Glaucoma

What is Glaucoma?

An increase in pressure of the eye with weakening of the optic nerve can cause damage to the optic nerve.

This eye condition is called Glaucoma.

Let’s understand what happens internally in the eye when affected with glaucoma. In every eye, a clear fluid (aqueous humor) is present in the front portion of the eye. This is circulated to maintain constant healthy eye pressure. Some fluid drains out of the eye through a tubular meshwork on a regular basis. In a glaucoma affected eye due to blockage in this meshwork, the drainage of the fluid gets affected and thereby increases the ocular pressure. When this is not treated or controlled, continuous increase in the intra ocular pressure may result in damage to the optic nerve fibers, which results in irreversible vision loss.

Glaucoma is one of the commonest causes of irreversible blindness worldwide. It is better known as the “silent thief of sight” as it silently causes damage before it is known and the symptoms surface when Glaucoma is severe. It usually occurs in both the eyes, but could be severe in one eye only.

Types of Glaucoma:

  • Open angle glaucoma: It is most commonly known type of glaucoma wherein the drainage channels are blocked although the drainage angle between the iris and the cornea are open. In early stage the vision could be normal and symptoms are not well defined.
  • Acute Closed or Narrow Angle glaucoma: A narrow angle between the iris and the cornea results in poor drainage of the eye fluid causing sudden build in pressure in the eye. This type is less commonly known.
  • Normal tension glaucoma: Although the eye pressure is below normal, vision is impaired and optic nerve is damaged.
  • Secondary glaucoma: This category is associated with other eye disorders like acute cataract, tumor, injury or inflammation in the eye.
  • Congenital glaucoma: In this category glaucoma that is present at birth is known as congenital glaucoma.

Other known Causes:

  • Eye infection
  • Corrective eye surgery
  • Inflammation

Symptoms:

  • Peripheral field vision loss (as in case of Chronic Open-Angle Glaucoma) – Blind spots appear less noticeable until optic nerve gets severely damaged.
  • Tunnel Vision- Peripheral vision could progress to Tunnel Vision. Vision gets narrowed gradually (like looking through a tunnel).
  • Blurred Vision, Halos, Dilated Pupil, Severe Pain and redness in the eye, Headache, Nausea (as in acute Closed or Narrow Angle Glaucoma)
  • Frequent rubbing, squint, tearing and sensitivity to light (as in congenital glaucoma)

Prevention: Glaucoma once diagnosed can be only controlled not reversed. Poor visual fields or visual field loss can lead to accidents in the elderly; hence the following steps may help to prevent this condition.

  • Early detection followed by effective treatment.
  • Beware of medications which indicate warning note on glaucoma e g. decongestants
  • Maintain active lifestyle with healthy diet and weight.
  • Avoid smoking

Risk factors:

  • Drugs used for other ailments like cold, bladder problems etc.
  • Genetics or Hereditary in nature
  • Side effects of steroid e g. Asthma
  • Eye trauma
  • Result of another eye problem undetected.

·       Ethnicity- narrow angles glaucoma more common in certain races (e g. Asians, Eskimos).

  • Thin cornea (less than .5mm)
  • Nearsightedness or farsightedness.
  • Older age group
  • Other health problems like migraines, diabetes and low blood pressure.

Treatment:             

Diagnosis: The common screenings for glaucoma includes tests such as:

  • Tonometry (to measure internal eye pressure or IOP)
  • Ophthalmoscopy(dilated eye exam to inspect the optic nerve)
  • Perimetry(visual field test)
  • Gonioscopy (to identity the drainage angle between the cornea and the iris)
  • Pachymetry (measure the thickness of the cornea)
  • Nerve fiber analysis (for thickness measurement of the nerve fibre)
  • Visual field test (to test side or peripheral vision)

The treatment options are:

  • Medications Eye drops and pills are prescribed to reduce the eye pressure. It helps in reducing the production of aqueous humor and improves drainage of the fluid of the eye.
  • Laser treatment: High energy laser beam is used to drain the fluid.
    • Laser trabeculoplasty
    • Laser iridotomy
    • Selective Laser Trabeculoplasty (SLT)
    • Argon Laser Trabeculoplasty (ALT)
  • Filtering surgery:
  • Trabeculectomy is mainly the gold standard of treatment. It is sometimes combined with cataract surgery
  • Operative surgery:
  • Microinvasive glaucoma surgery (MIGS)
  • Glaucoma drainage implants

Appropriate diagnostic techniques, follow-up examinations and the treatment depend on the nature and severity of glaucoma on the affected eye. The damage to the optic nerve at various intraocular pressures varies from person to person. In order to control progression of glaucoma, medication needs to be consistently followed as per prescription.

Vision researchers are working on stem cells and other treatments like vaccine, optic nerve regeneration and smart contact lenses to provide solution for treating glaucoma.

Effective diagnosis is very crucial in the treatment at the right time.

Let’s tackle the ‘silent thief of sight’ …let’s not get caught unawares.

 

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