Term
| What is the US definition of blindness? WHO's definition? |
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Definition
US: Worse than 20/100
WHO: Worse than 20/400 |
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Term
| What is the US definition of visual impairment? WHO definition? |
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Definition
US: 20/70 to 20/160
WHO: 20/70 to 10/400 |
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Term
| What is the ICD9 definition of moderate impairment? |
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Definition
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Term
| What is the ICD9 definition of severe impairment? |
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Definition
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Term
| What is the ICD9 definition of profound impairment? |
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Definition
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Term
| What is the ICD9 definition of near total impairment? |
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Definition
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Term
| What is the average age that a low vision child starts to walk independently? |
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Definition
| 18-24 months; normal vision children is 12-16 months |
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Term
| At what VA does a child possibly need help in developing walking and mobility? |
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Definition
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Term
| To what BCVA are brightfield magnifiers useful for children? |
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Definition
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Term
| At what CS does functional deficits begin to appear? |
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Definition
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Term
| How is cycles per degree calculated from MAR? |
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Definition
| Divide 30 by the MAR to get cycles/degree |
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Term
| How do you convert spatial frequency to VA? |
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Definition
| Divide 30 by the spatial frequency, the multiply by the test distance to get the snellen denominator |
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Term
| How do you convert VA to spatial frequency? |
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Definition
| Multiply the snellen fraction by 30 and solve for the quotient |
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Term
| How many 'points' for font size are there in 1 inch? |
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Definition
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Term
| What is the size of a 1.0M target? |
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Definition
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Term
| How to convert font 'points' to Snellen equivalent? |
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Definition
| Multiply font 'points' by 6.25 to get Snellen denominator |
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Term
| How to convert font 'points' to M notation? |
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Definition
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Term
| Name the different optotypes (7) in order of increasing difficulty |
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Definition
Grating
Tumbling E
Landolt C
Pictures/Shapes/Symbols (preferential looking, etc)
Numbers
Letters |
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Term
| Name the target presentation types (5) in order of increasing difficulty |
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Definition
Single character
Lind of random characters
Multiple lines of characters (full chart)
Single words
Continuous Text |
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Term
| What is the mathematical basis for VA levels in logMAR? |
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Definition
| Cube root of two per line (1.26) such that 3 lines then equals a doubling of acuity demand |
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