Author: Dr. Eileen Rinze,
The eye is like a ball filled with liquid. This liquid is called aqueous humor and it is constantly produced. If the eye does not have some sort of drain for this liquid to come out, there would be a point where the eye could break out due to excess liquid. The internal drainage system in charge of removing the aqueous humor of the eye is called the trabecular meshwork. It is like a sort of strainer that filters and directs the liquid into the circulation.
It is very important that this drainage system is in optimal conditions for the aqueous humor to drain out fast enough and maintain an ideal pressure inside the eye. The range of normal internal eye pressure is between 10 and 21 mmHg. When this drainage system is clogged or has scars, the ocular internal pressure may rise to incredibly high levels, as high as 70mmHg. This pressure can cause irreversible visual loss even in a few hours. Therefore, it is very important to have a routine screening once a year, because an ophthalmologist can detect any abnormality in the drainage system of your eyes and prevent an increased pressure and damage to the optic nerve.
Today you can often prevent these increases in intraocular pressure with the aid of a laser treatment. The reason for the indication of laser treatment is a narrow angle, referring to the angle formed between the iris and the cornea, where the trabecular meshwork is located.
Fig. 1 Open-angle and Closed-angle glaucoma
Narrow angle glaucoma, can be treated through a YAG Laser Peripheral Iridotomy. In this procedure, the Laser opens a microscopic hole in the iris that allows the fluid behind the iris to pass through it. This flattens the iris and often reopens the drainage.
Fig.2 YAG laser peripheral iridotomy
Fig. 3 Iridotomy
Depending on the anatomy of the eye, there is a possibility that the Peripheral Iridotomy will not open the drainage. If this is the case, another treatment called "Argon-Laser iridoplasty" could be necessary. This treatment stretches the iris to try to open the drain and it involves a higher amount of Laser shots.
Fig. 4 Argon-Laser Iridoplasty
Finally, there is another laser treatment to lower the intraocular pressure, even if there is an open drainage, or open-angle. This type of laser is called Argon-Laser Trabeculoplasty, and it has the ability to lower the intraocular pressure at the same degree as eye-drops would. It is often used in patients who have a contraindication to regularly use eye-drops. It is also used in patients who have failed to achieve the desired intraocular pressure with the maximum medical treatment and do not desire surgery. This laser opens small holes in the trabecular meshwork to increase the outflow of the aqueous humor.
Fig. 5 Argon-Laser Trabeculoplasty in open-angle glaucoma
The most important information you need to learn is that open or closed angle glaucoma may not show any symptoms and the only way to detect them is through a comprehensive eye exam. It is therefore important to visit your eye doctor regularly for early detection of any condition.