TRABECULAR HYPERPIGMENTATION
Pseudoexfoliation syndrome
Definition
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An uncommon, usually bilateral, condition that predisposes to glaucoma. It typically affects the elderly.
Signs
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Hyperpigmentation is most marked inferiorly. The pigment lies on the surface of the trabeculum and has a patchy distribution ( Fig. 7.1 ).
Fig. 7.1
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A scalloped band of pigment may extend anterior to Schwalbe line (Sampaolesi line).
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The trabeculum may also show ‘dandruff-like’ deposits of pseudoexfoliative material (PEM).
Look for
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PEM on the pupil margin and sphincter atrophy giving rise to ‘moth-eaten’ and transillumination defects (see Fig. 8.79 ).
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PEM on the anterior lens surface ( Fig. 7.2 ).
Fig. 7.2
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Mild aqueous flare.
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Trabecular block glaucoma.
Pigment dispersion syndrome
Definition
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An uncommon, bilateral, condition that predisposes to glaucoma. It typically affects young myopic males.
Signs
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Hyperpigmentation has a homogeneous appearance and forms a dense band involving the entire circumference of the meshwork uniformly ( Fig. 7.3 ).
Fig. 7.3
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The pigment is most marked over the posterior trabeculum. It is finer than in pseudoexfoliation and appears to lie on and within the trabecular meshwork.
Look for
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Fine pigment deposits on the endothelium (Krukenberg spindle – Fig. 7.4 ).
Fig. 7.4
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Mid-peripheral radial slit-like transillumination defects (see Fig. 8.77 ).
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Partial loss of the pupillary ruff.
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Very deep anterior chamber.
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Pigment granules on the anterior iris surface.
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Trabecular block glaucoma.
Megalocornea
Definition
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A rare bilateral XL condition.
Signs
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Hyperpigmentation is similar to that in pigment dispersion syndrome and is associated with a very wide angle ( Fig. 7.5 ).
Fig. 7.5
Look for
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Enlarged but clear cornea that has a horizontal diameter ≥ 13 mm.
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Very deep anterior chamber (see Fig. 6.1 ).
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Glaucoma is uncommon.
Naevus of Ota
Definition
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A rare unilateral congenital condition.
Signs
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Hyperpigmentation homogeneously involves the entire circumference of the trabeculum ( Fig. 7.6 ).
Fig. 7.6
Look for
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Hyperpigmentation of facial skin (see Fig. 1.47 ).
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Episcleral pigmentation (see Fig. 3.66 ).
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Heterochromia iridis (see Fig. 8.97 ).
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Iris mammillations (see Fig. 8.42 ).
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Fundus hyperpigmentation ( Fig. 7.7 ).
Fig. 7.7
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Trabecular block glaucoma.
Iris melanoma
Melanoma may cause trabecular hyperpigmentation by two mechanisms.
- a.
Direct infiltration of the meshwork by neoplastic cells is by far the most common ( Fig. 7.8 ).
Fig. 7.8
- b.
Indirect involvement by macrophages that have ingested pigment and tumour cells, similar to pigment dispersion syndrome ( Fig. 7.9 ).
Fig. 7.9
Angle recession
Cause
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Severe blunt ocular trauma.
Signs
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Localised trabecular hyperpigmentation and irregular widening of the ciliary body band ( Fig. 7.10 ).
Fig. 7.10
Look for
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Rupture of the iris sphincter ( Fig. 7.11 ).
Fig. 7.11
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Iridodialysis.
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Lens dislocation.
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Cataract.
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Late glaucoma.
Other causes
- a.
Pseudophakic pigment dispersion occurs as the result of rubbing of the haptics and optics of a posterior chamber IOL against the iris epithelium (see Fig. 8.78 ).
- b.
Subacute angle closure may be associated with heavy trabecular pigmentation where the iris root has been in contact with the angle.
- c.
Anterior uveitis may give rise to scattered trabecular pigmentation.
ANGLE CLOSURE
With pupil block
Primary
Pathogenesis
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Angle closure occurs in anatomically predisposed eyes.
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Aqueous flow from the posterior to the anterior chamber is obstructed by relative pupil block resulting in iris bombé and closure of the angle by the peripheral iris ( Fig. 7.12 ).
