Glaucoma

What is Glaucoma?

Glaucoma is a group of diseases that are generally distinguished by an increase in pressure inside the eye, which causes damage to the optic nerve. Interestingly, elevated eye pressure may not always be detected. To understand glaucoma, one must first understand the average circulation of the eye. The eye receives nourishment from a clear fluid called “aqueous fluid,” continually produced inside the eye. 

The aqueous is returned to the bloodstream through the eye’s drainage “angle” between the cornea (the clear window of the eye) and the iris (the colored part of the eye). When the fluid cannot drain fast enough, the pressure inside the eye begins to build. This excess fluid pressure pushes against the delicate optic nerve that connects the eye to the brain. If the pressure remains too high for too long, irreversible damage to the nerve and subsequent vision loss can occur.

Open Angle Glaucoma

Open-angle glaucoma, the predominant form, impacts 70% to 80% of individuals with the condition. It stands as the primary cause of blindness in American adults, posing a significant threat due to its subtle, gradual progression that often remains undetected for extended periods. Glaucoma usually affects both eyes. Regular eye examinations are vital for early detection to prevent escalation. These check-ups commonly involve a straightforward, painless pressure assessment.

Open-angle glaucoma typically occurs in patients over the age of 50, and the risk increases with age. African-Americans are at higher risk of developing the condition than Caucasians, and if there is a family history of glaucoma, the risk is up to six times higher than for the general population. Also, patients who are highly myopic (nearsighted) are at increased risk.

Normal Tension Glaucoma

Another form of open-angle glaucoma is called low-tension or normal-tension glaucoma. It is not known why, but patients with this condition are found to have regular eye pressure. Nonetheless, they develop optic nerve damage and vision loss, just like patients with high eye pressure. While open-angle glaucoma is incurable, its progression can be managed by reducing eye pressure through the use of eye drops, laser treatment, or surgery.

Narrow Angle Glaucoma

Narrow-angle glaucoma is another form of glaucoma independent from open-angle glaucoma, and it presents quite differently. A “narrow-angle” is an eye condition where the iris (colored part of the eye) is too close to the drainage angle of the eye. The iris is at risk of being drawn into the angle, blocking any drainage and resulting in angle closure glaucoma. 

Unlike open-angle glaucoma, where visual loss typically progresses gradually over months to years with mildly elevated eye pressure, angle-closure glaucoma can lead to rapid vision impairment within minutes to hours due to significantly elevated pressures. This excess fluid pressure damages the delicate optic nerve that connects the eye to the brain. Rapid and irreversible vision loss can occur if treatment is delayed.

Symptoms of angle-closure glaucoma include the onset of severe eye pain, eye redness, blurry vision with halos around lights, nausea, and sometimes vomiting. Since eye drainage typically halts once the drainage angle is obstructed, individuals at risk of angle closure glaucoma – specifically those with narrow angles – usually exhibit normal eye pressures and are asymptomatic before an attack occurs.

Patients at risk for angle closure include those farsighted, those with small eyes, and some with cataracts. Individuals diagnosed with narrow angles should steer clear of cold remedies containing Pseudoephedrine, Phenylephrine, or Neo-Synephrine; antihistamines like Chlorpheniramine, Diphenhydramine, or Benadryl; and medications for overactive bladder such as Detrol. These medications can narrow the angle further and lead to an attack of angle closure.

Angle-closure glaucoma is a true medical emergency. Fortunately, it is often preventable if patients at risk are identified and treated prior to an acute attack. An eye examination is necessary to establish the diagnosis and determine one’s risk for this condition. Should you experience any of the symptoms of angle closure as described above, you must see your Eye MD (ophthalmologist) immediately to prevent/limit vision loss from this potentially blinding condition.