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

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•IOP is usually very high (50–100 mmHg).

•Conjunctival hyperaemia with violaceous circumcorneal injection.

•Anterior chamber is shallow and aqueous flare may be present.

•Corneal epithelial oedema (Fig. 10.45A).

•Unreactive mid-dilated vertically oval pupil (Fig. 10.45B).

•Fellow eye generally shows an occludable angle (see Fig. 10.40).

3Resolved acute (post-congestive) angle closure

•Folds in Descemet membrane (Fig. 10.46A), (if IOP has been reduced rapidly), optic nerve head congestion and choroidal folds.

•Later there is iris atrophy with a spiral-like configuration, irregular pupil, posterior synechiae (Fig. 10.46B) and glaukomflecken (Fig. 10.46C).

•The optic nerve may be normal or exhibit varying degrees of atrophy (Fig. 10.46D).

•If PAS cover more than half of the TM, IOP control is unlikely with medical treatment alone.

4Subacute angle closure in which signs between episodes are similar to those of the chronic presentation although occasionally post-congestive-type findings may be present indicating one or more episodes of very high IOP.

Fig. 10.45 Acute (congestive) angle-closure. (A) Corneal epithelial oedema; (B) mid-dilated vertically oval pupil

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Fig. 10.46 Post-congestive angle-closure. (A) Stromal corneal oedema and folds in Descemet membrane; (B) glaukomflecken; (C) spiral-shaped atrophic iris, dilated pupil and posterior synechiae; (D) optic atrophy

Provocation testing

Although investigations are usually unnecessary provocation testing may aid decision-making in some circumstances. For example, in patients with only partially opened angles following laser iridotomy, to assess the propensity to develop a steep increase in IOP and so determine whether further intervention (e.g. iridoplasty) might be appropriate. In the dark room/prone provocation test the patient sits face down in a dark room for one hour. The IOP is checked and a rise of 8 mmHg or more is taken as being of significance but may also sometimes occur in normal eyes. A positive response is virtually always abolished following lens extraction.

Treatment

Primary angle-closure suspect (PACS)

1Prophylactic laser iridotomy is recommended. Iridotomy often widens the angle by about two grades (Fig. 10.47A and B), although this may not necessarily prevent the later development of angle-closure or raised IOP with an open angle.

2If significant ITC persists after iridotomy, optimal management remains undefined; options include observation, laser iridoplasty, prophylaxis with pilocarpine 1% and lens extraction.

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Fig. 10.47 Effects of peripheral iridotomy. (A) Closed angle before treatment; (B) open angle after treatment

Chronic presentation of PAC and PACG

•Management is as for PACS, but with a lower threshold for further intervention if there is inadequate angle widening after laser iridotomy, particularly if IOP remains elevated.

•Urgency and intensity of treatment and frequency of review is tailored to the individual patient, taking into account IOP, extent of angle-closure and glaucomatous damage, if present.

•Medical treatment as for POAG may be required for eyes with substantial synechial closure or with persistently elevated IOP despite an opened angle.

Acute and subacute presentation of PAC and PACG

Treatment intensity should be individualized dependent on severity. Hospital admission is usually required in an acute presentation, though not necessarily when subacute.

1Initial treatment

•The patient should assume a supine position to encourage the lens to shift posteriorly under the influence of gravity.

•Acetazolamide 500 mg is given intravenously if IOP >50 mmHg, and orally (not slow-release) if IOP is <50 mmHg.

•If treatment is intravenous an additional oral dose of acetazolamide 500 mg may be given.

•Topical apraclonidine 1%, timolol 0.5%, prednisolone 1% or dexamethasone 0.1% to the affected eye, leaving 5 minutes between each instillation.

•Pilocarpine 2–4% one drop to the affected eye, repeated after half an hour, and one drop of 1% as prophylaxis into the fellow eye.

•Some practitioners omit pilocarpine in an acutely presenting eye with very high IOP until a significant IOP fall has taken place, as the associated ischaemia will compromise the action of pilocarpine on the pupillary sphincter.

•Analgesia and an antiemetic may be required.

2Subsequent medical treatment

•Pilocarpine 2% q.i.d. to the affected eye and 1% q.i.d. to the fellow eye.

•Topical steroid (prednisolone 1% or dexamethasone 0.1%) q.i.d. if the eye is acutely inflamed.

•Any or all of the following should be continued as necessary according to response: timolol 0.5% b.d., apraclonidine 1% t.i.d. and oral acetazolamide 250 mg q.i.d. may be required.

3 If the above measures fail consider the following:

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•Central corneal indentation with a squint hook or indentation goniolens to force aqueous into the angle may break an attack.

•Corneal oedema can be cleared with topical 50% glycerol first to improve visualization and avoid abrasion.

•Further pilocarpine 2–4%, timolol 0.5%, apraclonidine 1% and topical steroid.

•Mannitol 20% 1–2 g/kg intravenously over 1 hour or glycerol 50% 1 g/kg, having checked for contraindications.

•Laser iridotomy or iridoplasty after clearing corneal oedema with glycerol.

•Surgical options in resistant cases include peripheral iridectomy, lens extraction, goniosynechialysis, trabeculectomy and cyclodiode.

4Following successful treatment with a clear cornea, reasonably quiet anterior chamber, and preferably a normalized IOP, bilateral laser iridotomy is performed. Topical steroids and any necessary hypotensives are continued for at least a week.

5Subsequent management is as for post-iridotomy chronic PAC/PACG. Options including observation, treatment of persistently raised IOP as for POAG, iridoplasty or long-term low dose pilocarpine if appositional closure persists. A relatively low threshold may be adopted for cataract surgery, particularly if a significant phacomorphic element is suspected. Trabeculectomy is occasionally necessary for persistent IOP elevation despite a successfully opened angle.

Differential diagnosis of an acute elevation of IOP

A key indicator that PAC/PACG may not be responsible is an open angle in a fellow eye.

1Lens-induced angle-closure due to an intumescent (swollen) or subluxated lens.

2 Malignant glaucoma, especially if intraocular surgery has recently taken place (usually trabeculectomy).

3Other causes of secondary angle-closure, with or without pupillary block; see below.

4Neovascular glaucoma may occasionally cause the sudden onset of pain and congestion.

5Inflammatory elevation with an open angle. Iridocyclitis with trabeculitis (particularly herpetic), glaucomatocyclitic crisis (Posner –Schlossman syndrome), scleritis without angle-closure.

6 Pigment dispersion with sudden elevation of IOP.

7Pseudoexfoliation with sudden elevation of IOP.

8 Orbital/retro-orbital lesions including orbital inflammation, retrobulbar haemorrhage and carotid-cavernous fistula.

9Others include atypical presentation of secondary open-angle glaucoma (see below).

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Classification of secondary glaucoma

Open-angle

Secondary open-angle glaucoma can be subdivided on the basis of the site of aqueous outflow obstruction as follows:

1Pre-trabecular glaucoma in which aqueous outflow is obstructed by a membrane covering the trabeculum (Fig. 10.48A), which may consist of:

•Fibrovascular tissue (neovascular glaucoma).

•Endothelial cellular membranous proliferation (iridocorneal endothelial syndrome).

•Epithelial cellular membranous proliferation (epithelial ingrowth).

2Trabecular glaucoma in which the obstruction occurs as a result of ‘clogging up’ of the meshwork (Fig. 10.48B) by the following:

•Pigment particles (pigmentary glaucoma).

•Red blood cells (red cell glaucoma).

•Degenerate red cells (ghost cell glaucoma).

•Macrophages and lens proteins (phacolytic glaucoma).

•Proteins (hypertensive uveitis).

•Pseudoexfoliative material (pseudoexfoliation glaucoma).

Trabecular glaucomas may also be caused by alteration of the trabecular fibres themselves by:

•Oedema (herpes zoster iritis/trabeculitis).

•Scarring (post-traumatic angle recession glaucoma).

3Post-trabecular glaucoma in which the trabeculum itself is normal but aqueous outflow is impaired as a result of elevated episcleral venous pressure due to conditions such as:

•Carotid-cavernous fistula.

•Sturge–Weber syndrome.

•Obstruction of the superior vena cava.

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Fig. 10.48 Pathogenesis of secondary glaucoma. (A) Pre-trabecular obstruction; (B) trabecular obstruction; (C) angle-closure with pupillary block; (D) angle-closure without pupillary block

Angle-closure

Secondary angle-closure is caused by impairment of aqueous outflow secondary to apposition between the peripheral iris and the trabeculum. Classification is based according to the presence or absence of pupillary block:

1With pupillary block (Fig. 10.48C)

•Seclusio pupillae (360° ‘ring’ posterior synechiae), usually secondary to recurrent iridocyclitis.

•Subluxated lens.

•Phacomorphic glaucoma.

•Capsular block syndrome with 360° iris-capsule adhesion.

•Aphakic pupillary block.

•Anterior chamber lens implant without a patent iridotomy.

2Without pupillary block (Fig. 10.48D)

•Secondary causes of PAS such as advanced neovascular glaucoma and chronic anterior uveitis.

•Cilio-choroidal effusion.

•Capsular block syndrome without iris-capsule adhesion.

•Ciliary body/iris cyst or other ciliary body or posterior segment tumour.

•Contraction of retrolenticular fibrovascular tissue such as in proliferative vitreoretinopathy and retinopathy of prematurity.

•‘Malignant’ glaucoma may arbitrarily be considered a form of secondary rather than primary angle-closure.

Most of the above conditions are described later.

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Pseudoexfoliation

Pseudoexfoliation syndrome

Introduction

The pseudoexfoliation syndrome (PXF), sometimes known as exfoliation syndrome, is a relatively common cause of chronic open-angle glaucoma, though subtle signs are easily overlooked. When an eye with PXF develops secondary open-angle glaucoma the condition is referred to as pseudoexfoliation glaucoma (PXG). PXF is more common in females but males appear to be at higher risk of developing glaucoma. The condition is particularly common in Scandinavia. A high risk of developing PXF and PXG is conferred by mutations in the LOXL1 gene at locus 15q22, coding for elastic fibre components of the extracellular matrix. The cumulative risk of glaucoma in eyes with PXF is 5% at 5 years and 15% at 10 years.

Pathogenesis

A grey-white fibrillary extracellular material composed of a protein core surrounded by glycosaminoglycans is produced by abnormal basement membranes of ageing epithelial cells in the trabeculum, equatorial lens capsule, iris and ciliary body. The material is then deposited on the anterior lens capsule (Fig. 10.49A), zonules, ciliary body, iris, trabeculum, anterior vitreous face and conjunctiva. In addition to its occurrence within the eye, exfoliative fibrillopathy has been reported in skin and visceral organs, suggesting that PXF may be an ocular manifestation of a systemic disorder; PXFS is associated with an increasing number of vascular disorders, hearing loss and Alzheimer disease.

Fig. 10.49 Pseudoexfoliation syndrome. (A) Christmas-tree like deposits of pseudoexfoliative material (PXF) on the lens capsule; (B) PXFon the pupillary margin; (C) transillumination defect corresponding to sphincter iris atrophy; (D) PXFon the lens; (E) gonioscopy shows patchy trabecular hyperpigmentation and Sampaolesi line

(Courtesy of J Harry and G Misson, from Clinical Ophthalmic Pathology, Butterworth-Heinemann 2001– fig. A; M Jager – fig. D; J Schuman, V Christopoulos, D Dhaliwal, M Kahook and R Noecker, from Lens and Glaucoma, in Rapid Diagnosis in Ophthalmology, Mosby 2008 – fig. F)

Diagnosis

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1Cornea occasionally shows PXF on the endothelium as well as pigment deposition that is usually diffuse although occasionally may take the form of a Krukenberg spindle.

2Mild aqueous flare is sometimes seen, and results from breakdown of the iris blood-aqueous barrier.

3Iris shows PXF on the pupillary margin (Fig. 10.49B) and sphincter atrophy characterized by ‘moth-eaten’ transillumination defects at the pupillary margin (Fig. 10.49C).

4PXF on the anterior lens surface

•The constant rubbing of the pupil scrapes the material off the midzone of the lens giving rise to a central disc and a peripheral band of PXF, with a clear zone between (Fig. 10.49D).

•The peripheral band is granular and has a well-delineated inner border with multiple radial striations. It can be detected only after the pupil has been dilated.

•Cataract surgery is more hazardous due to a combination of poorly dilating pupil, increased risk of zonular dialysis and capsular tear. Other problems include a postoperative pressure spike, corneal oedema, increased incidence of capsular opacification and contraction, and IOL subluxation.

6Gonioscopy

•Trabecular hyperpigmentation is common and is usually most marked inferiorly. It may antedate the appearance of PXF by several years. The pigment lies on the surface of the trabeculum and has a patchy distribution (Fig. 10.49E).

•A scalloped band of pigment running on to or anterior to Schwalbe line (Sampaolesi line) is common.

•PXF deposits in the trabeculum can give rise to a ‘dandruff-like’ appearance.

•Narrow angles are present in some cases, and there is an increased risk of angle closure, probably due to zonular laxity.

Pseudoexfoliation glaucoma

Pathogenesis

Probable causes of elevation of IOP include trabecular blockage due to a combination of ‘clogging up’ of the trabeculum by PXF material and/or pigment released from the iris.

Diagnosis

1Presentation is usually in the 7th decade.

2Signs. The majority of patients have a chronic open-angle glaucoma which is usually unilateral. Occasionally the IOP may rise acutely despite a wide-open angle and may be confused with primary angle-closure. There is no apparent association between angle characteristics and the severity of glaucoma, unless angle-closure develops.

Treatment

1Medical treatment is the same as for POAG. However, despite initial success in most cases, there is a high incidence of late failure and patients are more likely to require laser therapy or surgery.

2Laser trabeculoplasty is particularly effective, possibly because of trabecular hyperpigmentation. However, following an initial good response a gradual late rise of IOP occurs so that after 4 years the results are the same as in POAG.

3Trabeculectomy has the same success rate as in POAG.

4Trabecular aspiration with light tissue contact confers at least a short-term benefit, and can be performed at the same time as cataract surgery or trabeculectomy.

Prognosis

The prognosis is worse than in POAG; the IOP is often significantly elevated and may also exhibit great fluctuation. Severe damage may develop rapidly. It is therefore important to monitor patients closely, and some practitioners feel that review should take place at intervals of no more than 6 months for patients with PXF.

•A patient with unilateral PXG and only PXF in the fellow eye is at high risk (50% in 5 years) of developing glaucoma in the fellow eye.

•A patient with unilateral PXG who does not have PXF in the fellow eye has only a low risk of developing glaucoma in the normal eye.

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Pigment dispersion

Pigment dispersion syndrome

Introduction

Pigment dispersion syndrome (PDS) is a usually bilateral condition characterized by the liberation of pigment granules from the iris pigment epithelium and their deposition throughout the anterior segment. PDS primarily affects whites and may be inherited as AD with variable penetrance. There is a significant linkage between the disease phenotype and genetic markers located on 7q35-36. Myopia predisposes to the phenotypical manifestations and the development of a secondary open-angle ‘pigmentary’ glaucoma. However, some manifestations of PDS may be extremely subtle and go undetected.

Pathogenesis

Pigment shedding is caused by the mechanical rubbing of the posterior pigment layer of the iris against packets of lens zonules as a result of excessive posterior bowing of the mid-peripheral portion of the iris. It is postulated that an increase in anterior chamber pressure (relative to the posterior chamber) occurs due to ‘reverse pupil block’, with resultant posterior bowing of the iris and iridozonular touch (Fig. 10.50A). This is supported by the observation that neutralization of reverse pupil block with peripheral iridotomy flattens the iris and decreases iridozonular contact (Fig. 10.50B). The pigment epithelium itself may be abnormally susceptible to shedding. In some patients strenuous exercise may precipitate episodes of pigment dispersion associated with a rise in IOP. Pigment granules are released into the aqueous humour, dispersed by aqueous currents and deposited on all anterior chamber structures, including the zonular fibres and ciliary body.

Fig. 10.50 High-frequency ultrasonography in pigment dispersion syndrome. (A) Very deep anterior chamber and posterior bowing of the peripheral iris; (B) flattening of the peripheral iris following laser iridotomy

(Courtesy of J Salmon)

Diagnosis

1Cornea shows pigment deposition on the endothelium, in a vertical spindle-shaped distribution (Krukenberg spindle) (Fig. 10.51A). This finding, although common, is neither universal nor pathognomonic of PDS, and in long-standing cases may be more difficult to detect because it tends to become smaller and lighter in colour.

2Anterior chamber is very deep (Fig. 10.51B) and melanin granules may be seen floating in the aqueous.

3Iris

•Fine surface pigment granules that may extend onto the lens; partial loss of the pupillary ruff (frill) (Fig. 10.51C).

•Pigment epithelial atrophy due to shedding of pigment from the mid-periphery gives rise to characteristic radial slit-like

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transillumination defects (Fig. 10.51D).

4Gonioscopy

•The angle is wide open and there is a characteristic mid-peripheral iris concavity that may increase with accommodation.

•Trabecular hyperpigmentation is most marked over the posterior trabeculum (Fig. 10.51E). The pigment is finer than in PXF and appears to lie both on and within the trabecular meshwork. It also has a more homogeneous appearance and forms a dense band involving the entire circumference of the meshwork uniformly. Pigment may also be seen on or anterior to Schwalbe line.

5Lens may occassionally show a line or an annular ring of pigment on the peripheral posterior surface (Scheie line).

Fig. 10.51 Pigment dispersion syndrome. (A) Krukenberg spindle; (B) very deep anterior chamber; (C) pigment granules on the surface of the iris and partial loss of the pupillary ruff; (D) radial slit-like transillumination defects; (E) homogeneous trabecular hyperpigmentation

Pigmentary glaucoma

Pathogenesis

Elevation of IOP appears to be caused by pigmentary obstruction of the intertrabecular spaces and damage to the trabeculum secondary to denudation, collapse and sclerosis.

Risk factors

About a third of patients with PDS develop ocular hypertension or chronic open-angle glaucoma after 15 years. Men are affected twice as frequently as women. The optic disc may be more susceptible to the effects of elevated IOP because of the underlying myopia. It is therefore important to regularly follow patients with the condition, particularly myopic males with Krukenberg spindles. However, initial IOP, cup–disc ratio and degree of trabecular hyperpigmentation are not helpful in identifying those who will eventually develop glaucoma. Patients with pigmentary glaucoma have an increased incidence of steroid responsiveness.

Diagnosis

1Presentation is usually with chronic glaucoma most commonly in the 3rd and 4th decades although in women it tends to develop around 10 years later. Occasionally the sudden release of pigment granules spontaneously or following strenuous physical exercise may precipitate an acute rise in IOP, with corneal oedema and haloes.

2IOP may initially be very unstable, so that a single normal reading does not exclude glaucoma. Some patients exhibit higher levels and wider fluctuations of IOP than in POAG, and at the time of diagnosis it is common to find advanced disease in one eye and relatively mild damage in the other.

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