The danger of losing visual field without being aware of such loss for a long time: the silent thief of sight.
What is chronic glaucoma?
Chronic glaucoma is a disease affecting the optic nerve (neuropathy), which is characterised by a progressive loss of visual field. This follows a characteristic pattern (generally loss of peripheral visual field) and has the objective sign of changes in the appearance of the optic nerve.
Do you know what causes it?
Despite being considered a multifactorial disease, brought on by multiple causes, the best known and so far only treatable cause is raised intraocular pressure; ocular hypertension.
What symptoms does it cause?
Chronic glaucoma does not cause perceptible symptoms at disease onset. As the disease advances, defects in visual field become more perceptible, slowly increasing until central vision is affected late in the disease. In parallel to loss of visual field or peripheral vision, once glaucoma has advanced, the patient finds light and dark adaptation difficult. This occurs when the patient suddenly moves from a dark place to a light place. With these changes in lighting, the glaucoma patient feels blinded for a few seconds.
Are some people more at risk of developing glaucoma?
The prevalence of glaucoma increases with age, and although it is important to check the intraocular pressure of all patients, it is especially important after the age of 45 years.
Glaucoma is a disease with a significant genetic contribution, and given that there are many cases with a family history of the disease, it is important to rule out glaucoma in all direct relatives of patients previously diagnosed with glaucoma. We often recommend genetic studies that can accurately determine the risk of family members developing the disease.
Glaucoma is especially aggressive in black patients and therefore screening in this ethnic group should be more exhaustive.
How is it treated?
Chronic glaucoma is initially treated medically, with the aim of treatment being to reduce intraocular pressure. Eye drops may allow satisfactory control of IOP and keep the disease under control for many years, but if the pressure is not controlled effectively, or if eye drops are not tolerated as a result of systemic or local side effects, we then use laser or surgical techniques to keep IOP at safe levels for each patient.
Can it be prevented?
Glaucoma is prevented by detecting high-risk cases. Keeping intraocular pressure at satisfactory levels helps prevent the disease from developing. It is therefore vitally important to determine which patients have ocular hypertension (raised intraocular pressure) since, left untreated, these patients would develop glaucoma in the future. These patients must be closely monitored and given preventive treatment on an individual, case-by-case basis.
Can it be serious?
Chronic glaucoma is one of the leading causes of irreversible blindness worldwide. Its detection, prevention and suitable treatment can slow down and even prevent progression to blindness in most cases.