12 common eye conditions: What they look like and how to spot them
What is World Sight Day?
World Sight Day is an annual event. It raises awareness of sight loss and why it helps to look after your eyes. The International Agency for the Prevention of Blindness (IAPB) has run it since 2000, under the long-running theme #LoveYourEyes.
The aim? To get millions of people to book an eye test and take simple steps to look after their sight, before small issues become bigger problems.
Eye health in Britain: why it matters
Eye health plays a bigger role in everyday wellbeing than many of us realise.
The Royal National Institute of Blind People (RNIB) expects sight loss in the UK to keep rising. Its figures point to a 27% increase, reaching 2.8 million people by 2035. By 2050, the number living with sight loss is expected to double, to more than four million. [1] That means many more of us may come to rely on glasses or contact lenses to support our eyesight.
Some of the conditions below are well known, others less so — which is why knowing what to look for, and when to book an eye test, can make all the difference.
Below, we've listed 12 common eye conditions and diseases, and the changes in vision each one can cause.
12 common eye conditions
Most of us notice our eyes changing at some point, and it isn't always clear what's behind it. Not everything on this list is a disease. Some are refractive errors, eye disorders like astigmatism and long-sightedness. Here the eye simply focuses light imperfectly, and glasses or contact lenses usually put things right. Others are eye diseases, such as glaucoma or diabetic retinopathy, that need proper medical care. Whether you'd call a change in your sight an eye illness, a disorder, or just tired eyes, spotting it early is what matters most. Each summary below reflects how the NHS describes the condition and its signs. [2]
1. Astigmatism
Astigmatism is a type of refractive error that causes blurred or distorted vision. It happens when the eye is shaped more like a rugby ball than a football. This means light focuses at several points instead of one.
It's usually corrected with glasses or toric contact lenses, which are shaped to focus light evenly across the eye.
Normal Vision
Astigmatism
2. Short-sightedness (Myopia)
Myopia is another refractive error where distant objects appear blurry.
You may notice:
- Difficulty reading signs, number plates, or the TV from a distance
- Sitting closer to screens, or moving them nearer to you
- Frequent headaches, especially after looking into the distance
- Rubbing your eyes, or squinting to bring things into focus
Normal Vision
Myopia
3. Long-sightedness (Hyperopia)
Hyperopia affects your ability to focus on nearby objects. In moderate to high cases, distance vision may also be affected.
Common signs include:
- Squinting to sharpen up text, small print, or a phone screen
- Tired, aching eyes after reading or other close-up work
- Aching eyes during long stretches of screen use, not eased by a break
Normal Vision
Hyperopia
4. Colour vision deficiency
Often inherited, colour vision deficiency affects how the eye's cones detect colour. The three main types are protanopia (reduced sensitivity to red), deuteranopia (reduced sensitivity to green), and tritanopia (reduced sensitivity to blue). Complete colour blindness is rare, so red-green deficiency is by far the most common type.
Normal Vision
Protanopia
Tritanopia
Deuteranopia
5. Presbyopia
Presbyopia develops naturally with age as the lens becomes less flexible. It makes focusing on close work — like reading or sewing — more difficult.
It's a common age-related refractive change rather than a disease. Reading glasses or multifocal contact lenses can help bring near vision back into focus.
Normal Vision
Presbyopia
6. Glaucoma
Glaucoma is slow damage to the optic nerve that affects your vision. It often starts at the edges, with your peripheral (side) vision.
Early on, there may be no clear symptoms, which is why routine eye tests are important.
Normal Vision
Early Glaucoma
Advanced Glaucoma
Extreme Glaucoma
7. Macular degeneration (AMD)
Age-related macular degeneration damages the macula. That's the part of the retina you use for sharp, straight-ahead sight. As a result, it affects your central vision.
It can make reading, recognising faces and driving more difficult.
Normal Vision
Macular Degeneration Stage 1
Macular Degeneration Stage 2
Macular Degeneration Stage 3
8. Diabetic retinopathy
This is a complication of diabetes. High blood sugar damages the small blood vessels in the retina.
Left untreated, it can lead to sight loss. Caught early, it is much easier to manage.
Normal Vision
Diabetic Retinopathy
9. Cataracts
Cataracts cause the normally clear lens of the eye to become cloudy.
You might notice:
- Blurred or misty vision that a new prescription doesn't clear
- Difficulty seeing at night, or headlights that look dazzling
- Sensitivity to bright light, indoors as well as outdoors
- Colours looking faded, washed out, or a little yellow
Cataracts usually develop slowly, over months or years.
Normal Vision
Cataracts
10. Retinitis pigmentosa (RP)
Retinitis pigmentosa is a group of inherited conditions. They slowly break down the retina over time.
Early signs include difficulty seeing in low light (night blindness). Over time, peripheral vision narrows, sometimes leading to tunnel vision.
Normal Vision
Retinitis Pigmentosa
11. Double vision (Diplopia)
Double vision occurs when one object appears as two images.
It can come from problems with the eye muscles or nerves. Sudden double vision should always be checked by an optometrist.
Normal Vision
Double Vision (diplopia)
12. Floaters
Floaters are small specks or squiggly lines that drift across your field of vision. They are common and usually harmless.
However, get checked promptly if you notice a sudden increase in floaters, especially with flashes of light. This can be a sign of a problem with the retina.
Normal Vision
Floaters
How can you tell if you have an eye condition?
It can be hard to tell whether a change in your sight really matters. Vision changes are not always dramatic, and sometimes they develop slowly, making them easy to overlook.
You may want to book an eye test if you notice:
- Blurred or distorted vision, whether near or far away
- Focusing that comes and goes, or feels harder than before
- Frequent headaches, especially after reading or screen time
- More sensitivity to light than you're used to
- A narrowing of your side, or peripheral, vision
- Sudden flashes, spots, or other visual disturbances
Even small changes in how well you see can point to a problem. A full eye exam can pick up refractive errors and check for more serious conditions.
When should you see an optometrist about vision changes?
No one likes a sudden change in their sight. Many vision changes can be managed, but a few need urgent attention.
Book an appointment as soon as possible if you experience:
- A sudden loss of vision, in one eye or in both
- A sudden jump in floaters, drifting across your view
- Flashes of light, particularly if they are new to you
- A dark shadow, or a curtain, moving across your sight
- Sudden double vision that doesn't settle on its own
These can be signs of a serious problem at the back of the eye that needs urgent assessment. [2]
Regular eye tests are one of the simplest ways to look after your eyesight. Even if your vision feels stable, routine checks can spot the early signs of glaucoma, diabetic retinopathy, and macular degeneration. That's often before they affect daily life.
Looking after your eyes doesn't need to feel complicated — small, consistent steps make a big difference.
Roshni Patel BSc (Hons) MCOptom
Optometrist and Professional Services Manager
