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Vision Screening

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Given to measure individuals visual acuity Given as part of physical exam or to detect eye disease Conduct exam in a well-lighted room (natural light, with no direct sunlight Watch for squinting, leaning toward eye chart, closing one eye when both eyes are being tested, excessive blinking, watering of eyes

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Snellen chart Used to test distant vision> nearsightedness=Myopia Come in a variety of types> some contain pictures for use with small children, some contain letters of the alphabet, some contain the letter E in a variety of positions (pt points in the direction that the E points- used for non English speaking people or nonreaders) When standing 20 feet from the chart, a person with normal visual acuity should be able to see characters that are 20mm high= 20/20 vision (top number represents distance and bottom number represents height of the characters)

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Examples Person has 20/30 vision Means when standing 20 feet from the chart, pt sees characters 30mm high Also, it means that this pt standing 20 feet from the chart can see what a normal visual acuity pt can see standing 30 from the chart Person has 20/100 >person can only see characters 100mm high standing 20 feet from chart >person with normal visual acuity would be able to see same figures while standing 100 feet from chart

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Hyperopia (farsightedness) Problems reading small print and seeing close up Use the Jaeger system to test Uses a printed card with different short paragraphs> each paragraph is printed in a different size type, ranging from 0.37 to 2.5mm high; card with different characters/pictures is available for small children or individuals who cannot read> card is held 14-16 inches away from eyes Pt will read printed text or identify pics that gradually become smaller> smallest print/pic that the pt can read without error is recorded

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Color vision Tested using the Ishihara method Ishihara book has a series of numbers printed in colored dots against a background of dots in contrasting color Pts with normal color vision can identify the numbers Pts with color blindness either are unable to see the numbers or identify incorrect numbers Most accurate conducted in a room with natural daylight and not bright sunlight

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Terms/Abbreviations OD= right eye (oculus dexter) OS= left eye (oculus sinister) OU= both eyes; each eye (oculus uterque) Myopia= nearsightedness> defect in distant vision Hyperopia= Farsightedness> defect in close vision Ophthalmoscope= instrument for checking the eyes Tonometer= instrument used to measure intraocular pressure (increased pressure could mean ?)

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Procedure Assemble equipment; check lighting; wash hands; introduce yourself; identify pt; explain procedure to pt Snellen: Pt will stand facing chart, toes on taped lined, pts eyes will be 20 feet from chart What if pt wears glasses/contacts? Watch and make sure pt is not? Use an eye shield (occluder) to screen each eye- Ask pt not to close eye that is covered. Why? Make sure you _________ occluder after each pt use. Use abbreviations OD, OS, OU to document results

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Jaeger Seat in comfortable position Pt to hold Jaeger card 14-16 inches from eyes Pt will read paragraphs out loud (If pt cannot read- provide Jaeger card that contains pictures/characters) Have pt read with OS, OD, and OU > record smallest line of print pt can read with OS, OD, and OU

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Ishihara (color vision) -Seat pt in a comfortable position -Hold plate approx. 30 inches from pts eyes -Ask pt to read number on the plate -Some plates contain color lines instead of numbers- Ask the pt to trace the line with a finger -Document how many plates the pt identifies correctly with OS, OD, OU - Report any frame that the pt misses so that the MD can determine type of color blindness