Ординатура / Офтальмология / Английские материалы / Primary Care Ophthalmology_Palay, Krachmer_2005

344CHAPTER 16 • Ocular Trauma

•With a suspected high-speed metal-on-metal or other projectile injury, a dilated fundus examination with indirect ophthalmoscopy by an ophthalmologist is essential. This evaluation will rule out globe penetration with intraocular foreign body. CT scanning or B-scan ultrasound examination also may be indicated.

•For deep foreign bodies, the Seidel test is performed to determine whether fluid (aqueous) is leaking from the eye:

The examiner places a drop of anesthetic (e.g., proparacaine) in the eye to be tested and on a sterile fluorescein strip. Excess anesthetic drips off the strip, which is then used to “paint” the area on the eye where the leak is suspected.

The examiner uses the cobalt-blue filter on the slit lamp to observe the area. Because of pH differences between the aqueous humor and the tear film, leaking aqueous manifests as a color change in the bright green stain as the aqueous dilutes the dye (Fig. 16–10). This finding is deemed Seidel positive; a Seidel-negative wound does not eliminate the possibility of intermittent leakage.

Treatment

•For globe penetration, the eye is shielded and the patient is immediately referred to an ophthalmologist.

•For superficial foreign material, simple irrigation often removes the material. If this procedure is unsuccessful, a cotton-tipped applicator can be used. The clinician instills a drop of topical anesthesia (e.g., proparacaine) into the eye and wets a sterile cotton-tipped applicator with saline solution or topical anesthetic. Most foreign bodies can be easily removed with minimal manipulation. If this procedure is also unsuccessful, the back of a sterile blade can be used to gently scrape the foreign body off the cornea. Use of a foreign body spud or sterile jeweler’s forceps also may

FIGURE 16–10 Seidel-positive wound.

be effective. Hypodermic needles should not be used for corneal foreign body removal, to prevent additional corneal injury or accidental perforation.

•For deep foreign material, referral to an ophthalmologist is indicated. Overaggressive manipulation or “digging” for a foreign body can cause more scarring and corneal damage. Similarly, overuse of an ophthalmic burr to remove a deep rust ring may cause extensive scarring that can compromise visual acuity. Removal in the operating room may be needed for deep, large, central, or infectious foreign bodies (such as vegetable matter). Also, uncooperative patients (especially young children) may require mask anesthesia.

•Corneal rust rings may be removed with an ophthalmic burr, a procedure probably best performed by an ophthalmologist. Patients with central rust rings should be referred to an ophthalmologist for management within 24 hours of the initial diagnosis. The natural propensity of corneal rust rings is for them to migrate superficially and become a white scar.

•Patients with numerous foreign bodies (as with an explosive injury) should be immediately referred to an ophthalmologist. If an attempt is made to remove each small object, undue scarring may result.

•After the foreign body is removed, the patient is given topical antibiotics (e.g., polymyxin B/bacitracin [Polysporin] ophthalmic ointment) until the epithelial defect has healed.

Follow-up

•The patient is seen daily until the epithelium heals; close follow-up reduces infectious complications.

•The residual corneal defect (epithelial defect) is treated as a corneal abrasion. If the corneal defect is large and central and associated with a discharge or other signs of infection (e.g., severe pain, corneal clouding, marked anterior chamber reaction), the patient should be immediately referred to an ophthalmologist. Topical corticosteroids are not used.

•Multiple, deep, central, iron-containing foreign bodies confer the worst visual prognosis. Patients with injuries caused by small, single, peripheral foreign bodies generally have excellent visual outcomes.

Corneal Laceration

A corneal laceration may be a full-thickness or partial-thickness injury. Depending on location and size, partial-thickness lacerations can be associated with an excellent visual prognosis and can be treated with patching and antibiotics, much as for corneal abrasions. Patients with deep or full-thickness lacerations should be urgently referred for ophthalmologic evaluation.

Symptoms

•A history of trauma with a sharp object or projectile (high velocity) is reported.

•Pain, decreased vision (depending on the depth and location of the laceration), involuntary lid closure (blepharospasm), and a red eye are characteristic.

346 CHAPTER 16 • Ocular Trauma

•The patient may have observed a brief flow of fluid (aqueous) from the eye immediately after the injury.

Signs

•A positive result on Seidel’s test is indicative of full-thickness corneal laceration.

•A corneal wound may be seen.

•More often, the iris prolapses out of the corneal wound, or the iris and cornea are in contact where the iris has plugged the corneal defect. A corneal laceration of this type is nearly always associated with a “peaking” or “teardrop” shape to the pupil, with the “peak” pointing in the direction of the corneal defect (Fig. 16–11).

•Other signs of a penetrated globe include an asymmetrical anterior chamber depth relative to that of the uninvolved eye, a hyphema, conjunctival injection and chemosis, reduced (in most cases) or normal or even elevated (in a few cases) intraocular pressure, lens injury, and pupillary asymmetry. Vision often is decreased.

Workup

•A complete examination of both eyes, including Seidel’s test, is indicated. If rupture of the globe becomes evident (or rupture is suspected), the examination ends, the eye is shielded, and the patient is referred to an ophthalmologist immediately. Excessive manipulation of the globe or exertion of pressure on the eyelids during an examination may result in extrusion of intraocular contents.

•A CT scan of the orbits (in axial and coronal planes) is needed to evaluate possible intraocular or intraorbital foreign bodies.

•A slit lamp examination is performed to examine the extent and depth of the corneal injury. Distinguishing deep, nonpenetrating lacerations from penetrating, wellapposed wounds often is difficult. For this reason, if the extent of the injury is questionable, the patient should be referred to an ophthalmologist immediately.

1

Treatment

•To prevent extrusion of ocular contents, patients referred to the ophthalmologist must have a shield (without patch) over the eye with a suspected penetrating injury.

•Antibiotic ointment is not used in any patient with a suspected ruptured globe, because the medication may enter the eye.

•For a suspected or confirmed full-thickness laceration, operative intervention usually is necessary, and broad-spectrum intravenous antibiotics are administered preoperatively. Adults may receive 1 g of cefazolin (Ancef) every 8 hours. Children receive 25 to 50 mg/kg/day of cefazolin (Ancef) in three divided doses. Recent evidence shows better ocular penetration with thirdand fourth-generation fluoroquinolones (even when given orally).

•The patient’s tetanus immune status is addressed.

Scleral Laceration or Rupture

Symptoms

•A history of trauma, often with a high-velocity projectile or sharp object, is reported.

•Conjunctival swelling, red eye, pain, decreased vision, and possible inadvertent lid closure (blepharospasm) are characteristic.

Signs

•A defect may be noted in the conjunctiva or sclera, with or without subconjunctival hemorrhage (Fig. 16–12). Marked chemosis (clear swelling) or hemorrhagic suffusion may obscure the underlying scleral injury.

•Uveal or vitreous prolapse may occur through the scleral wound. Prolapsed uvea (iris, ciliary body, or choroid) may appear as a brownish discoloration beneath the conjunctiva, sometimes mistaken for blood. The pupil may be abnormally shaped (e.g., peaked), if the wound is close to the corneal limbus.

348 CHAPTER 16 • Ocular Trauma

•The intraocular pressure is low in most cases. Less commonly, the intraocular pressure is normal or elevated.

Etiology

•Usually, sharp objects or missiles (e.g., metal-on-metal projectile, broken glass, knife, bullet) cause the injury.

•Severe blunt trauma (e.g., from a fist, bottle, or club) is a common cause.

Differential Diagnosis

Diagnostic possibilities include the following:

•Conjunctival laceration without scleral injury

•Intraocular foreign body

•Clear or hemorrhagic chemosis without obvious scleral injury

Workup

•As with corneal and conjunctival lacerations, a complete examination of both eyes is indicated. If rupture of the globe is suspected, the eye is shielded, no antibiotic ointment or patching is used, and the patient is immediately referred to an ophthalmologist.

•A diagnosis of scleral rupture or laceration requires a high index of suspicion because these conditions often are obscured by chemotic or hemorrhagic conjunctiva. Minimal manipulation of the globe is prudent in cases in which the diagnosis is uncertain.

•A CT scan of the orbit (in axial and coronal planes) is indicated. If an intraocular foreign body is suspected, inform the radiologist to perform thin cuts.

Treatment

•In cases of partial-thickness laceration of the sclera (which is rare), the patient is referred to an ophthalmologist for evaluation and possible surgical repair.

•In cases of suspected or confirmed full-thickness laceration, the patient is immediately referred for ophthalmologic evaluation and surgical repair. Topical therapy is avoided. Prophylactic antibiotics are administered pre-operatively.

•The patient’s tetanus immune status is addressed.

Follow-up

•The focus and frequency of follow-up evaluation vary depending on the extent of the injury.

Chemical Injury

Chemical injuries to the eye may be caused by acid, alkali, and other chemically active organic substances such as mace and tear gas. Acid and alkali injuries may cause profound visual loss. Organic agents (e.g., isopropyl alcohol) rarely cause severe vision loss, and exposures involving these agents are associated with a good prognosis.

Symptoms

•Severe pain, redness, blurred vision, and eyelid spasm are characteristic.

•A history of chemical exposure is reported.

Signs

•Signs vary depending on the severity of the injury and the time elapsed since the chemical exposure.

With Mild to Moderate Injuries

•Initial signs include corneal epithelial loss, chemosis and conjunctival hyperemia, subconjunctival hemorrhage, intact episcleral and conjunctival vessels, and mild periocular skin involvement (first-degree burns).

•Chronic signs include minimal corneal scarring.

With Severe Injuries

•Initial signs include severe chemosis; corneal edema and opacification; loss of conjunctival and episcleral vessels (limbal blanching), which causes a patchy avascular appearance to the sclera (Fig. 16–13); severe periocular skin involvement (secondor third-degree burns); and a marked anterior chamber reaction, which may not be visualized.

•Chronic signs include foreshortened fornices (loss of normal conjunctival cul-de- sac) with symblepharon formation (conjunctival and globe adhesions), cicatricial eyelid abnormalities such as trichiasis (misdirected eyelashes), entropion (in-turned lid), or ectropion (out-turned lid), severe tear film abnormalities (loss of mucinproducing cells in the conjunctiva); corneal scarring and opacification (Fig. 16–14); and phthisis bulbi (shrunken, nonseeing eye).

Etiology

•The most serious chemical burns to the eye are alkali burns such as from lye

(NaOH), caustic potash (KOH), and ammonia (NH3). Fresh lime ([Ca(OH)2] and magnesium hydroxide [Mg(OH)2]) also are alkaline but usually cause less severe

FIGURE 16–13 Acute, severe alkali burn with conjunctival and scleral ischemia and marked corneal edema.

350 CHAPTER 16 • Ocular Trauma

FIGURE 16–14 Severe alkali burn after 1 year. The cornea is scarred, and vascularization is extensive. The prognosis following corneal transplant surgery in patients with severe alkali burns to the eye is poor.

injury than other alkaline compounds. Household cleaners, fertilizers, and refrigerants contain ammonia. Plaster, cement, mortar, and whitewash contain fresh lime. “Sparklers” and flares contain magnesium hydroxide. Alkalis penetrate rapidly through the cornea and anterior chamber, causing disruption of the cell membrane lipids and secondary cellular necrosis. The degree of injury is correlated with the amount of chemical involved, as is the time from exposure to irrigation.

•Acid burns caused by strong acids in car batteries (sulfuric acid [H2SO4]), and swimming pool acid (hydrochloric acid [HCl]), do not penetrate the ocular tissues as readily because of the precipitation of tissue proteins. The protein precipitate acts as a barrier to further tissue penetration. An exception can be injuries from glassetching chemicals (hydrofluoric acid [HF]).

Workup and Treatment

•As with other ocular injuries, the history guides the evaluation and treatment. It is important to ascertain the nature of the offending chemical agent.

•In cases of severe exposure, immediate treatment must precede the ocular evaluation. Copious irrigation with water on site should be followed with irrigation with at least 1 to 2 L of normal saline solution (0.9%) or lactated Ringer’s solution over 1 hour in the emergency room. Topical anesthetic (e.g., proparacaine) is instilled initially and then every 10 to 15 minutes, to make this a much less painful procedure. Lid retractors are used if significant orbicularis spasm is present. Various contact lenses (e.g., Morgan lens) that connect to intravenous tubing are available commercially to assist in the irrigation.

•In cases of less severe exposure or questionable history (e.g., the patient reports getting a drop of cleaner in the eye but washing it out at home), less copious irrigation with pH measurement is performed initially.

•The clinician sweeps the conjunctival fornices with a moistened cotton-tipped applicator to remove any retained foreign matter, especially lime, which exists as particulate matter.

•The clinician everts the upper and lower lids to ensure that no retained chemical is present after sweeping the fornices.

•The possibility of early perforation is unlikely, but the globe is carefully assessed. Minimal pressure is placed on the globe during lavage when this diagnosis is a possibility or is indicated by the history.

•Irrigation continues until the conjunctival pH normalizes (i.e., 7.3 to 7.6); the pH is checked with the pH section of a urinalysis strip or pH paper. Two or three normal readings should be obtained at 15-minute intervals to ensure stability of the pH.

•Intraocular pressure may fluctuate widely and should be assessed. Broad areas of limbal blanching may be associated with markedly elevated intraocular pressure.

•Cycloplegic agents (e.g., homatropine 5%) and mydriatic agents (e.g., phenylephrine 2.5%) are instilled to dilate the pupil. Note: In severe injury, some researchers discourage instillation of phenylephrine because of the possibility of further vasoconstricting the conjunctival vessels.

•Antibiotics (e.g., polymyxin B/bacitracin [Polysporin], erythromycin ophthalmic ointment) are instilled and a pressure patch is placed over the eye.

•Immediate referral to an ophthalmologist is needed once the initial lavage is complete. Management of severe burns includes treatment of the intraocular pressure problems, exposure, scarring, and tear film dysfunction; therapy involves early topical corticosteroid administration, ascorbate or citrate supplementation (in cases of alkali burns only), and surgery (e.g., conjunctival grafting, corneal transplantation), if necessary.

Follow-up

•Patients usually are monitored daily for several days.

•The prognosis mainly depends on the type of injury.

•Even in the most severe alkaline injuries, the primary care physician can play a significant role in reducing the chronic sequelae by instructing the patient to irrigate at the place of injury (e.g., home, work) using a sink, shower, or garden hose, rather than immediately summoning the patient to the emergency room. As stated, the prognosis is directly affected by the adequacy of the lavage immediately after exposure.

Thermal Injury

Symptoms

•Pain, tearing, a foreign body sensation, a red eye, and decreased vision are characteristic.

•A history of exposure to a hot object (e.g., curling iron, tobacco ash, electrical arc, explosion) is reported.

Signs

•Corneal whitening indicates an epithelial or a stromal burn (Fig. 16–15).

•A corneal epithelial defect is evident.

•Conjunctival chemosis and injection occur.

•A minimal anterior chamber reaction is noted.

•Burns of the eyelids and periocular region are evident.

352 CHAPTER 16 • Ocular Trauma

FIGURE 16–15 Corneal thermal injury from a curling iron.

Differential Diagnosis

Diagnostic possibilities include the following:

•Corneal abrasion or infection (especially if no history is available)

•Ultraviolet injury (welder’s flash)

Workup

•A complete examination of both eyes, intraocular pressure evaluation, and careful notation of depth of burn (if corneal) are needed.

•Fluorescein instillation and a careful description or drawing of the epithelial defect should be performed.

•The diagnosis of globe perforation should be ruled out or confirmed if this condition is suggested by the history.

•Associated alkaline injury should be ruled out or confirmed if the thermal burn was caused by fireworks or flares (magnesium hydroxide).

Treatment

•In cases of mild injury involving only the superficial cornea, topical antibiotic ointment (e.g., polymyxin B/bacitracin [Polysporin]) is administered and a pressure patch is applied. Symptoms should resolve within 24 to 48 hours. The pressure patch is removed in 24 hours, and the cornea is reexamined.

•Cycloplegic agents (e.g., homatropine 5%) are administered before patching.

•In cases of deep burns of the cornea, patients are immediately referred to an ophthalmologist.

•Periocular burns are treated with ophthalmic antibiotic ointment preparations (e.g., polymyxin B/bacitracin [Polysporin], erythromycin ophthalmic ointment). Skin preparations may enter the ocular surface and cause irritation and corneal epithelial toxicity.

Hyphema 353

Follow-up

•An ophthalmologist or an oculoplastic surgeon is consulted if severe periocular injury accompanies the ocular injury. Cicatrization (scarring) of the eyelids from severe burns may lead to exposure and corneal scarring.

Hyphema

Hyphema, or blood in the anterior chamber of the eye, is an important indicator of the severity of trauma an eye has sustained. A microhyphema is a condition in which red blood cells are suspended in the aqueous fluid, not yet visibly layered in the dependent portion of the anterior chamber. Hyphemas require ophthalmologic management and follow-up evaluation because they can be associated with severe complications. The role of the primary care provider is to confirm the presence of vision, if possible, and to perform an initial examination with minimal manipulation of the globe, because concomitant ocular injury may be present, or the bleeding may be aggravated.

Symptoms

•A history of blunt trauma usually is reported; spontaneous hyphema is unusual.

•Pain, blurred vision, and a red eye are characteristic.

•Somnolence is noted, especially in children.

Signs

•Presence of red blood cells in the anterior chamber, either suspended (microhyphema) or layered along the dependent portion of the anterior chamber, is noted (Fig. 16–16). Isolated clots on the iris also may be seen.

•The red blood cells are not always found at the 6 o’clock position, because the patient may come for treatment after lying with the head in any position.

•Conjunctival injection, a sluggish or peaked pupil (resulting from a clot), pupillary sphincter or iris tears in some cases, and sometimes active bleeding from an iris vessel are other possible findings.

FIGURE 16–16 Hyphemas layer with time, much as with a hematocrit blood sample in a test tube. Here, a 30% hyphema is noted.