NBEO Optics & Lens Design

Question 1

What is the diopter?

Accepted Answer

The unit of measurement for the refractive power of a lens, equal to the reciprocal of the focal length in meters

Answer

A type of eye disease

Answer

An instrument for measuring pupil size

Answer

A unit of visual acuity

Question 2

What is astigmatism?

Accepted Answer

A refractive error caused by an irregularly curved cornea or lens that creates two focal points, causing blurred or distorted vision at all distances

Answer

Only a problem for near vision

Answer

An age-related condition

Answer

A disease of the retina

Question 3

What is presbyopia?

Accepted Answer

The age-related loss of accommodation (near focusing ability) due to hardening of the crystalline lens, typically becoming noticeable after age 40

Answer

A childhood vision problem

Answer

An infection of the eye

Answer

A type of color blindness

Question 4

What is a progressive addition lens (PAL)?

Accepted Answer

A multifocal lens with a gradual power change from distance at the top to near at the bottom, without visible dividing lines

Answer

A lens that changes color in sunlight

Answer

A single-vision lens with progressive tint

Answer

A disposable contact lens

Question 5

What is the difference between CR-39 and polycarbonate lens materials?

Accepted Answer

CR-39 has better optical clarity; polycarbonate is lighter, thinner, and significantly more impact-resistant

Answer

They are identical materials

Answer

CR-39 is always preferred

Answer

Polycarbonate has better optics

Question 6

What is prism in ophthalmic lenses?

Accepted Answer

An optical element that shifts the apparent position of images to correct binocular vision problems like strabismus and convergence issues

Answer

A decorative lens coating

Answer

A type of lens tint

Answer

A measurement of lens thickness