|PIGMENT DISPERSION SYNDROME & PIGMENTARY GLAUCOMA
SIGNS AND SYMPTOMS
With the slit lamp, patients with PDS and pigmentary glaucoma demonstrate bilateral liberation of iris pigment in the anterior chamber. Often, this is seen as a granular brown vertical band along the corneal endothelium, known as Krukenberg's spindle.
You may also see pigment dusting on the lens, the surface of the iris and at Schwalbe's line. With the gonio lens, you may see dense pigmentation, which looks similar to melted chocolate, covering the trabecular meshwork in 360 degrees, though it will be most prominent in the inferior quadrant. The angle itself remains patent, and in some cases appears atypically wide open. Radial, spoke-like transillumination defects of the mid-peripheral iris are another common finding. While the intraocular pressure is normal in PDS, it may rise sharply in cases of pigmentary glaucoma, particularly after vigorous exercise or pharmacologic dilation. Likewise, PDS presents with a normal optic nerve appearance, while patients with pigmentary glaucoma manifest evidence of glaucomatous optic atrophy and associated field loss.
Studies using ultrasound biomicroscopy show anatomic differences in the angles of some patients with PDS and pigmentary glaucoma, whereby there is a posterior bowing of the peripheral iris which precipitates the zonular touch. In addition, it's possible that so-called "reverse pupillary block" can contribute to PDS; the pressure in the anterior chamber may intermittently exceed that in the posterior chamber, causing this backward displacement of the iris that increases pigment liberation and leads to IOP spikes.
Miotics are preferable to beta-blockers or adrenergic agents because they have a dual effect: (1) lowering the IOP and (2) contracting the pupil, thereby pulling the peripheral iris away from the zonular fibers. Begin with 1 or 2% pilocarpine solution QID; in younger patients consider 4% pilocarpine ointment administered once daily at bedtime as an alternative. If this is unsuccessful in controlling the IOP, or if a pre-presbyopic patient is affected by miotic side effects, consider adding an additional medication such as timolol, dipivefrin, dorzolamide or latanoprost.
Progressive, poorly responsive cases may require surgical intervention, either argon laser trabeculoplasty or filtering surgery. More recently, some doctors have recommended laser peripheral iridotomy in patients with evidence of posterior iris bowing to flatten the iris profile. While this procedure has demonstrated success in select cases, it is still somewhat controversial.
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Eyelids & Eyelashes | Conjunctiva & Sclera | Cornea
Uvea | Vitreous & Retina | Optic Nerve & Brain | Oculosystemic Disease
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