Ординатура / Офтальмология / Английские материалы / Ophthalmology A Short Textbook_Lang_2000

Cutaneous Horn.

Fig. 2.23 The yellowish brown cutaneous protrusions consist of keratin. They frequently (25% of all cases) develop into a malignant squamous cell carcinoma in later years if they are not surgically removed.

Keratoacanthoma.

Fig. 2.24 The rapidly growing benign tumor has a central keratin mass that opens on the skin surface.

2.7.1.6Hemangioma

Definition

Congenital benign vascular anomaly resembling a neoplasm that is most frequently noticed in the skin and subcutaneous tissues.

Epidemiology: Girls are most often affected (approximately 70% of all cases). Facial lesions most commonly occur in the eyelids (Fig. 2.25).

44 2 The Eyelids

Cavernous hemangioma.

Fig. 2.25 The congenital vascular anomaly occurs as a facial lesion most commonly occur in the eyelids. The lesion regresses spontaneously in approximately 70% of all cases.

Symptoms: Hemangiomas include capillary or superficial, cavernous, and deep forms.

Diagnostic considerations: Hemangiomas can be compressed, and the skin will then appear white.

Differential diagnosis: Nevus flammeus: This is characterized by a sharply demarcated bluish red mark (“port-wine” stain) resulting from vascular expansion under the epidermis (not a growth or tumor).

Treatment: A watch-and-wait approach is justified in light of the high rate of spontaneous remission (approximately 70%). Where there is increased risk of amblyopia due to the size of the lesion, cryotherapy, intralesional steroid injections, or radiation therapy can accelerate regression of the hemangioma.

Prognosis: Generally good.

2.7.1.7Neurofibromatosis (Recklinghausen’s Disease)

Definition

A congenital developmental defect of the neuroectoderm gives rise to neural tumors and pigment spots (café au lait spots).

Neurofibromatosis is regarded as a phacomatosis (a developmental disorder involving the simultaneous presence of changes in the skin, central nervous system, and ectodermal portions of the eye).

Neurofibroma.

Fig. 2.26 Larger fibromas can lead to elephantiasis of the eyelids.

Symptoms and diagnostic considerations: The numerous tumors are soft, broad-based, or pediculate, and occur either in the skin or in subcutaneous tissue, usually in the vicinity of the upper eyelid.

They can reach monstrous proportions and present as elephantiasis of the eyelids (Fig. 2.26).

Treatment: Smaller fibromas can be easily removed by surgery. Larger tumors always entail a risk of postoperative bleeding and recurrence. On the whole, treatment is difficult.

2.7.2Malignant Tumors

2.7.2.1Basal Cell Carcinoma

Definition

Basal cell carcinoma is a frequent, moderately malignant, fibroepithelial tumor that can cause severe local tissue destruction but very rarely metastasizes.

46 2 The Eyelids

Epidemiology: Approximately 90% of all malignant eyelid tumors are basal cell carcinomas. Their incidence increases with age. In approximately 60% of all cases they are localized on the lower eyelid. Morbidity in sunny countries is 110 cases per 100000 persons (in central Europe approximately 20 per 100000 persons). Dark-skinned people are affected significantly less often.

Gender is not a predisposing factor.

Etiology: Causes of basal cell carcinoma may include a genetic disposition.

Increased exposure to the sun’s ultraviolet radiation, carcinogenic substances

(such as arsenic), and chronic skin damage can also lead to an increased incidence. Basal cell carcinomas arise from the basal cell layers of the epidermis and the sebaceous gland hair follicles, where their growth locally destroys tissue.

Symptoms: Typical characteristics include a firm, slightly raised margin (a halo resembling a string of beads) with a central crater and superficial vascularization with an increased tendency to bleed (Fig. 2.27).

Ulceration with “gnawing” peripheral proliferation is occasionally referred to as an ulcus rodens; an ulcus terebans refers to deep infiltration with invasion of cartilage and bone.

Diagnostic considerations: The diagnosis can very often be made on the basis of clinical evidence. A biopsy is indicated if there is any doubt.

Loss of the eyelashes in the vicinity of the tumor always suggests malignancy.

Treatment: The lesion is treated by surgical excision within a margin of healthy tissue. This is the safest method. If a radical procedure is not feasible,

Basal cell carcinoma.

Fig. 2.27 A halo resembling a string of beads, superficial vascularization, and a central crater with a tendency to bleed are characteristic signs of this moderately malignant tumor.

the only remaining options are radiation therapy or cryotherapy with liquid nitrogen.

Prognosis: The changes of successful treatment by surgical excision are very good. Frequent follow-up examinations are indicated.

The earlier a basal cell carcinoma is detected, the easier it is to remove.

2.7.2.2Squamous Cell Carcinoma

This is the second most frequently encountered malignant eyelid tumor. The carcinoma arises from the epidermis, grows rapidly and destroys tissue. It can metastasize into the regional lymph nodes. Remote metastases are rarer. The treatment of choice is complete surgical removal.

2.7.2.3Adenocarcinoma

The rare adenocarcinoma arises from the meibomian glands or the glands of Zeis. The firm, painless swelling is usually located in the upper eyelid and is mobile with respect to the skin but not with respect to the underlying tissue. In its early stages it can be mistaken easily for a chalazion (see p. 39). The lesion can metastasize into local lymph nodes.

An apparent chalazion that cannot be removed by the usual surgical procedure always suggests a suspected adenocarcinoma.

The treatment of choice is complete surgical removal.

49

3 Lacrimal System

Peter Wagner and Gerhard K. Lang

3.1Basic Knowledge

The lacrimal system (Fig. 3.1) consists of two sections:

Structures that secrete tear fluid.

Structures that facilitate tear drainage.

Anatomy of the lacrimal system.

Superior lacrimal canaliculus

Fundus of the

lacrimal sac

Plica semilunaris

Lacrimal sac

Nasolacrimal

duct

Inferior concha

Inferior punctum lacrimale

Fig. 3.1 The lacrimal system consists of tear secretion structures and tear drainage structures.

the eyelid. The primary function of this layer is to stabilize the tear film. With its hydrophobic properties, it prevents rapid evaporation like a layer of wax.

2.The middle watery layer (approximately 8 µm thick) is produced by the lacrimal gland and the accessory lacrimal glands (glands of Krause and Wolfring). Its task is to clean the surface of the cornea and ensure mobility of the palpebral conjunctiva over the cornea and a smooth corneal surface for high-quality optical images.

3.The inner mucin layer (approximately 0.8 µm thick) is secreted by the goblet cells of the conjunctiva and the lacrimal gland. It is hydrophilic with respect to the microvilli of the corneal epithelium, which also helps to stabilize the tear film. This layer prevents the watery layer from forming beads on the cornea and ensures that the watery layer moistens the entire surface of the cornea and conjunctiva.

Lysozyme, beta-lysin, lactoferrin, and gamma globulin (IgA) are tear-specific proteins that give the tear fluid antimicrobial characteristics.

Tear drainage: The shingle-like arrangement of the fibers of the orbicularis oculi muscle (supplied by the facial nerve) causes the eye to close progressively from lateral to medial instead of the eyelids simultaneously closing along their entire length. This windshield wiper motion moves the tear fluid medially across the eye toward the medial canthus (Figs. 3.3a–c).

The superior and inferior puncta lacrimales collect the tears, which then drain through the superior and inferior lacrimal canaliculi into the lacrimal sac. From there they pass through the nasolacrimal duct into the inferior concha (see Fig. 3.1).

Combined function of the orbicularis oculi muscle and the lower lacrimal system.

Figs. 3.3a–c As the eyelids close, they act like a windshield wiper to move the tear fluid medially across the eye toward the puncta and lacrimal canaliculi.

52 3 Lacrimal System

3.2Examination Methods

3.2.1Evaluation of Tear Formation

Schirmer tear testing: This test (Fig. 3.4) provides information on the quantity of watery component in tear secretion.

Test: A strip of litmus paper is inserted into the conjunctival sac of the temporal third of the lower eyelid.

Normal: After about five minutes, at least 15 mm of the paper should turn blue due to the alkaline tear fluid.

Abnormal: Values less than 5 mm are abnormal (although they will not necessarily be associated with clinical symptoms).

The same method is used after application of a topical anesthetic to evaluate normal secretion without irritating the conjunctiva.

Tear break-up time (TBUT): This test evaluates the stability of the tear film.

Test: Fluorescein dye (10 µl of a 0.125% fluorescein solution) is added to the precorneal tear film. The examiner observes the eye under 10–20 power magnification with slit lamp and cobalt blue filter and notes when the first signs of drying occur (i) without the patient closing the eye and (ii) with the patient keeping the eye open as he or she would normally.

Normal: TBUT of at least 10 seconds is normal.

Rose bengal test: Rose bengal dyes dead epithelial cells and mucin. This test has proven particularly useful in evaluating dry eyes (keratoconjunctivitis sicca) as it reveals conjunctival and corneal symptoms of desiccation.

Measuring tear secretion with Schirmer tear testing.

Fig. 3.4 A strip of litmus paper is folded over and inserted into the conjunctival sac of the temporal third of the lower eyelid. Normally, at least 15 mm of the paper should turn blue within five minutes.