GLAUCOMA

                 

            By Yinka-Balogun Olumuyiwa

Definition

Glaucoma is defined as an optic neuropathy with progressive optic nerve head damage and characteristic visual field changes with intraocular pressure as a modifiable risk factor.

Aetiology

• The fluid inside the eye, called aqueous humour, usually flows out through a mesh-like channel. If this channel gets blocked, or the eye is producing too much fluid, the fluid builds up. Sometimes, experts don’t know what causes this blockage. But it can be inherited, meaning it’s passed from parents to children.
• Less-common causes of glaucoma include a blunt or chemical injury to the eye, severe eye infection, blocked blood vessels inside the eye, and inflammatory conditions. It’s rare, but eye surgery to correct another condition can sometimes bring it on. It usually affects both eyes, but it may be worse in one than the other.

Risk Factors

• African American, Irish, Russian, Japanese, Hispanic, Inuit, or Scandinavian descent
• Greater than 40 years old
• Family history of Glaucoma
• Near-sighted or farsighted
• Poor vision
• Certain steroid medications such as prednisone
• Certain drugs for bladder control or seizures, or some over-the-counter cold remedies
• Previous injury to your eye or eyes
• High blood pressure, heart disease, diabetes, or sickle cell anaemia
• Have high eye pressure

Types

There are two main kinds:

Open-angle glaucoma; This is the most common type. It is also known as wide-angle glaucoma. In this type the trabecular meshwork is fine but the fluid still doesn’t flow out properly.

Angle-closure glaucoma; This is more common in Asia. It is also called acute or chronic angle-closure or narrow-angle glaucoma. Your eye doesn’t drain like it should because the drain space between your iris and cornea becomes too narrow. This can cause a sudden build-up of pressure in your eye. It’s also linked to farsightedness and cataracts, a clouding of the lens inside your eye.

Less common types of glaucoma include:

• Secondary glaucoma: This is when another condition, like cataracts or diabetes, causes added pressure in your eye.
  • Normal-tension glaucoma: This is when you have blind spots in your vision or your optic nerve is damaged even though your eye pressure is within the average range. Some experts say it’s a form of open-angle glaucoma.
  • Pigmentary glaucoma: With this form, tiny bits of pigment from your iris, the coloured part of your eye, get into the fluid inside your eye and clog the drainage canals.

Symptoms

Most people with open-angle glaucoma don’t have symptoms. If symptoms do develop, it’s usually late in the disease. That’s why glaucoma is often called the “sneak thief of vision.” The main sign is usually a loss of side, or peripheral, vision.

Symptoms of angle-closure glaucoma usually come on faster and are more obvious. Damage can happen quickly. If you have any of these symptoms, get medical care right away:

• Seeing halos around lights
• Vision loss
• Redness in your eye
• Eye that looks hazy (particularly in infants)
• Upset stomach or vomiting
• Eye pain

Possible Treatments

• Eye drops.
• Oral medication.
• Laser surgery. This procedure can slightly raise the flow of fluid from your eye if you have open-angle glaucoma. It can stop fluid blockage if you have angle-closure glaucoma. Procedures include:
  • Trabeculoplasty: This opens the drainage area.
  • Iridotomy: This makes a tiny hole in your iris to let fluid flow more freely.
  • Cyclophotocoagulation: This treats areas of the middle layer of your eye to lower fluid production.
• Microsurgery.