Our vision is something we just take for granted. You open your eyes in the morning and as the fog clears, you can see your toes. Yes, the full complement of 10 are all there. But remember, toes falling off in the night is a fairly rare occurrence.
Vision, as one of our senses, is very interesting. Even though you may be looking at the same picture as the person next to you, you may not actually be experiencing the same view.
Take color vision. What is the color of your shirt? This knowledge is something you learned from your mother, who would point out articles to you and say, “This is red.” Eventually you came to know that the particular shade or hue was called “red”. That does not mean that the person next to you “sees” the same “red” as you do, but just that his mother also told him that the shade he sees is also called “red”.
Now, what is the similarity between high blood pressure leading to a stroke and the eye condition called “Glaucoma” which can lead to blindness? The answer is simple – both of these conditions are “silent” in the fact they do not produce symptoms on their own till very late in the piece, and secondly, both of these conditions can be detected by simple testing, and both respond well to treatment.
So what exactly is glaucoma? In simple terms it is a build up of pressure inside the eye, which eventually pressurizes the optic nerve and causes it to malfunction. The optic nerve is a bundle of more than 1 million nerve fibers that connect the retina, the light sensitive membrane in the back of your eye with the visual centers in the brain. If this pathway degenerates, so does your vision. Glaucoma is the cause of 10 percent of blindness in the USA.
The fluid pressure build-up in the eye comes from poor function in the ‘drain’ which is a mesh of tissue where the iris (the colored part) and the cornea meet. If the ‘drain’ blocks for any reason, then the pressure can build, until it becomes so high it produces pressure symptoms on the functioning of the optic nerve.
There are various types of glaucoma, but the commonest by far is called Open Angle Glaucoma and covers about 80 percent of all cases of glaucoma. The condition affects both eyes and comes on very gradually, with little or no symptoms initially.
Narrow Angle Glaucoma accounts for around 10 percent of the cases, and Asians have the greatest incidence, especially those of Chinese origin, with the Asian “short” eyeball. This generally comes on much quicker and often will only affect one eye. This condition is an ocular emergency.
The final 10 percent of cases comes from a condition we call Secondary Glaucoma. This happens after another condition, such as diabetes, tumors or infection can block up the ‘drain’ hole. Some cases arise when steroid eye drops are used, which shows again the dangers of ‘self-prescribing’.
In the majority of cases, and after a long period of time, the patient begins to notice that the edges of the visual fields are going, until it is like looking through a tube or tunnel. The deterioration continues from there and next up is the white stick and the Labrador.
Detection of the condition is the most important factor. The testing for the increased pressure in glaucoma is called tonometry and is painless and easily carried out by the eye specialist. Those at risk should have the test done every year after the age of 40, and for the rest of us, we can probably leave it till we get to 60 – but the choice is yours if you want to commence testing earlier.
The treatment includes special eye drops and surgery is also an option, to open up the ‘drain’ hole using a laser. However, the eye drops generally have to be continued as well.
So now you should add tonometry testing for glaucoma to your annual check-up list which includes blood pressure testing and cholesterol levels, mammograms (for the ladies) and prostate checks for the men.
