Acute glaucoma, also known as acute angle-closure glaucoma or narrow-angle glaucoma, is a serious condition characterized by a rapid increase in pressure inside the eye. This sudden elevation of intraocular pressure can lead to significant discomfort and potential vision loss if not promptly treated. Unlike chronic glaucoma, which develops gradually, acute glaucoma presents with sudden and severe symptoms, necessitating immediate medical attention.
Causes of Acute Glaucoma
Acute glaucoma arises when the flow of aqueous humor, the clear fluid that nourishes the eye, is suddenly blocked. This fluid is produced continuously and normally drains through a channel called the trabecular meshwork, located at the angle where the iris (the colored part of the eye) meets the cornea (the clear front surface of the eye).
Several factors can cause this blockage. One factor is anatomical predisposition, where individuals with naturally narrow angles between the iris and cornea are at higher risk. This is often associated with farsightedness (hyperopia), where the eye is shorter than normal. Another factor is pupil dilation; in susceptible individuals, dilation of the pupil can cause the iris to bunch up and block the drainage angle. This dilation can be triggered by certain medications (such as antihistamines, decongestants, and some antidepressants), or by being in dimly lit environments. Lens enlargement, as people age, can also cause the lens of the eye to thicken, pushing the iris forward and narrowing the angle. In less common cases, acute glaucoma can be caused by other eye conditions such as tumors, inflammation, or trauma.
Symptoms of Acute Glaucoma
The symptoms of acute glaucoma are typically sudden and severe, prompting individuals to seek immediate medical care. Common symptoms include severe eye pain, which is intense pain in the affected eye, often described as a throbbing or stabbing sensation. Blurred vision, a rapid decline in visual acuity, making it difficult to see clearly, is another symptom. Patients may also experience halos around lights, seeing colored rings or halos around lights, due to corneal edema (swelling of the cornea). Redness of the eye, where the white part of the eye (sclera) appears red and inflamed, is another common symptom. Some patients may experience a headache, often localized around the eye or temple, as well as nausea and vomiting due to the intense pain and pressure.
Diagnosis of Acute Glaucoma
A prompt and accurate diagnosis is crucial to prevent permanent vision loss. The diagnostic process typically involves a medical history, where the doctor will inquire about the patient’s symptoms, medical history, and any medications they are taking. An eye examination will also be conducted, including a visual acuity test to assess the sharpness of vision, a slit-lamp examination using a microscope with a bright light to examine the structures of the eye, and gonioscopy, where a special lens is used to view the drainage angle and determine if it is blocked. Tonometry, the measurement of the intraocular pressure (IOP), is also performed; in acute glaucoma, the IOP is typically very high. Finally, a pupil examination will assess the pupil’s reaction to light; in acute glaucoma, the pupil may be dilated and unresponsive to light.
Treatment Options for Acute Glaucoma
The primary goal of treatment is to rapidly lower the intraocular pressure and relieve the blockage of the drainage angle. Treatment options include medications, such as eye drops with medications like beta-blockers, alpha-adrenergic agonists, and miotics (to constrict the pupil) to lower IOP, and oral or intravenous medications, where carbonic anhydrase inhibitors and osmotic agents (such as mannitol) may be administered to quickly reduce fluid production in the eye. Laser iridotomy is also a treatment option; once the IOP is reduced to a safer level, a laser iridotomy is typically performed. This procedure involves creating a small hole in the iris to provide an alternate route for aqueous humor to flow, bypassing the blocked drainage angle. In rare cases, if laser iridotomy is not possible or effective, a surgical iridectomy (removal of a small piece of the iris) may be necessary.
Prevention of Acute Glaucoma
While it is not always possible to prevent acute glaucoma, certain measures can reduce the risk. Individuals with risk factors, such as a family history of glaucoma or farsightedness, should undergo regular eye examinations to monitor their eye pressure and angle. People with narrow angles should be cautious about using medications that can dilate the pupil, such as antihistamines, decongestants, and certain antidepressants. Prompt treatment of any underlying eye conditions that may contribute to angle closure is also important.
Takeaway
Acute glaucoma is a medical emergency that requires immediate attention to prevent permanent vision loss. Recognizing the symptoms and seeking prompt treatment are crucial. Individuals with risk factors should undergo regular eye examinations and discuss preventive measures with their eye care provider. Early diagnosis and appropriate management can significantly improve the prognosis and preserve vision.