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

2-66 Chapter 1 1: Anterior Segment Examination

Severe intraocular inflammation is often associated with the presence of fibrin in the anterior chamber, seen as strands or clumps of hazy yellow-white or gray-white material.

Lens material and vitreous

Fragments of lens material or vitreous humor are sometimes seen in the anterior chamber after trauma or cataract surgery. Lens material consists of white clumps that are several times larger than inflammatory cells. Vitreous can be present as a single strand, usually extending through the pupil to the site of a corneal or scleral wound, or vitreous can fill the entire anterior chamber. The material is clear, but large amounts are seen to contain some fine, gray strands.

Foreign bodies and cysts

The anterior chamber sometimes contains foreign bodies, including artificial lens implants. Traumatic implantation of epithelial cells into the anterior chamber can result in the formation of a cyst as the cells proliferate; such an epithelial implantation cyst is at first small (less than 1 mm in diameter), round, and white (pearl cyst). Larger cysts are more clear and can fill a large part of the anterior chamber, indenting and pushing the iris posteriorly.

Direct focal illumination is used most often for examining the iris. Indirect illumination is useful for evaluating the interior of lesions that are not transparent. Transillumination can reveal areas of partial or full-thickness iris atrophy. Sequelae of inflammation, synechiae are fibrous adhesions between the iris and the cornea (anterior synechiae) or between the iris and the crystalline lens (posterior synechiae). Posterior synechiae sometimes involve the entire circumference of the pupillary margin (seclusio pupillae), preventing aqueous humor from reaching the anterior chamber; glaucoma results, and the accumulation of aqueous behind the iris causes it to bow forward (iris bombe). Iris bombe also can occur when the entire pupil becomes covered by a fibrous membrane (occlusio pupillae).

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Nodules

Inflammatory nodules are usually granulomas. They appear with some cases of intense intraocular inflammation. They can be white, yellow, or pigmented. Nodules at the pupillary margin are called Koeppe nodules, whereas those on the surface of the iris are called Busacca nodules.

Neovascularization

Rubeosis iridis is neovascularization of the iris, usually caused by retinal ischemia. The abnormal vessels are fine, irregular, and plentiful. They appear on the surface of the iris, first in the area of the pupillary margin and peripherally at the root of the iris. The condition often leads to the formation of extensive peripheral anterior synechiae and glaucoma.

Rubeosis iridis is to be differentiated from mere hyperemia of otherwise normal iris vessels. Hyperemia is manifested by the presence of one or more individual cord-like vessels coursing in iris crypts somewhere between the pupillary margin and the peripheral iris. Rubeotic vessels are seen more as tight masses of very fine, tangled vessels.

Cysts and Tumors

"Iris" cysts are usually epithelial implantation cysts of the anterior chamber (discussed above). Most tumors of the iris are nevi or melanomas. They are variably pigmented, ranging from tan to brownblack in color (Figure 11.45). Thev usually cause thickening of the iris, and they can be associated with a dragging onto the front surface of the iris of the dark brown or black pigment epithelium of the posterior surface of the iris (ectropion uveae).

Figure 11.45 Pigmented

esion (melanoma) of iris.

268 Chapter 11: Anterior Segment Examination

Persistent Pupillary Membrane Remnants

'•* •- A membrane is normally present over the pupil during embryonic development. It generally disappears, but remnants sometimes persist. They are usually not extensive, but it is not uncommon to see a few spider-web-like strands of this tissue that originate from the iris near the pupillary margin; the other ends can be freely floating or attached elsewhere to the iris, to the anterior lens capsule, or even to the cornea. Stellate deposits of brown pigment are often found on the anterior lens capsule (epicapsular stars) as part of this condition.

Other Abnormalities

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:of the lack of support of the iris by the lens and its zonular attachments.

Crystalline Lens

I j u i p t c r i i : Anterior Segment l'.v.imni;Uion

Capsular cataracts

Capsular cataracts are usualK' superficial, sharplv demarcated white areas and are most commonly congenital. They can also develop secondary to inflammation and fibrosis (organization of fibrin). The posterior capsule sometimes manifests a small white dot lnreronasal to the visual axis (Mittendort dot).

Cortical cataracts

Cortical cataracts develop in the anterior and posterior cortex and are mostly associated with age and diabetes mellitus. In the age-related type, fluid accumulates among the lens fibrils, producing lamellar separation. This is seen as roughly parallel, reluceat lines (resembling linear air pockets in an ice cube). These areas then opacify, producing radially oriented cortical spokes (Figure 1 1.47). i.-'i<iccuiciu, snow flakelike opacities can also develop, especially in diabetic patients who have ketoacidosis (the rare, true diabetic cataract); these opacities are sometimes reversible with treatment or the ketoacidosis.

Glaukomfleckcn are grav-white anterior cortical dots that appear after episodes of very high intraocular pressure. The1.- usually indicate prior acute angle-closure glaucoma.

Nuclear cataracts

Nuclear cataracts are the most common, and classic, age-related

F re 11.47

changes to yellow-white, vellovv, yellow-brown, and finally brown (brunescent) discolorations (see Figure 11.47). Nuclear cataracts are apt to progress slowly, often requiring years to affect vision.

Subcapsular cataracts

Subcapsular cataracts are usually found in the posterior subcapsular area of the lens and appear as silver}- and granular, bubbly opacifications in the visual axis. The patient might see well as long as a tew clear areas remain, but the vision drops rapidly as soon as those clear areas opacify. Posterior subcapsular cataract develops, along with nuclear sclerosis, in some cases of age-related cataract, but it is also clearly related sometimes to corticosteroid therapy (topical or systemic) or to prior uveitis.

or posterior), the Y sutures, the fetal or embrvonic nuclei, or the capsule (usually anterior). The lamellar (also called zonular) form of congenital cataract is common. It shows opacification ot the periphery of a particular zone (for example, the fetal nucleus) of the lens, yet the interior of the zone is clear (Figure 11.48). These cataracts are often associated with "riders;" horseshoe-shaped opacities that cap the zonular opacitv; riders are located in a slightly more peripheral level of the lens than is the zonular opacitv itself.

Soemmerring ring

Soemmerring ring is a ring of opacified equatorial (peripheral) lens material, enclosed in lens capsule. It can result from trauma causing

althouqn some punctate opacities are also seen in the area of me retal Y sutures.

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272 Chapter 11: Anterior Segment Examination

rupture of the lens capsule and consequent resorption of most of the lens material, or from incomplete extracapsular cataract extraction.

Pseudophakia and aphakia

Patients who have had cataract extraction with implantation of an artificial intraocular lens implant are said to be pseudophakic. The implant is nowadays almost always in a posterior position (behind the iris), although implants in the anterior chamber or in one way or another fixed to the iris are occasionally seen. It is important in pseudophakia to ascertain whether or not the posterior lens capsule is present (as it is in most patients who have had the current extracapsular type of surgery) and whether or not it is clear or opaque. Laser capsulotomy might be indicated if the posterior capsule has become opaque. Aphakia is the complete absence of the lens (and its capsule) and is seen in patients who have had intracapsular (complete) cataract extraction.

Subluxation and Luxation

The crystalline lens is held in its normal position by multiple fine fibrils, the zonule (zonular fibers) of Zinn. The fibers can be disrupted by trauma or systemic disease (most notably Marfan syndrome or homocystinuria), resulting in partial or complete dislocation of the lens from its normal position. In the case of subluxation, the edge of the lens might be visible in the pupil. Complete dislocation (luxation) allows the lens to be displaced into the vitreous or, rarely, into the anterior chamber.

Other Conditions

-- Peters' anomaly, a congenital anomaly, manifests a corneal leukoma that is often attached to a cataractous lens by way of a fibrous band that extends across the anterior chamber. The band is sometimes attached to the iris instead of the lens. Pseudoexfoliation (or exfoliation) syndrome causes deposits of basement-membrane-like fibrillogranular material to accumulate on various intraocular tissues, but most prominently the anterior lens capsule, where it appears as a disk of fine, graywhite flecks centrally or paracentrally. The condition is associated with small areas of iris atrophy near the pupillary margin (seen by retroillumination), hyperpigmentation of the iris and trabecular meshwork, glaucoma, and fragility of the zonules. The last accounts for an increased risk of zonular rupture during extracapsular cataract extraction (including phacoemulsification).

Gonioscopx

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Retrolental Space and Anterior Vitreous

Evidence of inflammation can be seen with the slit lamp in the retrolental space and anterior vitreous, just as it can be seen in the anterior chamber. Grading of flare and cell in these areas is listed in Table 11.1.

Flare and cell in the anterior chamber alone are typical of the lorm of uveitis known as iritis. If flare and cell are found also in the retrolental space or anterioFvitreous, the condition is called jridocyclitis. Uveitis of the posterior segment can also manifest flare and cell in the anterior chamber, retrolental space, and anterior vitreous, but the mostprominent inflammation is then more posterior.

Gonioscopy

Gonioscopy is examination of the angle of the anterior chamber (the structures between the peripheral iris and cornea including, especially, the trabecular meshwork, through which aqueous exits the eye). Gonioscopy might not be performed during routine anterior segment examinations. However, it is especially important in the evaluation ol glaucoma (for differentiating angle-closure and open-angle types, for

Table 11.1 Grading of Retrolental and Vitreal Flare and Cell

Figure 11.50 (A) Goldmann th gonioscopy lens. (B, C) The lens's ent angles, allowing for examinat internal eye; rwror 4 permits exa anterior chamber and the area o" used for viewing the peripheral f midperipheral fundus; and lens T of the posterior pole of the fundi Streit AG, Bern, Switzerland.)

Figure 11.51 shows a composite drawing of the anatomy of the angle. The trabecular meshwork (or trabeculum) is bounded superiorly by Schwalbe's line (the peripheral termination of Descemet's membrane) and inferiorly by the scleral spur (into which the longitudinal muscles of the ciliary body insert). Schwalbe's line appears as a thin, opaque, white, linear ridge. The scleral spur is also white and opaque. Between the two structures, the trabecular meshwork appears grayish and somewhat translucent. The meshwork can show varying degrees of pigmentation (from none to heavy). If pigmentation is light or absent, a slightly darker-gray line can sometimes be seen in the lower area of the trabecular meshwork. This is Schlemm's canal, a tubule into which aqueous enters after passing through the trabeculum, and from which it then enters the vascular circulation. Posterior to the scleral spur are often a few normal blood vessels and normal iris processes (fine filaments extending from the iris to the lower trabecular meshwork). Still more posterior is an area known as the angle recess; this represents a dipping of the peripheral iris as it inserts into the ciliary body.

The angle may be described in the patient's record merely by noting the most posterior angle structure that can be seen. For example, if only Schwalbe's line can be seen, the angle is very narrow, but it the scleral spur can be seen, the angle is open. Usually, however, the width of the angle is graded, most often by the Shaffer method, as described