Refractive error

Question 1

Myopia:

• What is it?
• Length of eyeball
• What is this also called?
• What type of lens is used to correct this?

Answer 1

Can’t see far

Due to long eyeball

Short-sighted

Concave lens )( - refracts light less

Question 2

Hypermetropia - age-related:

• What is it?
• Length of eyeball
• What is this also called?
• What type of lens is used to correct this?

Answer 2

Can’t see near

Due to short eyeball

Long-sighted

Convex lens () - refracts light more

Question 3

Presbyopia:

• What is it?
• Why does this happen?
• What type of lens is used to correct this?

Answer 3

Age-related inability to accommodate - so affects near vision - that is why older people need reading glasses

The lens stiffens

Convex lens - repairs accommodation

Question 4

Astigmatism:

• What is it?

Answer 4

Distortion or blur due to an unequal cornea and lens curvature.