Chronic open-angle glaucoma is one of the main causes of irreversible blindness worldwide, including Portugal. It is a silent eye disease characterized by progressive damage to the optic nerve with gradual and silent loss of peripheral vision, which can end in absolute blindness. It is estimated that there are approximately 200,000 people with glaucoma in Portugal and that a large percentage may not know they have the disease, due to the lack of obvious symptoms in its early stages. Risk factors for the disease include ocular hypertension, a family history of glaucoma, myopia, black race and age.

Chronic open-angle glaucoma is known as the "silent thief of sight". Symptoms are non-existent in the early stages. However, in the more advanced stages they can appear:

• Reduced peripheral vision, resulting in the formation of blind spots (scotomas);
• Tunnel vision, where the person can only see what is directly in front of them;
• Finally, absolute blindness.

It is very important to diagnose glaucoma early in order to prevent its progression and irreversible loss of vision. Regular visits to your eye doctor, especially after the age of 40, are essential for early detection. Waiting until you see badly before having your doctor assess you is a costly mistake in this disease, as in many others. Lost sight can never be recovered. And although there is a loss of vision, firstly peripheral vision, most of the time the patient is unaware of this loss. Through regular eye examinations, which include measuring intraocular pressure, assessing the optic nerve and analyzing the visual field, it is possible to identify changes suggestive of glaucoma before there is a loss of visual field.

The main aim of treating chronic open-angle glaucoma is to control high intraocular pressure, which is a significant risk factor for the development and progression of the disease. If glaucoma is treated early and properly, the risk of blindness is reduced. Treatment options may include:

Eye drops: Ophthalmic medicines (drops) that help reduce intraocular pressure, usually applied daily. It is very important that the drops are always placed properly and according to the prescription of the eye doctor. One of the causes of a lack of response to treatment is incorrect placement of the drops.

Laser treatment: An outpatient procedure to improve the drainage of aqueous humor and reduce intraocular pressure.

Surgery: In more advanced cases, surgery may be necessary to improve aqueous humor drainage and reduce intraocular pressure.

Chronic open-angle glaucoma is a relatively common eye disease in Portugal, capable of causing total and irreversible blindness. Early diagnosis and appropriate, timely treatment are fundamental to preserving vision throughout life. The absence of symptoms until advanced stages of the disease and the lack of regular visits to the ophthalmologist, especially after the age of 40, partly explain the large number of patients in Portugal who lose sight and become irreversibly blind due to glaucoma. Adherence to treatment, as prescribed by the ophthalmologist, and regular monitoring of its effectiveness are fundamental to treating this condition that silently "steals sight" from patients.