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170 Cards in this Set
- Front
- Back
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+3.00 -1.00 × 60. Horizontal prism in this lens needs to be calculated with prentice rule. The Rx is 60°/120° away from the horizontal meridian (0°/180°). Add this percentage of cylinder power to the sphere to use in prentice rule: |
75% (-0.75 of the cylinder power). Power used in prentice rule = +2.25 |
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+3.00 -1.00 × 45. Horizontal prism in this lens needs to be calculated with prentice rule. The Rx is 45°/135° away from the horizontal meridian (0°/180°). Add this percentage of cylinder power to the sphere to use in prentice rule: |
50% (-0.50 of the cylinder power). Power used in prentice rule = +2.50 |
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+3.00 -1.00 × 90. Horizontal prism in this lens needs to be calculated with prentice rule. The Rx is 90° away from the horizontal meridian (0°/180°). Add this percentage of cylinder power to the sphere to use in prentice rule: |
100% (-1.00 of the cylinder power). Power used for prentice rule = +2.00 |
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+3.00 -1.00 × 180. Horizontal prism in this lens needs to be calculated with prentice rule. The Rx is 0° away from the horizontal meridian (0°/180°). Add this percentage of cylinder power to the sphere to use in prentice rule: |
0% (none of the cylinder power). Power used for prentice rule = +3.00 |
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+3.00 -1.00 × 30. Horizontal prism in this lens needs to be calculated with prentice rule. The Rx is 30°/150° away from the horizontal meridian (0°/180°). Add this percentage of cylinder to the sphere to use in prentice rule: |
25% (-0.25 of the cylinder power). Power used for prentice rule = +2.75 |
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Polycarbonate's index of refraction is: |
1.582 |
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Crown Glass's index of refraction is: |
1.523 |
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Cr39's index of refraction is: |
1.498 |
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When the optical center of a plus lens is below the pupil, the prism base direction is: |
base down |
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When the optical center of a minus lens is below the pupil, the prism base direction is: |
base up |
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When the optical center of a plus lens is to the outer side of the pupil, the prism base direction is: |
base out |
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When the optical center of a minus lens is to the outer side of the pupil, the prism base direction is: |
base in |
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When the optical center of a plus lens is to the inner side of the pupil, the prism base direction is: |
base in |
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When the optical center of a minus lens is to the inner side of the pupil, the prism base direction is: |
base out |
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To determine the spherical equivalent of a cylindrical prescription, this amount of the cylinder power is combined with the sphere power: |
50% |
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When choosing between two minus lenses for slab off , slab off the lens with this power: |
Highest minus or if lenses are in plus form, slab off the lens with lowest plus power |
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When choosing the lens to slab off between two plus lenses, slab off the lens with this power: |
The least plus lens |
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When choosing between one plus and one minus lens to slab off, always slab off this lens: |
Minus |
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To calculate vertical prism using prentice rule, you need to determine the power at this axis: |
90° |
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To calculate horizontal prism using prentice rule, you need to determine the power at this axis: |
180° |
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+3.00 -1.00 × 30. Unwanted verical prism in this lens needs to be calculated with prentice rule. The Rx is 60° away from the vertical meridian (90°). Add this much cylinder to the sphere to use in prentice rule: |
75% (-0.75 of the cylinder power). Power used for prentice rule = +2.25 |
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+3.00 -1.00 × 45. Unwanted vertical prism in this lens needs to be calculated with prentice rule. The Rx is 45° away from the vertical meridian (90°). Add this much cylinder to the sphere to use in prentice rule: |
50% (-0.50 of the cylinder power). Power used for prentice rule = +2.50 |
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+3.00 -1.00 × 90. Unwanted verical prism in this lens needs to be calculated with prentice rule. The Rx is 0° away from the vertical meridian (90°). Add this much cylinder to the sphere to use in prentice rule: |
0% (none of the cylinder power). Power used for prentice rule = +3.00 |
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+3.00 -1.00 × 180. Unwanted verical prism in this lens needs to be calculated with prentice rule. The Rx is 90° away from the vertical meridian (90°). Add this much cylinder to the sphere to use in prentice rule: |
100% (-1.00 of the cylinder power). Power used for prentice rule = +2.00 |
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+3.00 -1.00 × 60. Unwanted verical prism in this lens needs to be calculated with prentice rule. The Rx is 30° away from the vertical meridian (90°). Add this much cylinder to the sphere to use in prentice rule: |
25% (-0.25 of the cylinder power). Power used for prentice rule = +2.75 |
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Prentice rule formula is: |
Meridonial power × decentration in cm. (1mm = .1cm, 10mm =1 cm) |
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To calculate the prism imbalance between two lenses for slab off, prentice rule is used for each lens. Determine the power used for prentice rule in this meridian for each lens: |
90th meridian (power at axis 90°)
(slab off the difference in prism between the two lenses) |
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When light passes through the vitreous chamber, tiny cells cast moving shadows on the retina. This creates an visible effect called: |
Floaters |
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Whenever pressure is applied against the retina, it creates these bright visible effects called: |
Flashes |
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When this PT looks below the optical center to read, the right lens has 2.50D base up prism and the left lens has 2.50D base down prism. Slab off ____ prism diopters: |
5 prism diopters |
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The right temple piece of the eyeglasses is in alignment but the left temple piece is misaligned downward. What effect to the frame front appearance will this make? |
The left side of the frame front will be higher than the right side. |
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The right and left lenses were unintentionally made with un-even oc heights. The amount of prism created needs to be calculated using prentice rule. The power in each lens needs to be determined for prentice rule in this meridian: |
90th meridian (axis 90°) (vertical prism) |
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The right and left lenses were unintentionally made with the wrong pupillary distance. The amount of prism created needs to be calculated using prentice rule. The power of each lens needs to be determined for prentice rule in this meridian: |
0/180th meridian (axis 0° or 180°) (horizontal prism) |
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+3.00 -1.00 × 180 Add: +2.50. What percentage of the reading add needs to be added to the sphere for computer distance? |
50%. (+1.25D) |
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+3.00 -1.00 × 180 Add: +2.50. How many diopters of the reading add needs to be added to the sphere for reading distance? |
+2.50D |
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The distance measured between the closed eyelid and back of the spectacle lens is called: |
vertex distance |
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Vertex distance is measured with this instrument: |
Distometer |
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When a plus prescription's vertex distance is increased, the power is: a. increased b. decreased |
a. increased (more magnified) |
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When a minus prescription's vertex distance is increased, the power is:
a. increased b. decreased |
b. decreased (less minified) |
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When a minus prescription's vertex distance is decreased, the power is: a. increased b. decreased |
a. increased (more minified) |
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When a plus prescription's vertex distance is decreased, the power is: a. increased b. decreased |
b. decreased (less magnified) |
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Increasing a frames pantoscopic tilt adjusts the oc height: a. higher b. lower |
a. higher (optical center raises) |
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For every 2° of pantoscopic tilt, lower the oc height by: |
1mm |
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ANSI tolerance for PAL +/- =/>3.37D prism at 180° is:
a. 0.33D b. 0.67D c. 2/3D d. 1mm |
b and c (ones in decimal form and the others a fraction) (2 dived by 3 is 0.67) (2/3=0.67) |
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ANSI tolerance for PAL +/- =/<3.37D prism at 180° is:
a. 0.33D b. 0.67D c. 2/3D d. 1mm |
d. 1mm |
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ANSI tolerance for PAL +/- =/>3.37D prism at 90° is: a. 0.33D b. 1/3D c. 2/3D d. 1mm |
a and b (ones in decimal form the others a fraction) (1 divided by 3 is 0.33) (1/3=0.33) |
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ANSI tolerance for PAL +/- =/<3.37D prism at 90° is:
a. 0.33D b. 0.67D c. 2/3D d. 1mm |
d. 1mm |
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ANSI tolerance of axis for +/- 0.25 cylinder is:
a. 14° b. 7° c. 5° d. 2° |
a. 14° |
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ANSI tolerance of axis for +/- 0.50 cylinder is: a. 14° b. 7° c. 5° d. 2° |
b. 7° |
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ANSI tolerance of axis for +/- 0.75 cylinder is: a. 14° b. 7° c. 5° d. 2° |
c. 5° |
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ANSI tolerance of axis for +/- 1.50 cylinder is: a. 14° b. 7° c. 3° d. 2° |
c. 3° |
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ANSI tolerance of axis for +/- <1.50 cylinder is: a. 14° b. 7° c. 3° d. 2° |
d. 2° |
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The slab off method is achieved by grinding off the vertical prismatic imbalance between two lenses in this area of the most minus/least plus lens: |
Reading portion. |
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1. The slab off formula requires the power in the 90th meridian of both lenses to be determined, and then multiply each power by: 2. The difference between the two results is slabbed off this lens: |
1. Multiplied by the centimeters away from the optical center the patient reads at. 2. The difference between the two results gets slabbed of the most minus/least plus lens. (Conventional Slab Off) (Difference between the two is the prismatic imbalance) |
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Binocular pupillary distance is measured: |
from the opening of one eyes pupil to the opening of the opposite eyes pupil. |
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Monocular pupillary distance is measured: |
from in between the eyes to the opening of each pupil separately. |
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This ocular reflex remains present in an eye that is blind:
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Near reflex
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This reflex contracts the pupil when a light is shined in the opposite eye:
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Consensual reflex.
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The onset of presbyopia is caused in part by:
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a less elastic lens
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The functions of the lids include:
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secretion and protection
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The orbicularis oculi muscle serves what purpose?
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closes the eye lids
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A strong flash of light, a loud noise or physically touching the eye will trigger this ocular reflex:
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The blink reflex.
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The layer of the cornea which is most anterior is:
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epithelium
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The total power of the eye is:
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60D
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The blink reflex triggers this muscle:
a: orbicularis oculi b: levator |
a: orbicularis oculi
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Corneal incisions in cataract or other intraocular surgeries are generally made at the:
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limbus
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Most corneal transplants color are:
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colorless
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The three tunics of the eye from anterior to interior are:
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fibrous, vascular and neural
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The visual function that allows a person to see the two retinal images as a single image is called: |
fusion |
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The three sections of the conjunctiva are:
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bulbar, fornix, palpebral
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The retinal cells primarily responsible for color vision are called:
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Cones.
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Virtreous detachment might be suspected if a person complains of:
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flashes and floaters
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An eye may be suspected to be blind if this reflex is absent:
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Direct reflex.
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The fibrous tunic is this layer of the eyeball: It consists of two parts of the eye called:
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The outer protective coat. It consists of sclera and cornea.
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The neural coat is this layer of the eyeball: It consists of this part of the eye:
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The inner layer. The retina.
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The Retina consists of three types of cells:
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containing photoreceptor cells (rods & cones), intermediate cells (bipolars), terminal nerve cells (ganglion's) whose extensions are optic nerves.
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Opening the eye lids is controlled by which muscle?
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Levator muscle.
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Closing the eye lids are controlled by which muscle?
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Orbiculous Oculi muscle.
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The conjuctivia is a mucous membrane that consists 3 parts:
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the portion lining the lids (palpebral), the backward curving portion (fornix) and the portion adherent to the eyeball (bulbar)
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What tunic and layer of the eyeball is the cornea?
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Part of the fibrous tunic. The outer anterior layer.
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The cornea is made up of 5 distinct layers, listed from anterior to interior:
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epithelium (outer) Bowman's membrane, stroma, Descemet's membrane, and endothelium (inner)
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The cornea is bathed on each side with fluid. The front fluid is: The back fluid is: |
The front is the tear film. The back is the aqueous humor. |
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The vascular tunic is also called: It's purpose is:
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The uveal tract. To insulate and nourish.
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The purpose of the neural coat is:
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It acts like a photographic film.
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What is the sclera? It serves what purpose?
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The outer white layer of the eyeball. It resists intraocular pressure and is an anchor for the attachment of extraocular muscles.
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The exterior and interior layers of the cornea are:
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Epithelium (exterior) and Endothelium (interior)
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The outer and inner membranes of the cornea are:
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Bowman's membrane (outter), and Descemet's membrane (inner)
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The cornea's middle layer that makes up 90% of the corneal thickness is called:
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The Stroma
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The three tunics of the eyeball are called:
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Fibrous Tunic, Vascular Tunic and Neural Tunic
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The 1mm transition zone between the sclera and the cornea is:
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The limbus. (important surgical landmark)
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The tear film is composed of 3 distinct layers, listed from anterior to interior: |
Lipid layer, Aqueous layer, and Mucin layer. |
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A factor thought to make the elderly susceptible to glaucoma is:
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The shallowing of the anterior chamber with advancing age
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How does a mydriatic drug affect the eye?
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Pupil dialates due to the drugs effect on the autonomic nerve fibers.
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How does a miotic drug effect the eye?
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Pupil constricts due to the drugs effects on the autonomic nerve fibers.
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The pupil responds to light by three reflexes:
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Direct, Consensual, and Near
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The direct reflex will cause the pupil to: |
Constrict to when exposed to light |
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The pupils consensual reflex is best described as: |
illuminating only one eye with light and both eyes pupil's constrict. |
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The near reflex will cause: |
Both eyes to constrict when looking at a near object (not illuminated) |
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If an eye is blind, which reflexes will be absent or present?
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Direct and consensual will be absent. Near will be present.
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The pinhead size area in the retina used to distinguish details in an image is called:
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The Fovea
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The posterior chamber is between:
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The iris and the lens
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The largest ocular chamber located between the lens and the retina is called:
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Vitreous chamber.
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The outer oily layer of the tear film is called:
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Lipid Layer
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The watery middle layer of the tear film is called:
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Aqueous.
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The inner lubricated layer of the tear film is called:
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Mucin.
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The largest portion of the uveal tract is:
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The Choroid
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The choroid is a thin membrane made up of:
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blood vessels.
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Choriocapillaries are on the retina side of the:
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Choroid
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Bruch's membrane is located between the:
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Choriocapillaries and the Retina
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Senile Macular Degeneration is:
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Bruch's membrane cracks and degenerates causing blood from the choriocapillaries of the choriod to leak into the retina.
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The biconvex, semisolid, transparent body that consists of an elastic capsule is called:
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The Crystalline Lens
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New layers of the crystalline lens grow through out life and cause shallowing of:
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The Anterior Chamber
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Opacities of the crystalline lens are called:
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Cataracts
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The retinal cells primarily responsible for color vision are called:
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Cones
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The far point for an emmetropic eye is:
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Optical infinity (20ft and further)
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The far point for an eye that is myopic is: |
Somewhere between the eye and 6 meters |
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The lids can be squeezed together to increase the depth of focus for a [ __ ] eye.
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Myopic
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An image can be brought into focus by sufficient accommodation for a [ __ ] eye.
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Hyperopic
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Floaters most noticeable when:
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Looking into the sky or a blank surface, tiny cells appear to be floating before our eyes.
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Floaters are caused by:
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When light passes through the vitreous chamber and tiny cells cast shadows on the retina.
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Symptoms of the vitreous chamber decreasing in size are:
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Floaters
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Flashes in vision are caused by:
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Pressure against retina
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Higher Abbe values are preferred because of: a. higher light transmission. b. less dispersion. c. more dispersion. |
b. less dispersion. |
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The nanometer range for UV wavelegths is: a. 400 nm and down. b. 750 nm and up. |
a. 400 nm and down. |
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The nanometer range for infrared wavelengths is: a. 400 nm and down. b. 750 nm and up. |
b. 750 nm and up. |
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Power tolerance for prescribed prism of 2.00∆ Diopters or less is:
a. +/- 0.12∆ b. +/- 0.25∆ c. +/- 0.37∆ d. +/- 0.50∆ |
b. +/- 0.25∆ |
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To test a lens for impact resistance, drop a: a. 7/8" steel ball 100 inches. b. 7/8" steel ball 50 inches. c. 5/8" steel ball 50 inches. d. 5/8" steel ball 100 inches. |
c. 5/8" steel ball 50 inches. |
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A -3.00 +1.50 × 180 lens has ___ prism 3mm above center.
a. .9 ∆ base up b. .45 ∆ base down c. .9 ∆ base down d. 45 ∆ base up |
d. 45 ∆ base up |
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A -5.00 sphere lens has ___ diopters 5mm from the optical center.
a. 1.5 ∆ b. 2.0 ∆ c. 2.5 ∆ d. 3.0 ∆
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c. 2.5 ∆ |
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Blurring of images due to greater amount of refraction toward the lens edge is called: a. spherical aberration b. marginal astigmatism c. chromatic aberration d. distortion |
a. spherical aberration |
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What is marginal astigmatism and how is it controlled? |
An astigmatic error that occur when the eye looks away from the optical center of a lens. Best form base curves provided by the manufactures minimize the effect. |
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Outside rays cross in front of the focal point in all lenses and is called: |
Coma |
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A spherical aberration where small overlapping circles result from outside rays crossing in front of the focal point is know as: |
Coma |
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Distortion is the effect of: |
unequal magnification. |
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Distortion creates a barrel field of view with this correction: a. high powered plus lenses. b. high powered minus lenses. |
b. high powered minus lenses.
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Distortion creates a pincushion field of view with this correction:
a. high powered plus lenses. b. high powered minus lenses. |
a. high powered plus lenses.
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Rule to determine minimum blank size for single vision semi finished lens is: |
Larger lens diameter than the effective diameter (ED) of the frame. |
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The rule for minimum blank size for a single vision finished lens is: |
Effective diameter + twice the amount of decenteration. |
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An Rx is marked OD: NLP. The abbreviation means: |
Right Eye: No Light Perception (total blindness) |
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Legal blindness is defined as visual acuity of: a: 20/100 b: 20/200 c: 20/300 d: 20/400 |
b: 20/200
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