Diseases & Conditions

 

Glaucoma

Diseases & Conditions

 

What is glaucoma?

Glaucoma refers to a group of disorders that damage the optic nerve and can result in vision loss and blindness. The optic nerve carries information from the eye to the brain and is vital to good vision. Glaucoma occurs when fluid builds up in the front part of the eye increasing the pressure on the eye and damaging the optic nerve.

The current global prevalence of glaucoma for population aged 40-80 years is 3.54%. The number of people with glaucoma worldwide is expected to increase to 111.8 million in 2040.1

 

What causes glaucoma?

Elevated eye pressure due to the build-up of fluid is a major risk factor for optic nerve damage. There are several types of glaucoma:2

  • Open-angle glaucoma: This is the most common form of glaucoma in which fluid does not flow properly through the drain of the eye.
  • Angle-closure glaucoma: This condition occurs when the angle between the iris and the cornea is too narrow and physically blocked by the iris causing poor drainage and increasing the pressure on the optic nerve.

 

What are the risk factors for glaucoma?

Risk factors for glaucoma and optic nerve damage include:3

  • Elevated eye pressure
  • Older age
  • Ethnicity: Blacks and Hispanics are more prone to develop glaucoma than Whites.
  • Family history
  • Diabetes mellitus
  • Heart disease
  • Hypertension
  • Sickle cell anemia
  • Having certain eye conditions, such as nearsightedness
  • Having an eye injury
  • Having done an eye surgery
  • Early estrogen deficiency (removal of both ovaries)
  • A long time use of certain medications such as corticosteroid (eye drops)

 

What are the symptoms of glaucoma?

The signs and symptoms of glaucoma depend on the type and stage of the condition.4

In its early stages, open-angle glaucoma has no symptoms. As the disease progresses, blind spots develop in the peripheral view.

On the other hand, the signs and symptoms of angle-closure glaucoma include:

  • Severe pain in the eye or forehead
  • Redness of the eye
  • Decreased vision or blurred vision
  • Seeing rainbows or halos
  • Headache
  • Nausea
  • Vomiting

 

How is glaucoma diagnosed?

Tests and diagnosis of glaucoma include:5

  • Visual acuity test: This test is used to determine the smallest letters a patient can read on a standardized chart held 20 feet away.
  • Visual field test: This test is an eye examination that can detect dysfunction in central and peripheral vision.
  • Dilated eye exam: This test consists of instilling dilating drops to enlarge the pupils allowing in more light and giving the doctor a better view of the back of the eye.
  • Tonometry: This test consists of measuring the pressure inside the eye by using an instrument called a tonometer.
  • Pachymetry: This test consists of measuring the thickness of the cornea.

 

How is glaucoma treated?

The damage caused by glaucoma is irreversible. Treatment can slow the damage and prevent loss of vision. The aim of the treatment is to reduce the pressure on the eye by improving how fluids drain from the eye or by decreasing the amount of fluid the eye generates. Treatments of glaucoma include eye drops, laser treatment or surgery.6

Eye drops:

  • Prostaglandins: These eye drops increase the outflow of the fluid in the eye and reduce pressure.
  • Beta blockers: These eye drops decrease the pressure in the eye by reducing the production of fluid.
  • Alpha-adrenergic agonists: These eye drops decrease the production of fluid in the eye and increase its outflow.
  • Carbonic anhydrase inhibitors: These eye drops reduce the production of fluid in the eye.
  • Oral medications: Oral medications such as carbonic anhydrase inhibitor decrease the pressure on the eyes.

Laser treatment:

Laser trabeculoplasty is an option for people with open-angle glaucoma that uses a laser beam to open clogged channels in the eye.

 Surgery:

  • Filtering surgery: A trabeculectomy is a surgical procedure in which the doctor creates an opening in the white of the eye and removes part of the clogged channels reducing the pressure on the eye.
  • Drainage tubes: This procedure consists of inserting a small tube in the eye.

 

 References:

  1. Tham, Yih-Chung, et al. "Global prevalence of glaucoma and projections of glaucoma burden through 2040: a systematic review and meta-analysis." Ophthalmology 121.11 (2014): 2081-2090.
  2. WebMD http://www.webmd.com/eye-health/glaucoma-eyes?page=2#1 (Accessed January 25, 2016)
  3. Risk factors http://www.mayoclinic.org/diseases-conditions/glaucoma/basics/risk-factors/con-20024042 (Accessed January 25, 2016)
  4. American Academy of Ophthalmology http://www.aao.org/eye-health/diseases/glaucoma-symptoms (Accessed January 25, 2016)
  5. Facts About Glaucoma https://nei.nih.gov/health/glaucoma/glaucoma_facts (Accessed January 25, 2016)
  6. Treatments and drugs http://www.mayoclinic.org/diseases-conditions/glaucoma/basics/treatment/con-20024042 (Accessed January 25, 2016)