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The extra-ocular muscles are inserted into the sclera and serve to rotate the eye in all possible directions. these are _____ of these muscles in each eye.
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The fibrous tunic is comprised of the :
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optician abo exam 2
from abo review book
| Question | Answer |
|---|---|
| The extra-ocular muscles are inserted into the sclera and serve to rotate the eye in all possible directions. these are _____ of these muscles in each eye. | six |
| The fibrous tunic is comprised of the : | Sclera and cornea |
| Fusion occurs : | in the brain |
| The aqueous fluid is continually being manufactured by? | the ciliary body |
| The ability of the eye to bring objects of varying distances to focus on the retina is known as? | accommodation |
| when accommodation is at rest, rays of light from a distant source come to focus in front of the retina. this condition is known as? | myopia |
| when accommodation is at rest, rays of light from a distance source come to focus behind the retina , this condition is called? | hyperopia |
| Impulses are carried from the retina to the brain along the | optic nerve |
| while reading, or performing other near vision tasks | the pupil constricts,the eyes converge, and the crystalline lens accommodates |
| that area of the retina capable of perceiving the greatest amount of detail is ? | fovea centralis |
| the average cornea has a refractive power of approximately | 43 diopters |
| that layer of the cornea which is highly regenerative is ? | the epithelium |
| night vision is chiefly a function of the ? | rods |
| a tendency of the visual axis to deviate inward when the eyes are in a position of rest is known as? | esophoria |
| A "farsighted "eye is one that is? | hyperphoria |
| the term used to indicate Double vision is ? | diplopia |
| the condition in which the ability to accommodate for near vision becomes inadequate because of loss of elasticity of the crystalline lens is called? | presbyopia |
| when there is loss of vision without any apparent disease of the eye, known as? | amblyopia |
| a refractive error in which the rays of light do not come to a single point of focus is called? | astigmatism |
| the condition in which the crystalline lens of the eye gradually loses it transparency with consequent loss of visual acuity is known as | cataract |
| An ocular disease having as its primary characteristic a sustained increase in intraocular pressure | glaucoma |
| The space between the back of the iris and the front of the lens which is filled with aqueous is the? | posterior chamber |
| a tendency of one eye to deviate upward is? | Hyperphoria |
| The photosensitive receptors of the retina which are responsible for sharp visual and color are? | cones |
| the layer if the cornea which comprises ninety percent of its thickness is? | the stroma |
| a condition in which the refractive error of one eye significantly differs from each other and where both eyes have the same sign? | ansiometropia |
| the refractive error which results in two points of focus falling behind the retina is? | compound hyperopic astigmtism |
| the refractive condition caused by a damaged cornea so that rays of light come to many focal points on the retina is called? | irregular astigatism |
| the transparent ,colorless mass of soft , gelatinous material which fills the eyeball behind the lens is the ? vitreous humor | vitreous humor |
| the index of refraction of the crystalline lens is ? | 1.42 |
| the cornea has an index of refraction of? | 1.37 |
| the index of refraction is lowest in? | air |
| when parallel rays of light enter a prism, the light is deviated? | toward the base |
| one meter is equal to ____ inches. | 39.37 |
| two meters equal ____centimeters. | 200 |
| the index of refraction of any given transparent material can be determined by? | dividing the speed of light in air by the speed of light in the material |
| the speed of light in air is approximately | 186000 miles per second |
| when the direction of light is deviated in the course of passing from one transparent medium to another it is known as? | refraction |
| If a prism can displace an image one centimeter at a distance of one meter it is said to have a power of ? | 1 prism diopter |
| the distance between the crests of two waves is called the | wavelength |
| the focal length of a -5 diopter lens is ?/ | -20 cm |
| decentering a plus lens upward will result in ? | bas up prism |
| Prentice's rule states that the amount of induced prism is equal to? | power of the lens times the decentration in millimeters divided by 10 |
| a pair of spectacles were ordered with rx of -2 .00 D in each eye and pd of 63mm. they were received from the lab with optical centers set 66mm apart. how much total prism was induced and in which direction is the base? | .6 prism diopters base in |
| a diverging lens produces a ____image. | Magnified |
| rays emanating from a point source of light are said to be? | diverging |
| to determine the power of a thin lens in air, it is necessary to consider? | front curve, back curve, and index of refraction |
| A standard lens measure is calibrated for an index of refraction of ? | 1.530 |
| A 1.75 diopter lens fabricated with a + 6.00 base curve will require a back curve of ? | -4.25 D |
| Toric transposition is used to determine ? | lens power in the principal meridians |
| a patient presents to you with a prescription reading +2.75 -1.00x180 in each eye. The refractive anomaly indicated by this rx is? | compound hyperopic astigmatism |
| Corrected curve lenses are designed to ? | increase the useful area of the lens |
| the following lenses are all made with the same radius of curvature on the front surface. which of these materials will yield the greatest front surface power? | flint glass |
| rx +2.50-.50x180 +2.50 sph PD 67 during final inspection it was determined that the optical centers of the lenses were placed 63 mm apart. how much total prism will this produce, and in which direction is the base? | 1.0 prism diopters base in |
| if the rx -3.00 +.50 x90 is decentered 2 mm to much how much prism will be created and in which direction is the base? | .50 diopters base out |
| As a corrected curve lens increases in minus power, the base curve tends to become gradually ? | flatter |
| as the radius of curvature of a spherical surface increases in length, its curve becomes gradually ? | flatter |
| as a corrected curve lens increases in plus power, the base curve tends to become gradually? | steeper |
| RX : plano -2.00x180 which of the following refractive conditions is this lens designed to correct? | simple myopic astigmatism |
| RX: +.50-.75x10 which of the following conditions is this lens designed to correct? | mixed astigmatism |
| Compound ophthalmic lenses usually of? | both cylindrical and spherical surfaces |
| the power of a cylinder along its axis contains ? | no cylinder power |
| The power of a compound lens in any given meridian will vary as the axis of the cylinder changes. which of the following lenses contain no power in the 90 degree meridian? | -2.50+2.50x180 |
| when a plus lens is moved closer to the eye its effective power | increases |
| when a high powered minus lens is moved closer to the eye the compensated power must? | be decreased |
| A +10 diopter lens is fit at a 14 mm vertex distance . a new frame is selected which positions the back surface of the lens 9mm from the cornea. the power of the new lens needed to compensate for the change in vertex distance is? | +10.50 |
| Its important to consider vertex distance in spectacle lenses when the power exceeds | +/- 7 diopters |
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