Glaucoma is one of the main causes of blindness. Described as abnormally high pressure in the eye, there are actually different types of glaucoma.

The most common eye disease after AMD (age-related macular degeneration), glaucoma can lead to complete blindness of the eye. It mainly affects the over 40s, and concerns nearly a million patients in France.

Glaucoma is a chain of disorders of the eye which often result in irreversible damage to the optical sensors. These, located behind the retina, are compressed by thevitreous humor, the thick fluid of the eyeball. This is itself pushed towards the bottom of the cavity because of an increase in the eye pressure, caused by excessaqueous humor.

At the base of glaucoma, a dysregulation of the flow of aqueous humor

If we look at an eye in section, we see the presence of two large “compartments”. At the back of the eye and in contact with the optic nerve Along with the blood vessels, we find the eyeball filled with vitreous humor. At the front, in the optical chamber, we find the combination of the cornea (interface with the external environment of the eye), the iris and the lens. These elements are bathed in a liquid less viscous than the vitreous humor, it is the aqueous humor.

Aqueous humor is secreted by glands of the ciliary port, in the posterior chamber (between the iris and the lens). This fluid naturally passes through the iris to reach the anterior chamber, between the cornea and the pupil, before evacuating into the blood through the trabecular system. This system normally acts as a filter to prevent residues from entering the blood. It is often its dysregulation that causes glaucoma.

In summary, glaucoma is a degenerative optic disease, which without treatment leads to the destruction of the optical capacities of the affected eye, and therefore to complete blindness.

Glaucoma is the logical consequence of an increase in eye pressure, but the latter can have different causes.

Open Angle Glaucoma or Chronic Glaucoma

The most frequent glaucoma, in 90% of cases, is the so-called “chronic” or more generally “open angle” glaucoma. It is caused by a poor drainage of aqueous humor. That is to say that the latter is correctly secreted by the ciliary body, but will be less and less well evacuated by the trabecular system, located between the pupil and the cornea. A bit like a blocked bathtub, the anterior chamber of the eye will therefore retain more and more vitreous humor, which will not be able to evacuate and will therefore press on the rest of the eye, pupil to the optic nerve, and compress the blood vessels.

This glaucoma therefore results in a loss progressive of the field of vision, since it will usually be the edges of the eye that will be affected first. These vessels will be destroyed irreversibly, so you must consult very quickly if you suspect incipient glaucoma.

This glaucoma is called “open angle” because the angle between the pupil and the cornea remains “open”, greater than 0 °, the liquid continuing to flow slowly.

Diagnosis and symptoms:

• Hypertension inside the eye
• Widening of the papillary excavation (the papillae of the eye widens)
• Loss of acuity of the visual field

Treatment

• Medicines: by taking eye drops that will lower eye pressure
• Surgical: by treatment of the trabecular system to unclog this natural filter

Closed Angle Glaucoma, Acute Glaucoma

Second type of glaucoma, much more strict, narrow-angle glaucoma is characterized by a very rapid progression and a sudden loss of the visual field.

This time it’s a initial eye strain which leads to “closing” the access to the trabecular system, necessary to evacuate the aqueous humor. This closure can be for no particular reason, so we say “ primitive “, Or else linked to another disease, it will then be” secondary “. One of the reasons for primary narrow-angle glaucoma is the aging of the lens, which expands and will push the iris forward, and close access to the outflow channels. Conversely, an eye disease such as diabetic retinopathy or uveitis can trigger secondary acute glaucoma.

In either case, this closure will result in a much faster rise in eye pressure compared to open-angle glaucoma. The optic nerve and its vessels will be compressed quickly, within a few hours the eye can lose all of its vision. Closed-angle glaucoma is therefore an ophthalmologic emergency.

Diagnosis and symptoms

• Blurred vision or sudden loss of vision
• Rapid rise in intraocular pressure
• Red eye, redness around the eye

Treatment

• Quick medication (timolol, brimonidine, etc.)
• Surgery: laser (to clear the passage and evacuate the aqueous humor)

Neovascular glaucoma

Neovascular glaucoma is caused by the proliferation of vessels directly on the iris. These can also block the evacuation of aqueous humor, without having an open or closed angle.

Congenital glaucoma

This type of glaucoma is the rarest, and is inherited or has a genetic defect. It starts at birth or soon after, but given an infant’s poor vision it will take several months to appear and be detected.