GLAUCOMA: The Silent Thief of Sight

                   GLAUCOMA- The Silent Thief of Sight

Glaucoma is an eye disease, which can make you blind , without you being aware of it, until the last stage. I’ll try to explain this disease in simple terms.

Our eye is like a table tennis ball. The shape of it is maintained by the pressure inside the eye. This pressure is called “Intra-ocular pressure” which literally means , the pressure inside the eye. Without this pressure , the eye would collapse, just like a balloon without air. The pressure which keeps the balloon inflated, comes from the pressure of air inside. The pressure in the eye comes from the fluid inside, which is called “Aqueous humour”. This fluid exerts pressure which keeps the eye inflated and thus healthy.

Aqueous humor is produced in a structure called “ciliary body”. It circulates in the eye, and finally exits the eye ball through the structure called “Angle”. It is similar to the water flow in bathroom. The water comes from the tap, it gets utilized by us and finally drains out into the outlet. Aqueous humor circulates in the same fashion. This aqueous humour, if in normal levels, keeps the Intraocular pressure normal, and thus eye is healthy.

If for some reason, the aqueous level increases, the intraocular pressure increases. This increased pressure has bad effects on eye, especially on optic nerve. Optic nerve is the nerve which carries signals from the eye to brain. It is like the cable which connects the digital camera to the computer. Optic nerve is made of several thin nerve fibres, just like an electric wire. If you cut a wire, you see lots of thin fibres within the wire. Similarly optic nerve has about a million of such fibres. This nerve remains healthy as long as the intra-ocular pressure is normal. If the pressure in eye is raised, this pressure is transmitted to the optic nerve, and this leads to the death of the fibres in the optic nerve. In the initial stages, when few fibres are damaged, peripheral vision gets affected, which cannot be noticed by the patient, as his central vision is normal. A stage will reach when most or all of the fibres are damaged. This will lead to total blindness. Central vision is the last to go, and that’s the reason, patient would not be aware of the disease except in last stage, when the central vision is lost. This optic nerve damage is irreversible. Any nerve in the body cannot regenerate to the full potential. So once the vision is lost, it cannot be gained later. This process wherein the intraocular pressure becomes more than normal, leading to optic nerve problem is called as Glaucoma.

Now consider two situations: one, your tap is fully open with more than normal water coming out, and two, the water outlet is blocked with no outflow. In these two situations, the water level increases. Similarly, in the eye, the IOP can be raised either with increased aqueous production or by decreased outflow. Decreased outflow may be because of the closure of “Angle”. Depending on the angle status, there are two different types of glaucoma. If the angle is open, it’s called “Open Angle Glaucoma”. If the angle is closed, it’s called “Angle Closure Glaucoma”.

Sometimes other eye problems can lead to glaucoma. These types of glaucomas are called “Secondary glaucomas”. The treatment would be to treat the primary cause. Many times the glaucoma develops without any reason. Such glaucomas are called “Primary Glaucomas”. By far Primary glaucoma is more common.

Primary Open angle glaucoma is the common form of glaucoma. In this, the angle is open with normal outflow. But there is increased production of aqueous. People more than 45 years of age, People with Hypertension and Diabetes, People with family history of glaucoma are at more risk of developing this glaucoma. Patient usually do not have any symptoms in the early stages. It can only be detected by detailed evaluation. Since there are no symptoms, patient would not seek medical advice, which would lead to blindness. All people at risk, should get their eyes checked for glaucoma. Once the disease is diagnosed, the treatment would be for life long, with eye-drops. This is similar to Hypertension, where the patients use BP medicines through-out life. The treatment aims at the control of Intra-ocular pressure, and not at the regeneration of damaged optic nerve. The lost vision is lost forever, and cannot be got back. The eye-drops would control the pressure in many patients, but some patients need surgery to decrease the pressure.

          

Regular screening and timely intervention is the only way to prevent blindness.

Angle closure glaucoma is a less common variety of glaucoma, where in the outlet is blocked. The patient may develop symptoms like coloured haloes, decreased vision, pain, redness and watering. These patients usually require LASER procedure, where-in an additional outlet is created for the outflow of aqueous.

To conclude, glaucoma is a blinding disease, which snatches your vision, without your knowledge. If you are at risk, get your eyes checked for any hidden glaucoma, and get it treated, before you lose vision.