COT Low Vision and Optical Aids 3

Question 1

A bioptic telescope is prescribed primarily to assist with which visual task?

Accepted Answer

Brief 'spotting' tasks such as reading street signs and traffic signals

Answer

Bioptic telescopes are mounted high in the spectacle carrier and used for brief spotting tasks (signs, signals) while routine vision is maintained through the carrier lens below.

Question 2

Which optical device can be mounted on spectacles to redirect images from a blind visual field area into the patient's seeing field?

Accepted Answer

Fresnel prism

Answer

Fresnel prisms attached to spectacle lenses shift images from the hemianopic or sector-loss field into the functional seeing field, providing field expansion.

Question 3

In a Galilean telescope, the eyepiece (ocular) lens is:

Accepted Answer

A concave (minus) lens

Answer

A Galilean telescope uses a concave (minus) lens as the eyepiece and a convex (plus) lens as the objective, producing an erect, upright image without requiring inverting prisms.

Question 4

What is the primary practical advantage of a hand-held magnifier over spectacle-mounted high-plus lenses for certain low vision patients?

Accepted Answer

It allows the patient to vary the working distance and is convenient for brief or intermittent tasks

Answer

Hand magnifiers allow flexible working distance and are easy to use for brief tasks, unlike spectacle magnifiers that demand a strict, short focal distance at all times.

Question 5

When prescribing progressively higher-plus reading additions for a low vision patient, the key optical trade-off is:

Accepted Answer

Greater image magnification but a progressively shorter working distance

Answer

As plus power increases, focal length shortens, requiring reading material to be held progressively closer, which can limit comfort and practical use.

COT - Certified Ophthalmic Technician Practice Test

COT - Certified Ophthalmic Technician Practice Test

COT Low Vision and Optical Aids 3