Glaucoma is an eye condition that develops when too much fluid pressure builds up inside of the eye. It tends to be inherited and may not show up until later in life.
The increased pressure, called intraocular pressure, can damage the optic nerve which transmits images to the brain. If damage to the optic nerve from high eye pressure continues, glaucoma will cause loss of vision. Without treatment, glaucoma can cause total permanent blindness within a few years.
Symptoms of Glaucoma
Because most people with glaucoma have no early symptoms or pain from this increased pressure, it is important to see your ophthalmologist regularly so that glaucoma can be diagnosed and treated before long-term visual loss occurs.
If you are over the age of 45 and if you have a family history of glaucoma, you should have a complete eye exam with an ophthalmologist every one to two years. If you have health problems such as diabetes or a family history of glaucoma or are at risk for other eye diseases, you may need to visit your ophthalmologist more frequently.
What Causes the Pressure Inside the Eye to Increase?
Glaucoma usually occurs when intraocular pressure increases. This happens when the fluid pressure in the eye’s anterior chamber, the area between the cornea and the iris, rises.
Normally, this fluid, called aqueous humor, flows out of the eye through a mesh-like channel. If this channel becomes blocked, fluid builds up, causing glaucoma. The direct cause of this blockage is unknown, but doctors do know that it is most often inherited, meaning it is passed from parents to children.
Less common causes of glaucoma include a blunt or chemical injury to the eye, severe eye infection, blockage of blood vessels in the eye, inflammatory conditions of the eye and occasionally eye surgery to correct another condition. Glaucoma usually occurs in both eyes, but it may involve each eye to a different extent.
Types of Glaucoma
There are two main types of glaucoma:
- Open-angle glaucoma. Also called wide-angle glaucoma, this is the most common type of glaucoma. The structures of the eye appear normal, but fluid in the eye does not flow properly through the drain of the eye, called the trabecular meshwork.
- Angle-closure glaucoma. Also called acute or chronic angle-closure or narrow-angle glaucoma, this type of glaucoma is less common, but can cause a sudden buildup of pressure in the eye. Drainage may be poor because the angle between the iris and the cornea (where a drainage channel for the eye is located) is too narrow. Or the pupil opens too wide, narrowing the angle and blocking the flow of the fluid through that channel.
Your doctor will determine which surgical procedure is best for you:
- Laser trabeculoplasty
- Laser iridotomy
- Glaucoma drainage tube implants (Baerveldt drainage tube, Ahmed drainage valve)
- Minimally invasive glaucoma procedures (iStent)
A laser is used to treat the trabecular meshwork, the filter over the drainage system inside the eye.This procedure lowers eye pressure by increasing the outflow of fluid inside the eye.This procedure is performed in the office, is non-invasive, and carries less risk than other surgical procedures.The full effect of trabeculoplasty often takes 3-4 weeks and the benefits usually last for several years.
This procedure involves accessing an internal drainage canal and injecting a thick fluid, called viscoelastic, into it.This procedure expands the drainage canal, facilitating the drainage of fluid from inside the eye. Because this procedure uses the eye’s natural drainage system, there is little risk of excessive pressure reduction after surgery. Another advantage of viscocanalostomy is that it stimulates the body’s healing mechanism less than trabeculectomy, so there is less of a tendency for scar tissue to form.
Although viscocanalostomy takes longer than trabeculectomy and is more technically challenging to perform, it is much simpler for the patient. This procedure can be performed alone or along with cataract surgery. Compared to trabeculectomy, this procedure carries less risk and requires fewer postoperative visits.
A trabeculectomy involves surgically creating a reservoir (bleb) on the top of the eye, usually under the upper eyelid. Aqueous fluid from inside the eye flows into the bleb and then is absorbed into the blood-stream. The new drain is entirely inside the eye. The fluid does not enter your tears or flow down your cheek. Although this cannot reverse existing damage from glaucoma, it may prevent further loss of vision from glaucoma. Anti-scarring medications, such as 5-Fluorouracil or Mitomycin-C are usually used during surgery to achieve more long-lasting control of the eye pressure after surgery.
After surgery, the vision in your operative eye may be blurry for a few months. You will need to use multiple drops at frequent intervals after the surgery. You will also have frequent postoperative visits, often weekly, until the eye has healed.
Glaucoma Drainage Device
Baerveldt drainage tubes and Ahmed valves are used by the doctors at Clarus to control eye pressures when needed. A reservoir is placed on the top of the eyeball and a small tube is directed into the front chamber of the eye.The implant is covered with donor tissue and the natural tissue that covers the eyeball. The tube is often tied off with a dissolvable suture to prevent excessive pressure reduction in the first several weeks.It usually takes between 6 and 10 weeks to see the full effect of the tube implant.
Minimally Invasive Glaucoma Procedures
There are many devices available for the management of glaucoma and more are expected to be available in the coming years.Currently, the doctors at Clarus offer the iStent, which is a microscopic titanium tube that is inserted into the eye’s natural drainage system to help lower the pressure inside the eye. This procedure is FDA approved for use during cataract surgery for mild to moderate open angle glaucoma. Not every glaucoma patient is a candidate for the iStent, but for many, it is an excellent, low-risk method of reducing eye pressures.
If you are experiencing vision changes, schedule an eye exam to find out if Glaucoma may be developing.