Term
| Change a bifocal Rx to a single vision Rx |
|
Definition
Add the bifocal power to the sphere powers.
OD: -0.50
OS: -0.25-0.25x172
Add: +1.75
Turns into-
OD: +1.25
OS: +1.50-0.25x172 |
|
|
Term
|
Definition
| There is a difference of 3 diopters between both eyes; when the vision of the eyes differs by a large margin. |
|
|
Term
|
Definition
Refers to Rx's that differ in sign.
Ex. OD: +0.25
OS: -0.75 |
|
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Term
|
Definition
| The Rx will be a + sphere |
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Term
|
Definition
|
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Term
|
Definition
| Tests to see if both pupils constrict when a light is shined in one eye. Tests for abnormalties in pupillary reaction. |
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Term
|
Definition
| letters on the Snellen Chart |
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|
Term
| Who is said to be the pioneer lens designer (1268) |
|
Definition
|
|
Term
| Who is generally credited with the invention of spectacles? |
|
Definition
| Salvino d'Armati of Florence, Italy (1285) |
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|
Term
| When were minus or concave lenses invented? |
|
Definition
| 16th century for correction of myopic eyes (nearsightedness) |
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|
Term
| When were toric lenses invented and by whom? |
|
Definition
|
|
Term
| Who is credited with making the first bifocals? |
|
Definition
|
|
Term
| Who aroused the interest of physicians concerning the exam of the eye and prescribing spectale lenses? |
|
Definition
|
|
Term
|
Definition
| a paramedical technician who designs, fabricates, hand paints, and fits ocular protheses for those who have lost one or both eyes |
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Term
|
Definition
|
|
Term
|
Definition
| an inflammation of the iris. |
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Term
|
Definition
| pertaining to the opposite eye |
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Term
|
Definition
| recession of the eyeball into the orbit |
|
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Term
|
Definition
| eyes do not maintain parallelism, but take a permanent position of convergence or divergence |
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Term
|
Definition
| inflammation involving the uveal tract |
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Term
|
Definition
| blood in the anterior chamber of the eye |
|
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Term
|
Definition
| pertaining to both eyes, the use of both eyes simutaneously |
|
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Term
|
Definition
| abscence of an eyeball (newborn) |
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Term
|
Definition
| a curve of multiple radii |
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Term
|
Definition
| a totally color blind individual, a lens free from chromatic abberation |
|
|
Term
|
Definition
| blood (hemmorrhage) within the eye |
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Term
|
Definition
| complete or partial absence of the iris |
|
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Term
|
Definition
| inflammation of the tissues of the internal structures of the eye |
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Term
|
Definition
| unequal turning of the eyes |
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|
Term
|
Definition
|
|
Term
|
Definition
| abnormal protrusion of the eyeball outward and forward |
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Term
|
Definition
| blindness in half the visual field of one or both eyes |
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Term
|
Definition
| an instrument for viewing the fundus and interior of the eye |
|
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Term
|
Definition
| an upward rotation of the eye |
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Term
|
Definition
| an instrument for viewing or shinning light on the retina to determine the refractive state of the eye |
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Term
|
Definition
| inflammation of the cornea |
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Term
|
Definition
| deformity of the cornea in which it becomes cone shapped, due to stretching of tissues in its central area. |
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|
Term
|
Definition
|
|
Term
|
Definition
|
|
Term
|
Definition
|
|
Term
|
Definition
|
|
Term
|
Definition
|
|
Term
|
Definition
|
|
Term
|
Definition
|
|
Term
|
Definition
| the tendency for one eye to deviate as the other remains fixed |
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|
Term
|
Definition
| muscular imbalance where an eye has a tendency to move outward |
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|
Term
|
Definition
| tendency for one eye to deviate upward |
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|
Term
|
Definition
| normal muscular balance and alignment of the eyes with no tendency to deviate |
|
|
Term
|
Definition
| instrument for examining the curvature of the cornea |
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|
Term
|
Definition
|
|
Term
|
Definition
| abnormal excess of watery fluid in the tissue spaces of the eyelid. |
|
|
Term
|
Definition
| tendency for one eye to deviate downward |
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|
Term
|
Definition
| move decimal 2 places right |
|
|
Term
|
Definition
| move decimal 1 place right |
|
|
Term
|
Definition
| move decimal 3 places right |
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|
Term
|
Definition
| move decimal 3 places left |
|
|
Term
|
Definition
| move decimal 1 place left |
|
|
Term
|
Definition
| move decimal 2 places left |
|
|
Term
| system of angular measurement |
|
Definition
A circle= 360 degrees
1 degree= 60 minutes
1 minute= 60 seconds |
|
|
Term
| conversion between units of angular measurements |
|
Definition
1. degrees to minutes: multiply degrees by 60
2. minutes to seconds: multiply minutes by 60
3. seconds to minutes: divide seconds by 60
4. minutes to degrees: divide minutes by 60 |
|
|
Term
| Isaac Newton's corpuscular theory of light |
|
Definition
| light is small particles of energy |
|
|
Term
| Christian Huygens wave theory of light |
|
Definition
| light is a series of waves of varying lengths |
|
|
Term
|
Definition
| 186,000 miles per second (in air) |
|
|
Term
|
Definition
violet: 380 nm
blue: 460 nm
green: 510 nm
yellow: 560 nm
orange: 610 nm
red: 660 nm |
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|
Term
|
Definition
|
|
Term
|
Definition
|
|
Term
| formula to solve for diopters of power knowing the focal length in meters |
|
Definition
D= 1/f(m)
Example: If the focal length of the lens is 1 meter
D=1/1
D=1
So, Diopter of a lens with a focal length of 1 meter is 1 diopter in power |
|
|
Term
| What is the focal length of a 3 diopter lens? |
|
Definition
|
|
Term
| The higher the index of refraction of a material, the ________ light travels through the medium |
|
Definition
|
|
Term
| The power of a lens is the combination of its true front surface power and the true back surface power |
|
Definition
front: +3.00
back: -6.00
= -3.00 |
|
|
Term
| If a lens surface is made of two different curves 90 degrees apart (perpendicular to each other) the surface is said to be _______ |
|
Definition
|
|
Term
What are the steps to transposing a Rx
+1.00+2.50x180 |
|
Definition
1. Add sphere and cyl algebraically
+1.00 + +2.50 = +3.50
2. Change the sign of the cyl
+ 2.50 becomes -2.50
3. Change the axis by 90 degrees
180 becomes 90 |
|
|
Term
| The amount of diopters of curvature can be determined from a radius by: |
|
Definition
D= index of refration of the material - 1/radius of curvature
Ex. Crown glass with a front radius of 10 cm and a back radius of 52 cm.
Front: D=1.523-1/.10m=5.23
Back: D=1.523-1/.52=1.046
+5.23 + -1.00 = +4.23 (round to +4.25)
(if the radii were switched, the power would be -4.25) |
|
|
Term
| Which color travels the fastest through a medium? |
|
Definition
|
|
Term
| What is the avg. refractive power of the cornea? |
|
Definition
|
|
Term
| What is the average refractive power of the crystalline lens? |
|
Definition
|
|
Term
| What are the 3 chambers of the eye? |
|
Definition
1. anterior chamber: the space between the back of the cornea and the front of the iris
2. posterior chamber: space between the iris and the lens
3. vitreous chamber: largest space between the lens and the retina |
|
|
Term
What are the 5 layers of the cornea?
(from outward in) |
|
Definition
1. Epithelium: highly regenerative
2. Bowman's Membrane
3. Stroma: comprising 90% of thickness
4. Desemets Membrane
5. Endothelium |
|
|
Term
|
Definition
| day vision, detail, color |
|
|
Term
|
Definition
| night vision, peripheral vision, black and white |
|
|
Term
| Does the eye generally contain more rods or cones? |
|
Definition
120 million rods
6 million cones |
|
|
Term
| Where can the greatest density of cones be found? |
|
Definition
|
|
Term
| What is the index of refraction of the cornea? |
|
Definition
|
|
Term
| What is the index of refraction of the crystalline lens? |
|
Definition
|
|
Term
| What is the index of refraction of the aqueous humor and the vitreous humor? |
|
Definition
|
|
Term
| Once the optic nerves leave the eye they cross at an X like structure called the ________? |
|
Definition
|
|
Term
| What are the 3 tunics of the eye? |
|
Definition
1. Fibrous tunic: outer protective coat of the eye that consists of the cornea and sclera
2. Vascular tunic: Consists of the iris, ciliary body, and the choroid
3. Neural tunic: consists of the retina |
|
|
Term
|
Definition
the eye adjusts for viewing objects at various distances, this is accomplished by:
1. the ciliary muscle relaxes allowing for the thickening of the crystalline lens
2. the eyes converge
3. the pupils constrict |
|
|
Term
| How many extra-ocular muscles are there? |
|
Definition
| six, they rotate the eye in all directions |
|
|
Term
| The fibrous tunic consists of... |
|
Definition
| the cornea and the sclera |
|
|
Term
| fusion occurs in the ______? |
|
Definition
|
|
Term
| The aqueous fluid is manufactured by the ________? |
|
Definition
|
|
Term
| The ability of the eye to bring objects of varying distances to focus on the retina is known as: |
|
Definition
|
|
Term
| When accomodation is at rest, rays of light from a distant source come to focus in front of the retina. This is called ________? |
|
Definition
|
|
Term
| When light rays come to focus behind the retina: |
|
Definition
|
|
Term
| Impulses are carried from the retina to the brain along the ________? |
|
Definition
|
|
Term
| The area of the retina capable of perceiving the greatest amount of detail is ___________? |
|
Definition
|
|
Term
| a farsighted eye is one that is __________? |
|
Definition
|
|
Term
| A tendency of the visual axis to deviate inward while the eyes are in a position of rest is known as _______? |
|
Definition
|
|
Term
| The condition in which the ability to accomodate for the near vision becomes inadequate because of the loss of elasticity of the crystalline lens is called: |
|
Definition
|
|
Term
| A refractive error in which the rays of light do not come to a single point of focus is called ________? |
|
Definition
|
|
Term
| When there is a loss of vision without any apparent disease of the eye it is know as ________? |
|
Definition
|
|
Term
| The condition in which the lens of the eye gradually loses its transparancy with consequent loss of the visiual acuity is called ______? |
|
Definition
|
|
Term
| An ocular disease having as its primary characteristic a sustained increase in intra-ocular pressure |
|
Definition
|
|
Term
| A tendency of the eye to deviate upwards |
|
Definition
|
|
Term
| The space between the cornea and iris that is filled with aqueous fluid: |
|
Definition
|
|
Term
| The layer of the cornea which comprises 90% of its thickness |
|
Definition
|
|
Term
| Refractive error which results in two points of focus falling behind the retina |
|
Definition
| compound hyperopic astigmatism |
|
|
Term
| A condition in which the refractive error of one eye differs from that of the other (both eyes have the same sign) |
|
Definition
|
|
Term
| The refractive condition caused by a damaged cornea so that rays of light come to many focal points on the retina |
|
Definition
|
|
Term
| The transparant colorless mass of soft, jelly-like material which fills the eyeball behind the lens |
|
Definition
|
|
Term
| the cornea has an index of refraction of _____? |
|
Definition
|
|
Term
| The index of refraction of the crystalline lens |
|
Definition
|
|
Term
| white of the eye, composed of tough inelastic fibers tightly laced together. It resists the intraocular pressure without losing shape. |
|
Definition
|
|
Term
| Acts as a diaphragm to regulate the amount of light entering the eye |
|
Definition
|
|
Term
| Complex tissue containing rods and cones |
|
Definition
|
|
Term
| Average range of intraocular pressure |
|
Definition
|
|
Term
| What is the index of refraction of Crown Glass? |
|
Definition
|
|
Term
| What is the index of refraction of CR-39 plastic? |
|
Definition
|
|
Term
| What is the index of refraction of Polycarbonate? |
|
Definition
|
|
Term
| What is the index of refraction of high index plastic? |
|
Definition
|
|
Term
| The index of refraction of any material is calculatd by... |
|
Definition
| dividing the speed of light in air by the speed of light in the material |
|
|
Term
| What is the standard index of refraction used? |
|
Definition
|
|
Term
|
Definition
| Prism=power of lens X decentration in mm / 10 |
|
|
Term
| How much prism is induced 4mm away from the optical center of a +3.00D lens? |
|
Definition
|
|
Term
|
Definition
| Optical centers are more narrow than PD |
|
|
Term
|
Definition
| optical centers are wider than PD |
|
|
Term
| A patients PD was noted to be 62mm when the actual measurement is 66mm. If the power of the lenses are -2.00D in both eyes how much prism will be induced and in what direction? |
|
Definition
Right eye: -2.00 X 2/10=0.4
Left eye: -2.00 X 2/10=0.4
Total: 0.8 base out
because OCs are more narrow than PD |
|
|
Term
| When parallel rays of light enter a prism the light is devaited... |
|
Definition
|
|
Term
| One meter is equal to _____ inches |
|
Definition
|
|
Term
| When the direction of light is deviated in the course of passing from one transparent medium to another is known as: |
|
Definition
|
|
Term
| The focal length of a +1.00 diopter lens is _______ |
|
Definition
|
|
Term
| If a converging lens has a focal length of +2 meters its power is |
|
Definition
|
|
Term
| The range of wavelengths which are perceived as visible light are generally understood to lie between: |
|
Definition
|
|
Term
| The focal length of a -5.00 diopter lens is: |
|
Definition
-20cm
1/5=0.2 move decimal 2 places right |
|
|
Term
| decentering a plus lens upward will result in |
|
Definition
|
|
Term
|
Definition
| power of lens X decentration in mm / 10 |
|
|
Term
-2.00D OU with a PD of 63.
The were made with PD of 66. How much total prism and in what direction? |
|
Definition
0.6 BI
OD: -2.00 X 1.5 /10=0.3
OS: -2.00 X 1.5 /10=0.3
Total: 0.6 BI because OC's wider than PD |
|
|
Term
| A diverging lens produces _______ image |
|
Definition
|
|
Term
| What is the total power of a lens that has a front surface power +15.00 and a back surface power of -14.00? |
|
Definition
|
|
Term
| A +1.75D lens fabricated with a +6.00 BC will require a back curve of? |
|
Definition
-4.25
Why? +6.00-4.25=1.75 |
|
|
Term
+2.75 -1.00 x 180
The refractive anomaly indicated by this Rx is |
|
Definition
| simple hyperopic astigmatism |
|
|
Term
| If the Rx: -3.00+0.50x90 is decentered 2mm too much, how much prism and in which direction? |
|
Definition
1.0 BO
for every 2mm decentration 1.0 prism is induced. BO because the question says {too much} or OCs are more narrow than PD |
|
|
Term
| As corrected curve lenses increase in minus power, the base curve tends to become gradually _________. |
|
Definition
|
|
Term
| As the corrected curve lenses increase in + power the base curve becomes gradually __________ |
|
Definition
|
|
Term
Rx: plano-2.00x180
what type of astigmatism is this? |
|
Definition
| simple myopic astigmatism |
|
|
Term
Rx: +0.50-0.75x10
What type of astigmatism is this? |
|
Definition
|
|
Term
| compound opthalmic lenses usually consist of what kind of surface(s)? |
|
Definition
| spherical and cylindrical |
|
|
Term
| The power of a cyl along its axis has how much power? |
|
Definition
|
|
Term
| When the surfaces of a 1.530 lens are measured with a lens clock, the front curve is +6.00 and the back curve is -5.50. The focal length is __________? |
|
Definition
2 meters
+6.00-5.50= 0.50
1/0.50=2 |
|
|
Term
| When a plus lens is moved closer to the eye its effective power ________ |
|
Definition
|
|
Term
| When a high minus lens is moved closer to the eye the compensated power must _______. |
|
Definition
|
|
Term
| a +10 lens is fit at a 14mm vertex distance. A new frame is chosen which positions the back surface 9mm from the cornea. The power of the lens needed to compensate for the change is: |
|
Definition
+10.50
General rule of thumb: a +10.00 lens moved a distance of 5mm will change by approx. 0.50D |
|
|
Term
| It is important to consider the vertex distance in spectacle lenses when the power exceeds ________. |
|
Definition
|
|
Term
| When a lens shape contains one convex surface and one concave surface it is called a __________ lens. |
|
Definition
|
|
Term
|
Definition
| The weight in grams of 1 cubic centimeter of any given material. The higher the number the more it will weigh. |
|
|
Term
|
Definition
| A relative measure of the dispersion of color distortion of a lens. Through the OC of any lens color distortion is virtually non-existent. The lower the Abbe value the greater tendency for chromatic abberration. |
|
|
Term
| formula for the smallest possible blank size |
|
Definition
|
|
Term
| formula for the amount of decentration required in the eye |
|
Definition
|
|
Term
| Formula for verticle decentration |
|
Definition
|
|
Term
| In the boxing system the B measurement is: |
|
Definition
|
|
Term
| A patient has a monocular PD of OD: 31mm and OS: 33mm. The box measurement of the frame is 52/18. Locate the major reference point for each eye. |
|
Definition
Right: 4mm inward
Left: 2mm inward
52+18=70/2=35
Right:35-31=4mm
Left:35-33=2mm
In because OC wider than PD |
|
|
Term
| When measuring a frame, the term DBL is used to mean: |
|
Definition
| the least distance between lenses |
|
|
Term
| describe a semi-rimless mounting |
|
Definition
| a bridge with lens bars, connecting the end pieces and temples. |
|
|
Term
| When the measurement of the patients PD is less than the GCD's of the frame, ideally the frame should be adjusted with what type of face form? |
|
Definition
|
|
Term
| excessive pantoscopic tilt may be fixed by: |
|
Definition
| angling the temples upward from endpieces. |
|
|
Term
| If the left temple is angled in, this will cause.... |
|
Definition
| the right side of the frame to move out |
|
|
Term
| a frame with pantoscopic tilt is fit so that |
|
Definition
| the bottom of the eyewires are in closer than the top. |
|
|
Term
| a frame with retroscopic tilt is fit so that |
|
Definition
| the bottom of the eyewires are out farther than the top |
|
|
Term
| Bowing the temples is a term used to describe |
|
Definition
| curving the temples around the head |
|
|
Term
| You notice the bottom of the eyewires touch the cheek, what do you do? |
|
Definition
| decrease the pantoscopic angle. |
|
|
Term
| a frame contains 8 degrees of pantoscopic angle ideally, the gaze will be directed _______ above the OC of the lens |
|
Definition
|
|
Term
| an epoxy frame material which is light in weight and contains "memory" which causes it to revert to its original shape when heated is called ______. |
|
Definition
|
|
Term
What is the minimum blank size for the following frame measurements and PD?
A=54 DBL=20 ED=56 PD=63 |
|
Definition
GCD-PD+ED
54+20=74
74-63=11
11+56=67 min blank size |
|
|
Term
B=54; seg=23
For a FT-28 where is the seg relative to the datum line? |
|
Definition
54/2=27
27-23=4 mm below datum line |
|
|
Term
| The ANSI document covering ophthalmic standards |
|
Definition
|
|
Term
| Which lenses are not exempt from drop ball testing? |
|
Definition
|
|
Term
| The part of the lensometer which is capable of measuring the amnt of prism is the: |
|
Definition
|
|
Term
| What is the lensometer not capable of measuring? |
|
Definition
|
|
Term
| You have been asked to neutralize a lens. The 3 closely spaced parallel lines come into sharp focus when the power drum reads -2.50D and the axis wheel is set at 180. To bring the 3 widely spaced lines into focus, the power drum is moved to read -3.00. What is the Rx? |
|
Definition
|
|
Term
| The ______ is a non-governmental agency that functions to establish standards for a wide variety of industrial and commerical interests |
|
Definition
| ANSI American National Standards Institute |
|
|
Term
| According to ANSI standards, a lens containing 0.25D of cyl must be within ________ of the specified axis |
|
Definition
|
|
Term
| A lens containing over 1.50D of cyl must be within _____ of the specified axis |
|
Definition
|
|
Term
| Glass lenses in which the power exceeds _____ diopters should generally not be heat treated |
|
Definition
|
|
Term
| Internal lens stress can be detected through the use of a: |
|
Definition
|
|
Term
| In a round bifocal segment you will find the OC located... |
|
Definition
|
|
Term
| The intermediate power most common in trifocal lenses is: |
|
Definition
|
|
Term
| What type of bifocal segment contains the least amount of image jump? |
|
Definition
|
|
Term
Rx: -2.00-0.75x30 ADD: +2.50
If this lens was made utilizing a standard trifocal design, what would be the power through the intermediate portion? |
|
Definition
-0.75-0.75x30
Half the ADD and add to the sphere |
|
|
Term
| The refractive index of polycarbonate is: |
|
Definition
|
|
Term
| The usefulness of cataract spectacle lenses can be improved by using: |
|
Definition
|
|
Term
| The minimum fitting height for most progressive addition lenses is: |
|
Definition
| 22-25 mm depending on the brand |
|
|
Term
| The best candidates for progressive powered lenses are: |
|
Definition
|
|
Term
| "Conventional" slab-off is ground with base up prism in the reading portion only on the lens with the ________ in the verticle meridian. |
|
Definition
|
|
Term
| Bicentric grinding or slab-off is generally prescribed for the correction of: |
|
Definition
| excessive prismatic imbalance at the reading level |
|
|
Term
Rx: +4.50+0.50x90
+2.00+0.25x90
ADD: +1.75
What is the vertical prismatic imbalance at a 10mm reading level? |
|
Definition
2.5 prism diopters
power in 90 degree meridian
Right: +4.50
Left: +2.00
subtract the two
4.50-2.00=2.50 |
|
|
Term
| The innermost layer of the lid which is closest to the cornea |
|
Definition
|
|
Term
| What structures of the eye are embedded in the tarsal plates of the eyelids and secrete oily layer in the precorneal film |
|
Definition
|
|
Term
| The position of a target that produces a sharp image in an ametropic eye is called: |
|
Definition
|
|
Term
| the cornea recieves oxygen and nutrients from: |
|
Definition
| precorneal film and limbal capillary network |
|
|
Term
| The steepest portion of the anterior corneal surface is at the : |
|
Definition
|
|
Term
| What acts as a barrier to aqueous humor and is a single cell layer |
|
Definition
|
|
Term
| The average diameter of the cornea is: |
|
Definition
|
|
Term
| The cornea can become cloudy by: |
|
Definition
| edema and rise in intraocular pressure |
|
|
Term
| What disease of the eye can be caused by pigment flakes from the iris, decreased aqueous outflow, and closed canal of Schlemn |
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Definition
nucleus of the lens
capsule of the lens
and cortex of the lens |
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| The total power of the eye is: |
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| Corneal incisions are generally made at the: |
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| Most corneal transplants are what color? |
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| Too much water in cell tissue is called |
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| The three tunics of the eye from air inwards are: |
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Definition
| fibrous, vascular, and nueral |
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Term
| drugs that dilate the pupil are called |
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Term
| Which glands produce fluid to keep tears from evaporating |
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| Bacteria attacking the cornea might be killed by what layer? |
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| The cornea recieves its nutrition from: |
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Definition
| blood vessels at the limbus, aqueous humor, and tears |
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Term
| When we turn our eyes to look at an object, the region we look with is the: |
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| Even though an eye is blind, which reflex will still be present? |
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| Once damaged, the retina cannot regenerate because? |
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| The highest resolving power of the retina is found at the: |
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| vitreous detachment might be suspected if a person complains of: |
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Term
| An eye may be suspected to be blind if what reflex is absent? |
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| If a lens has a front surface power of +6.50D and a back surface power of -4.50, what is the focal length and the total power? |
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Definition
+6.50-4.50=+2.00
1/+2.00=0.50meters |
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Term
| A lens of 7mm (.007m) thickenss has a front surface power of +12.00D, and a back surface power of -2.00D. If the lens is constructed of crown glass (N=1.523), what is the nominal or total power? |
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Definition
12 + (-2)= +10
+10 + (.007/1.523) x 144
+10 + (.0046 x 144)
+10 + .66
=10.66D |
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Term
| If the vertex distance of a plus lens increases the effective power... |
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Definition
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| If the vertex distance of a minus lens decreases, the effective power... |
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| Find the prismatic effect 5mm (.5cm) above the optical center of a +2.00D lens |
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Definition
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| A Rx requires 4 base in. Rx=4.00D O.U. (4 Base In would be equal to 2 Base In for each eye) What is the decentration required? |
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Definition
| 2/4=0.50 cm or 5mm in each eye |
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Term
| a Rx requires 2.00 Base Up, in a +5.00D lens. Where must the MRP be located? |
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Definition
2/5=0.40cm below optical center
or 4mm |
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Term
| When were lenses first set in frames? |
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Definition
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Term
| Who were the first spectacle frame makers? |
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Definition
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Term
| Which frame material was not used until the twentieth century? |
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Definition
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Term
| Why did the FDA ban cellulose nitrate as a frame material? |
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Definition
| It was too flammable to be considered safe |
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Term
| Why is plastic a popular material for spectacle frames? |
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Definition
| it can be easily molded and shaped |
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Term
| What special care is required for nylon frames? |
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Definition
| Periodic soaking in water overnight |
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Term
| What special care is required for nylon frames? |
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Definition
| Periodic soaking in water overnight |
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Term
| What plastic frame material is the only one that can be either pantographed of injection molded? |
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Definition
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Term
| Because this material is black in its original form this plastic must apply color through the use of baked on enameling. |
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Definition
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Term
| What material is difficult to adjust due to its tendency to relax? |
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Definition
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Term
| Which of the following materials recommends "cold snap" lens insertion? |
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Definition
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Term
| Which ANSI standard regulates safety eyewear? |
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Definition
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Term
| What is meant by a "2/1 hinge? |
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Definition
| Has two barrels on front and one barrel on temple |
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Term
| The points of attachment of drilled rimless frames are called the _______ areas |
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Definition
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Term
| What style of frames are not frames at all but rather mountings |
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| What style temple would be recommended for a 10 yr old boy? |
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Definition
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Term
| What is a good general use style of temple that distributes weight over a large area? |
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Definition
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Term
| What measurement is designated by the datum line? |
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Definition
| the length of the lens at the 180 line |
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Term
| Name two reference points from which segment height is measured? |
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Definition
| Datum line or the lowest point in B box |
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Term
| If a temple was marked 4 3/4-6 what is its overall length? |
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Definition
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Term
Which of the following is the steepest base curve?
+2.25
+4.25
+6.25
-2.25 |
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Definition
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Term
| Plastic lenses weigh about ______% less than glass |
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Definition
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Term
| The specific gravity of a lens material is the weight in _____ of a cubic ____ of that material. |
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Definition
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Term
| lower v value means ________ chromatism |
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Definition
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Term
| In fitting aspheric lenses the optical center should be: |
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Definition
| lowered 1mm for every 2 degrees of pantoscopic tilt. |
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Term
| According to the ANSI Z80.1-1999 lens power standard, the amount of power tolerance: |
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Definition
| Gets greater as lens power increases. |
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Term
| According to Z80.1/1999, a cylinder power ranging between .75 and 1.50 is allowed a tolerance of: |
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Definition
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Term
| According to Z80.1/1999, the power tolerance for a bifocal add power of 4.00D or less is: |
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Definition
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Term
| According to Z80.1/1999, the power tolerance for a bifocal add power over +4.00D is |
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Definition
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Term
| According to Z80.1/1999, the power tolerance for prescribing prism of +2.00D or less is: |
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Definition
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Term
| According to Z80.1/1999 the horizontal prism tolerance for a pair of mounted lenses is: |
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Definition
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Term
| According to Z80.1/1999 the horizontal prism tolerance for a pair of mounted lenses is: |
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Definition
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Term
| The prism that results in a plus powered Rx when centers are ground wider than the patients PD is: |
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Definition
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Term
| The prism that results in a minus powered Rx when centers are ground wider than the patient's PD is: |
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Definition
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Term
| Looking above the optical center in a plus lens will result in which type of prism to the wearer? |
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Definition
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Term
| Looking above the optical center in a minus lens will result in the following type of prism to the wearer? |
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Definition
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Term
| According to Z80.1/1999, the tolerance for variation from an ordered base curve is: |
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Definition
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