Glaucoma is a group of eye diseases that are usually triggered by an increase in the intraocular pressure (pressure inside the eyes). If this condition is not treated properly, it can cause irreversible damage to the eyes leading to blindness.
Glaucoma is a term used to signify a group of eye diseases that can damage the optic nerves. It usually involves the loss of retinal ganglion cells, which if left untreated, can damage the optic nerves permanently. The optic nerves are responsible for receiving light from the retina, and sending them as impulses to the brain. So, when these nerves get damaged, it can eventually lead to blindness. In fact, glaucoma has been found to be the second leading cause of blindness.
An increase in intraocular pressure is considered to be one of the most important factors that can cause this condition. However, in many instances, glaucoma has been found to occur in individuals having normal eye pressure. On the other hand, some people with a constantly high intraocular pressure may not develop the condition. Intraocular pressure depends on the production, as well as the drainage of a liquid, known as aqueous humor, which nourishes the various structures of the eye.
The aqueous humor is produced by the ciliary bodies, and it fills the anterior chamber of the eye. This fluid is transported through a drainage system, known as trabecular meshwork. Any condition that can cause a blockage or a reduction in the flow of aqueous humor through the trabecular meshwork can lead to the accumulation of this fluid in the anterior chamber. This can raise the pressure inside the eye. If left untreated, this condition can cause permanent damage to the optic nerves and the retina.
Glaucoma is more common in nearsighted individuals. The long-term use of certain drugs, such as steroids can also cause this condition. Sometimes, this eye disease can be caused by conditions like inflammation or ocular trauma as well.
Generally, this eye disease is divided in two categories – open-angle and closed-angle glaucoma. In the open-angle form, the flow of aqueous humor through the trabecular meshwork reduces, which causes an accumulation of this fluid in the anterior chamber of the eye. This increases the pressure inside the eye. Open-angle glaucoma is the more common than the closed-angle form.
Exfoliation syndrome is a very common type of open-angle glaucoma, that occurs due to the deposition of some whitish materials on the lens and the drainage angle of the eye. This can increase the intraocular pressure by blocking the drainage system of the eye.
Another type of open-angle glaucoma is pigmentary glaucoma, which occurs when the iris bends backwards and comes in contact with its neighboring structures, particularly those found near the lens. As a result, the pigment layers present at the back of the iris rub against the lens, and get damaged. Subsequently, the pigment particles get released into the aqueous humor, and block its flow through the trabecular system, which raises the intraocular pressure.
In the closed-angle form, the iris of the eye is pressed to the front against the trabecular meshwork, which narrows down the space between the iris and the cornea. This in turn, prevents the flow of aqueous humor through the trabecular meshwork, leading to an increase in the intraocular pressure.
Besides these, there are some other types of glaucoma. For example, the congenital glaucoma is a rare condition that is commonly observed in infants. Another type, known as secondary glaucoma, is usually associated with some other diseases like diabetes and tumors.
In the early stage, this disease may not exhibit any signs or symptoms. As it develops slowly, it is hardly detectable in the early stage. However, the closed-angle form may produce a few signs and symptoms like eye pain, red eye, headaches, nausea, blurred vision, and light sensitivity.
The signs and symptoms of congenital glaucoma is very difficult to recognize, as this condition mostly affects infants. But if a child shows an increased sensitivity to light (photophobia), then it may be an indicator of this condition. Along with photophobia, one can also observe an enlargement of the eye (due to an increase in eye pressure), watery or hazy eye, and squint or jerking eye movements.
Diagnosis and Treatment
The absence of symptoms makes it quite difficult to detect the condition in the early stage. As people older than 40 years are more prone to this eye disease, they should opt for regular eye checkups to find out their intraocular pressure. This can be done with the help of a tonometer. Ophthalmoscopy is a test carried out to evaluate the health of the optic nerves, or a change in the cup-to-disk ratio.
An ophthalmologist can examine your peripheral vision with the help of visual field tests. Besides these, optical coherence tomography (OCT), scanning laser polarimetry (GDx), and/or scanning laser ophthalmoscopy are some statistical imaging techniques, that are employed to examine the retinal nerve fiber layer.
Glaucoma can be treated with medications like eye drops that can lower the intraocular pressure. There are many different medications available for treating this condition, but they may have certain side effects. If medications fail to improve the condition, then surgery, either laser or the conventional surgery can be carried out. Laser trabeculoplasty, laser cycloablation, and viscocanalostomy are some common surgical procedures used for treating this condition.
Studies have shown that older people are at a greater risk of developing the open-angle form of the disease due to myopia and their thinner corneas. Some communities like Chinese, Japanese, Mongolian, and Vietnamese on the other hand, have a high risk of developing the closed-angle form, due to the shallower anterior chamber of the eyes. Diabetic patients are also prone to this condition. People who have a high risk of developing glaucoma should get their eyes examined at regular intervals, as this condition can advance slowly without showing any signs.
Disclaimer: This HealthHearty article is for informative purposes only, and should not be replaced for the advice of a medical professional.