AOC AOC Visual Optics and Refraction Concepts 1 — Questions and Answers
Question 1: Which type of lens is used to correct myopia (nearsightedness)?
- Plus (convex) lens
- Minus (concave) lens (Correct answer)
- Prism lens
- Plano lens
Correct answer: Minus (concave) lens
Myopia is corrected with minus (concave) lenses, which diverge light and shift the focal point back onto the retina.
Question 2: The measurement of the refractive error in which the two principal meridians have different powers is called:
- Myopia
- Hyperopia
- Astigmatism (Correct answer)
- Presbyopia
Correct answer: Astigmatism
Astigmatism results from an asymmetric cornea or lens where different meridians have different focal points, producing a blurred image.
Question 3: Which instrument measures the curvature of the anterior corneal surface to aid in contact lens fitting and astigmatism assessment?
- Tonometer
- Keratometer (Correct answer)
- Pachymeter
- Lensometer
Correct answer: Keratometer
The keratometer (ophthalmometer) measures the radius of curvature of the central cornea, providing K-readings used in lens fitting and refractive assessment.
Question 4: A patient with +2.50 sphere in each eye most likely has which refractive condition?
- Myopia
- Hyperopia (Correct answer)
- Emmetropia
- Anisometropia
Correct answer: Hyperopia
A plus sphere prescription indicates hyperopia (farsightedness), where the eye focuses light behind the retina.
Question 5: The near point of accommodation is defined as:
- The farthest point seen clearly without accommodation
- The closest point at which the eye can maintain clear focus (Correct answer)
- The point of maximum divergence
- The point of equal retinal image size
Correct answer: The closest point at which the eye can maintain clear focus
The near point of accommodation is the closest distance at which the eye can maintain clear focus using maximum accommodative effort.
Question 6: Anisometropia refers to:
- Equal refractive error in both eyes
- Unequal refractive error between the two eyes (Correct answer)
- High myopia in both eyes
- Loss of accommodation with aging
Correct answer: Unequal refractive error between the two eyes
Anisometropia is a condition in which the two eyes have a significant difference in refractive error, which can disrupt binocular vision and cause amblyopia.
AOC AOC Visual Optics and Refraction Concepts 1
Which type of lens is used to correct myopia (nearsightedness)?