Glaucoma

It can take yoursight away

Glaucoma also known as “Kala Motia” or “Kach Bindu “ is one of the leading cause of blindness all over the world. In India one out of every 50 patients who have lost their sight are glaucoma patients. One of every seven patients of glaucoma is totally blind before they reach the hospital for treatment. The most disturbing fact is thatthis blindness is needless and preventable. A proper awareness, careful examination and meticulous adherence to prescribed treatment can certainly prevent blindness due to glaucoma.

What is glaucoma?

To retain configuration and biodynamicfunctions of the eye, a fluid is formed inside the eye. This fluid is called aqueous humour. This fluid is being continuouslyformed and simultaneously drained out of the eye. Nature has provided a very delicate balance of inflow and outflowof this fluid. As long as this balance is retained, the eye functions normally. This balance can be disturbed if either the production of aqueous increases or drainage is hampered resulting increase in pressure that presses on the blood vessels that bring blood supply to the optic nerve, resulting inpoor nutrition and oxygenation of the optic nerve. This process eventually kills the optic nerve fibres. Optic nerve is like an electric cable. It contains millions of wires, each carrying messages of vision from the eye to the brain. They join together to provide sharp central vision as well as “side vision: or peripheral vision.

Glaucoma damages these wires, causing blind spots in the peripheral vision. Unfortunately, patients rarely notice these blind areas in their side vision until significant optic nerve damage has occurred. In advanced cases, total visual loss can result as the entire optic nerve may be damaged. Unlike cataract, this loss of sight is permanent and irrecoverable. Fortunately, this can be prevented if glaucoma is diagnosed early and treated before major damage happens.

Proper and periodic examination of the eyes by competent specialist is of utmost importance for all adults, especially over the age of 40 years.

Causes and symptoms

Generally,glaucoma patients have no complaints and they are diagnosed on routine eye examination. It is for this reason that Glaucoma has been rightly labeled as the silent thief of vision. Depending on the manner in which the exit channels get closed or obstructed, glaucoma manifests itself in 4 ways.

Open angle glaucoma:

Here the rise in pressure of the eye ball is gradual and is due to increased resistance to the drainage channels which start to narrow down. The process is so gradual that the eye usually gets acclimatized to the new pressure levels. This condition can steal vision so quietly, that the patient is generally unaware of visual loss until the optic nerve is severely damaged. As glaucoma remains untreated, people may lose side vision significantly. The only way to prevent this loss of peripheral sight is by periodic eye check up and early diagnosis. Occasionally, patients with this type of glaucoma may complain of frequent change of glasses.

Angle closure glaucoma

Sometimes the drainage channels get clogged rapidly, resulting in sudden rise of pressure inside the eye. Such a sudden blockage of fluid flowing out of the eye results in “Acute angle closure glaucoma”. Blurred vision, severe pain, rainbow halos around light, nausea and vomiting will develop and these patients should be quickly brought to an eye specialist.

Congenital glaucoma

Here the drainage channels are poorly formed at birth. An infant’s tissue being more elastic than adults, these eyes expand in size with increasing pressure. The front portion of the eye (Cornea)becomes enlarge andfoggy and the eye acquires a bluish hue (Bull’s eye). These children should be taken to the eye centre at earliest.

Secondary glaucoma

Any injury, drugs like steroids, tumours, bleeding, inflammation etc can sometimes block the outflow channels. This can lead to increased pressure and is called secondary glaucoma.

Detection and dianosis

Early detection of glaucoma is of utmost importance. The most common form of glaucoma is “ Open angle Glucoma” which is asymptomatic and generally occurs in adults over 40 years of age. Hence a thorough yearly eye check by your ophthalmologist is essential especially in this age group.

Glaucoma detection requires a comprehensive eye exam with the help of a few specialized equipments.

Tonometer

This measures the pressure inside the eye, a non contact air pulse or Goldmann applanation tonometer is routinely used. Anaesthesia drops are applied to your eyes for this test.
Non-aspheric (traditional) lens

Non-aspheric lenses are lenses whose surfaces are parts of a plane or parts of a sphere. Compared to aspheric lens, non aspheric lens are simple and relatively cheaper.

How is the IOL power calculated before surgery?

IOL power calculations at NIO are done by trained personnel and every endeavor is made to minimize errors. This is done using Ziess IOLMaster and or ultrasound biometry.

What is the life span of an IOL?

Once implanted in the eye, it remains in place for the remainder of one’s lifetime.

What will happen if you decide not to go for operation?

Cataract usually gets worse day by day. Leaving a Cataract untreated will not threaten your vision immediately; however, it can slowly disable your eyes until you have little vision left. In worst case scenario, untreated Cataract can also damage the optic nerve of your eye due to raised intraocular pressure which can damage the nerve.

What type of anesthesia is used during surgery?

The surgery usually takes about 20 minutes. The operation is usually performed under a local anesthesia in the form of injection or eye drops. Rarely, a general anesthesia is used. Your anesthetist or surgeon will discuss the options with you and recommend the best form of anesthesia for you.

Dilated eye exam

This is to visualize the optic nerve at the back of the eye after drop are added to widen, or dilate the pupils. Your eye care professional uses a special magnifying lens to assess the damage. After the exam, your near vision may remain blurred for few hours.

perimetry

Perimetry is a special test that produces a map of the complete field of vision. Glaucoma damage firstappears as slight changes in peripheral (side) visual field.

In automated perimetry, a computer flashes points of light in a bowl shaped area. Patient is asked to respond by pressing a buzzer as soon as they see the light, even though it might be dim. One area of the visual field where it is normal not to see the light in a perimetry test is “blind spot” . This corresponds to the area where the optic nerve enters the back of the eye.

Gonioscopy

This is used to visualize the drainage channels of the eye with specialized contact lenses and a slit lamp.

when you need to worry?

  • Have possible history of glaucoma in the family.
  • Intermittent blurring of vision
  • Loss of field of vision
  • Difficulty in seeing at night.
  • Frequent change of glasses.
  • Seeing coloured haloes around light.

Treatment

One need to be meticulous in following the treatment prescribed by the eye surgeon depending on the evaluation of glaucoma. Glaucoma can be treated with drugs, laser or by surgery. Regular instillation of eye drops and maintenance of proper periodicity of drug is very important. These medicines either reduce the aqueous formation or improve the drainage channels.

Surgery and laser are used to create artificial channels if the drugs fail to achieve targed pressure.

Complications of modern glaucoma surgery are thankfully rare:

In conclusion

Visual loss due to cataract is recoverable unlike glaucoma that can blind you permanently. The key is to consult your eye specialist periodically for glaucoma if you are above 40 years of age or if you are experiencing any of the symptoms listed above.

Your doctor is the only person who can guide you to preserve your own vision.

Eye Care Learning