What is Glaucoma?
layer of the retina that is typically caused by an elevation in the intraocular pressure. It can go undetected until
extreme visual loss has taken place. People at risk for glaucoma include those with a family history of glaucoma,
diabetics, those with hypertension, individuals of African-American decent, and those of increasing age. In
general, most glaucomas are painless and asymptomatic. The visual loss that initially occurs is in the periphery
of the visual field, so that most people do not even notice the visual loss. As glaucoma progresses, and if left
untreated, it can affect the central vision in an irreversible fashion. Glaucoma is diagnosed on a routine
screening eye examination. The initial treatment for glaucoma is the use of eye drops in order to reduce the
intraocular pressure. If eye drops fail, then laser or even surgical repair is necessary. That's why it is crucial for an
individual to undergo an annual eye examination, especially if there is a risk factor for such a blinding disease.
What are the symptoms?
Symptoms are: (a) Frequent change of glasses (none of which is satisfactory)
(b) Difficulty in dark adaptation.
(c) Bumping into things at unfamiliar places.
(d) Blurred or foggy vision.
(e) Coloured halos (rainbow coloured rings) around lights.
More detailed information about Glaucoma
Glaucoma– “The silent thief of Sight”
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
Glaucoma there for must consist of 3 basic findings
1. Increased pressure in the eye (normal is usually taken as less than 21 millimeters 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 before 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
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
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, laser and eyedrops otherwise it will lead to blindness.
Diagnosis... State of the Art!
The Heidelberg Retina Tomograph or HRT is the finest techinique in the early detection, evaluation and to check
progression of Glaucoma. It is a confocal scanning laser imaging device that obtains three-dimensional images of
the optic nerve head and retina in the posterior segment, checking the height changes or differences of the optic
nerve head. There is now good evidence that the HRT can diagnose glaucoma 5 years before changes become
evident by any other technique. The HRT is now the gold standard for imaging the optic nerve. The Mehta
International Eye Institute uses the Heidelberg Retina Tomograph in its continuous effort to provide quality care to
its patients. The test is usually repeated thrice a year, and helps the physician assess if changes are occurring in the
nerve fiber layer or the optic nerve head. These changes almost always occur prior to any visual symptoms the
The Humphrey Computerised Field analyzer: An instrument which evaluates what you can see with your “fields”
of from the periphery of your eye while keeping the eye fixated in the middle. It evaluates the extent of loss. In
gluacoma the fileds progressively decrease till only a central island is left, which if untreated, extinguishes leading
to blindness. The Humphrey Analyzer is the Gold standard all over the world. Fields are normally done twice a year.
Intraocular pressure evaluation: Non Contact Pneumotonometer: Acts as an analyzing tool and excellent as a
survey instrument. Reasonably accurate when kept properly gradted. The Topcon is perhaps the most sensitive
of this genere.
Goldman Applanation Slit Lamp Biomicroscope mounted Tonometer: Exceptionally accurate but requires steady
fixation. Can identify pressure accurately even in post operative and highly myopic eyes.
Schiotz Tonometry: When the surface is grossly irregular or as a verification device the Schiotz tonometry is an
Treatment for Glaucoma: Glaucoma can be treated medically or surgically. Early glaucoma is usually easily
treated with just eye drops. These eye drops will have 2 actions:
1. Reduce the amount of fluid produced in the eye and or
2. Speed up the exit of fluid from the eye by action on the meshwork and other pathways.
Most glaucoma eye drops cause a little bit of irritation and dryness of the eye along with redness and must be
used under the doctors orders only. Some eye drops like Timolol can aggravate a patients asthma and some like
Prostaglanding cause the skin around the eye to darken and eyelashes in that eye to grow. Do speak with your
eye doctor about the side effects of glaucoma eye drops. Rarely when eye pressure does NOT come under control
Diamox tablets are prescribed. A common side effect is tingling and numbness in the hands and feet.
Laser: In case there is a Attack of glaucoma it can be controlled by application of YAG : Laser SLT is a new laser
that can treat the chronic simple glaucoma as well.
Surgery: Since the seventies the most common surgery for glaucoma is Trabeculectomy. In this a flap is made in the white of the eye and
under that a hole is cut into the eye from which the fluid flows out. Problems with this were bleeding, very low pressure and poor vision after
surgery. Such problems led to patients fearing glaucoma surgery and led to many patients losing their sight rather than opting for this
In the late nineties a new procedure came out of Switzerland and western Europe called Non Penetrating Deep Sclerectomy. Here the eye
is NOT OPENED and only the sclera i.e. the white of the eye is thinned until the fluid canal called Canal of Schlemm is opened. The
advantage with this is that the pressure is maintained low and there is no chance of bleeding, poor vision, too low pressure etc. This
procedure now is the glaucoma surgery of choice in the west. In India it still has to catch on. The author began performing this surgery
back in 2001 and has reported excellent results with it.