Ординатура / Офтальмология / Английские материалы / Clinical Ophthalmology A Systematic Approach 7th Edition_Kanski, Bowling_2011

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Chapter 8 – Episclera and Sclera

ANATOMY 252 EPISCLERITIS 252

Simple episcleritis 252 Nodular episcleritis  252

IMMUNE-MEDIATED SCLERITIS 253 Anterior non-necrotizing scleritis 254

Anterior necrotizing scleritis with inflammation  255

Scleromalacia perforans 257 Posterior scleritis 258

Important systemic associations of scleritis 259 Treatment of immune-mediated scleritis 261

INFECTIOUS SCLERITIS 261 SCLERAL DISCOLORATION 261

Alkaptonuria 261

Haemochromatosis  261

BLUE SCLERA 262 Osteogenesis imperfecta 262

Ehlers–Danlos syndrome type VI  262

Other systemic associations 263

MISCELLANEOUS CONDITIONS 263 Congenital ocular melanocytosis 263 Idiopathic sclerochoroidal calcification  264

Scleral hyaline plaque 267

Anatomy

The scleral stroma is composed of collagen bundles of varying size and shape that are not as uniformly orientated as in the cornea. The inner layer of the sclera (lamina fusca) blends with the suprachoroidal and supraciliary lamellae of the uveal tract. Anteriorly the episclera consists of a dense, vascular connective tissue which lies between the superficial scleral stroma and Tenon capsule. The three vascular layers that cover the anterior sclera are as follows:

1 The conjunctival vessels are the most superficial; arteries are tortuous and veins straight. 2 The superficial episcleral plexus vessels are straight with a radial configuration.

•In episcleritis, maximal congestion occurs within this vascular plexus (Fig. 8.1A). Tenon capsule and the episclera are infiltrated with inflammatory cells, but the sclera itself is not swollen.

•Instillation of topical phenylephrine will cause blanching of the conjunctival and to a certain extent the superficial episcleral vessels, allowing visualization of the underlying sclera.

3The deep vascular plexus lies in the superficial part of the sclera and shows maximal congestion in scleritis (Fig. 8.1B). There is also inevitably some engorgement of the superficial vessels, but this should be ignored. Examination in daylight is important to localize the level of maximal injection; scleritis often has a purplish hue.

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Fig. 8.1 (A) Episcleritis with maximal vascular congestion of the superficial episcleral plexus; (B) scleritis with scleral thickening and maximal vascular congestion of the deep vascular plexus.

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Episcleritis

Episcleritis is a common, benign, usually idiopathic, recurrent and frequently bilateral condition. It is usually self-limiting and an attack typically lasts a few days.

Simple episcleritis

Simple episcleritis accounts for three-quarters of all cases and predominantly affects females. It has a great tendency to recur either in the same eye, or sometimes both together. The attacks become less frequent and after many years disappear completely.

1Presentation is with redness and mild discomfort.

2Signs

•Redness may be sectoral (Fig. 8.2A) or diffuse (Fig. 8.2B). Often it has an interpalpebral distribution, in contrast with scleral disease which commonly starts in the upper temporal quadrants.

•The attack often reaches its peak within 12 hours and then gradually fades over the next few days.

•The episcleritis often flits from one eye to the other or may be bilateral.

3Treatment

•If mild, no treatment is required.

•Cool artificial tears may be adequate in some cases.

•A weak topical steroid q.i.d. for 1–2 weeks is usually sufficient, though occassionally more intensive instillation is needed initially.

•Oral NSAIDs are sometimes required such as flurbiprofen 100 mg t.i.d. for 10 days.

Fig. 8.2 Simple episcleritis. (A) Sectoral; (B) diffuse

(Courtesy of JH Krachmer, MJ Mannis and EJ Holland, from Cornea, Mosby 2005 – fig. B)

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Nodular episcleritis

Nodular episcleritis also tends to affect young females but has a less acute onset and a more prolonged course than the simple variety.

1Presentation is with a red eye typically first noted on waking. Over the next 2–3 days the area of redness increases in size, becomes more uncomfortable, but remains in the same position.

2Signs

•One or more tender nodules, almost always within the interpalpebral fissure (Fig. 8.3A).

•A thin slit-lamp section shows that the anterior scleral surface is flat, indicating absence of scleral involvement (Fig. 8.3B).

•Instillation of 2.5% phenylephrine drops will decongest the conjunctival and episcleral vessels allowing better visualization of underlying sclera.

•Each attack is self-limiting and usually clears without treatment but tends to last longer than simple episcleritis.

•After several attacks the vessels surrounding the inflamed area may become permanently dilated.

•It is important to exclude a local cause for an episcleral nodule such as a foreign body or granuloma.

3Treatment is similar to that of simple episcleritis.

Fig. 8.3 (A) Nodular episcleritis; (B) slit-lamp examination shows that the deep beamis not displaced above the scleral surface

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Immune-mediated scleritis

Scleritis is an uncommon condition characterized by oedema and cellular infiltration of the entire thickness of the sclera. It is much less common than episcleritis and covers a spectrum ranging in severity from trivial self-limiting episodes to a necrotizing disease that may involve adjacent tissues and threaten vision.

The classification shown in Table 8.1 not only facilitates communication regarding the clinical presentation, but also has prognostic significance since patients presenting with one form will usually suffer recurrences of the same type of the disease, with less than 10% progressing to more aggressive disease.

Table 8.1 -- Classification of immune-mediated scleritis

Anterior

Anterior non-necrotizing scleritis

Diffuse

Diffuse disease is slightly more common in females and usually presents in the 5th decade.

1Presentation is usually with ocular redness followed a few days later by aching and pain which may spread to the face and temple. The pain typically wakes the patient in the early hours of the morning and improves later in the day; it responds poorly to common analgesics.

2Signs

•Vascular congestion and dilatation associated with oedema. If treatment is started early, which rarely happens, the disease can be completely inhibited.

The redness may be generalized (Fig. 8.4A) or localized to one quadrant. If confined to the areas under the upper eyelid the diagnosis may be missed if the eyelid is not elevated.

•As the oedema resolves, the affected area often takes on a slight grey/blue appearance because of increased scleral translucency; this is due to rearrangement of scleral fibres rather than a decrease in scleral thickness (Fig. 8.4B).

•Recurrences at the same location are common unless the underlying cause is treated.

•The duration of disease is approximately 6 years and the frequency of recurrences decreases after the first 18 months. The long-term visual prognosis is very good.

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Fig. 8.4 (A) Diffuse non-necrotizing anterior scleritis; (B) scleral translucency following recurrent disease

(Courtesy of M Jager – fig. B)

Nodular

The incidence of nodular and diffuse anterior scleritis is the same but a disproportionately large number of those with nodular disease have had a previous attack of herpes zoster ophthalmicus. The age of onset is similar to that of diffuse scleritis.

1Presentation is with the insidious onset of pain followed by increasing redness, tenderness of the globe and the appearance of a scleral nodule.

2Signs

•Scleral nodules may be single (Fig. 8.5A) or multiple and most frequently develop in the interpalpebral region 3–4 mm away from the limbus. They have a deeper blue-red colour than episcleral nodules and are immobile.

•Slit-lamp examination shows that the slit beam is displaced by the scleral nodule (Fig. 8.5B).

•Instillation of 2.5% phenylephrine drops will constrict the conjunctival and superficial episcleral vasculature but not the deep plexus over the nodule.

•Multiple nodules may coalesce, become confluent, expanding sometimes to an enormous size if treatment is delayed.

•As the inflammation in the nodule subsides, increased translucency of the sclera becomes apparent.

•The duration of the disease is similar to diffuse scleritis.

•Over 10% of patients with nodular scleritis develop necrotizing disease but if treatment is instituted early superficial necrosis does not occur and the nodule heals from the centre leaving a small atrophic scar.

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Fig. 8.5 (A) Nodular non-necrotizing anterior scleritis; (B) slit-lamp examination shows displacement of the entire beam

Anterior necrotizing scleritis with inflammation

Necrotizing disease is the aggressive form of scleritis. The age at onset is later than that of non-necrotizing scleritis, averaging 60 years. The condition is bilateral in 60% of patients and unless appropriately treated, especially in its early stages, it may result in severe visual morbidity and sometimes loss of the eye.

Clinical features

1Presentation is with gradual onset of pain which becomes severe and persistent and radiates to the temple, brow or jaw; it frequently interferes with sleep and responds poorly to analgesia.

2 Signs vary according to the following three types of necrotizing disease as follows:

aVaso-occlusive is often associated with rheumatoid arthritis.

•Isolated patches of scleral oedema with overlying non-perfused episclera and conjunctiva.

•The patches coalesce, and if unchecked rapidly proceed to progressive scleral necrosis (Fig. 8.6A and B).

bGranulomatous is often associated with Wegener granulomatosis and polyarteritis nodosa.

•The disease typically starts with injection adjacent to the limbus and then extends posteriorly.

•Within 24 hours, the sclera, episclera, conjunctiva and adjacent cornea become irregularly raised and oedematous (Fig. 8.7).

cSurgically-induced scleritis typically starts within 3 weeks of the surgical procedure, but much longer intervals have been reported.

•Scleritis may be induced by any type of surgery including strabismus repair, trabeculectomy (Fig. 8.8A) and scleral buckling (Fig. 8.8B), and treatment of pterygium with adjunctive mitomycin C (Fig. 8.8C).

•The necrotizing process starts at the site of surgery and then extends outwards but, unlike other forms of necrotizing disease, it tends to remain localized to one segment.

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Fig. 8.6 Vaso-occlusive necrotizing scleritis with inflammation. (A) Early stage; (B) advanced disease

Fig. 8.7 Granulomatous necrotizing scleritis with inflammation

(Courtesy of P Watson)

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Fig. 8.8 Surgically-induced necrotizing scleritis. (A) Following trabeculectomy; (B) following scleral buckling; (C) following use of mitomycin Cin the treatment of pterygium

(Courtesy of R Fogla – fig. C)

Investigations

1Laboratory. The commonest association of scleral inflammation is a connective tissue disease. Unfortunately there are few specific and reliable tests so the results should be employed as adjuncts to clinical signs. Specific tests include RF, ANA, ANCA (cANCA, pANCA) and antiphospholipid antibodies.

2FA can aid in deciding if necrotizing scleritis is present or is likely to occur. In most patients with necrotizing scleritis there is vascular non-perfusion. However, in patients with a systemic vasculitis, such as Wegener granulomatosis, the pattern is primarily of transudation, localized areas of vasculitis and new vessel formation.

Complications

1Acute infiltrative stromal keratitis may be localized or diffuse.

2Sclerosing keratitis, characterized by chronic thinning and opacification in which the peripheral cornea adjacent to the site of scleritis resembles sclera (see Fig. 6.31D).

3Peripheral ulcerative keratitis is characterized by progressive melting and ulceration which may eventually be more serious than the scleritis (Fig. 8.9). In granulomatous scleritis the destruction extends directly from the sclera into the limbus and cornea. This characteristic pattern is seen in Wegener granulomatosis, polyarteritis nodosa and relapsing polychondritis. Peripheral corneal ulceration can occur at any stage of a necrotizing scleritis and, in rare cases, precede its onset.

4Uveitis, if severe, usually denotes aggressive scleritis.

5Glaucoma is the most common cause of eventual loss of vision. The intraocular pressure is very difficult to control in the presence of active scleritis.

6 Hypotony may be the result of ciliary body detachment, inflammatory damage or ischaemia. 7 Perforation of the sclera as a result of the inflammatory process alone is extremely rare.

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Fig. 8.9 Peripheral ulcerative keratitis secondary to necrotizing scleritis

Scleromalacia perforans

Scleromalacia perforans is a specific type of necrotizing scleritis without inflammation that typically affects elderly women with longstanding rheumatoid arthritis. The use of the word ‘perforans’ is unfortunate because perforation of the globe is extremely rare as the integrity of the globe is maintained by a thin, but complete, layer of fibrous tissue.

1Presentation is with slight non-specific irritation and keratoconjunctivitis sicca may be suspected; pain is absent and vision unaffected.

2Signs

•Necrotic scleral plaques near the limbus without vascular congestion (Fig. 8.10A).

•Coalescence and enlargement of necrotic areas.

•Very slow progression of scleral thinning and exposure of underlying uvea (Fig. 8.10B).

3Treatment may be effective in patients with very early disease but by the time most patients present, either no treatment is needed or is unlikely to be effective. Repair of scleral perforation is very difficult but must be attempted otherwise phthisis bulbi ensues.

4Differential diagnosis. A scleral hyaline plaque is an oval, dark-greyish area located close to the insertion of the horizontal rectus muscles (see Fig. 8.22). It typically affects elderly patients and is innocuous.

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