Correcting Vision Defects

Question 1

How can a person be short- or long-sighted?

Answer 1

If the lens cannot refract the light by the right amount (so that it focuses on the retina).

Question 2

What can long-sighted and short-sighted people unable to do?

Answer 2

Long-sighted - unable to focus on near objects.

Short-sighted - unable to focus on distant objects.

Question 3

When do long-sighted eyes occur? How can this be fixed? What is the medical term of this?

Answer 3

1. When the lens is the wrong shape and doesn’t refract the light enough or the eyeball is too short.
2. The images of near objects are brought into focus behind the retina.
3. You can use glasses with a convex lens (a lens which curves outwards) to correct it. The lens refracts the light rays so they focus on the retina.
4. The medical term for long-sightedness is hyperopia.

Question 4

When do short-sighted eyes occur? How can this be fixed? What is the medical term of this?

Answer 4

1. This occurs when the lens is the wrong shape and refracts the light too much or the eyeball is too long.
2. The images of distant objects are brought into focus in front of the retina.
3. You can use glasses with a concave lens (a lens which curves inwards) to correct it so that light rays focus on the retina.
4. The medical for short-sightedness is myopia.

Question 5

What are some alternatives to glasses for treating vision defects?

Answer 5

1. Contact lenses - are thin lenses that sit on the surface of the eye and are shaped to compensate for the fault in focusing. They’re popular because they are lightweight and almost invisible. They’re also more convenient than glasses for activities like sports. The two main types of contact lenses are hard lenses and soft lenses. Soft lenses are more comfortable but carry a higher risk of eye infection than hard lenses.
2. Laser eye surgery - can sometimes be an option. A laser can be used to vaporise tissue, changing the shape of the cornea (and so changing how strongly it refracts light into the eye). Slimming it down makes it less powerful and can improve short sight. Changin the shape so that it’s more powerful will improve long sight. Changing the shape so that it’s more powerful will improve long sight. The surgeon can precisely control how much tissue the laser takes off, completely correcting the vision. However, like all surgical procedures, there is a risk of complications, such as infection or the eye reaching in a way that makes your vision worse than before.
3. Replacement lens surgery - sometimes long-sightedness may be more effectively treated by replacing the lens of the eye (rather than altering the shape of the cornea with laser eye surgery). In replacement lens surgery, the natural lens of the eye is removed and an artificial lens, made of clear plastic, is inserted in its place. As it involves work inside the eye, replacing a lens carries higher risks than laser eye surgery, including possible damage to the retina (which could lead to loss of sight).