Glaucoma: A Silent Disease

50% of patients with glaucoma do not know they have it. In most cases, it does not cause obvious symptoms, such as pain or sudden decrease in vision, and can go unnoticed until the damage is already significant and much of the visual field has been reduced, affecting the patient's daily activities and converting other in dangerous, such as driving. Some specific types of glaucoma can cause acute attacks of the disease and lead to a red eye, severe pain, blurred vision, halos around lights, sudden nausea or vomiting. In that case, you should immediately consult your ophthalmologist.

More information here.