What is Glaucoma?

Glaucoma is a disease where the pressure inside the eye is raised to the extent that it may cause visual damage. So it is an abnormally high fluid pressure within the eye. As pressure builds, it can “pinch” both the optic nerve and the blood vessels, which nourish the retina. The result is usually a slow loss of peripheral, or vision, and eventual blindness. So Glaucoma is the leading preventable cause of blindness.

Generally our eye needs a certain amount of pressure to keep the eyeball in shape so that it can work properly. In some people, the damage is caused by raised eye pressure. Others may have an eye pressure within normal limits but damage occurs because there is a weakness in optic nerve. In most case both factors are involved but to a varying extent. Eye pressures is largely independent of blood pressure.

Types of Glaucoma:

Following are a few types of Glaucoma:-

1. Open Angle Glaucoma
2. Closed Angle Glaucoma
3. Secondary Glaucoma (precipitated by other factors)
4. Primary glaucoma (glaucoma originating without secondary causative factors)
5. Juvenile Glaucoma (children)
6. Congenital glaucoma (meaning from birth)

In Open-angle glaucoma. The transparent fluid inside the eye (Aqueous Fluid) cannot be drained quickly enough, because the drainage channels (Trabecular meshwork) within the eye have become restricted. Open-angle glaucoma is often inherited from parents, although this is rarely the case with Closed-angle glaucoma.

In Closed-angle glaucoma, the angle or periphery of the anterior chamber of the eye is closed and so the eye cannot drain the fluid quickly enough.

The most common is chronic glaucoma (chronic = slow) in which the aqueous fluid can get to the drainage channels (open angle) but they slowly become blocked over many years. The eye pressure rise very slowly and there is no pain to show there is a problem, but the field of vision gradually becomes impaired.

Acute glaucoma (acute = sudden) happens when there is a sudden and more complete blockage to the flow of aqueous fluid to eye. This is because a narrow ‘angle’ closes to prevent fluid ever getting to the drainage channels. This can be quite painful and will cause permanent damage to your sight if now treated promptly.

Childhood glaucoma

Childhood glaucoma is a rare form of glaucoma that often develops in infancy, early childhood, or adolescence. Prompt medical treatment is important in preventing blindness.      

Congenital glaucoma  

Congenital glaucoma, a type of childhood glaucoma, occurs in children born with defects in the angle of the eye that slow the normal drainage of the fluid. Prompt medical or surgical treatment is important in preventing blindness.

Primary glaucoma

Both open-angle and angle-closure glaucoma can be classified as primary or secondary. Primary glaucoma cannot be contributed to any known cause or risk factor.

Secondary glaucoma

Both open-angle and angle-closure glaucoma can be classified as primary or secondary. Secondary develops as a complication of another medical condition or injury. In rare cases, secondary of another medical condition or injury. In rare cases, secondary is a complication following another type of eye surgery.

Symptoms of Glaucoma:

Symptoms may include:

• Frequent mild headache, especially upon waking;
• Increased difficulty with night vision;
• Recurring redness in one or both eye, especially if accompanied by blurred vision and/or pain;
• A frequent change of eyeglass prescription;
• A noticeable loss of peripheral vision.
• Severe pain, pain, foggy vision and rainbow haloes.

If your experience there symptoms, seek treatment immediately.

Main Cause for Glaucoma:

The main underlying reason why increased intra ocular pressure develops (glaucoma) is because the outflow of intra ocular fluid gets impaired (obstructed) in one way or another. This leads to increased pressure of the fluid inside the eye.

• Anyone can develop glaucoma, however, it is rare in people under 45 year of age. The people, who run the highest risk of developing glaucoma, are people who have a close blood relative who have suffered glaucoma. (E.g. mother, father, sister or brother)
• Certain eye conditions are more prone to developing glaucoma :-
• People who are very short- sighted
• Detachment of the Retina
• Certain illnesses of retina e.g. Retinitis pigmentosa
• Also, Patient with diseases of the thyoid gland.
• Patient with Diabetes mellitus (impaired sugar tolerance)

Detection & Diagnosis of glaucoma:

Glaucoma can only be detected through a series of tests performed by your eye doctor. The loss of vision is usually so gradual and painless that most people are unaware of it until damage is permanent. Once vision has been lost due to glaucoma, it cannot be restored. If you are over 45 years of age, your eye surgeon will use an instrument called a “Tonometor”. This instrument takes a pressure reading from your eye by placing the machine on your eye (Applanation or Schiotz Tonometer) or by firing a puff of air (Pneumotonometer).

In addition to a complete medical history and eye examination, your eye care professional may perform the following tests to diagnose glaucoma:

• Visual acuity test – the common eye chart test, which measures vision ability at various distances.
• O.P. Measurement – Either by Schiotz Tonometer (lying down position) or by Applanation or Pneumotonometer (sitting position on the slit lamp)
• Pupil dilation – the pupil is widened with eye drops to allow a close-up examination of eye’s retina & optic nerve head.
• Gonioscopy – To see the angle of the eye with the help of 3 or 4 mirror Gonioscope.
• Visual field – a test to measure a person’s side (peripheral) vision. Lost peripheral vision may be an indication of glaucoma.

In a simple, painless test, doctor measures the fluid pressure or “hardness” of the eye manually high or if the optic nerve proves abnormal upon examination, your doctor will probably suggest you undergo a “visual fields” test to determine if any peripheral or side vision has been lost.

Treatment of Glaucoma:

In glaucoma is detected, it can be treated one of three ways: with medications, conventional surgery or lasers. Traditional treatment includes eye drops and tablets to control fluid pressure. These drugs will reduce the production of the transparent fluid within the eye. This relieves the pressure from within the eye and prevents damage caused by Glaucoma. If medication is ineffective, either laser or conventional surgery will be used to open channels in the eye through which fluid may drain.

“The best defense against glaucoma is regular eye checkups by a qualified eye care specialist.”

• LASER: The laser, actually an intense beam of light, produces short bursts of precisely directed energy to create fluid channels within the eye. A typical laser treatment takes 15 minutes or less and requires only eye drops for anesthesia. Blurred vision for an hour or so after surgery is usually the only discomfort. The laser is not a “cure” for glaucoma, but it often makes it possible to avoid surgery and reduce dependence on medications. If laser and medical treatment fails to bring glaucoma under control, conventional glaucoma surgery to open a drainage channel will almost certainly be required.
• TRABECULAR SURGERY: This method is used to improve the drainage of fluids from your eye. The “trabecular meshwork” is fine net of fiber between the cornea and the iris. If fluid is blocked from passing through this net, pressure on the eye build, pinching the optic nerve. The surgery is usually done under local anaesthesia. The usual surgical time is around 30-35 minutes. Bandage is kept for a day or two depending on the healing. Slight pricking or watering & redness following surgery, will be there for 5-7 days. Though the complication rate is less, but few complications viz. bleeding, failure of surgery or loss of vision may be expected in less than 1% of cases.