If you can read this, congratulations: you can see. It doesn’t matter whether you are reading through eyeglasses or not. What matters is that you're here, reading this.
That you're here now may also suggest you’re worried about your eyes. Perhaps your vision is getting blurry, and you wonder if you’re going blind. Your fears are understandable.
The World Health Organization (WHO) estimates that more than 250 million people worldwide are visually impaired. This figure is predicted to increase to 703 million by 2050. In Nigeria, experts estimate that 4.25 million people are blind. These statistics are enough to make anyone jittery.
But what does it mean to be blind? Is it when you can’t see at all and your vision is pitch black, or is it when you need glasses and other visual aids to read and do basic activities? Blindness can be that and more.
What is blindness?
lindness is a condition in which a person cannot see anything or has extremely poor vision. Clinically, blindness is defined as visual acuity of less than 3/60 or a visual field of less than 10 degrees in your better eye, with the best correction.
Eye doctors, or ophthalmologists, define vision in terms of visual acuity and visual field. Visual acuity measures the eye’s ability to see things clearly and in detail, whether near or far away. The visual field is how much of a space your eyes can see with a steady gaze.
Vision acuity is expressed as a fraction. The top number is the distance that your vision is tested. This is usually 6 metres or 20 feet. The bottom number is the distance at which a person with normal vision is expected to see the image or text. It’s also 6 metres or 20 feet.
If your eyes are okay, you should be able to see an object clearly from six metres away, so you’ll score 6/6 or 20/20. The 6/6 records visual acuity in metres, while 20/20 is recorded in feet. We use 6/6 in Nigeria. A visual acuity lower than 6/6 often suggests a problem with your vision.
- Glasses and contact lenses can correct mild and moderate vision problems. If, after correction, the vision is less than 3/60 (20/400) in the better eye, an individual will be considered blind.
- Blindness can occur due to injury, infections, or genetic disorders. Whatever the cause, blindness can affect your ability to perform basic tasks.
What are the causes of blindness?
The most common cause of blindness worldwide is age-related macular degeneration. The macula is a thin layer behind the eyes that helps us to note the tiny details of an object and focus effectively. It deteriorates as we age, leading to vision loss.
However, in Nigeria and Africa, the leading causes are cataracts, glaucoma, and corneal opacity.
Other causes include:
- Injury from heavy blows, penetrating objects, toxic chemicals, or radiation exposure.
- Genetic disorders like retinitis pigmentosa and albinism
- Diabetes
- Hypertension
- Stroke
- Vitamin A deficiency
- Trachoma
- Onchocerciasis
Symptoms of blindness
Photo by Nathan Dumlao on Unsplash
One early symptom of deteriorating vision is blurry or hazy vision. Objects may appear fuzzy to you. You may struggle to identify figures and shapes at a distance or squint to read texts with regular font sizes and lighting conditions.
It could also be that you find it more challenging to move around at home, recognize faces, or function outdoors.
Other symptoms include:
- Difficulty seeing at night or in low-light conditions
- Increased sensitivity to light or glare
- Narrowed visual field
- Loss of peripheral vision, or the ability to see side objects
- Total loss of vision, or the ability to see light
Depending on the cause, you may experience frequent headaches, eye pain or discomfort, and light sensitivity. Pay attention to these symptoms and seek medical attention if you experience them.
