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30 Cards in this Set
- Front
- Back
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How is distance visual acuity assessed?
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The snellen chart.
Page 72 |
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At what distance is visual acuity assessed? What is the term given to this set distance?
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It is 20 feet (6m) away which is called optical infinity.
Page 72 |
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What eye should you start with when testing visual acuity?
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Left then the right.
Page 72 |
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What does 20/40 mean? What does 20/200 mean?
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20/40 means the patient can see the line 20' at what the average person sees at 40' away. 20/200 means the patient can see the line 20' what the average person can see at 200' away.
Page 73 |
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What if the patient can't see from 20 feet?
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The refractionist may ask the patient to stand 10 feet away.
Page 73 |
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What visual acuity is acceptable by the DMV?
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20/40
Page 73 |
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What does the tonometer test for?
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Tests the eye for intraocular pressure.
Page 73 |
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What is presbyopia?
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It is when the crystalline lens loses its flexibility and when it is unable to perform accommodation to see near.
Page 80 |
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What is a cataract?
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When the crystalline lens becomes cloudy.
Page 80 |
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What is a monocular patient?
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When the patient has one functioning eye.
Page 81 |
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What is strabismus?
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Muscle imbalance.
Page 81 |
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What is diplopia?
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Double vision.
Page 81 |
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What is macular degeneration?
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Mainly age related and affects individuals 65 and older.
Wet: Blood vessels grow in macular area which might break and leak. In a normal macula there are no blood vessels. Dry: Macular area becomes thin and pigments may deposit in the area. Blood vessels prevent cones from functioning correctly. Page 68 |
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What is emmetropia?
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An eye that has no refractive error.
Page 69 |
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What is ametropia?
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An eye that has refractive error.
Axial:eye too big or too small Refractive:refractive system of the eye is either too strong or too weak. Page 69 |
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What is myopia? What are the causes?
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Nearsightedness. When the image formed anterior to the retina. It is caused by the eye being too big or the refractive system is too strong. (steep) Requires minus lens.
Page 69 |
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What is hyperopia? What are the causes?
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Farsightedness. The image formed is posterior the retina. It is caused by the eye being too small or the eye's refractive system is too weak(flat). Requires plus lens.
Page 70 |
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What is simple myopic astigmatism?
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There are two images formed; one on the retina and one in front the retina. True powers of one plano and one minus.
Page 70 |
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What is simple hyperopic astigmatism?
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There are two images formed; one on the retina and one behind the retina. True powers of one plano and one plus.
Page 70 |
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What is compound myopic astigmatism?
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Two images formed in front of the retina. True powers are both minus.
Page 70 |
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What is compound hyperopic astigmatism?
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Two images formed both behind the retina.True powers of Rx both plus.
Page 70 |
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What is mixed astigmatism?
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Two images formed; one in front of the retina and one behind the retina. The true powers of Rx one plus and one minus.
Page 70 |
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What conditions are not considered to be refractive error?
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Cataract, aphakia, pseudopakia, strabismus, glaucoma, and sometimes presbyopia.
Page 70 |
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What is stereopsis?
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Binocular vision- depth perception- 3D images
Page 71 |
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What is fusion?
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The ability to convert separate images coming from both eyes to form one clear image. Takes place in the brain.
Page 71 |
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When will fusion take place?
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The images perceived by both eyes should be equal size to within 5%.
Page 71 |
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What is anisometropia?
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Not equal dificiency. A difference of 2.00D or more between OD and OS.
Page 71 |
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What is antimetropia?
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When the OD and OS have different signs.
Page 71 |
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What is the definition of the optic center of a lens?
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The point on a lens that light can pass through without bending (no refraction or prismatic effect) Also known as point of no refraction.
Page 102 |
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What is prism?
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A wedge shaped optical material.
Page 101 |
