Abo Test

Which of the following lenses has no power in the 90

+1.00-2.00 x 45

Transpose the following prescription: -0.75 +3.00 X 180

+2.25 -3.00 X 090

If the prescription is O.D. +1.00 +2.50 x 45, what would be the total power at axis 90?

+2.25D

The spherical equivalent of the lens +1.00 +2.50 x 90 is:

+2.25D

Transpose the following prescription: +2.25 +1.75 X 085

+4.00 -1.75 X 175

The focal length of a +2 diopter lens is

+50 cm

Using the prescription -1.00 -1.50 X 90, what is the power of the lens at the 180th meridian?

-2.5

A lens has a front surface power of +2.00D and a back surface power of -8.25D. The corrective power is

-6.25D

Given the prescription +1.00 +1.00 axis 90, how much of the +1.00 cylinder is in effect at axis 90 (the vertical meridian of the lens)?

0%

How much cylinder power is in effect at the specified axis?

0%

The vertical difference in power between lenses in the following Rx is: O.D.-1.00 +0.50 x 045 O.S. -1.00 +0.50 x 090

0.25D sph

If a +10D lens is moved 5 mm nearer the eye, it will be about:

0.50D weaker plus

You are fitting a patient with a Titan-10 frame, 24 DBL, 44 eye size, and 5V2 inch skull temples. The distance P.D. is only 62 mm. If by some unfortunate error the lenses are NOT decentered at all, how much prism is created in each eye? Rx O.U.-2.25-1.50x45

0.9 ? B.O.

A +5.00 diopter lens decentered 2 mm creates ____ diopters of prism.

1

Using the prescription +2.00 -1.50 X 45, what is the power of the lens at the 90th meridian?

1.25

The index of refraction of the cornea is

1.37

The refractive index of CR-39 is:

1.5

The dioptric difference between the lenses for the prescription of O.D. +2.00 sph, O.S. +0.50 sph would be:

1.50D

1 Prism Diopter can be described as deviating a ray of light:

10 centimeters / 1000 centimeters

How much cylinder power is in effect 90 degrees away from the specified axis?

100%

There are approximately ____ million rods located mainly in the periphery of the retina and ____ million cones located centrally in retina.

120, 6

The speed of light is:

186,000 miles / second

Light rays pass through a lens and converge at a point 50cm behind the lens, what is the power?

2.00 D

A +3.00D lens has the following prismatic effect 8 mm below the optical center:

2.4 base up

Using Prentice's Rule a -4.00 lens must be decentered ___ to induce 1.00 Prism Diopter:

2.5 mm

3 Prism Diopters base in on the right eye can also be described as:

3 @ 000

The P.D. written on the order is mistakenly noted as 70 mm, when the actual measurement should be 66 mm. What unwanted prism would be found in the prescription if the distance prescription is O.U. -15.00D sphere?

3D base in each eye

What is the best base curve for a -3.75D lens?

4

The onset of presbyopia generally begins at age:

40

What is the best base curve for a +2.50D lens?

8

The index of refraction is lowest in

Air

Trifocals are most generally prescribed when the patient is:

An advanced presbyope

A slab off is used to compensate for differences in induced prism between the eyes caused by

Anisometropia

An Rx with the O.D. minus and the O.S. plus is an obvious case of _______.

Antimetropia

Cataract surgery removes the crystalline lens of the eye causing the patient to lose the ability to focus. This condition is known as

Aphakic

The term for the refractive condition where light comes to a focus on 2 different points:

Astigmatism

It is generally accepted procedure to fit the top of the trifocal segment to the:

Bottom edge of the pupil

Plastic lenses are made of a hard resin material known as:

CR-39

The focal length of a lens may be altered by:

Changing the curvature of one surface

Aqueous humor is produced by the

Ciliary body

A lens of -2.00 +2.00 x 90 power corrects _______ .

Compound myopic astigmatism

Which material is known to have the best optical properties?

Crown glass

Astigmatism is corrected by a lens having:

Cylinder power

If the lenses of a patient wearing -15.00 spheres are brought closer to his/her eyes, what if any effect will this have on the effective power?

Decrease minus power effect

One prism diopter _______ .

Deviates a ray of light 1 cm at a distance of one meter

In a minus powered lens light rays ____ and come to a focal point ____ the lens.

Diverge, in front of

The term for the refractive condition where light comes to a focus directly on the retina:

Emmetropia

The corneal consists of 5 layers which in order from anterior to posterior are:

Epithelium, Bowmans membrane, Stroma, Descemets membrane, Endothelium

Phorias and tropias are further defined by their direction of movment: ____ as meaning outward (temporally), ____ as meaning inward (nasaly), ____ as meaning downward, and ____ as meaning upward. (place them in the correct order)

Exo, eso, hypo, hyper

The eye is made up of three layers, they are the:

Fibrous tunic, Vascular tunic, and Nervous tunic

The term for the refractive condition where light comes to a focus behind the retina:

Hyperopia

The amount of light entering the eye is controlled by the:

Iris

The 6 extraocular muscles responsible for stabilization of the eye are:

Lateral rectus, Medial rectus, Superior rectus, Inferior rectus, Superior oblique, Inferior oblique

Multifocal height is usually determined by measuring from the:

Lower edge of the lens

Most commonly, opticians use a Geneva lens measure to:

Measure lens base curve

A lens having one concave and one convex surface is called a __________ lens.

Meniscus

A characteristic most single vision CR-39 lens series have in common is:

Minus cylinder form

A myope always has in his or her prescription the following kind of power:

Minus power

When light entering the eye, without corrective lenses, comes to a focus partially in front of the retina and partially in back of the retina, the patient's refractive error is ______ .

Mixed astigmatism

A patient comes in with a prescription requiring a large amount of plus power (+12.50 diopters) and with a notation Vertex Distance 12 mm. You find that when fitted with a frame, the lens will set 14 mm from his eye. What change will be necessary in the lens to be ordered?

More plus sphere power

The patient normally has no need for any visual correction for distance, but does require prescription lenses to see well at near. This patient's refractive error is known as

Myopia

The term for the refractive condition where light comes to a focus in front of the retina:

Myopia

If the pupillary distance is measured while the patient is focusing on a point 16 inches in front of his eyes, the P.D. measured is known as the _______ P.D.

Near

One of the ways of identifying a lens with minus power is to look for:

Objects seen through the lens seem to move in the same direction as the lens is moving

When the eye has a tendency to turn from its normal position it is called:

Phoria

Which of the following lens materials requires a UV coating to protect from ultraviolet radiation?

Plastic

A hyperope always has in his or her prescription the following power:

Plus power

What lens treatment best reduces glare from water and road surfaces?

Polarized

Given an Rx with all specifications equal but ground in material of different indices, which set of lenses will be the thinnest?

Polycarbonate

Which material is known for its superior impact resistance?

Polycarbonate

Which one of the following lens materials is generally thought to provide the best impact resistance for children's eyewear?

Polycarbonate

Bifocals are used to correct for a condition called:

Presbyopia

Multifocal lenses are generally used to correct for:

Presbyopia

The process used to reduce the bottom thickness of a progressive lens is called

Prism thinning

The wavelength of 700nm is seen as what color:

Red

When the direction of light changes as it passes from one medium to another, it is called

Refraction

The relationship of front and back curvatures on a spectacle lens will determine:

Refractive power

The fibrous tunic consists of the

Sclera and cornea

Given an Rx of: Plano +1.00 x 090, when ground, the resulting lens is prescribed for which of the following conditions?

Simple hyperopia

The optical cross is a graphic representation used to show the _________ of a lens.

Surface curvature

As the pantoscopic angle is increased:

The optical centers are effectively raised

AR coatings cause light incident upon the lens to be

Transmitted

When the eye has a definite or obvious turning from its normal position it is called:

Tropia

A ptosis crutch is used to give support to:

Upper lid

Axis is ____________.

a notation of position

The reason for using a "best form" lens is to minimize

aberrations

A lens clock is used to measure

base curve

Fusion occurs in the

brain

We really see with our _______ .

brain not our eyes

A plus lens

converges light

Eyeglass prescription powers are written in _________.

diopters

A perfect human eye is said to be ____________.

emmetropic

A minus lens

is thin in the center

Plus lenses ________ and minus lenses ________.

magnify, minify

Equiconcave, flat concave, and meniscus are ALL types of

minus lenses

Astigmatism means that the patient's cornea is _____.

misshapen

Equiconvex, flat convex, and meniscus are ALL types of:

plus lenses

Everyone will suffer from __________ if they live long enough.

presbyopia

Accommodation is defined as _____________.

the act of the crystalline lens changing its shape to focus for objects at varying distances

To switch between minus and plus cylinder forms we use _____.

transposition