Free ABO NOCE MCQ Question and Answers

Question 1

How is the strength of a lens measured?

Accepted Answer

Diopters

Answer

The strength or optical power of a lens is measured in diopters (D). One diopter is defined as the reciprocal of the focal length in meters (D = 1/f). A higher diopter value indicates a stronger lens that converges or diverges light more significantly, providing the necessary correction for refractive errors.

Question 2

What is the 400 mm focal length lens' dioptric strength?

Accepted Answer

+2.50

Answer

To calculate the dioptric strength, first convert the focal length from millimeters to meters: 400 mm = 0.4 meters. Then, use the formula Diopters = 1 / focal length (in meters). So, D = 1 / 0.4 = +2.50 D. The positive sign indicates a converging (plus) lens, which is typical for a lens with a real focal point.

Question 3

What component of the prescription for eyeglasses serves as a gauge for the patient's myopia or hyperopia?

Accepted Answer

Sphere

Answer

The 'sphere' component of an eyeglass prescription indicates the spherical power needed to correct myopia (nearsightedness, represented by a minus sign) or hyperopia (farsightedness, represented by a plus sign). This power is uniform across all meridians of the lens and addresses the overall focusing error of the eye, bringing images into clear focus on the retina.

Question 4

What always happens to light beams that pass through a "plus" lens?

Accepted Answer

Converge

Answer

A 'plus' lens, also known as a convex lens, is thicker in the center and thinner at the edges. Its primary function is to converge parallel light rays to a single focal point. This converging action is used to correct hyperopia (farsightedness) by bringing the focal point forward onto the retina, allowing for clear vision.

Question 5

What is the term for the distance between the inside surface of a corrective lens and the surface of the eye?

Accepted Answer

Vertex distance

Answer

Vertex distance is the measurement from the back surface of the spectacle lens to the apex of the cornea. This measurement is crucial, especially for higher prescriptions, because changes in vertex distance can affect the effective power of the lens at the eye. Accurate measurement ensures the prescribed power functions as intended, providing optimal vision correction.

ABO NOCE Basic Opticianry Practice Test

ABO NOCE Basic Opticianry Practice Test

Free ABO NOCE MCQ Question and Answers