Glaucoma: symptoms, causes, diagnosis, treatments and its different types.


English 緑内障

Definition of Glaucoma

When you have glaucoma, you have partial vision loss which continues with time. You may not notice a change in vision and in some cases, you may become blind. In fact, glaucoma is one of the leading causes of blindness in Japan.

It's quite difficult to notice your vision loss because when you have vision loss in one eye, the other eye can compensate. Also, even if a part of vision is missing, your brain compensates it and it is quite usual to not notice the abnormality. About 5 % of Japanese over the age of 40 and about 10 % over the age of 60 has glaucoma. This disease is very frequent for many people.

Main symptoms of Glaucoma

In the early stage of glaucoma, a blind spot appears in your vision which finally becomes worse leading to a vision loss. These symptoms are not sudden. In the early stage, your vision is partially blurred. In the middle stage, the blurry vision spreads gradually. In the late stage, the vision becomes blurry like if you were in a fog. Because vision loss due to glaucoma can't be recovered, if you delay the treatment, it can lead to blindness.

Causes of Glaucoma

Our vision is possible when the light goes through the crystallin and reaches the retina where information goes to our brain via the optic nerve. When you have glaucoma, the optic nerve is deteriorated by the eye pressure.

The eye pressure is necessary to maintain the form of the eye ball. It is regulated by the aqueous humor. The aqueous humor is made by organs supporting the crystallin. Running out by the cornea angle, this aqueous humor sets a constant pressure in the eye ball. However, when the cornea angle clogs or shuts, the aqueous humor cannot builds up and increases pressure within the eye leading to constrain the optic disc. This compression on the optic disc damages the optic nerve which cannot transmit the information to the brain causing a vision loss.

3 types of Glaucoma

There are 3 types of glaucoma.

Type1: Open-angle Glaucoma  The cornea angle is obstructed causing a high eye pressure.

Type2: Angle-closure Glaucoma  The cornea angle is open, but adjacent structures are clogged. Aqueous humor builds up and increases pressure within the eye.

Type3: Normal-Tension Glaucoma  Open cornea angle and the eye pressure is normal.

70 % of Japanese having glaucoma of this type 3: open cornea angle and a normal eye pressure.

Even if your eye pressure is normal (within the right range), its pressure is high enough to damage the optic nerve. It is not very clear why people have glaucoma having a normal eye pressure. However, it might be because of the optic disk which is less resistant to the pressure than usual.

Diagnosis of Glaucoma

As the sight cannot be recovered once lost, an early detection is important in order to start a treatment. Glaucoma diagnosis is made by doing several examinations like doing an eyesight test, measuring intraocular pressure (tonometry), fundoscopy (ophthalmoscopy), inspecting your eye drainage angle, doing a visual field test. The diagnosis is done with those global results.

Even though an eyesight test and eye pressure examination are done when you go through a Medical checkup, it is not enough to diagnosis glaucoma. Because once again, when you notice a vision loss, it is often when glaucoma is already in an advanced stage. And in many cases, Japanese have glaucoma even if they have a normal eye pressure. As you can easily have glaucoma after your forties, you have to check every few years your fundoscopy, your drainage angle (gonioscopy) and your visual field test.

Treatments of Glaucoma

Glaucoma is mainly treated with eyedrops, lowering the eye pressure (intraocular pressure). The damage caused by glaucoma can't be reversed. But treatment and regular checkups can help slow or prevent vision loss, especially if you catch the disease in its early stages. This is also available in case of Type 3, when your eye pressure is normal.

In case of clogged drainage angle (congested) or when the use of eyedrops is inefficient to reduce eye pressure, laser treatment, surgery or a combination of any of these will be necessary.

Among eyedrop medications, you have Prostaglandins: These increase the outflow of the fluid in your eye (aqueous humor). "Beta blockers" or "Carbonic anhydrase inhibitors": These reduce the production of fluid in your eye.

Prostaglandins can be prescribed with Beta blockers or Carbonic anhydrase inhibitors. More than three of the eyedrops may need to be prescribed. In nowadays, you also have some combination eyedrops. We recommend you to wait more than 5 minutes between the introduction of each eyedrop.

You have to be careful on the following points when you introduce eyedrop. It's important not to forget the introduction of eyedrops.

Important points when you introduce eyedrops

・Eyelashes must not touch the eyedrop container

・Introduce one drop

・Close your eyes without blinking

・Compress slightly the inner corners of the eye