Glaucoma is often called the “silent thief of sight,” as it is often a painless, symptom-less disease that gradually takes away vision permanently. It affects about three million Americans and only half of those affected even know that they have the disease!
Glaucoma is a disease that progressively damages the optic nerve. The optic nerve is of critical importance to vision because it transmits all signals from the retina to the brain. Without a functioning optic nerve, a person cannot see anything and is blind.
Inside the front part of the eye is a fluid filled space called the anterior chamber. This “chamber” is filled with a fluid called Aqueous Humor, which is constantly being freshly made and drained in order to provide nutrition and oxygen to the front part of the eye. An imbalance of this fluid’s production and drainage can lead to high pressure within the eye, which in many cases of glaucoma can lead to nerve damage. Of note, this eye pressure is unrelated to the body’s blood pressure and the eye pressure can be normal even if the blood pressure is high (and vice versa).
What Is Glaucoma?
In certain situations, the “Aqueous” fluid does not flow out of the eye like it should. This can cause the pressure to build up, which in turn can eventually damage fibers in the optic nerves. This chronically elevated pressure causes characteristic optic nerve damage and resultant visual field defects (i.e. cause certain parts of the visual field to be lost), characteristic of glaucoma.
There are many types of glaucoma, categorized by the mechanism of action:
- Open-Angle Glaucoma, the most common kind of glaucoma – the drainage structures, while not obstructed, do not work adequately enough to keep the pressure normal.
- Closed-Angle Glaucoma (also known as Angle-Closure Glaucoma) – the drainage structures are obstructed preventing the egress (outflow) of aqueous and hence the subsequent buildup of pressure.
- Congenital Glaucoma – the drainage structures are malformed born, leading to high pressures.
- Secondary glaucoma – due to a variety of conditions such as diabetes, etc., the eye develops abnormalities in aqueous drainage, leading to high pressure.
- Low-Tension or Normal-Tension Glaucoma – where the drainage structure of the eye works well and the pressure can remain normal (compared to the general population), but the eye needs an even lower pressure to keep the nerve healthy.
Glaucoma is a serious problem that affects many people of any race, age, gender, or background. It is a leading cause of preventable blindness that often goes undiagnosed and untreated because of the lack of symptoms. It then slowly steals away the vision and can lead to blindness.
Who Is At Risk?
Because symptoms are usually gradual, Glaucoma is often not detected until later in the course of the disease, when irreversible damage has already occurred.
Anyone can have glaucoma. This is why it’s so important to have your eyes checked by your ophthalmologist regularly. However, studies have shown the following to convey a slightly higher risk of glaucoma than the general public:
People who are older have higher risk of developing Glaucoma. In certain groups, the risk of developing Glaucoma can even be higher as one ages, depending on their ethnic background.
Some ethnicities predispose people to higher risks of certain types of glaucoma. For example, African-American patients often are at a higher risk of open-angle glaucoma than their white counterparts at any age. Similarly, Asians are at a higher risk of closed-angle glaucoma than their African-American counterparts.
Intraocular pressure or the internal eye pressure is one of the main indicators of Glaucoma. If your intraocular pressure is higher than the normal level, then you are at higher risk.
Family history is also a major factor for developing Glaucoma. If someone in your family has a history of Glaucoma, then you and other members of the family can be at a greater risk of developing Glaucoma.
Medical Diseases And Conditions
Some medical conditions can lead to Glaucoma. Heart-related diseases, high blood pressure, hypothyroidism, and diabetes are some of the most common conditions that can put someone at a higher risk of Glaucoma.
Other eye conditions
- Other eye conditions and injuries can trigger glaucoma like retinal detachment, lens dislocation, eye inflammation, and eye tumors. Eye surgeries can also increase the risk for glaucoma.
- Long-term use of corticosteroid medications in eye drop or systemic form.
- History of trauma, inflammation
Signs And Symptoms
Signs and symptoms may differ depending on the type of Glaucoma you have. The most common type of glaucoma, open-angle glaucoma, has no obvious symptoms or signs. However, in the later stages, these symptoms can include a gradual deterioration of the peripheral vision in both eyes, leaving only a small island of vision intact, referred to as tunnel vision.
- Redness of the eye
- Severe eye pain or pain around the eyes
- Blurring of the vision with halos or rainbows
- Headache, nausea, or vomiting
If you have severe eye pain or pain around the eyes or blurring of the vision with halos or rainbows, you could be having an attack of angle closure glaucoma. In this case, you should seek immediate consultation with your eye doctor or go to the emergency room. There is always an eye doctor on call at Eye Associates Northwest.
How Is It Diagnosed?
A diagnosis of Glaucoma is derived only after many factors have been considered. To diagnose Glaucoma, your eye doctor will record your medical history then perform various tests, which can include:
- Tonometry – a simple and painless test done to determine the intraocular pressure that can help stratify your risk for glaucoma or set your target eye pressure when treating the glaucoma.
- Ophthalmoscopy – Your Ophthalmologist will assess the risk or stage of glaucoma using a slit lamp and magnifying lenses to visualize the internal structures of the eyes which include the Optic nerves.
- Visual Field Test – This test determines the condition of your peripheral vision and to detect blank spots in your field of vision.
- Optical Coherence Tomography (OCT) – A scan that is done using special laser light that can very accurately measure the thickness and health of the nerve.
- Visual Acuity
- Pachymetry – a quick, painless test done to check the corneal thickness. This can help gauge the risk of developing glaucoma.
- Gonioscopy – another quick and painless test to visualize the drainage structures of the eye, in order to classify the type of glaucoma (e.g. Open-angle vs. closed-angle).
How is it treated?
To effectively treat Glaucoma, the internal pressure in the eye must be lowered. There are many treatment options to lower the eye pressure, including drops, lasers, and surgery in the operating room. The choice of a treatment modality will depend on the stage of glaucoma, the overall state of the eye, and the preference and lifestyle of the patient.
Eye drops: Most commonly used are prescription eye drops that can help either decrease the production of the aqueous or improve the eye’s ability to drain the fluid from the eye. It is important to note that often these drops will not make the vision better—they may also occasionally sting or leave a bad after-taste. However, they are important in lowering the pressure in the eye, and thereby helping to preserve vision. It is very important that you tell your ophthalmologist about any other medical conditions you have or medications that you are taking, as this may impact your treatment.
It is important to remember to always take the drops exactly as prescribed – never stop taking a drop or pill unless instructed to do so by your doctor. If you run out, you should ask your doctor for a refill.
Laser Surgery: Occasionally a selective laser surgery can be used to treat the most common type of glaucoma, open-angle glaucoma. There are two types of lasers, the argon (ALT) and selective (SLT) laser trabeleculoplasty. At Eye Associates Northwest, we offer both types of laser and can adapt the preferred laser based on each individual case.
Laser Iridotomy: Performed for Angle-closure Glaucoma. With this procedure, a tiny hole is made in the iris. The hole allows the aqueous fluid to circulate from the posterior chamber to the anterior chamber, which prevents the iris from being pushed forward and into the angle, where it would impede outflow. An iridotomy can help improve the openness of the drainage structures and thereby help prevent episodes of acute angle-closure. It can even lower the eye pressure.
There are two main types of surgery:
Trabeculectomy – a filtering surgery where a small flap is made in the sclera (the white part of your eye) so that the fluid from inside the eye can drain to a reservoir, a “bleb”, thus bypassing the normal drainage mechanisms of the eye. The bleb is covered by the conjunctiva, the thin filmy membrane that normally covers the sclera. When successfully completed, the bleb will appear like a blister. This bleb allows the aqueous to be absorbed back into the blood vessels of the eye.
Drainage Implant Surgery – a small plastic tube or valve is connected to a reservoir, which helps again to avert the native drainage system and thereby help improve the pressure. This type of procedure is usually reserved for certain types of glaucoma or cases in which previous surgeries have failed.
There are newer surgical procedures coming down the pipeline as well. It is important to remember that each treatment modality has its risks and benefits. The decision to pursue one type of treatment over another should be made in conjunction with your ophthalmologist with the knowledge that any risks incurred have to be weighed against the greater risk of losing vision from untreated glaucoma. Your ophthalmologist will discuss these treatment options with you and help you decide which would be best for you.