Glaucoma

Glaucoma

What is Glaucoma

Glaucoma is an eye disease where the optic nerve at the back of the eye is damage and thus leads to progressive, irreversible vision loss. The optic nerve functions to send visual information from the retina to the brain.

What Causes Glaucoma?

In most cases, increase in eye pressure is usually the cause of Glaucoma. Normal eye pressure should range between 10 mmHg to 20 mmHg. Increase in eye pressure is mainly due to blockage of the circulation or drainage of the eye fluid called the aqueous humor.

Progression of Glaucoma Causing Blindness

Glaucoma field loss

Who is at Risk?

  • Age above 40 years old
  • Family history of Glaucoma
  • High myopia or hyperopia
  • Use of steroid medications
  • Hypertension
  • Eye injury
  • Diabetes

Optic Nerve Cupping Progression in Glaucoma

Different types of Glaucoma

  1. Open Angle Glaucoma (POAG): POAG is the most common form of glaucoma. It happens when the aqueous drainage fluid canals are obstructed over time thus causes the eye pressure to increase. There will be no symptoms present until eyesight is lost at a later stage. Damages progresses slowly and starts off with the peripheral vision.
  2. Angle Closure Glaucoma (ACG): ACG is an emergency case whereby the eye pressure will usually rise very quickly. The angle between the cornea and the iris is narrow and causes blockage of the drainage. Those with ACG will be present with eye pain, sudden blurring of vision, headache, nausea and vomiting.
  3. Normal Tension Glaucoma (NTG): In NTG, the optic nerve is damaged even though the eye pressure remains in normal range. Causes of NTG is still unknown.
  4. Secondary Glaucoma: Secondary glaucoma occurs as a result of any eye injury, inflammation, infections or in advanced stage of cataract and diabetes.
    Prolong use of certain medications such as steroid can also cause secondary glaucoma.
  5. Congenital Glaucoma: Congenital glaucoma refers to glaucoma diagnosed in infancy or early childhood. It may be due to hereditary defect or abnormal development during pregnancy.
    Signs & symptoms include cloudy, white & enlarge protruding eye, sensitive to light and excessive tearing.

How is Glaucoma Detected?

  1. Dilated eye examination: Dilating drops will be instill onto your eyes to open your pupil. Thus, making it easier for the Ophthalmologist to look at your optic nerve.
  2. Tonometry: An instrument called the tonometer is used to measure the pressure of your eyes. Anesthetic eye drops and dye will be put in your eyes. A small probe will then be placed against the surface of the eye to measure the pressure.
  3. Gonioscopy: Special lenses are used to enable the Ophthalmologist to access the structure inside the eye mainly the drainage angle.
  4. Corneal thickness assessment: Corneal thickness can affect the measurement of the eye pressure. A thicker cornea may falsely give a higher pressure and a thinner cornea may falsely give a lower pressure.
  5. Optical Coherence Tomography:A sophisticated non-invasive imaging technology that helps to evaluate the optic nerve and internal structures.
  6. Visual Field Test:This test is done to determine if you have vision loss from glaucoma. It involves staring straight into the machine and clicking a button if you notice a blinking light in your peripheral vision.

Treatment

  1. Medications: Eye Drops. This treatment is usually the first line treatment for most type of glaucoma. There are different types of eyedrop that works in different way either to reduce the production of fluid in the eye or promoting drainage of fluid from the eye.
  2. Pills: When eye drops don’t sufficiently control the eye pressure, pills may be prescribed in addition to eye drops.
    When medication does not achieve the desired results and causing complications, your Ophthalmologist may suggest Laser Treatment of Surgery.
  3. Laser:
    • Laser Peripheral Iridotomy (LPI) is done in eye with narrow angle. This helps to facilitate the flow of fluid in the eye.
    • Argon Laser Trabeculoplasty and Selective Laser Trabeculoplasty are performed on Open Angle Glaucoma. The eye drainage system is altered so that the fluid in the eye can drain out easily.
  4. Surgery:
    • Trabeculectomy. The eye surgeon will create a passage in the white part of the eye for draining excess eye fluid.
    • Drainage Implant Surgery.Drainage devices which consist of small silicone tube is extended into the anterior chamber of the eye to aid the drainage of eye fluid.