What is it?

Glaucoma is a collection of eye disorders which cause damage to the optic nerve. The optic nerves are the structures which carry information from the retina (the part of the eye which senses light) to the brain, allowing us to see. When the delicate fibers of these nerves become damaged, blind spots can begin to develop in a person’s visual field. The blind spots usually start in the periphery, and the field of view will narrow inward as the condition progresses. Unfortunately, this may not be noticeable until a significant amount of visual field loss has already occurred.

What causes it?

Although the exact cause of optic nerve damage from glaucoma is not understood completely, it most likely has to do with physical compression and blood loss to the nerve from elevated pressure inside the eye. The eye naturally produces a special fluid, called aqueous, which circulates inside and contributes to the health and function of the structures there. You can think of this as being like the plumbing system of the eye; once the fluid circulates, it needs somewhere to drain! If the normal drainage channels are narrow or blocked, the fluid will not drain effectively, and pressure can slowly but steadily start to increase over time. However, it’s also important to know that sometimes optic nerve damage can occur even when the pressure inside the eye is normal.

Types of Glaucoma

There are two main types of glaucoma: open-angle and angle-closure. (Angle refers to the drainage structures in the eye.) In open-angle glaucoma, the drainage channels are narrowed or only partially blocked, leading to a gradual increase in pressure. This process is usually painless, which unfortunately means that symptoms often go unnoticed until substantial and irreversible damage to the optic nerve has occurred. This is one reason why regular eye health check-ups are so important, especially if there is a family history of glaucoma.

Angle-closure glaucoma is less common, but can also be more immediately sight-threatening. It occurs when the angles of the eye become completely blocked. If this happens suddenly, it is called an acute angle-closure. Symptoms of an acute angle-closure may include sudden severe eye pain, redness of the eye, the appearance of rainbow-colored haloes around lights, headaches, and nausea and vomiting. If you experience these symptoms, it is critical to seek treatment from an ophthalmologist as soon as possible to prevent potential blindness.

Diagnosis

Regular eye examinations are the most effective way to detect any early signs of glaucoma. Most comprehensive exams already include measurements of the pressure inside the eyes and inspections of the patient’s optic nerves and angles, and the doctor may order some additional tests based on those results. Glaucoma testing is not invasive. It involves specialized equipment to scan the optic nerves for evidence of damage, and a special test to measure the patient’s visual field for signs of loss. These special tests are not necessary at every visit, but they will be repeated at regular intervals in order to closely monitor any changes that may occur.

Treatment

Not everyone with high eye pressure needs to be treated for glaucoma, but if your provider decides that treatment is necessary, there may be multiple options available. The most common treatment is a regimen of prescription eye drops used a few times per day. There are a variety of eye drops with the ability to lower eye pressure, and your doctor will decide which one is best for your individual needs.

Another option for reducing eye pressure is an elective procedure called a selective laser trabeculoplasty (SLT). In this procedure, the doctor will use a finely tuned beam of light to carefully open up the drainage channels in the eye, allowing the aqueous fluid to circulate more effectively. This procedure is often used in addition to, or sometimes in place of, a regimen of eye drops.

A further option may be a surgical procedure called a goniotomy, in which the doctor will remove a small section of the drainage channel to allow fluid to freely circulate. Since this procedure is significantly more invasive than other options, it is often reserved for more advanced cases that have not responded well to medication, or for those who will already be undergoing a separate procedure such as cataract surgery.

Risk Factors

Having high eye pressure does not necessarily mean that a persona has glaucoma, but it is one important factor that will help your doctor determine your risk for developing the condition. Other important factors include age, nearsightedness, and a history of prolonged use of steroid medications. A person’s ethnic background may also be an important factor, since people of African ancestry are 3 to 4 times more likely to develop open-angle glaucoma. They are also more likely to be affected by the condition at an earlier age. Ultimately, since anyone of any background can potentially be susceptible to the sight-robbing effects of glaucoma, regular and thorough eye health maintenance is important for everyone!