Glaucoma
Glaucoma is a group of disorders characterized by intraocular pressure (IOP) high enough to damage the optic nerve. If untreated, it leads to gradual peripheral vision loss and, ultimately, blindness.
Glaucoma occurs in several forms: chronic open-angle (primary), acute angle-closure, low tension (normal IOP that’s too high for a particular person), congenital (inherited as an autosomal recessive trait), and secondary to other causes.
Glaucoma is the second most common cause of blindness in the United States. About 2.5 million Americans are afflicted with the disease, but only 1 million know that they have it. Its incidence is highest among blacks, and it’s the single most common cause of blindness in that group. The visual prognosis is good with early treatment.
Causes
The cause of glaucoma varies according to the type of disorder:
Chronic open-angle glaucoma results from overproduction of aqueous humor or from obstructed outflow of aqueous humor through the trabecular meshwork or the canal of Schlemm. This form of glaucoma frequently runs in families and affects 90% of all patients with glaucoma.
Acute angle-closure (narrow-angle) glaucoma results from obstructed outflow of aqueous humor caused by anatomically narrow angles between the anterior iris and the posterior corneal surface, shallow anterior chambers, a thickened iris that causes angle closure on pupil dilation, or a bulging iris that presses on the trabeculae, closing the angle. Adhesions in the angle, referred to as peripheral anterior synechiae, may be the cause.
Secondary glaucoma can result from uveitis, trauma, or drugs such as steroids. Neovascularization in the angle can result from vein occlusion or diabetes.
Signs and symptoms
Clinical features vary with the form of glaucoma.
Chronic open-angle glaucoma
Usually bilateral, chronic open-angle glaucoma has an insidious onset and a slowly progressive course. Symptoms appear late in the disease and include mild aching in the eyes, loss of peripheral vision, seeing halos around lights, and reduced visual acuity (especially at night) that’s uncorrectable with glasses.
Acute angle-closure glaucoma
An ophthalmic emergency, acute angle-closure glaucoma typically has a rapid onset. Symptoms include unilateral inflammation and pain, pressure
over the eye, moderate pupil dilation that’s nonreactive to light, a cloudy cornea, blurring and decreased visual acuity, photophobia, and seeing halos around lights.
over the eye, moderate pupil dilation that’s nonreactive to light, a cloudy cornea, blurring and decreased visual acuity, photophobia, and seeing halos around lights.
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