3.1 - Introduction to refractive error

Question 1

What is refractive error

Answer 1

Inability of the eye to produce a sharp image on the retina = AMETROPIA

Question 2

What is refractive error measured in

Answer 2

Dioptres

Question 3

Where is refractive error measured

Answer 3

At spectacle plane ( spectacle refraction )
At eye ( ocular refraction )

Question 4

What can refractive error be corrected by

Answer 4

By optical means – spectacle lenses, contact lenses or refractive surgery

Question 5

What are the two types of refractive error

Answer 5

Spherical ametropia - ( hypermetropia and myopia )

Astigmatism

Question 6

What is spectacle refraction

Answer 6

Whats required for glasses correction

Question 7

What is ocular refraction

Answer 7

Whats required for CL’s or refractive surgery ( both at eye )

Question 8

What is emmetropia

Answer 8

Don’t need any refractive correction to see clearly

Question 9

What is importance of refractive error

Answer 9

• Accounts for 42% of world visual impairment (2010)
• 285 million people visually impaired due to uncorrected refractive error
• 85% live in low income countries = less access to refractive correction
• Easily corrected

Question 10

What is meant by visual impairment

Answer 10

Visual impairment = Vision < 6/18 [WHO]

Question 11

What is effect of refractive error

Answer 11

Effects ability to see small things
Significant loss of vision in smaller lines
Decreases quality of vision