ABO Refraction & Visual Acuity 2 — Questions and Answers
Question 1: What is the term for the condition where one eye has a significantly different refractive error than the other?
- Anisometropia (Correct answer)
- Amblyopia
- Aniseikonia
- Anisocoria
Correct answer: Anisometropia
Anisometropia is a condition where there is a significant difference in refractive error between the two eyes, which can lead to amblyopia if uncorrected.
Question 2: Which type of lens is used to correct presbyopia?
- Convex (plus) lens for near addition (Correct answer)
- Concave (minus) lens
- Prism lens
- Plano lens
Correct answer: Convex (plus) lens for near addition
Presbyopia is corrected with a plus (convex) add power for near vision, compensating for the loss of accommodation with age.
Question 3: A patient's vertex distance changes from 12mm to 14mm. How does this affect the effective power of a minus lens?
- The effective power decreases (Correct answer)
- The effective power increases
- The effective power remains the same
- The lens becomes a plus lens
Correct answer: The effective power decreases
Moving a minus lens farther from the eye (increasing vertex distance) decreases its effective power at the corneal plane.
Question 4: What is the typical working distance used for near visual acuity testing?
- 40 cm (16 inches) (Correct answer)
- 20 cm (8 inches)
- 100 cm (40 inches)
- 60 cm (24 inches)
Correct answer: 40 cm (16 inches)
The standard near testing distance is 40 cm (16 inches), which corresponds to a 2.50 D accommodative demand.
Question 5: In retinoscopy, a 'with' motion of the reflex indicates what type of refractive error?
- Hyperopia or insufficient minus correction (Correct answer)
- Myopia beyond the working distance
- Emmetropia
- Astigmatism only
Correct answer: Hyperopia or insufficient minus correction
A 'with' motion during retinoscopy indicates that the eye is hyperopic or has insufficient minus power, requiring additional plus power to reach neutralization.
Question 6: What does the term 'emmetropia' describe?
- An eye with no refractive error (Correct answer)
- An eye with myopia
- An eye with hyperopia
- An eye with astigmatism
Correct answer: An eye with no refractive error
Emmetropia describes the ideal refractive state where parallel light rays focus precisely on the retina without any corrective lens.
ABO Refraction & Visual Acuity 2
What is the term for the condition where one eye has a significantly different refractive error than the other?