Understanding the leading causes of blindness: A patient’s guide | 4 min read

Vision is one of our most precious senses, yet millions of people worldwide suffer from visual impairment and blindness. According to the World Health Organization (WHO), at least 2.2 billion people globally have a vision impairment, with at least 1 billion of these cases being preventable or yet to be addressed. Unless you have your eyes checked regularly by a professional, you might not even be aware that your sight is in danger. The good news is that many eye problems and diseases can be treated if detected early. Specific symptoms to look out for include blurry vision, a sudden loss of vision, double vision, flashes and floaters and halos and glare around lights. These symptoms may indicate a very serious problem.

The most common causes of blindness in South Africa are cataracts, glaucoma, age-related macular degeneration (AMD) and diabetic eye disease. Most of these potentially blinding conditions can be treated if detected early through the proper diagnostic tests.

1. Cataracts are the leading cause of blindness globally. They occur when the eye’s clear, natural lens becomes cloudy (hazy or opaque). This prevents light from entering the eye, leading to blurred vision and eventual blindness if left untreated. While cataracts are often associated with aging, they can also affect infants and younger individuals. Symptoms include cloudy vision, difficulty seeing at night, and increased sensitivity to glare. Fortunately, cataract surgery – where the human lens is removed and replaced with a clear synthetic lens – is highly effective in restoring vision in most cases. Patients with diabetes are at an increased risk of developing cataracts.

2. Diabetic retinopathy is the leading cause of vision impairment in working-age adults. This potentially very serious complication of diabetes affects blood vessels in the retina (light-sensitive back lining of the eye). The retina can develop bleeding and/or swelling in anyone with type 1 or type 2 diabetes, and the risk increases the longer a person has diabetes. Good blood sugar control and regular dilated eye exams are essential for prevention and early detection.

3. Glaucoma is a group of eye conditions that damage the optic nerve (nerve leading from the eye to the brain), often due to abnormally high pressure within the eye. This damage causes peripheral loss of vision and eventually irreversible complete blindness. It’s the second leading cause of blindness worldwide. The most common form, open-angle glaucoma, develops slowly and often without noticeable symptoms in its early stages, earning it the nickname “the silent thief of sight.” Regular eye exams are crucial for early detection and treatment, which can help prevent or slow vision loss. Glaucoma can be treated in the early stages by using medication or drops to lower the intraocular pressure.

4. Age-related Macular Degeneration (AMD) is an irreversible loss of central vision due to damage in the cells of the macula, the central part of the retina responsible for sharp, detailed vision. It’s a leading cause of vision loss in people over 50. There are two types: dry AMD (the more common form) and wet AMD (more severe but less common). Symptoms include blurred or distorted central vision. While there’s no cure, treatments are available to slow progression and maintain vision, especially for wet AMD. Treatment is limited in the early stages but in advanced stages, injections can dramatically improve central vision and limit the progression of vision loss.

Prevention and management

While not all causes of blindness are preventable, many can be managed effectively with early detection and treatment. Here are some key steps for maintaining eye health:

• Regular eye exams: Adults should have comprehensive eye exams every 1-2 years, or more frequently if recommended by an eye care professional.
• Healthy lifestyle: Maintain a balanced diet rich in vitamins A, C, and E, as well as omega-3 fatty acids. Regular exercise and avoiding smoking can also benefit eye health.
• Protect your eyes: Wear sunglasses with UV protection and use proper eye protection during sports or hazardous activities.
• Manage chronic conditions: Keep diseases like diabetes and hypertension under control, as they can affect eye health.
• Be aware of family history: Many eye conditions have genetic components, so knowing your family history can help with early detection and prevention.

Understanding the causes of blindness is the first step in preserving vision health. While some causes are unavoidable, many forms of blindness can be prevented or treated with early intervention. If you experience any changes in your vision, don’t hesitate to consult an eye care professional promptly.

Reviewed: October 2024