Ординатура / Офтальмология / Английские материалы / Pocket Textbook Atlas Of Ophthalmology_Lang, Thieme_2000

In severe cases the eye will be reddened, and the tear film will contain thick mucus and small filaments that proceed from a superficial epithelial lesion (filamentary keratitis; see Fig. 5.11). The corneal lesion can be demonstrated with fluorescein dye. In less severe cases the eye will only be reddened, although application of fluorescein dye will reveal corneal lesions (superficial punctate keratitis; see p. 138). The rose bengal test (see p. 52) and impression cytology (see p. 53) are additional diagnostic tests that are useful in evaluating persistent cases.

Treatment: Depending on the severity of findings, artificial tear solutions in varying viscosities are prescribed. These range from eyedrops to high-viscos- ity long-acting gels that may be applied every hour or every half hour, depending on the severity of the disorder. In persistent cases, the puncta can be temporarily closed with silicone punctal plugs (Fig. 3.11) to at least retain the few tears that are still produced. Surgical obliteration of the puncta may be indicated in severe cases.

Patients should also be informed about the possibility of installing an air humidifier in the home and redirecting blowers in automobiles to avoid further drying of the eyes. Dry eyes in women may also be due to hormonal changes, and a gynecologist should be consulted regarding the patient’s hormonal status.

Prognosis: The prognosis is good for those treatments discussed here. However, the disorder cannot be completely healed.

Treatment of dry eyes.

Fig. 3.11 Treatment can be augmented by temporarily closing the puncta with silicone punctal plugs.

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64 3 Lacrimal System

3.4.2Illacrimation

Illacrimation or epiphora may be due to hypersecretion from the lacrimal gland. However, it is more often caused by obstructed drainage through the lower lacrimal system.

Causes of hypersecretion:

Emotional distress (crying).

Increased irritation of the eyes (by smoke, dust, foreign bodies, injury, or intraocular inflammation) leads to excessive lacrimation in the context of the defensive triad of blepharospasm, photosensitivity, and epiphora.

Causes of obstructed drainage:

Stricture or stenosis in the lower lacrimal system.

Eyelid deformity (eversion of the punctum lacrimale, ectropion, or entropion).

3.5Disorders of the Lacrimal Gland

3.5.1Acute Dacryoadenitis

Definition

Acute inflammation of the lacrimal gland is a rare disorder characterized by intense inflammation and extreme tenderness to palpation.

Etiology: The disorder is often attributable to pneumococci and staphylococci, and less frequently to streptococci. There may be a relationship between the disorder and infectious diseases such as mumps, measles, scarlet fever, diphtheria, and influenza.

Symptoms and diagnostic considerations: Acute dacryoadenitis usually occurs unilaterally. The inflamed swollen gland is especially tender to palpation.

The upper eyelid exhibits a characteristic S-curve (Fig. 3.12).

Differential diagnosis:

Internal hordeolum (smaller and circumscribed).

Eyelid abscess (fluctuation).

Orbital cellulitis (usually associated with reduced motility of the eyeball).

Treatment: This will depend on the underlying disorder. Moist heat, disinfectant compresses (Rivanol), and local antibiotics are helpful.

Clinical course and prognosis: Acute inflammation of the lacrimal gland is characterized by a rapid clinical course and spontaneous healing within eight

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Acute dacryoadenitis.

Fig. 3.12 Characteristic S-curve of the upper eyelid.

to ten days. The prognosis is good, and complications are not usually to be expected.

3.5.2Chronic Dacryoadenitis

Etiology: The chronic form of inflammation of the lacrimal gland may be the result of an incompletely healed acute dacryoadenitis. Diseases such as tuberculosis, sarcoidosis, leukemia, or lymphogranulomatosis can be causes of chronic dacryoadenitis.

Bilateral chronic inflammation of the lacrimal and salivary glands is referred to as Mikulicz’s syndrome.

Symptoms and diagnostic considerations: Usually there is no pain. The symptoms are less pronounced than in the acute form. However, the S-curve deformity of the palpebral fissure resulting from swelling of the lacrimal gland is readily apparent (see Fig. 3.12).

Differential diagnosis:

Periostitis of the upper orbital rim (rare).

Lipodermoid (no signs of inflammation).

Treatment: This will depend on the underlying disorder. Systemic corticosteroids may be effective in treating unspecific forms.

Prognosis: The prognosis for chronic dacryoadenitis is good when the underlying disorder can be identified.

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66 3 Lacrimal System

3.5.3Tumors of the Lacrimal Gland

Epidemiology: Tumors of the lacrimal gland account for 5–7% of orbital neoplasms. Lacrimal gland tumors are much rarer in children (approximately 2% of orbital tumors). The relation of benign to malignant tumors of the lacrimal gland specified in the literature is 10:1. The most frequent benign epithelial lacrimal gland tumor is the pleomorphic adenoma. Malignant tumors include the adenoid cystic carcinoma and pleomorphic adenocarcinoma.

Etiology: The WHO classification of 1980 divides lacrimal gland tumors into the following categories:

I.Epithelial tumors.

II. Tumors of the hematopoietic or lymphatic tissue. III. Secondary tumors.

IV. Inflamed tumors.

V. Other and unclassified tumors.

Symptoms: Tumors usually grow very slowly. After a while, they displace the eyeball inferiorly and medially, which can cause double vision.

Diagnostic considerations: Testing motility provides information about the infiltration of the tumor into the extraocular muscles or mechanical changes in the eyeball resulting from tumor growth. The echogenicity of the tumor in ultrasound studies is an indication of its consistency. CT and MRI studies show the exact location and extent of the tumor. A biopsy will confirm whether it is malignant and what type of tumor it is.

Treatment: To the extent that this is possible, the entire tumor should be removed; orbital exenteration (removal of the entire contents of the orbit) may be required. Systemic administration of corticosteroids is indicated for unspecific tumors.

Prognosis: This depends on the degree of malignancy of the tumor. Adenoid cystic carcinomas have the most unfavorable prognosis.

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67

4 Conjunctiva

Gerhard K. Lang and Gabriele E. Lang

4.1Basic Knowledge

Structure of the conjunctiva (Fig. 4.1): The conjunctiva is a thin vascular mucous membrane that normally of shiny appearance. It forms the conjunctival sac together with the surface of the cornea. The bulbar conjunctiva is loosely attached to the sclera and is more closely attached to the limbus of the cornea. There the conjunctival epithelium fuses with the corneal epithelium. The palpebral conjunctiva lines the inner surface of the eyelid and is firmly attached to the tarsus. The loose palpebral conjunctiva forms a fold in the conjunctival fornix, where it joins the bulbar conjunctiva. A half-moon- shaped fold of mucous membrane, the plica semilunaris, is located in the medial corner of the palpebral fissure. This borders on the lacrimal caruncle, which contains hairs and sebaceous glands.

Function of the conjunctival sac: The conjunctival sac has three main tasks:

1.Motility of the eyeball. The loose connection between the bulbar conjunctiva and the sclera and the “spare” conjunctival tissue in the fornices allow the eyeball to move freely in every direction of gaze.

2.Articulating layer. The surface of the conjunctiva is smooth and moist to allow the mucous membranes to glide easily and painlessly across each other. The tear film acts as a lubricant.

3.Protective function. The conjunctiva must be able to protect against pathogens. Follicle-like aggregations of lymphocytes and plasma cells (the lymph nodes of the eye) are located beneath the palpebral conjunctiva and in the fornices. Antibacterial substances, immunoglobulins, interferon, and prostaglandins help protect the eye.

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68 4 Conjunctiva

Anatomy of the conjunctiva.

Accessory lacrimal glands:

Glands of Krause Glands of Wolfring

Bulbar conjunctiva

Conjunctival fornix

Palpebral conjunctiva

Surface of the cornea (functions as a part of the conjunctival sac)

Meibomian gland

Fig. 4.1 The conjunctiva consists of the bulbar conjunctiva, the conjunctival fornices, and the palpebral conjunctiva. The surface of the cornea functions as the floor of the conjunctival sac.

4.2Examination Methods

Inspection: The bulbar conjunctiva can be evaluated by direct inspection under a focused light. Normally it is shiny and transparent. The other parts of the conjunctiva will not normally be visible. They can be inspected by everting the upper or lower eyelid (see eyelid eversion below).

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Dye staining: Defects and tears in the conjunctiva or cornea can be visualized by applying a drop of fluorescein dye or rose bengal and inspecting the eye under illumination with a cobalt blue filter (see Fig. 5.11, p. 139).

Eyelid eversion: Even the non-ophthalmologist must be familiar with the technique of everting the upper or lower eyelid. This is an important examination method in cases in which the conjunctival sac requires cleaning or irrigation, such as removing a foreign body or rendering first aid after a chemical injury. See Chapter 1 for a detailed description of the examination method.

4.3Conjunctival Degeneration and Aging Changes

4.3.1Pingueculum

Definition

Harmless grayish yellow thickening of the conjunctival epithelium in the palpebral fissure.

Epidemiology: Pinguecula are the most frequently observed conjunctival changes.

Etiology: The harmless thickening of the conjunctiva is due to hyaline degeneration of the subepithelial collagen tissue. Advanced age and exposure to sun, wind, and dust foster the occurrence of the disorder.

Symptoms: Pingueculum does not cause any symptoms.

Diagnostic considerations: Inspection will reveal grayish yellow thickening at 3 o’clock and 9 o’clock on the limbus. The base of the triangular thickening (often located medially) will be parallel to the limbus of the cornea; the tip will be directed toward the angle of the eye (Fig. 4.2).

Differential diagnosis: A pingueculum is an unequivocal finding. Treatment: No treatment is necessary.

4.3.2Pterygium

Definition

Triangular fold of conjunctiva that usually grows from the medial portion of the palpebral fissure toward the cornea.

Epidemiology: Pterygium is especially prevalent in southern countries due to increased exposure to intense sunlight.

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Etiology: Histologically, a pterygium is identical to a pinguecula. However, it differs in that it can grow on to the cornea; the gray head of the pterygium will grow gradually toward the center of the cornea (Fig. 4.3a). This progression is presumably the result of a disorder of Bowman’s layer of the cornea, which provides the necessary growth substrate for the pterygium.

Symptoms and diagnostic considerations: A pterygium only produces symptoms when its head threatens the center of the cornea and with it the visual axis (Fig. 4.3b). Tensile forces acting on the cornea can cause severe corneal astigmatism. A steadily advancing pterygium that includes scarred conjunctival tissue can also gradually impair ocular motility; the patient will then experience double vision in abduction.

Differential diagnosis: A pterygium is an unequivocal finding.

Treatment: Treatment is only necessary when the pterygium produces the symptoms discussed above. Surgical removal is indicated in such cases. The head and body of the pterygium are largely removed, and the sclera is left open at the site. The cornea is then smoothed with a diamond reamer or an excimer laser (a special laser that operates in the ultraviolet range at a wavelength of 193 nm).

Clinical course and prognosis: Pterygia tend to recur. Keratoplasty is indicated in such cases to replace the diseased Bowman’s layer with normal tissue. Otherwise the diseased Bowman’s layer will continue to provide a growth substrate for a recurrent pterygium.

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Pterygium.

a

b

Fig. 4.3 a Triangular fold of conjunctiva growing from the medial portion of the palpebral fissure toward the cornea. b Pterygium that has grown on to the cornea and threatens the optical axis.

4.3.3Pseudopterygium

A pseudopterygium due to conjunctival scarring differs from a pterygium in that there are adhesions between the scarred conjunctiva and the cornea and sclera. Causes include corneal injuries and/or chemical injuries and burns. Pseudopterygia cause pain and double vision. Treatment consists of lysis of the adhesions, excision of the scarred conjunctival tissue, and coverage of the defect (this may be achieved with a free conjunctival graft harvested from the temporal aspect).

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72 4 Conjunctiva

Subconjunctival hemorrhage.

Fig. 4.4 Extensive bleeding under the conjunctiva.

4.3.4Subconjunctival Hemorrhage

Extensive bleeding under the conjunctiva (Fig. 4.4) frequently occurs with conjunctival injuries (for obtaining a history in trauma cases, see Chapter 18, conjunctival laceration). Subconjunctival hemorrhaging will also often occur spontaneously in elderly patients (as a result of compromised vascular structures in arteriosclerosis), or it may occur after coughing, sneezing, pressing, bending over, or lifting heavy objects. Although these findings are often very unsettling for the patient, they are usually harmless and resolve spontaneously within two weeks. The patient’s blood pressure and coagulation status need only be checked to exclude hypertension or coagulation disorders when subconjunctival hemorrhaging occurs repeatedly.

4.3.5Calcareous Infiltration

A foreign-body sensation in the eye is often caused by white punctate concrements on the palpebral conjunctiva. These concrements are the calcified contents of goblet cells, accessory conjunctival and lacrimal glands, or meibomian glands where there is insufficient drainage of secretion. These calcareous infiltrates can be removed with a scalpel under topical anesthesia.

4.3.6Conjunctival Xerosis

Definition

Desiccation of the conjunctiva due to a vitamin A deficiency.

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