JCAHPO Corrective Lenses 2

Question 1

A patient has a spectacle prescription of -3.00 -1.50 x 090. What is the power in the 180-degree meridian?

Accepted Answer

-4.50 D

Answer

The power at 180° equals the sphere plus the cylinder: -3.00 + (-1.50) = -4.50 D.

Question 2

Which type of bifocal segment provides the widest reading area at the bottom of the lens?

Accepted Answer

Executive (Franklin) bifocal

Answer

The Executive or Franklin bifocal has a full-width segment line across the entire lens, providing the widest reading area.

Question 3

A prism of 2Δ base-in is prescribed for the right eye. In which direction will the image appear to shift for the patient?

Accepted Answer

Temporally (away from the nose)

Answer

Prism displaces images toward the apex; base-in means the apex is out (temporal), so the image shifts temporally.

Question 4

What is the vertex distance, and why does it matter for high-power prescriptions?

Accepted Answer

Distance from cornea to lens; affects effective power for powers >±4.00 D

Answer

Vertex distance is the distance from the back surface of the spectacle lens to the cornea, and it significantly affects effective power for prescriptions above ±4.00 D.

Question 5

Polycarbonate lenses are most often recommended for which patient population?

Accepted Answer

Children and patients requiring impact-resistant lenses

Answer

Polycarbonate is highly impact-resistant and is the material of choice for children and monocular patients requiring eye protection.

(JCAHPO) International Joint Commission Allied Health Personnel in Ophthalmology Practice Test

(JCAHPO) International Joint Commission Allied Health Personnel in Ophthalmology Practice Test

JCAHPO Corrective Lenses 2