Science & Research

Glaucoma patients have different susceptibility to optic nerve damage. "Normal tension glaucoma" is a sub-category of primary open-angle glaucoma where optic nerve damage occurs at pressures in the "normal" range (below 20 mmHg). In addition to increased susceptibility to damage from intraocular pressure, the optic nerves seen in patients with normal-tension glaucoma may have poor regulation of blood flow, which compounds the risk of damage. The treatment of this type of glaucoma is similar to other forms of glaucoma by lowering the intraocular pressure, which delays the progression of optic nerve damage. In patients who may have had an attack of glaucoma or prior optic nerve damage, their optic nerves may be even more susceptible to the damaging effects of intraocular pressure. From your history, it sounds as if you had an attack of angle-closure glaucoma that was successfully treated with lensectomy, but now have a component of normal-tension glaucoma that requires additional monitoring and treatment. Your doctor can provide you with more detailed information.

How glaucoma will affect your career as a pilot really depends on the amount of optic nerve damage that you have currently. If the glaucoma was diagnosed prior to any visual field defects that would prevent you from maintaining a pilot's license, then your career will likely be unaffected. Treatment with medications, laser or surgery to maintain the eye pressure at a level where there is no progression of optic nerve damage is possible, thus enabling you to continue in your current vocation. You should speak to your eye care provider about the health of your optic nerve and any visual field defects you have, highlighting your concerns about how your career might be affected. With continued treatment and monitoring, prevention of further optic nerve damage is possible.

The Ahmed valve is a type of glaucoma implant designed to lower the intraocular pressure to prevent further optic nerve damage. It does not reverse any visual deficits that a patient already has prior to surgery. It has two main components: a plastic plate with a valve mechanism that is positioned on the surface of the eye and a flexible tube that is positioned in the anterior chamber of the eye. This device is designed with a valve that opens to relieve the intraocular pressure when it is at a level greater than about 14 mmHg. Many patients have received this implant as part of the treatment for glaucoma. Like other glaucoma surgeries, it carries with it the small risk of infection, cataract development, inflammation, and corneal swelling. It is often the procedure most recommended for patients with glaucoma that is associated with uveitis and proliferative diabetic retinopathy.

It sounds as if your daughter has ocular hypertension, or elevated eye pressure without any detectable optic nerve damage. In patients with ocular hypertension, studies from large clinical trials demonstrate a decrease in the risk of a developing glaucoma from approximately 10% to 5% over a 5 year period with the reduction of intraocular pressure. Many factors must be considered in the decision to treat elevated eye pressures, including central corneal thickness, patient age, race, family history, and others. If your daughter has thick corneas and only mildly elevated pressures, close monitoring may be indicated over starting medications to lower the eye pressure. Her eye care provider should be able to explain the risk of developing glaucoma so that your daughter can make an informed decision regarding her treatment options.

Population studies have shown that supplemental estrogen does not increase the prevalence of glaucoma, and may actually be associated with lower odds of glaucoma. Experimental studies have shown potential protective effects of estrogen on the retina and vascular system. Oral contraceptives usually contain both estrogen and progesterone derivatives, and both of these hormones have complex action in the eye. Oral contraceptives can also increase levels of a hormone, called cortisol, and if the blood levels of this hormone are high, eye pressure can become elevated. There have been rare reports of increased eye pressure in patients who are taking oral contraceptives, and in these cases, the eye pressures normalized once the medication was stopped.

Glaucoma that affects patients under the age of 40 is often referred to as juvenile-onset glaucoma. This type of glaucoma can occur sporadically or can have a genetic component. It is uncommon for glaucoma to affect patients under the age of 40. Because he was diagnosed at a young age, he does have his entire lifetime to deal with this eye disorder. However, if his glaucoma was detected in the early stages, the prognosis is very good with diligent treatment and monitoring.

Tachyphylaxis, or loss of the eye pressure-lowering effect, can occur with topical beta-blocker therapy, but usually this phenomenon is seen early (within the first year) in the treatment course. Cosopt contains two medications: timolol (a beta-blocker) and dorzolamide (a carbonic anhydrase inhibitor). Xalatan (latanoprost) is a prostaglandin agonist and is rarely associated with tachyphylaxis. Because some medications do lose their affect over time, and because an individual patient's outflow of aqueous humor may decrease with time, patients with glaucoma must continue to be monitored. If your vision is deteriorating, further investigation into the causes of the visual decline is warranted. This might include testing of your visual field, examination of the ocular surface, evaluation for cataract, and a retinal evaluation.

Congenital glaucoma most commonly affects both eyes, but can affect only one eye. This type of glaucoma is related to improper development of the drainage tissue (trabecular meshwork) of the eye. Congenital glaucoma can be either genetically inherited or sporadic, and is associated with a mutation in a gene known as CYP1B1. Mutations in this gene are also associated with juvenile-onset glaucoma. A genetic counselor should be able to help you identify the risk of congenital glaucoma for your children. You are at an increased risk for developing glaucoma in your other eye, thus monitoring of your good eye yearly is recommended to detect any signs of the disease at the earliest stages.