Glaucoma & Blindness


Glaucoma is an eye condition which affects the pressure of the eye. When the aqueous humour, which is created naturally behind the iris, builds up then the liquid drains from small channels in the cornea called angles. Normally, the liquid passes through the angle and back into the bloodstream but when the angle gets blocked the liquid can’t escape causing intraocular, or inside the eye, pressure. If the pressure is allowed to build for too long, it will press against the retina at the back of the eye decreasing the blood supply to the optic nerve causing it to degenerate, thus preventing the retina from sending the light-image into the brain to be analysed.

Types of Glaucoma

There are two primary types of the disease, chronic and acute. Chronic glaucoma occurs when there is a gradual blockage in the angles and thus a gradual increase in intraocular pressure which can be difficult to detect until more advanced stages.  As the pressure builds, the eye’s field of vision gradually decreases. A person with chronic glaucoma will not have any major signs that there is something wrong aside from slightly worse vision in one eye or a small arc of vision loss around the periphery. This arc will increase and develop into tunnel vision until complete blindness occurs if it is not treated.

Unlike chronic glaucoma which happens gradually over time without any painful symptoms, acute glaucoma occurs abruptly with extreme eye pain. While chronic glaucoma has gradual blockage of the angles, acute glaucoma involves the shifting of the iris so that it can close the angles completely. When the iris blocks the angles, they can no longer exude the excess liquid and a sudden aqueous humour build-up causes rapid intraocular pressure leading to severe pain, nausea, vomiting, and the vision in that eye may go black. 

Testing & risk factors for Glaucoma

Because chronic glaucoma may not present with any symptoms in its early stages, it is important to have regular eye exams.  To test for glaucoma, the optometrist will use tonometry, measurement of the eye’s pressure. The doctor will numb the eye with an orange dye before testing its pressure so there is no pain involved in the test.  Two other glaucoma tests, shining a light into the pupil so the doctor can see if there is degeneration of the optic nerve and having the patient view a sequence of spots to identify which ones are or are not visible, can also be effective in ensuring there is no sign of glaucoma. If you are at risk for chronic glaucoma, it is even more essential that you get tested regularly since the signs of this disease are so unnoticeable. People at risk include: those over 40, those of African descent, those with a close relative suffering from chronic glaucoma, and those with short sight.

Although acute glaucoma happens suddenly, it is often not without warning. Mild attacks involving blurry vision, eye discomfort, and rainbow rings appearing around white lights can all be signs of glaucoma and should be checked by a doctor immediately. People of East Asian descent are most susceptible to this form of glaucoma.

How is Glaucoma treated?

Chronic glaucoma can be treated with eye drops to reduce the amount of aqueous humour or to open the angles for better flow. If this doesn’t work, laser surgery or trabeculectomy may be the next step. The point of these surgeries is to open up the angle-channels.

Acute glaucoma requires immediate hospitalisation to save the eyesight. Drugs to reduce the aqueous liquid will be administered and a surgery called iridotemy to put a hole in the iris’s border will allow the fluid to drain normally. Acute glaucoma is also called closed-angle glaucoma because the entire channel has been blocked, so a hole in the iris can take that angle’s place. If acute glaucoma is not treated, total blindness in that eye can occur within days. If you have acute glaucoma in one eye, you are more likely to have it in the other and a preventative iridotemy in the second eye may be suggested by your surgeon.

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