Colour blindness – Difficulty distinguishing between different colours
Myopia – Cannot see far away objects clearly
Hyperopia – Nearby objects look blurry
A cataract is the clouding of the eye’s natural lens.
Cataracts get worse over time and they can only be treated effectively by replacing the cloudy lens with an artificial lens.
Myopia (also known as short-sightedness) is a common defect where the image is in focus in front of the retina. A person that is short-sighted can see near objects clearly, but distant objects are not focused properly.
There are two main causes of myopia:
The eyeball is too elongated, so it is oval-shaped instead of round – So the distance between the lens and the retina is too great
The cornea (protective outer layer) is too curved – Leading to the incorrect focusing of light that enters the eye, causing it to focus in front of the retina
Myopia can be corrected with a concave lens (glasses), which refracts the rays of light so that they focus on the retina.
Hyperopia (also known as long-sightedness) is a common defect where the image is brought into focus behind the retina. A person who is long-sighted can see distant objects clearly, but near objects are not focused properly.
There are two main causes of hyperopia:
The eyeball is too short from front to back – So the distance between the lens and the retina is too small
The cornea is not curved enough – Leading to the incorrect focusing of light that enters the eye, causing it to focus behind the retina
Hyperopia can be corrected with a convex lens (glasses), which refracts the rays of light so that they focus on the retina.
Treatments for myopia and hyperopia
Both myopia (short-sightedness) and hyperopia (long-sightedness) are typically treated with spectacle lenses (glasses). New available technologies provide treatment for both defects instead of using spectacle lenses. For example:
Hard and soft contact lenses – Invisible lenses that sit on the surface of the eye
Laser surgery – Change the shape of the cornea, which changes how it refracts light onto the retina. To treat myopia, the cornea is slimmed down to reduce the refraction of light. Whereas, to treat hyperopia, the shape of the cornea is changed to increase the refraction of light.
Lens replacement surgery – Replaces the eye’s lens with an artificial lens