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

108 CHAPTER 6 • Corneal Abnormalities

FIGURE 6–7 In this case of herpes simplex keratitis, an epithelial dendrite stains green with fluorescein dye.

FIGURE 6–8 The corneal scarring and corneal vascularization present in this eye are due to herpes simplex keratitis.

“red eye” with a topical corticosteroid or a topical antibiotic/corticosteroid combination. Patients with herpes simplex keratitis should be referred for management to an ophthalmologist familiar with the diagnosis and treatment of this disorder.

Herpes Zoster Ophthalmicus

Symptoms

• Pain, headache, and photophobia are symptoms of this disorder.

Signs

•A vesicular rash is seen in the distribution of the first division of the fifth cranial nerve. If the tip of the nose is involved (Hutchinson’s sign), ocular involvement is

FIGURE 6–9 A vesicular rash and Hutchinson’s sign are present in herpes zoster ophthalmicus.

FIGURE 6–10 Severe scarring in the cornea has resulted from repeated corneal inflammation from herpes zoster ophthalmicus.

likely, because both regions are supplied by the nasociliary branch of the first division of the fifth cranial nerve (Fig. 6–9).

•Ocular findings include conjunctivitis, corneal involvement (Fig. 6–10), uveitis (Fig. 6–11), glaucoma, and scleritis (Fig. 6–12).

•Corneal involvement, uveitis, and glaucoma can develop into a chronic disorder possibly refractory to treatment.

•Rare ocular complications include optic neuritis with resultant visual loss and cranial nerve palsies with resultant diplopia.

110 CHAPTER 6 • Corneal Abnormalities

FIGURE 6–11 Uveitis has resulted from herpes zoster ophthalmicus. Multiple white keratic precipitates have formed on the posterior cornea from repeated inflammation. Many patients with this disorder also have elevated intraocular pressure, which can lead to severe glaucoma.

FIGURE 6–12 Injection of the conjunctiva and deep episcleral blood vessels with severe pain are present in this example of herpes zoster ophthalmicus with scleritis.

Differential Diagnosis

•The vesicular rash of herpes simplex virus does not follow a dermatomal distribution, although characteristics of the disorder may be otherwise identical to those of herpes simplex infection.

Treatment

•Oral acyclovir (800 mg) is administered five times a day for 7 to 10 days. Immunocompromised patients may require intravenous therapy. Treatment alternatives include famciclovir (Famvir), with an oral dosage of 500 mg three times a day for 7 days, and valacyclovir (Valtrex), with an oral dosage of 1 g three times a day for 7 days. The use of valacyclovir is contraindicated in immunocompromised patients. Thrombotic thrombocytopenic purpura or hemolytic-uremic syndrome has developed in some immunocompromised patients on this regimen. Bioavailability of these new agents is greater than that of oral acyclovir.

•Patients with ocular involvement should be referred to an ophthalmologist within 24 hours. Treatment usually involves administration of topical corticosteroids. Some patients have a protracted clinical course, with keratitis, uveitis, and glaucoma.

Infectious Corneal Ulcer

Symptoms

• Pain, redness, decreased vision, and photophobia are characteristic.

Signs

•A dense corneal infiltrate with an overlying defect in the epithelium is observed (Fig. 6–13).

•A layering of white cells in the anterior chamber (hypopyon) may be evident (Fig. 6–14).

•Severe corneal ulcers, particularly those resulting from gram-negative pathogens, can lead to rapid corneal destruction and ocular perforation (Fig. 6–15).

•Fungal ulcers may have a feathery border (Fig. 6–16).

Associated Factors and Diseases

•The disorder usually is associated with a history of trauma, poor lid apposition, or contact lens wear.

•Fungal ulcers usually are associated with a history of trauma involving vegetable matter or chronic topical corticosteroid use.

Treatment

•Immediate referral to an ophthalmologist is necessary for corneal scraping for Gram stain and culture.

•Bacterial ulcers often are treated with fortified antibiotics (e.g., gentamicin, cefazolin).

112 CHAPTER 6 • Corneal Abnormalities

FIGURE 6–14 In this example of bacterial corneal ulcer, a dense corneal infiltrate and hypopyon are seen.

Pterygium 113

FIGURE 6–15 Severe bacterial corneal ulcer has resulted from Pseudomonas infection. The entire cornea is white and necrotic. Corneal perforation is imminent.

FIGURE 6–16 In this fungal corneal ulcer, the infiltrate has feathery margins. Hypopyon (1) also is evident.

1

Pterygium

Symptoms

•Patients usually are symptom free.

•Intermittent irritation, redness, and a mild disturbance in visual acuity may be noted.

Signs

•Fibrovascular growth extending from the conjunctiva onto the cornea is present (Fig. 6–17).

Treatment

•Surgical resection is performed for pterygia that interfere with vision or are actively growing.

114 CHAPTER 6 • Corneal Abnormalities

FIGURE 6–17 Fibrovascular growth extending from the conjunctiva onto the cornea is evident in this case of pterygium.

FIGURE 6–18 In this example of recurrent corneal erosion, a defect in the epithelium is evident. The adjacent epithelium is irregular and loose, and the entire area stains lightly with fluorescein dye.

Recurrent Erosion Syndrome

Symptoms

•Patients report sudden onset of severe eye pain, blurred vision, and redness in the middle of the night or on awakening.

Signs

•In the acute stage of the disorder, the epithelial defect stains with fluorescein (Fig. 6–18).

•After the epithelial defect heals, there is diffuse irregularity of the epithelial surface.

Etiology

•Poor epithelial adhesion to Bowman’s membrane and the underlying corneal stroma causes the disorder.

Associated Factors and Diseases

•The disorder usually is associated with a previous episode of trauma that resulted in a corneal abrasion.

116 CHAPTER 6 • Corneal Abnormalities

Corneal Surgery

Corneal Transplantation

Corneal transplantation (penetrating keratoplasty) is performed to restore vision in patients with corneal scarring, corneal edema, or abnormal corneal shape. Donor corneas are harvested post mortem and kept in storage media for up to a week. The central area of corneal malformation is replaced with a circular piece of donor tissue and sutured into place with fine nylon sutures (Fig. 6–20).

Refractive Surgery

Laser in situ keratomileusis (LASIK) is the most common procedure used to correct refractive errors of the eye. In LASIK, a corneal flap is dissected with a microkeratome. The flap is retracted, and an excimer laser is used to reshape the stromal bed. The flap is replaced; subsequently, it heals around the peripheral cut edge (Fig. 6–21). This procedure does not cause central corneal scarring, is relatively painless, and usually results in rapid visual recovery.

A B

FIGURE 6–20 A, Preoperative view of a central corneal scar from a resolved bacterial corneal ulcer. B, The same eye 3 weeks after corneal transplantation. Fine nylon sutures hold the transplant in place. The visual axis is clear.