COT Refraction and Retinoscopy 4

Question 1

A patient has a cycloplegic refraction of +4.50 D and a manifest refraction of +1.50 D. What is the amount of latent hyperopia?

Accepted Answer

+3.00 D

Answer

Latent hyperopia = cycloplegic refraction − manifest refraction = +4.50 − (+1.50) = +3.00 D.

Question 2

In retinoscopy, what is the purpose of the sleeve adjustment on a streak retinoscope?

Accepted Answer

To change from a diverging (plane mirror) to a converging (concave mirror) beam

Answer

Moving the sleeve up or down shifts between plane and concave mirror modes, affecting the direction of beam divergence.

Question 3

When performing retinoscopy at 50 cm, what is the working distance lens value that must be subtracted?

Accepted Answer

+2.00 D

Answer

At 50 cm, vergence = 1/0.50 = +2.00 D, so +2.00 D must be subtracted from the gross finding to obtain the net refraction.

Question 4

What technique is used to control accommodation during manifest refraction in young patients without cycloplegia?

Accepted Answer

Fogging with excess plus and asking the patient to read smallest legible letters

Answer

Fogging relaxes accommodation by making the optical system slightly hyperopic, preventing over-minusing during subjective refraction.

Question 5

A patient's refraction is plano +2.00 ×045. This represents what type of astigmatism?

Accepted Answer

Simple hyperopic astigmatism

Answer

One meridian (plano) is emmetropic and the other (+2.00 D) is hyperopic, defining simple hyperopic astigmatism.

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