Glaucoma

Glaucoma:  A group of disorders characterized by abnormally high IOP (Intraocular pressure).  Glaucoma is an increase in IOP causing changes in the optic disk (nerve).  It occurs in three primary forms: 1.) chronic open-angle (primary), 2.) acute closed-angle, 3.) congenital.  It may also be secondary to other causes. In the united States approximately 12%  over the age of 40 accounts for new cases of blindness.  Prognosis is good with early treatment.

Cause:  Chronic open -angle glaucoma results from over production of aqueous humor or obstruction of its outflow through the trabecular meshwork or the canal of Schlemm.  Most common glaucoma affecting 90% of all patients.

Acute closed -angle glaucoma, also called narrow-angle glaucoma, results from obstruction to the outflow of aqueous humor from anatomically narrow angles between the anterior iris and the posterior corneal surface.  It also results from 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 - peripheral anterior synechiae

Congenital glaucoma is inherited as an autosomal recessive trait.  Secondary glaucoma can result from uveitis, trauma, or drugs such as corticosteroids.  Vein occlusion or diabetes can cause neovascularization in the angle.

Symptoms:

Mild aching in the eyes

Gradual loss of peripheral vision

Seeing halos around lights

Reduced visual acuity (especially at night, that is not correctable with glasses)

The onset of acute closed-angel glaucoma is typically rapid, constituting an ophthalmic emergency.  If not treated promptly, this glaucoma produces blindness in the affected eye in 3 to 5 days.  Symptoms may include:

Unilateral inflammation and pain

Pressure over the eye

Moderate pupil dilation that's nonreactive to light

Cloudy cornea

Blurring and decreased visual acuity

Photophobia

Seeing halos around lights

Nausea and or Vomiting

Treatment:

For chronic open-angle glaucoma:  to decrease IOP through administration of beta-blockers, such as timolol or betaxolol, epinephrine, or diuretics, such as acetazolamide.

Drug treatment may also include:  miotic eyedrops - to facilitate outflow of aqueous humor

Argon laser trabeculoplasty or surgical filtering procedure called trabeculectomy - which creates an opening for aqueous outflow.  (This may be done if drug therapy does not work)

For treating acute closed-angle glaucoma as an emergency, drug therapy may lower IOP.  If pressure does not decrease, laser iridotomy or surgical peripheral iridectomy must be performed immediately to save the patient's vision.

Iridectomy relieves pressure by excising part of the iris to reestablish aqueous humor outflow.  A prophylactic iridectomy is performed a few days later on the normal eye.

Narcotic analgesics may be needed for pain.

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