Components of refraction

Question 1

In eye care the term _________ is used to describe the process of measuring a patient’s refractive error and determining the optical correction needed to focus light rays from distant objects onto the retina and provide the patient with clear vision

Answer 1

Refraction

Question 2

The process of refraction has 2 main components, what are they?

Answer 2

Refractometry, clinical judgement

Question 3

What are the 3 steps of refractometry?

Answer 3

Retinoscopy, refinement, binocular balancing

Question 4

Refractometry performed with the use of a drug that temporarily paralyzes the ciliary muscle, thus blocking accommodation is called

Answer 4

Cycloplegic refraction

Question 5

Refractometry performed without the use of cycloplegic drugs is called

Answer 5

Manifest refraction

Question 6

The use of a retinoscope to determine refractive error; the first step in refractometry

Answer 6

Retinoscopy

Question 7

Retinoscopy is sometimes referred to as ____ _____ because it requires no participation or response from the patient

Answer 7

Objective refractometry

Question 8

The handheld instrument used for measuring refractive error; consisting of a light source and a viewing component. Used with a phoropter or trial lenses is a ______

Answer 8

Retinoscope

Question 9

The flat lighting effect of a retinoscope that produces slightly divergent rays is called the

Answer 9

Plano mirror effect

Question 10

The lighting effect of a retinoscope that produces convergent rays is called the

Answer 10

Concave mirror effect

Question 11

The retinoscopic reflex movement that is in the same direction as the movement of the streak of light from a retinoscope and is typical of the hyperopic eye is known as

Answer 11

“With motion”

Question 12

The retinoscopic reflex movement that is in the opposite direction from the movement of the streak of light from the retinoscope and is typical of the myopic eye is known as

Answer 12

“Against motion”

Question 13

The lens power that is the approximate correction for a refractive error is called the

Answer 13

Neutralization point

Question 14

During retinoscopy and neutralization the examiner selects various lenses to introduce before the patient’s eye by means of a ________ and _________ or with a ____________.

Answer 14

Trial lens set and Trial frame

Refractor/Phoropter

Question 15

The subjective step of refractometry, requiring patient participation and responses, which confirms information produced by retinoscopy. Is also known as subjective refractometry or manifest refractometry.

Answer 15

Refinement

Question 16

A special lens consisting of two cylinders of equal power, one minus and one plus, with their axes set at right angles to each other; used for determining the axis and power of an astigmatic correction

Answer 16

Cross cylinder

Question 17

A procedure performed on both eyes at once to ensure that the optical correction determined by refractometry for distance vision does not include an uneven overcorrection or undercorrection. May also be referred to as binocular balancing

Answer 17

Balancing

Question 18

What is the standard format for prescription spectacle lenses?

Answer 18

First is the sphere, followed by the power of the cylinder with its sign and axis if a cylinder is required

Question 19

The conversion of a lens prescription from plus-cylinder form to minus-cylinder form or vice versa is called

Answer 19

Transposition

Question 20

What are the steps of transposition?

Answer 20

1. Add algebraically the cylindrical power to the spherical power.
2. Reverse the sign of the cylinder, from plus to minus or vice versa as appropriate.
3. Add or subtract 90 degrees to make the new axis 180 degrees or less