COT Refraction and Retinoscopy 3

Question 1

Which test is used during subjective refraction to balance accommodation between the two eyes after binocular balancing?

Accepted Answer

Prism dissociation test

Answer

The prism dissociation test uses vertical prisms to dissociate the two eyes so that each eye's accommodation can be balanced independently.

Question 2

A Jackson cross cylinder (JCC) is used to refine which two components of a refraction?

Accepted Answer

Cylinder power and cylinder axis

Answer

The JCC is a ±0.25 or ±0.50 D cross cylinder used to refine both the axis and power of the correcting cylinder.

Question 3

During static retinoscopy, the examiner uses a streak retinoscope. Rotating the streak reveals the principal meridians of astigmatism when the streak is:

Accepted Answer

Aligned parallel to the axis of the reflex to show the fastest or brightest reflex

Answer

In streak retinoscopy, aligning the streak with a principal meridian shows the reflex in that meridian most clearly for neutralization.

Question 4

A patient's best-corrected visual acuity is 20/30 with −4.00 +2.00 ×090. If you add −0.50 D of sphere and acuity drops to 20/40, what does this indicate?

Accepted Answer

The endpoint was correct; additional minus over-minuses the patient

Answer

A drop in acuity with additional minus confirms the previous endpoint was correct and more minus causes over-correction.

Question 5

What is vertex distance and why is it clinically important?

Accepted Answer

Distance from corneal apex to lens back surface; affects effective power for high corrections

Answer

Vertex distance is the distance from the corneal apex to the spectacle lens back surface and significantly affects the effective power for prescriptions above ±4.00 D.

COT - Certified Ophthalmic Technician Practice Test

COT - Certified Ophthalmic Technician Practice Test

COT Refraction and Retinoscopy 3