Ординатура / Офтальмология / Английские материалы / Practical Ophthalmology A Manual for the Beginning Ophthalmology Residents 4th edition_Wilson_1996

246 Chapter 11: Anterior Segment Examination

Bulbar Conjunctiva

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'*•'•"• '•' tions, the bulbar conjunctiva can manifest chemosis, lymphangiectasia and lymphedema, telangiectasia, hyperemia, epithelial defects and ulcers, and a variety of less common abnormalities.

2 48 Chapter 11: Anterior Segment Examination

Chemosis is most often caused by allergy, although it can be caused by a variety of inflammatory conditions, including conjunctivitis, episcleritis, scleritis, uveitis, endophthalmitis, and orbital cellulitis.

Lymphangiectasia and lymphedema

One or more lymphatic channels of the conjunctiva can become dilated (lymphangiectasia), producing the appearance of a clear, slightly elevated, tube-like structure. It is often sacculated, resembling a segment of intestine. Blood is occasionally seen in a lymphangiectasis, usually after trauma or inflammation. Lymphangiectasia is often idiopathic, but it is sometimes related to trauma.

Lymphedema of the conjunctiva results from obstruction of lymphatic outflow, leading to a straw-colored, chemosis-like change. The problem is generally caused by scarring or, rarely, rumor in the orbit.

Telangiectasia

Telangiectasia is permanent dilation of small blood vessels. It can occur in the palpebral conjunctiva or in the skin of the eyelids, but it is perhaps most common in the bulbar conjunctiva. The cause is often unknown, but it can be congenital or secondary to chronic inflammation, hypertension, atherosclerosis, orbital vascular abnormalities, rosacea, blood dyscrasias, or hemoglobinopathy (sickle-cell disease). The condition can occur in at least four rare diseases, namely, ataxia telangiectasia, Fabry's disease, Sturge-Weber syndrome, and Osler- Wcber-kcndu disease.

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Hyperemia

Increased blood flow with associated dilation of blood vessels (hyperemia) in the conjunctiva produces more or less diffuse redness that is usually. most prominent peripherally, tending to fade as the limbus is approached (Figure 11.28). This is because the conjunctival blood supply is most prominent in, and enters from, the peripheral bulbar conjunctiva. This blood supply is distinct from the one that produces a ciliary flush.

Papillae do not develop in the bulbar conjunctiva because of the absence of fibrous septa. Conjunctival hyperemia is an entirely nonspecific finding that can occur with practically any ocular inflammation, dryness, environmental irritants, and the like.

Epithelial defects and ulcers

Absence or disruption of a portion of the conjunctival epithelium is referred to as an epithelial defect or erosion. The term ulcer implies some loss of conjunctival stroma as well. Epithelial defects and ulcers are detected by the absence of normal conjunctival luster, and bv an - actual depression in a particular area, often surrounded by some hyperemia. Staining with fluorescein (discussed later in this chapter) can also make evident a defect or ulcer. Defects and ulcers have many causes but are especially common after trauma, including chemical burns.

Other Conjunctival Abnormalities

A detailed discussion of other possible abnormalities of the bulbar conjunctiva is beyond the scope of this book, but such discussions can be found in Section 8, External Disease and Cornea, of the Basic and Clinical Science Course of the American Academy of Ophthalmology and many other textbooks. A list of the most important additional

Figure 11.28 Hyperemia of the buibar conjunctiva in bacteriai conjunctivitis.

250 Chapter 11: Anterior Segment Examination

•Pigmentations and deposits (accumulation or deposition of melanin, drugs, or systemic or topical heavy metals)

•Dermoid tumors (choristomas, or benign congenital tumors)

•Concretions (epithelial inclusion cysts, rare in bulbar conjunctiva)

•Pingueculae (yellowish, often slightly elevated limbal lesion

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resulting from ultraviolet exposure)

•Pterygia (idiopathic triangular fibrovascular bulbar conjunctival growth associated with Pingueculae)

•Phlyctenules (or phlyctens, white or yellow-white round-to-ovoid subepithelial infiltrates often associated with staphylococcal blepharitis or conjunctivitis, or with systemic tuberculosis)

•Keratinization (dry, lackluster, pearly gray alteration of the conjunctival or corneal epithelial surface, sometimes covered with superficial foamy sebaceous matter)

•Tumors, including cysts, papillomas, squamous neoplasia (referred to as conjunctival, or corneal, intraepithelial neoplasia, or CIN), squamous carcinoma, sebaceous carcinoma (secondarily affecting the conjunctiva), nevi, melanomas, lymphomas or benign lymphoid hyperplasia, and angiomas

Episclera and Sclera

Most episcleral and scleral abnormalities are easily observed even with a penlight. A number of differences help the clinician distinguish between conjunctival and scleral or episcleral signs. The episclera and sclera have a blood supply deeper than and separate from that of the conjunctiva. Blood vessels in the conjunctiva are generally finer and less tortuous than the deeper vessels. Furthermore, conjunctival hyperemia has a red appearance, whereas deeper (episcleral and scleral) hyperemia is often violaceous. Conjunctival vessels can be moved by massaging the conjunctiva through the eyelid or directly with a cotton

swab; the deeper vessels do not move with such maneuvers. Finally, topical vasoconstricting agents affect conjunctival vessels much more than the deeper vessels.

Episcleritis

Episcleritis is an immunologically mediated inflammation of the tissue that lies between the deep conjunctival stroma and the sclera (Figure 1 1.29). It is typically benign, short-lived, and not associated with tenderness, ciliary pain, or flare and cell in the anterior chamber. It is diagnosed by the features just mentioned and by noting that deep hyperemia is present. Thought to be caused most often by allergy to foods or, perhaps, airborne allergens, episcleritis can also occur with rosacea.

Episcleritis occurs in three forms, depending on the distribution and extent of the deep hyperemia, and on whether or not edema (causing a nodular elevation) is present: diffuse (involving much, or all, of the episclera); sectoral; and nodular (see Figure 11.29).

Scleritis

Sclentis is an immunologically mediated inflammation of the sclera itself (always associated with secondary inflammation of the episclera). Deep hyperemia is again seen, along with tenderness, ciliary pain (or, at least, photophobia), and, often, flare and cell in the anterior chamber. Scleritis is likely to have a more prolonged course than episcleritis and can cause damage in the form of scleral thinning (which creates a bluish appearance to the sclera) and complications from uveitis (including glaucoma).

Unlike episcleritis, scleritis is associated with, and is caused by, detectable systemic disease in about one half of afflicted patients. The most common causes are autoimmune collagen-vascular (connective

Figure 11.29 Nodular episcleritis; lesion is nodular but superficial to the sclera; this is also an example of sectoral episcleritis, in that it affects only the superonasal aspect of the left eye.

252 Chapter 1 1. Anterior Segment K.xamination

tissue) diseases, granulomatous diseases such as syphilis or tuberculo-

necrotizing. Necrotizing scleritis with inflammation (ischemic scleritis) occurs in patients who have autoimmune vasculitis (systemically, as well as in the eye) and is characterized bv severe inflammation and scleral necrosis (Figure 11.32). The affected area often appears to be ischemic in that there are foci of blanched, avascular tissue in or around other nearby areas of severe hyperemia. Conjunctival necrosis can also occur.

ance and are referred to as staphylomas (referring to the grape-like appearance).

The inflammation of scleritis sometimes affects secondarily the corneal stroma, producing cellular infiltrate, with or without vascularization (sclerokeratitis).

Pigmentations

A branch of a long ciliary nerve, often accompanied bv an anterior ciliary artery, sometimes loops up into or through the sclera, often along with some uveal pigment, producing a blue-black spot in the superficial sclera 3-4 mm from the limbus. This anomalv is known as Axenfeld's nerve loop.

Congenital melanosis oculi (ocular melanocytosis) is an anomalv that produces deep, slate-gray patches of scleral and episcleral pigmentation, nearly always unilaterally Associated findings can include ipsilateral hvperpigmentation of the iris, the fundus, and the periocular skin (nevus of Ota; oculodermal melanocytosis).

A blue nevus is one located deep in the conjunctiva or in the episclera that has a dark-blue color. Brown or brown-black pigmentation is produced bv pigmented minors of the uveal tract (for example, ciliary body melanomas), which occasionally erode into the sclera or episclera.

Figure 11.34 Involutiona hyaline ielcidl plaque

Involutional Hyaline Plaques

Involutional hyaline and calcific plaques of the sclera are sometimes seen in elderly patients. The plaques develop in the areas of insertion of the medial and lateral (rarely the inferior) rectus muscles, rhev have a gray-brown or yellow-brown translucent appearance (Figure l 1.54).

Tear Film

, " Schirmer testing is used to evaluate tear production and is usually performed as part of the external examination (see Chapter 9). In the anterior segment examination, the tear film is evaluated with the slit lamp for its overall wetness, presence of meniscus, and breakup time, as well as a few minor abnormalities.

Overall Wetness

The general presence or absence of moisture on the ocular surface can be evaluated with diffuse illumination, looking for the normallv glistening character of the tear film, in contrast to the matte appearance of the severely dry eve. .< ^

Tear Meniscus

WTien viewed in cross-section with a thin slit-lamp beam (optica! section), the tear film forms a roughly triangular meniscus, or "lake," between the margin of the lower eyelid and the place where the eyelid margin apposes the globe (Figure 11.35). Absence of, or a smaller than usual, meniscus is indicative of tear deficiency. A higher than normal meniscus occurs with conditions of tearing or epiphora. The best way to become familiar with the appearance of a normal meniscus is to observe it in a number of patients whose tear films are normal.

Figure 11.35 Normally the tear film ^--•-•>: i 'oughiy triangular meniscus along the . • margin of the eyelid; this is reduced or absent in , the dry eye, and increased (higher and more

convex) in the wet eye.

Globe

Meibomian gland orifices

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Margin of lower eyelid