, traumatic iritis, angle recession, pupillary sphincter rupture, and posterior segment abnormalities.

Intraocular pressure is particularly likely to be elevated in large hyphemas, following a rebleed, or in a patient with sickle cell disease. Therefore, the intraocular pressure should be closely monitored in patients with hyphema. If history of bleeding disorders exists, obtain a laboratory workup that includes CBC, clotting studies, platelet count, and liver function tests. A sickle cell preparation and hemoglobin electrophoresis should be obtained in black patients. Baseline blood urea

nitrogen and creatinine should be obtained if aminocaproic acid (Amicar) is to be used tor treatment, to monitor the potential toxicity of the medication.

Rebleeding is the major concern after a traumatic hvphema and

suggests a poor visual prognosis. It is invariably more severe than the initial bleeding and more likelv to be associated with elevated intraocular pressure. Patients who experience rebleeding mav need to be hospitalized. Rebleeding typically occurs 2-5 davs after initial trauma. Therefore, patients with hyphema should be examined daily for at least the first 5 davs from onset and, it managed as outpatients, should be instructed to return immediately for reevaluation if sudden decrease in vision or increase in pain occurs. Patients may develop ocular hypertension with potential optic nerve damage and corneal blood staining,

especially if endothelial '.ion and ocular hypertension coexist.

Treatment

T h e treatment of traumatic hvphema is controversial. Guidelines concerning whether or not to hospitalize and whether or not to prescribe cvcloplegics, strict bed rest, or sedation are not strictly established. Generally, a protective eve shieiti, moderate restriction of physical