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  2. Snellen chart - Wikipedia

    en.wikipedia.org/wiki/Snellen_chart

    A Snellen chart is an eye chart that can be used to measure visual acuity. Snellen charts are named after the Dutch ophthalmologist Herman Snellen who developed the chart in 1862 as a measurement tool for the acuity formula developed by his professor Franciscus Cornelius Donders .

  3. Visual acuity - Wikipedia

    en.wikipedia.org/wiki/Visual_acuity

    If the optics of the eye were otherwise perfect, theoretically, acuity would be limited by pupil diffraction, which would be a diffraction-limited acuity of 0.4 minutes of arc (minarc) or 6/2.6 acuity. The smallest cone cells in the fovea have sizes corresponding to 0.4 minarc of the visual field, which also places a lower limit on acuity.

  4. Eye chart - Wikipedia

    en.wikipedia.org/wiki/Eye_chart

    An eye chart is a chart used to measure visual acuity comprising lines of optotypes in ranges of sizes. Optotypes are the letters or symbols shown on an eye chart. [ 1 ] Eye charts are often used by health care professionals, such as optometrists , physicians and nurses , to screen persons for vision impairment .

  5. Near visual acuity - Wikipedia

    en.wikipedia.org/wiki/Near_visual_acuity

    Near visual acuity or near vision is a measure of how clearly a person can see nearby small objects or letters.Visual acuity in general usually refers clarity of distance vision, and is measured using eye charts like Snellen chart, LogMAR chart etc. Near vision is usually measured and recorded using a printed hand-held card containing different sized paragraphs, words, letters or symbols.

  6. File:Snellen chart.svg - Wikipedia

    en.wikipedia.org/wiki/File:Snellen_chart.svg

    You are free: to share – to copy, distribute and transmit the work; to remix – to adapt the work; Under the following conditions: attribution – You must give appropriate credit, provide a link to the license, and indicate if changes were made.

  7. List of instruments used in ophthalmology - Wikipedia

    en.wikipedia.org/wiki/List_of_instruments_used...

    to test colour vision ••Ishihara's chart: to determine the type of colour blindness Stenopaeic slit: detection of axis of the cylindrical (astigmatism) power of the eye; glaucoma testing Implants - •Intraocular lens: prosthetic lenses implanted after lens (anatomy) removal •Artificial eyes: as non-functional cosmetic implants into the ...

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    mail.aol.com

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  9. Sloan letters - Wikipedia

    en.wikipedia.org/wiki/Sloan_letters

    Sloan letters, designed by Louise Sloan in 1959, are a set of optotypes used to test visual acuity generally used in Snellen charts and logMAR charts. This set of optotypes consists of ten specially formed "letters", C, D, H, K, N, O, R, S, V and Z. [ 1 ] These letters, unlike the ones used in older Snellen charts, are designed to give acuity ...