Ординатура / Офтальмология / Английские материалы / Primary Care Ophthalmology_Palay, Krachmer_2005
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A B
C D
E F
FIGURE 6–21 Laser in situ keratomileusis (LASIK) procedure. A, A lid speculum is used to retract the lids. B, A microkeratome (not shown) creates a thin corneal flap that remains attached to the underlying cornea with a small hinge. C, The excimer laser reshapes the stromal bed. D, The corneal flap is replaced; it will heal around the peripheral cut edge. E, In this example of the near-sighted (myopic) eye, the light is focused in front of the retina. F, After LASIK, the cornea has been reshaped so that light focuses directly on the retina. The cornea is less convex than the preoperative surface
(dotted line).
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CHAPTER 7
Scleritis
MICHAEL C. DIESENHOUSE
Related Anatomy
The episclera and sclera are composed of connective tissue, and together they provide a protective coat for the eye (Fig. 7–1). The episclera is a fascial sheath that encases the eye. It has a superficial layer, Tenon’s capsule, which acts as a synovial membrane to allow smooth movements of the eye. A deeper layer of the episclera contains a network of vessels. The episclera overlies the primarily avascular sclera and is partly responsible for scleral nutrition. The sclera is composed of collagen and elastic fibers arranged randomly. Its rigid structure is necessary for vision to remain stable during eye movements. The thickness of the sclera varies, ranging from approximately 0.3 mm behind the insertion of the rectus muscles to 1.2 mm posteriorly.
Inflammatory Conditions
Inflammation of the episclera and sclera is not commonly seen in clinical practice. Confusion with more common causes of a red eye, however, may lead to a delay in diagnosis. Conjunctivitis usually involves the entire conjunctiva (not just a section), usually is not associated with pain, and generally is accompanied by a discharge. Episcleritis and scleritis usually involve a section of the eye (although sometimes the entire eye is involved), are associated with mild pain (episcleritis) or severe pain (scleritis), and are not associated with a discharge. On the patient’s initial visit, distinguishing between episcleral and scleral inflammation is essential, because the management of these two diseases differs considerably. In addition, scleritis is more likely to be associated with exacerbation of a potentially serious systemic disease. A useful classification is presented in Box 7–1.
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120 CHAPTER 7 • Scleritis
Conjunctiva
Subconjunctival space
Anterior ciliary artery
Tenon's capsule
Sub Tenon's space
Sclera
Subchoroidal space
Choroid
Retina 
Lamina cribrosa
Subarachnoid space 
Central retinal artery
Optic nerve
Conjunctival vessels
Limbal arcade
Perforating arteries from long posterior ciliary artery
Episcleral arterial circle
Anterior ciliary artery
Episcleral artery
Long posterior ciliary artery
in suprachoroidal space
Sub Tenon's space
Tenon's capsule
Ophthalmic artery
FIGURE 7–1 Anteriorly, the episclera lies between the conjunctiva and underlying sclera, to which it is attached by fibrous bands. Posteriorly, it is continuous with the muscular sheath, extends backward to cover the whole of the globe, and merges with the optic nerve sheath behind the eye. It is perforated by the ciliary vessels and nerves and the vortex veins.
Episcleritis
Symptoms
•Redness of acute onset is noted by the patient.
•If pain is present, it often is described as a dull ache localized to the eye.
•Visual acuity usually is normal.
•The patient may report a history of recurrent episodes.
Signs
•Sectoral or diffuse redness of one or both eyes is evident.
•Episcleral vessels are engorged, but the vascular pattern is not disturbed.
•If a nodule is present, it is mobile over the underlying sclera.
•Neither discharge nor corneal involvement is present.
Episcleritis 121
BOX 7–1 Classification of Episcleritis and Scleritis
Episcleritis
•Simple
•Nodular (Fig. 7–2)
Scleritis
Diffuse Anterior
•Diffuse anterior scleritis is the most common but least destructive type (Fig. 7–3).
•Widespread involvement of the sclera is characteristic, but localized changes also are seen.
Nodular Anterior
•This form is distinguished by a painful localized elevation of the sclera, which may develop into a nodule (Fig. 7–4).
•Nodular anterior scleritis differs from nodular episcleritis in that the nodule is immobile.
•In approximately 20% of the patients, the condition progresses to necrotizing scleritis.
FIGURE 7–2 Nodular episcleritis in a patient with gout.
FIGURE 7–3 In diffuse anterior scleritis, widespread injection of the conjunctival and deep episcleral vessels is characteristic.
122 CHAPTER 7 • Scleritis
BOX 7–1 Classification of Episcleritis and Scleritis (Continued)
FIGURE 7–4 An elevated mass within the area of inflammation is seen in nodular anterior scleritis. Unlike the nodule in episcleritis, this nodule is immobile.
FIGURE 7–5 In this eye of a patient with rheumatoid arthritis and necrotizing scleritis, avascular areas with tissue loss are adjacent to areas of active inflammation. Prompt and aggressive immunosuppressive treatment is necessary.
Necrotizing
•Necrotizing scleritis is the least common but most destructive form (Fig. 7–5).
•Ocular and systemic complications are seen in 60% of patients.
•Progressive scleral necrosis can lead to scleral thinning and perforation of the globe.
•The disorder usually is associated with a potentially serious systemic disease.
Scleromalacia Perforans
•Scleromalacia perforans is the only form of scleritis without pain (Fig. 7–6).
•A lack of symptoms is characteristic. Some patients may note decreased vision or a change in the color of the sclera.
Episcleritis 123
BOX 7–1 Classification of Episcleritis and Scleritis (Continued)
FIGURE 7–6 Marked scleral thinning, a characteristic of scleromalacia perforans, allows exposure of the underlying choroid. This gives the sclera a bluish hue, a discoloration best seen in daylight.
•Scleral necrosis and thinning are observed in the absence of inflammation.
•Perforation of the globe may occur with minor trauma.
•The disorder is predominantly bilateral and seen almost exclusively in patients with rheumatoid arthritis.
Associated Factors and Diseases
•In 75% of cases, the origin is idiopathic.
•Other causes include the following:
Collagen-vascular diseases
Atopy
Rosacea
Gout
Herpes zoster
Lyme disease
Syphilis
Bisphosphonates
•The disorder is more prevalent in young adults.
Workup
•The phenylephrine test involves instillation of a drop of phenylephrine 2.5% in the eye, which helps distinguish between dilated episcleral and scleral vessels. Unlike the deeper scleral vessels, episcleral vessels blanch when topical phenylephrine is applied.
Treatment
•Referral to an ophthalmologist is necessary for confirmation and treatment. A careful review of systems should be performed.
124CHAPTER 7 • Scleritis
•Most cases are self-limited and resolve without treatment.
•Initially, cold compresses, artificial tears, and/or a topical vasconstrictor are used. Topical corticosteroids may be administered by an ophthalmologist. Topical nonsteroidal anti-inflammatory drugs (NSAIDs) are of questionable value in treatment.
•If topical medications do not provide relief, a course of an oral NSAID is instituted.
•Resistance to treatment may signify the presence of an associated systemic disease.
Scleritis
Several types of scleritis exist (see Box 7–1). Although each type has distinct characteristics, these entities have many of the same symptoms and signs.
Symptoms
•The onset of the disorder is gradual.
•The hallmark symptom is severe pain that may radiate to the temple or jaw. Often the pain awakens the patient at night.
•Photophobia is present.
•Tearing occurs.
•Vision is normal or mildly decreased.
•Episodes may recur.
Signs
•The globe is tender to palpation.
•Sectoral or diffuse edema of the sclera occurs, with engorgement of the overlying episcleral vessels.
•Nodules and scleral necrosis may be present.
•Corneal and intraocular inflammation may coexist.
Associated Factors and Diseases
•The origin usually is idiopathic, but almost half of the patients have an associated systemic disease. The inflammation of the eye may serve as a clue to an underlying disease or warn of increased severity in a known condition.
•Disorders and medications for which an association with scleritis has been documented include the following:
Rheumatoid arthritis
Systemic lupus erythematosus
Polyarteritis nodosa
Wegener’s granulomatosis
Relapsing polychondritis
Ankylosing spondylitis
Giant cell arteritis
Gout
Herpes zoster
Lyme disease
Scleritis 125
Syphilis
Tuberculosis
Bisphosphonates
Workup
•In the phenylephrine test, deep episcleral and scleral vessels do not blanch when topical 2.5% phenylephrine is applied.
•The patient’s eye is viewed with normal lighting. An eye with scleritis may have a bluish hue when seen in daylight, which can signify thinning of the sclera. This discoloration can be easily overlooked in a darkened room.
Treatment
•Referral to an ophthalmologist is necessary for confirmation and treatment.
•Because scleritis may be the presenting sign of a systemic disease, a thorough systemic evaluation is warranted. The management of scleritis necessitates the use of systemic medications. If an associated systemic disease is identified, therapy is appropriately modified.
•Initial treatment involves administration of oral NSAIDs or systemic corticosteroids.
•In advanced cases, cytotoxic agents may be prescribed. Because of the side effects and contraindications of these medications, the treatment protocol must be individualized for each patient.
•Treatment guidelines are based on the persistence of inflammation, with the degree of resolution of pain used to gauge disease control.
•For management of patients with scleritis, a team approach involving the ophthalmologist and the primary care physician is essential.
CHAPTER 8
Lens Abnormalities
JONATHAN H. ENGMAN • ANDREW R. HARRISON • JAY H. KRACHMER
Related Anatomy
The lens is a biconvex and grossly transparent structure located directly behind the iris. In adults, it is approximately 9 mm in diameter and 4 mm thick. The lens consists of 65% water and 35% protein (which is the highest protein content of any body tissue). No pain fibers, blood vessels, or nerves are present in the lens.
The lens has three layers: the capsule, cortex, and nucleus (Fig. 8–1). The lens capsule is a thin, semipermeable membrane that envelops the entire lens. The posterior capsule is markedly thinner than the anterior capsule. The lens cortex is composed of lens cells, or fibers, that are produced continuously throughout life. The old lens fibers migrate centrally as new fibers are produced. The oldest lens fibers, which are those that have lost their nuclei, make up the nucleus.
The lens is held in place by ligaments known as zonules, which are composed of numerous fibrils that arise in the ciliary body and insert into the lens capsule. Contraction of the ciliary body causes relaxation of zonules with resultant thickening of the lens, thereby allowing the eye to focus on near objects. This phenomenon is known as accommodation.
Presbyopia
Symptoms
•Reading is difficult.
•Reading material is held farther from the eyes.
•Distance vision is blurry after the patient reads.
Signs
•Only near vision decreases; the ability (or inability) to see distant objects remains the same.
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128 CHAPTER 8 • Lens Abnormalities
Posterior capsule
Posterior cortex
Nucleus
Zonules
Anterior cortex
Epithelium
Anterior capsule
FIGURE 8–1 Normal lens anatomy.
Etiology
•With age, the lens becomes increasingly inelastic and can no longer “thicken” to focus on near objects (Fig. 8–2). This disorder, also called “old sight,” usually becomes clinically significant at the age of 40 to 45 years.
Treatment
•For patients with normal distance vision, simple reading glasses may be purchased over the counter, without a prescription, at pharmacies.
•For patients with distance vision requiring correction, the following apply:
Spectacle correction with bifocal (distance and near) or trifocal (distance, intermediate, and near) lenses
Monovision contact lenses in which one eye is corrected for distance vision and the other eye for near vision
Contact lens correction of distance vision and simple reading glasses for near vision
Senile Cataract
A cataract is any opacity in the crystalline lens. Senile cataract is an age-related disorder, and four types occur: nuclear, cortical, posterior subcapsular, and dense white (Box 8–1).
Symptoms
•A slowly progressing visual loss or blurring occurs over months to years.
•Glare is a problem, particularly from oncoming headlights during night driving.
•Double vision in one eye (monocular diplopia) may be noted.
•Fixed spots in the visual field are present.