Ординатура / Офтальмология / Английские материалы / Primary Care Ophthalmology_Palay, Krachmer_2005
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Conjunctivitis Associated with Blepharitis |
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FIGURE 5–14 Acute allergic conjunctivitis caused by an airborne allergen. A diffuse conjunctivitis with swelling of the conjunctiva (chemosis) is present.
[Vasocon-A]) can be used four times a day for several days, but their chronic use can be associated with a worsening of the conjunctivitis from rebound vasodilation after discontinuation of the vasoconstrictor.
Topical antihistamines (e.g., levocabastine [Livostin]) are applied four times a day as the symptoms warrant.
Mast cell stabilizers (e.g., cromolyn sodium [Crolom], lodoxamide tromethamine [Alomide], pemirolast potassium [Alamast]) are applied three or four times a day. These agents require 10 to 14 days of use to reach their maximal effectiveness.
Topical nonsteroidal agents (e.g., ketorolac tromethamine [Acular]) are applied four times a day as symptoms warrant.
•If these treatments fail, patients should be referred to an ophthalmologist for further treatment and consideration of topical corticosteroid therapy.
Conjunctivitis Associated with Blepharitis
Symptoms
•Burning, itching, and foreign body sensation are typical complaints.
•Unlike dry eyes, in which symptoms worsen as the day progresses, symptoms in this disorder usually are worse in the morning. Blepharitis, however, often is associated with dry eyes; therefore, this distinction may not be useful in patients with severe dry eyes associated with blepharitis.
Signs
•Diffuse injection and inflammation of the lid margin involving the meibomian glands are present (Fig. 5–15).
•Moderate conjunctival injection is found.
•In rare cases, vascularization of the cornea occurs (Fig. 5–16).
•The disorder usually is bilateral but may be asymmetrical.
Etiology
Three distinct types of blepharitis may occur and cause conjunctivitis:
98 CHAPTER 5 • Conjunctival Abnormalities
FIGURE 5–15 In blepharitis, the lid margin is thickened, and vascularization of the lid margin is evident.
FIGURE 5–16 In severe blepharitis with rosacea, the lid margins and conjunctiva are inflamed, and corneal vascularization and scarring are present.
•Seborrhea often is associated with dandruff of the brows and scalp.
•Staphylococcal infection often is associated with styes (hordeola).
•Meibomian gland dysfunction (posterior lid margin disease and meibomianitis) often is associated with chalazia.
•Any combination of these causes is possible.
Associated Factors and Diseases
•Blepharitis is one of the most common causes of chronic conjunctivitis.
•Meibomian gland dysfunction is a disorder of the sebaceous glands frequently associated with rosacea, which is a sebaceous gland dysfunction of the skin (Fig. 5–17).
Treatment
• The underlying blepharitis is treated (see Chapter 4).
Pinguecula
Symptoms
• Patients are symptom free.
Signs
•An elevated, fleshy conjunctival mass is located on the sclera adjacent to the cornea (Fig. 5–18).
Conjunctival Intraepithelial Neoplasia |
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FIGURE 5–17 Occurring with greater frequency in females, rosacea often manifests with erythema, telangiectasia, and acne.
FIGURE 5–18 Pinguecula. Pingueculae are elevated, fleshy conjunctival masses located in the interpalpebral region, most commonly on the nasal side. These lesions are yellow or light brown.
•The pinguecula is yellow or light brown.
•Rarely, the pinguecula can become acutely inflamed.
Etiology
•The disorder usually is associated with chronic actinic exposure, repeated trauma, and dry and windy conditions.
Treatment
•No treatment usually is necessary; in rare cases in which the pinguecula is chronically irritated or cosmetically undesirable, resection is performed.
Conjunctival Intraepithelial Neoplasia
Symptoms
• Patients are symptom free.
100 CHAPTER 5 • Conjunctival Abnormalities
FIGURE 5–19 Conjunctival intraepithelial neoplasia. This raised, gelatinous lesion demonstrates hairpin-shaped vascular loops.
Signs
•An elevated, gelatinous mass, usually arising at the junction of the conjunctiva and cornea (Fig. 5–19), is present.
•Distinctive hairpin-shaped vascular loops are seen within the lesion.
Etiology
• The disorder usually is associated with chronic sun exposure in older white patients.
Treatment
•Surgical resection is indicated, because these lesions are dysplastic and can progress to invasive squamous cell carcinoma.
Nevi
Symptoms
• Patients are symptom free.
Signs
•Benign pigmented lesions of the conjunctiva are found (Fig. 5–20).
•The nevi usually occur on the conjunctiva covering the globe.
•The lesions are freely mobile over the sclera.
•In rare cases, a nevus may progress to a malignant melanoma (Fig. 5–21).
Workup
• A biopsy of nevi that show documented growth or change in appearance is done.
Treatment
• Resection of suspicious lesions is performed.
Nevi 101
FIGURE 5–20 Nevi are benign pigmented lesions of the conjunctiva. Occasionally, clear cystic spaces develop within the lesion.
FIGURE 5–21 In this case of malignant melanoma of the conjunctiva, the tumor is elevated, pigmented, and highly vascular.
FIGURE 5–22 In racial melanosis, a flat, deeply pigmented lesion of the conjunctiva commonly is found near the limbus.
102 CHAPTER 5 • Conjunctival Abnormalities
Racial Melanosis
Symptoms
• Patients are symptom free.
Signs
•This lesion of the conjunctiva is flat and deeply pigmented (Fig. 5–22).
•The lesion usually is found on the conjunctiva overlying the globe.
•The disorder occurs primarily in darkly pigmented patients and has no malignant potential.
Treatment
If the lesion is cosmetically undesirable, resection is performed.
CHAPTER 6
Corneal Abnormalities
DAVID A. PALAY
Related Anatomy
The cornea is the primary refractive element of the eye, and any disturbance in corneal clarity results in visual impairment. The cornea has five layers: the epithelium, Bowman’s layer, the stroma, Descemet’s membrane, and the endothelium (Fig. 6–1). The epithelium is four to six layers thick and composed of nonkeratinized, stratified squamous epithelium. Bowman’s layer is a thin, acellular area composed of collagen fibers. The stroma constitutes 90% of the corneal thickness and is composed primarily of keratocytes, collagen, and proteoglycans. Descemet’s membrane is a thin, collagenous layer produced by the endothelium. The endothelium is one cell layer thick and is responsible for removing fluid from the cornea, thereby preventing corneal edema. The cornea is approximately 12 mm in diameter and has a central thickness of 0.5 mm. The peripheral cornea is 0.65 mm thick (Fig. 6–2).
Dry Eye
Symptoms
•Foreign body sensation, irritation, dryness, and mild redness are characteristic.
•Patients may report symptoms out of proportion to the signs present.
•Symptoms worsen as the day progresses and may be exacerbated by smoke, cold, low humidity, wind, prolonged use of the eye without blinking, and contact lens wear.
Signs
•The disorder usually is bilateral.
•Mild conjunctival injection is present primarily medially and laterally.
•Excessive mucus production is evident (Fig. 6–3).
•Punctate staining of the cornea is found with fluorescein dye (Fig. 6–4).
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104 CHAPTER 6 • Corneal Abnormalities
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FIGURE 6–1 The normal cornea. The epithelium (1), epithe- |
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lial basement membrane (2), Bowman’s membrane (3), |
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stroma (4), Descemet’s membrane (5), and endothelium (6). |
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Associated Factors and Diseases
•Most cases of dry eye are idiopathic and occur in older persons. In younger persons, contact lens wear may precipitate dry eye signs and symptoms.
•Any eyelid abnormality resulting in poor lid closure, such as seventh nerve palsy and ectropion, can lead to exposure and drying of the cornea (Fig. 6–5).
•Graft-versus-host disease can cause severe dry eyes.
•Collagen-vascular diseases such as rheumatoid arthritis and systemic lupus erythematosus often are associated with dry eyes. The combination of dry eyes and dry mouth is termed primary Sjögren syndrome. The combination of dry eyes, dry mouth, and collagen-vascular disease, most commonly rheumatoid arthritis, is termed secondary Sjögren syndrome.
•The disorder often is associated with blepharitis.
Dry Eye |
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0.65 mm
12 mm
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0.50 mm
FIGURE 6–2 A, The normal cornea is 12 mm in |
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diameter. B, The central thickness is 0.5 mm, and |
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the peripheral thickness is 0.65 mm. |
FIGURE 6–3 In this case of dry eye, the corneal surface is dry, and mucus is evident on the surface.
106 CHAPTER 6 • Corneal Abnormalities
FIGURE 6–4 Punctate staining of the cornea with fluorescein dye in dry eye. The areas of abnormal epithelium stain green.
FIGURE 6–5 In seventh nerve palsy, the inability to close the lids and the out-turning of the lower lid (ectropion) can cause dry eye.
•Sarcoidosis can cause infiltration of the lacrimal gland and is associated with dry eyes.
•Many systemic medications are associated with dry eyes. Drugs with anticholinergic properties often are implicated.
Workup: Schirmer Test
•The Schirmer tear test can be performed with or without the instillation of anesthetic drops. (The procedure is described in Chapter 1.)
With anesthesia, this test provides an indication of the basal tear secretion—that is, the amount of tears being produced without any noxious stimuli to the eye, which probably is a more accurate measure of tear production.
Without anesthesia, this test measures the ability of the lacrimal gland to produce tears in response to a noxious stimulus; a false-negative result can occur, particularly in patients in whom the diagnosis is not clear.
Treatment
•For mild cases, artificial tear preparations (e.g., polyvinyl alcohol [HypoTears], hydroxypropyl methylcellulose [Tears Naturale II]), which typically contain a