Glaucoma is an eye disease, where the high fluid pressure within your eye damages the delicate fibers of the optic nerve. These delicate nerve fibres are responsible for carrying visual impulses from your eye to the brain. This damage is irreversible and can lead to blindness in advanced cases. It has been labeled as “lurking thief of vision”. Glaucoma is the second leading cause of blindness in the world with 70 to 105 million people affected worldwide (WHO).
Glaucoma causes damages which are preventable but not totally curable. It is therefore necessary that the disease should be detected and treated at its earliest stage to prevent blindness.
The disease can develop slowly and one may not even be aware of the gradual loss of sight until very late in the disease when your vision is seriously affected. Unfortunately, most cases of glaucoma do not occur with readily noticeable symptoms that warn of the irreversible optic nerve damage being done. However, the presence of the following warning signs indicates that you need a thorough examination by an eye doctor:
- Unusual trouble adjusting to dark rooms
- Difficulty focusing on near or distant objects
- Squinting or blinking due to unusual sensitivity to light or glare
- Change in color of iris
- Red-rimmed, encrusted or swollen lids
- Recurrent pain in or around eyes
- Double vision
- Dark spot at the center of viewing
- Lines and edges appear distorted or wavy
- Excess tearing or “watery eyes”
- Dry eyes with itching or burning; and
- Seeing spots, ghost-like images
The following may be indications of potentially serious problems that might require emergency medical attention:
- Sudden loss of vision in one eye
- Sudden hazy or blurred vision
- Flashes of light or black spots
- Halos or rainbows around light
Glaucoma is most common above the age of 40 years; it may affect any age group. A special type of glaucoma called Congenital Glaucoma may affect even a newborn or a child.
If you’re over age 40, diabetic or have a family member with glaucoma, Thyroid disease o Patients who are on long term steroid therapy for other diseases such as asthma, arthritis etc even if you have previous eye injury or surgery o Hypermetropia (farsightedness) then you are at higher risk for glaucoma than others.
There are 2 main types of glaucoma which are seen in adults :
- Chronic Glaucoma or Open-angle Glaucoma
- Acute Glaucoma or Closed-angle Glaucoma
Open-angle glaucoma, the most common form of glaucoma, accounting for at least 90% of all glaucoma cases:
Is caused by the slow clogging of the drainage canals, resulting in increased eye pressure
- Has a wide and open angle between the iris and cornea
- Develops slowly and is a lifelong condition.
- Has symptoms and damage that are not noticed.
“Open-angle” means that the angle where the iris meets the cornea is as wide and open as it should be. Open-angle glaucoma is also called primary or chronic glaucoma.
Angle-closure glaucoma, a less common form of glaucoma:
- Is caused by blocked drainage canals, resulting in a sudden rise in intraocular pressure
- Has a closed or narrow angle between the iris and cornea
- Develops very quickly
- Has symptoms and damage that are usually very noticeable
- Demands immediate medical attention.
It is also called acute glaucoma or narrow-angle glaucoma. Unlike open-angle glaucoma, angle-closure glaucoma is a result of the angle between the iris and cornea closing.
Individuals at high risk for glaucoma should have a dilated pupil eye examination at least every one to two years. Eye doctors use several tests to detect glaucoma; these tests include:
Tonometry measures the pressure inside the eye. Examples of tonometers include:
- The air puff or noncontact tonometer emits a puff of air. Eye pressure is measured by the eye’s resistance to the air.
- The applanation tonometer touches the eye’s surface after the eye has been numbed, and measures the amount of pressure necessary to flatten the cornea. This is the most sensitive tonometer, but a clear, regularly-shaped, cornea is needed for it to function properly.
- The electronic indentation method measures pressure by directly contacting anesthetized eyes with a digital pen-like instrument.
In pupil dilation, special drops temporarily enlarge the pupil so that the doctor can better view the inside of the eye.
Visual field testing measures the entire area seen by the forward-looking eye to document straight-ahead (central) and/or side (peripheral) vision. It measures the dimmest light seen at each spot tested. Each time a flash of light is perceived, the patient responds by pressing a button.
A visual acuity test measures sight at various distances. While seated 20 feet from an eye chart, the patient is asked to read standardized visual charts with each eye, with and without corrective lenses.
Pachymetry uses an ultrasonic wave instrument to help determine the thickness of the cornea and better evaluate eye pressure.
Ophthalmoscopy allows the doctor to examine the interior of the eye by looking through the pupil with a special instrument. This can help detect damage to the optic nerve caused by glaucoma.
Gonioscopy allows the doctor to view the front part of the eye (anterior chamber) to determine if the iris is closer than normal to the back of the cornea. This test can help diagnose closed-angle glaucoma.
Optic nerve imaging helps document optic nerve changes over time. Nerve imaging techniques include stereo optic nerve photographs, scanning laser polarimetry (GDx), confocal scanning laser ophthalmoscopy (Heidelberg Retinal Tomograph or HRT) and optical coherence tomography (OCT). All four techniques are painless and non-invasive. A doctor will determine which method(s) to use.
After the age of 40 years, one should get an eye check up for glaucoma every 3 to 4 years even if there are no symptoms.
If a family member has glaucoma, if you have diabetes, if you are on long term systemic steroids for some other disease, or if you have suffered a blunt eye injury in the past, you must get your eyes checked every 1 to 2 years.
Glaucoma is often treated with eye drops taken regularly several times a day, sometimes in combination with pills. These medications will alter the circulation of eye fluid and lower eye pressure, either by decreasing the production of fluid within the eye, or by increasing the flow leaving the drainage angle. It is important to tell all of your doctors about the eye medications you are using because glaucoma medications can have side-effects. You should notify your ophthalmologist immediately if you think you may be experiencing side-effects.
Laser surgery is also effective for glaucoma treatment. Trabeculoplasty is laser treatment to enhance the eye drain age function to control eye pressure within the eye when treating open-angle glaucoma. Iridotomy is laser treatment to create tiny holes in the iris to improve the flow of eye fluid to the drain when treating narrow angle glaucoma.
When operative surgery is needed to treat glaucoma, your ophthalmologist will use a microscope and specialized instruments to create a new bypass drainage channel for the eye fluid to leave the eye. The new channel helps to lower the eye pressure. Surgery will be recommended only if your ophthalmologist feels the benefit of a lower eye pressure achieved with an operation outweighs possible complications and/or further progression of optic nerve damage.
Yes, glaucoma can be hereditary. If any of your blood relatives has glaucoma, please get yourself checked at REH Glaucoma Family Clinic.