Pigmentary glaucoma (associated with pigment dispersion syndrome) occurs when pigment granules that normally form part of the back of the iris, flake off into the clear watery fluid that fills the front chamber of the eye (aqueous humor), clogging up the drainage canal. This may result in raised intraocular pressure. If the disease is not controlled, raised eye pressure leads to the optic disc becoming cupped, with resultant visual field loss. In such a case, pigment dispersion syndrome then becomes pigmentary glaucoma - a type of open-angle glaucoma.
Pigment dispersion syndrome may be inherited as an autosomal dominant disorder (i.e. requires only one affected parent with the gene to pass it on). Although the condition presents equally in both men and women, the onset of pigmentary glaucoma is more common in young white adult, near-sighted (myopic) males, aged 20 to 45 years. It usually (but not always) occurs in both eyes.
Signs and symptoms
Pigment dispersion glaucoma can remain undetected because there may be no symptoms (asymptomatic). However, some people experience episodes of blurred vision, eye pain and coloured halos around lights, particularly after vigorous exercise such as jogging and team ball games.
Advice about exercise: A certain amount of exercise generally is very beneficial and has specific benefits for example reducing cardiovascular disease. If, however, vigorous exercise leads to eye ache, then it is probably best to prevent the eye ache from occuring which may be achieved by limiting the exercise. Some patients report that only very vigorous exercise leads to eye eye. Others have no detectable eye pressure rise even after very long runs, for example. This effect is noted to be sporadic. If pain is very consistent following exercise, then it might be very reasonable to consider iridotomy.
Younger people presenting with symptoms of glaucoma may be misdiagnosed as having juvenile-onset glaucoma or primary open-angle glaucoma. A routine eye test may show 'Krukenberg spindles'*: characteristic spindle-shaped deposits of pigment on the back surface of the cornea. The spindles do go away if the pigment shedding stops but probably do not cause any significant problem with the cornea in any case.
Diagnosis
In diagnosing pigmentary glaucoma, the ophthalmologist may perform the following examinations:
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check the iris to look for defects by shining a small slit beam directly into the pupil using a slit-lamp
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measure intraocular pressure
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look at the anterior-chamber angle with a gonioscope
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evaluate the optic nerve for signs of damage caused by the onset of glaucoma
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take stereoscopic disc photographs which give a three-dimensional appearance to the single image
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perform a visual field test.
Excessive pigment particles seen on the back surface of the cornea and the trabecular meshwork, together with de-pigmented areas around the iris and raised intraocular pressure, will confirm pigmentary glaucoma.
Treatment
Treatment will depend on the extent of the symptoms. For patients with pigment dispersion without glaucoma - and without optic nerve damage - laser iridotomy may be of significant benefit and works by lifting the iris off the lens zonules. The iridotomy reduces that and, if performed at an early stage, can significantly reduce the amount of pigment being dispersed into the anterior segment of the eye. Younger patients often respond well to this treatment. If glaucoma is already present, medication also will be recommended to maintain intraocular pressure and prevent optic nerve damage.
Other advice
It might be worth discussing with your specialist about exercise. Specific types of vigourous exercise (eg jogging long distances) have been associated with eye pressure rises. It is sensible in some cases to test the effect of exercise, and measure IOP after prolonged exercise, particularly if exercise causes eye ache.
Outlook
The prognosis is generally good. Most patients respond well to laser and/or medical treatment. As with any other glaucoma, early diagnosis is generally associated with a better prognosis. Although pigment dispersion syndrome is fairly common, fewer than half will go on to develop ocular hypertension or glaucoma. However, it is important that patients with this condition undergo periodic eye examinations, probably every 1 to 6 months, with a formal visual field test every 6 to 12 months, depending on the severity of the symptoms.
*About Krukenberg spindles
Krukenberg's spindle ("KS") catches its name from Friedrich Ernst Krukenberg (1871-1946), interestingly a German gynaecologist and pathologist, specialising in Ophthalmology. KS is a spindle-shaped, vertical deposit of speckled brown coloured pigment in the cornea of the eye, created by flakes of pigment rubbed off the back of the iris.
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