Visual Acuity
Examination
- Checks acuity with Snellen and from proper distance
- Checks acuity both eyes separately
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Typically measured by Snellen acuity but there are many optotypes (letters, tumbling E, pictures)
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May be tested at any distance started by 6 meters (20 feet)
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Recorded as fraction (numerator is testing distance, denominator is distance at which person with normal vision would see figure) e.g., 6/60
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Measured without & without glasses (BCVA & UCVA).
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Occlude one eye, children need to be patched
- 20/20 to 20/400, CF (counting fingers), HM (hand motion), LP (light perception), NLP (no light perception)
Examples of Visual Acuity Charts
- (A) Snellen chart.
- (B) Landolt C chart.
- (C) Illiterate E chart.
Hand-Held Eye Chart
- Hold card approx 14” from pt’s nose
- Read smallest line
- Ask pt to cover one eye
- Cover other eye and repeat
Pinhole View
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Difference between refraction or not
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Use: 1 A 1
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The pinhole (PH) exam can show refractive error
- Need a pinhole occluder
- Central rays of light do not need to be refracted
Near Visual Acuity
Examination
- Ask patient to wear glasses
- Hand-held card at 14 inches or 40 cm
- Assess both eyes separately
- Direct the patient to read the smallest letter that he can see
Hand Held Acuity Card
Near Vision
