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Glaucoma - More Detailed Information
Just imagine a class of 100 people graduating from class 10 at age 15. If we check their eye pressure, maybe 2 or 3 would have elevated eye pressure. If the same group of people met after 2 decades and we checked their pressure again at least 5 to 7 would have elevated pressure. If they were all alive at the age of 75 i.e. 4 decades later, at least 20 of them would have developed glaucoma. Recent studies show that Glaucoma develops with increasing age to the tune of 2% per decade of life.

Glaucoma is not a new ailment. It was described hundreds of years ago by Greek, Arab and Indian surgeons who told of a “tightness” and “whitening” of the eye ,of a “black water”,that filled inside the eye robbing the patient of sight. To this day across India people refer colloquially to this as “Kala Motia” or in Gujarati as “Jhamar.”

The human eye has a part called the ciliary body that produces fluid called “Aqueous”. This aqueous has to flow out of the eye through a mesh similar to a tea strainer. With age, injury, diabetes, swelling, cataract etc the mesh gets blocked leading to rise in pressure in the eye. This rise in pressure presses on the optic nerve inside the eye. The peripheral vision (side vision) decreases. However there is usually no pain and central vision is preserved to the end. Since central vision and reading vision is preserved until the disease is very severe, it usually slips the patients attention and is detected accidentally by the ophthalmologist when the person visits them for some other eye complaint.

Glaucoma there for must consist of 3 basic findings

1. Increased pressure in the eye (normal is usually taken as less than 21 miilimeters of mercury)

2. Optic nerve changes which are seen by your eye doctor by looking inside the eye with an instrument.

3. Loss of “field” or side vision.

The pressure can be checked by a machine called a tonometer. Modern set-ups have a computerized device that blows a puff of air at the eye to measure its pressure. Field testing is done on a large unit called a “Automated Perimeter”. This machine shows spots of light at various places on a screen. Inability to see these spots are noted by the machine as field loss and a map is plotted by the computer.

In the very late stage of the disease the patient feels that he or she is looking through a tube as the side vision is gone. This is called tubular vision.

The optic nerve changes, today can be measured by a machine called a HRT-2 from Germany, which measures the changes and gives a report. This is performed every 4-6 months to know if the nerve changes are progressing or not. In the olden days the eye doctor would look in and draw a diagram, however today this machine plots for us 69,000 points on the nerve which is as small as 3 mm in diameter giving us a much more accurate assessment.

However modern technology or not it cannot replace the doctors experience. Remember the old saying, that, “In a car accident the loosest nut is the one behind the wheel”. HRT-2 has been proved to detect glaucoma upto 5 years befor field test and is our new warrior in the fight against Glaucoma. In some cases glaucoma can be there without increased pressure, called Normal Tension Glaucoma (NTG). It is now known that more than 40% of all glaucoma patients are NTG patients. These normal tension glaucoma patients eyes cannot stand even normal pressure and the pressure needs to be reduced by 30% lower than it is. For example if a patient has 18 pressure and is diagnosed by the eye doctor with normal tension glaucoma the pressure will have to be reduced to 12 to control the progress of the disease.

Glaucoma is not just a disease of old age. Newborn babies can have glaucoma as a congenital problem. When pressure rises in a babies eye the eye swells up and looks huge like a ox or buffalo eye. This appearance is called “Bupthalmos”. If the child is treated with the correct surgery before the age of 3 the eye usually returns to its normal size. If as is usually the case in rural areas the child does not receive the correct surgical treatment the eye becomes very large and vision is greatly reduced leading to blindness!

Glaucoma and the eye pressure rising can also be due to many other causes. Bleeding inside the eye can lead to pressure rising. Diabetes can cause a pressure rise. A mature cataract can cause a pressure rise. Any blow to the eye can lead to a rise in pressure even 6 months after the injury. Pressure can go up as a complication or a sequel to cataract surgery and was more common in the past when the eye was cut open and sutured.

A famous cause of pressure rising in the eye is the use of corticosteroid medicines. Patients who use steroid containing skin creams, eye drops and tablets or injections are at risk of rise in eye pressure. All these glaucomas which are due to other causes are called “Secondary Glaucomas”.

Finally glaucoma can sometimes be an emergency when due to the mesh getting totally blocked the pressure suddenly goes to 50 and above. Typically the patient will complain of pain watering and redness and poor vision. This type of acute glaucoma “Attack” is to be aggressively treated with IV injection of mannitol, laser and eyedrops otherwise it will lead to blindness.

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