Refract Theory Review Flashcards
The average power of the eye in total is +43.00D
T/F
False
The optical image is that image formed by the eyes optical system and may or may not be on the retina.
T/F
true
The retina image is that image formed on the retina and may or may not be clear.
T/F
True
The larger the blue circle on the retina, the stronger the refractive error.
T/F
true
All of the following are associated with hyperopia except:
Eyeball too small
Corrected with plus lenses
light from distance point comes behind retina
distance between lens and retina is too great
distance between lens and retina is too great
In regard to visual acuity, 20/20 Snellen E, 6/6 metric, and 1.0 all mean the same thing.
T/F
true
The fovea centrallis contains the highest percentage of rods in the retina.
T/F
false
The main function of the sclera is: Nourishment Muscular Protection Cosmetic
Protection
An uncorrected myope has good VA at distance but poor VA at near.
T/F
False
Axial Hyperopia is a refractive error in which the length of the eyeball is too long.
T/F
False
Latent Hyperopia is a condition in which a client diagnosed with Presbyopia sees clearly in the distance while looking through their reading Rx.
T/F
false
An uncorrected myope over accommodates and leans towards esophoria
T/F
false
The crystalline lens has 2 converging minus power surfaces
T/F
false
To see clearly, the eye’s optical system must form a point focus on the nerve of the retina.
t/f
false
The human seeing system consists of 2 sets of lenses, 2 sensing devices and 1 brain and is used to describe how we see.
t/f
true
The ability of the eye to change its shape to focus at near is known as:
accomatdation
Your pupil dilates during accommodation
t/f
false
One of the functions of the ciliary muscle of the eye is to stimulate accommodation.
t/f
true
Match the refractive error:
-2.50 sph
Simple Myopia
Match the refractive error:
+1.25 sph
Simple Hyperopia
Match the refractive error:
+1.50-1.50x180
Simple hyperopic astigmatism
pl+1.50x090
Match the refractive error:
pl-1.50x180
Simple Myopic Astigmatism
-1.50+1.50x090
Match the refractive error:
+1.00+050x090
Compound Hyperopic Astigmatism
+1.50-0.50x180
Match the refractive error:
-3.00-4.00x090
Compound Myopic Astigmatism
-7.00+4.00x180
Match the refractive error:
+1.50-2.50x090
Mixed Astigmatism
-1.00+2.50x180
Astigmatism is a refractive condition in which the eyes optical system is incapable of forming a point image for a point object.
t/f
true
Exophoria is a tendency for the eyes to turn in
t/f
false
An uncorrected myope under accommodates and leans towards exophoria.
t/f
true
An astigmatic eye could focus light rays both in front of and behind the retina.
t/f
true
Axial myopia is nearsightedness due to a longer than average global length of the eye.
t/f
true
Hyperopia can cause exophoria
t/f
false
The myope can improve VA by accommodating the object to be viewed.
t/f
false
The condition in which a client diagnosed with presbyopia sees clearing in the distance while looking through their reading rx is known as a latent hyperope.
t/f
true
Presbyopia can be corrected by refractive surgery.
t/f
false
An uncorrected hyperope over accommodates and leans towards esophoria.
t/f
true
The cornea has the greatest dioptric power.
t/f
true
Corneal Hyperopia is a refractive error in which the cornea of the eye is too steep.
t/f
false
Of all the refractive errors, myopia is the only one to show definite environmental factors on the incidence, distribution, degree and changes.
t/f
true
Steep K at 180 , flat K at 90 is considered MIX ATR WTR IRR
ATR
If the vertical light rays focus on the retina, and the horizontal light ray focus in front of the retina, then the error is:
CMA, CHA
SHA, SMA,
N/A
Simple Myopic Asitgmatism
The avg. 40 yr old has an amplitude of:
- 00D
- 00D
- 50D
- 50D
4.50D
BO ^ have been used to control myopic progression.
t/f
false
Pseudomyopia is a condition of on-going spasm of accommodation and requires plus lenses to correct.
t/f
true
Total Hyperopia plus latent hyperopia equals manifest hyperopia
t/f
false
Asthenopia is a symptom of an uncorrected refractive error
t/f
true
Fogging or cyclopliglics is commonly used to bring out latent hyperopia to manifest.
t/f
true
An example of an OBJECTIVE refraction is….
retinscopy or auto-refraction
Hyperopia that is uncovered during a cycloplegic refraction and is added to the latent hyperopia is known as:
total
Congenital myopia is normally acquired with excessive work on computers
t/f
false
Accommodation uncovered during a normal non cycloplegic refraction is known as
manifest or latent?
latent
Over accommodation can cause divergent strabismus.
t/f
false
Approx. 2/3 of the eyes refractive power is due to the cornea. The other refracting capability is due to the: Retina Choroids Crystalline lens Rods and cones
Crystalline lens.
Steep K @ 90, flat K @ 180 IRR WTR ATR MIX
WTR
Irregular astigmatism occurs when the meridians are 90 degrees apart an an oblique axis.
t/f
false
Accommodation uncovered during a normal non cycloplegic refraction is known as
Manifest or latent
manifest
Pseudmyopia can be corrected using minus lenses
t/f
false
Light focuses before retina
simple myopia
Light focuses behind retina
simple hyperopia
Light focuses on retina and focuses before
simple myopic astig
Light focuses on retina and focuses behind
Simple hyperopic astig
Light focuses behind retina on different points
CHA
Light focuses before retina in different points.
CMA
Light focuses before and after retina
Mixed
total hyperopia = manifest + latent
t/f
true
Latent Hyperopia-
not revealed by normal refraction.
manifest hyperope
revealed by routine refraction (what turns up in phoropter)
congenital myopia
Present at birth
acquired myopia
a result of prolonged stress on the eyes during close work.
