- Vision & Eye Care
Glaucoma and You
Glaucoma: What It Is
The most common type of Open Angle Glaucoma usually caused by increased pressure in the eyes. This elevated pressure is caused by backup of fluid known as aqueous humor. Without the proper drainage it pushes pressure on the optical disc and nerve, eventually causing damage and blindness. However, there are different types of glaucoma and not all involve the pressure in the eyes. I will discuss the various types of glaucoma, some of it’s causes, diagnosis and treatment of glaucoma in the following paragraphs.
Think of your eye as a continuous flowing kitchen sink. Now think about the drain getting clogged. What happens if you don’t turn off the water? Well, the sink overflows of course. However, the human eye is enclosed so the water can’t overflow. It’s stuck there. Because the aqueous humor, or the fluid between the iris and the lens, has no place to go it builds up pressure like a balloon. The human eye is too strong to pop like a balloon. Instead it finds another way out, which is an area in the sclera at which the optic nerve leaves the eye. When the pressure increases the optic nerve becomes damaged. The retinal cells go through a slow process of cell deterioration known as apoptosis. This results in permanent vision loss.
Let me explain more about the human eye in order to explain how this works. The human eye is much like a digital camera in that it records the information and sends it to the brain to process. A digital camera does the same and then outputs to your computer. In glaucoma, the lens and retina function normally, but optic nerve (much like a USB cable) is damaged so images cannot be processed to the brain (your computer).
The space in the eye containing the Aqeuous Humor is called the anterior chamber. It is filled with a water-like fluid which nourishes the cornea and the lens. The Aqeuous Humor also provides the necessary pressure to maintain the shape the eye. If you look at a person’s eyes who has glaucoma you will notice an immediate difference. Keep in mind, the damage caused by glaucoma is irreversible.
Typically, there are no detectable symptoms at the beginning of glaucoma. Most of the beginning vision loss is in the peripheral vision and is noticed right away. That is why a person with diabetes or any other vision harming disease should be tested once a year for glaucoma before vision damage has reached the center.
There are various diagnosis tools a doctor may use to diagnose glaucoma. A good eye doctor can determine whether you have it long before there are any symptoms. By using the following tools, your ophthmalogist can decide if you have it and what if any, treatments you need. The diagnosis tools used are: the tonometer, the pachymeter, ophthalmoscopy, gonioscopy, and imaging technology.
The Tonometer measures the pressure of the eye. After numbing your eye with an eye drop, the lamp used to magnify is moved forward until it barely touches the cornea to measure your IOP (intraocular pressure).
The Pachymeter measure corneal eye thickness. This measurement helps your doctor determine your IOP as well. This is also used as a predictor because most people who develop glaucoma have thin central corneal measurements.
The Ophthalmoscopy can be used to look directly through your pupil to see the optical nerve and determine if there is damage. Also, its color and appearance can indicate how much damage there is.
In recent years, imaging technology has become available to view the optical nerve and the retinal nerve. They are growing rapidly and are very promising to help diagnose glaucoma early on.
The Gonioscopy is used to closely examine the trabecular meshwork (this is sort of the drain of the eye and often gets clogged). It is also used to see the angle of the fluid draining from the eye. The other use for the gonioscope is to determine if anything, such as excessive pigment may be blocking the flow through the trabecular meshwork.
Once your doctor determines that you have glaucoma, a number of things may be done to treat it. However, remember that the damage that has already been done cannot be fixed or healed. The goal of these treatments is to prevent more damage.
Eye drops are used to help control the pressure within the eye. They are absorbed into the blood stream in the eye, so discussion of any other medications you may be on is highly important so that there are no drug interactions. Sometimes, when eye drops are not helping control IOP enough, pills are used. Pills usually have more side effects than eyedrops so are only prescribed when the eye drops are not bringing down the pressure substantially. Pills actually turn the “faucet” down so there is not so much fluid putting pressure on the eye.
When all else fails, doctors tend to turn to surgical procedures such as laser surgery. Other surgical options include: Argon Laster Trabeculoplasty, Selective Laster Trabeculoplasty, Laser Peripheral Iridotomy, Cycloablation andTrabeculectomy. About 50% of patients no longer require medication after surgery.
Not all glaucoma is alike. There are different types of glaucoma that aren’t affected by the pressure of the eye. An example of this is Secondary Glaucoma which usually develops as a result of another condition such as diabetes or eye injury. Pigmentary Glaucoma still causes IOP. The pigment of the eye flakes off slowly clogging the trabecular meshwork and building up the pressure.
More often than not, blindness and vision loss can be avoided by early detection of the disease. Please see your eye doctor if you think you have glaucoma or it runs in your family.