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Low vision chart


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Low vision chart

  4. 4. EARLY TREATMENT DIABETIC RETINOPATHY STUDY • It is based on log MAR chart. • Chart maintains a consistent number of letters (5) in each row with the optotype metric progression as follows: 40, 32, 25, 20, 16, 12, 10, 8, 6, 5, 4, 3, 2.5, 2 ft. • Geometric [LOG MAR] progression of size differences between lines. Optotypes on each line are 0.1 log unit, or 25% larger, than the preceding line.
  5. 5. The logarithmic progression and proportional spacing of optotypes allows for consistent and accurate evaluation of visual acuity levels Can be used at any distance, but testing distances are typically 4 m or 2 m The acuity obtained is easily translatable into Snellen 20-ft equivalent acuity by multiplying the fraction by 10/10. Available in  Landolt C configuration  Numeric optotypes  LEA Symbol Test System and  HOTV chart for pediatric low vision patients.
  6. 6. BAILEY LOVIE CHART – This chart is designed on a logarithmic basis. – Same no. Of letters at each level . – Between –letter & between-row spacing proportional to letter size . – Equal legibility for optotypes at each level. – Clinical scoring is reliable as each letter is given a score.
  7. 7. Advantage of log MAR chart over Snellen's chart • It is used to find minimum visual acuity . • It can be used for low vision patients. • The rate of progression is slow .Each line consists of 5 letters . • If the patient cant read the side letters ,this will give the motivation level to the patient . • It is measured at a distance of 3 meter the chart work up can also be done at a distance 1/2 meter .
  8. 8. Why Bailey Lovie Charts?? Advantages: • Choice of metric “M” notation or Snellen’s equivalent • A logarithmic size progression (constant ratio from one size to the next) • The same number of letters at each size level • Between-letter and Between-row spacing proportional to letter size • Equal (or similar) average legibility for the optotypes at each size level • Three choices of test distance (3m,4m and 6m)
  10. 10. Disadvantages • It is very costly. • Care should be taken .
  11. 11. CARDIFF ACUITY • The test is done at same eye level and the patients eye movement is seen . • It is a gross test and based on preferential looking . • It is the most common chart used for screening , visual acuity for pediatric patient . • The charts are changed fast so that patients eye movement can be seen.
  12. 12. • It is done at a distance of 1 meter and if patient can’t appreciate than the chart workup can be done at 1/2meter also. • The chart consist of a single picture object . • The patient is shown the first object and than the second card having the same object but at different position is shown or the same first card is rotated and shown to the patient . • Eye movements are observed.
  13. 13. • Pictures of various edge thickness are shown. • On a Rectangle Card , a picture is placed either on top or bottom and the other place is kept blank
  14. 14. • The pictures are of fish, house ,boat ,duck etc… • Another advantage of these chart is that the conversions in foot ,meter, decimal and log MAR for 1meter and ½ meter are given itself behind the card so that vision can be recorded accurately. •
  15. 15. FEIN BLOOM CHART • Fein bloom distance low vision flip chart. • Use at 10 Ft covers 10/10 to 10/700 all numbers. • Printed on styrene for durability with vinyl spiral bound covers. • The original Fein bloom low vision distance booklet is spiral bound at the bottom of the pages. • Size is 9×6 inch.
  16. 16. SLOAN CHART • This design given by lousie Sloan in 1959. • Sloan eye test uses logarithmic format and equivalent on each side. • Uses traditional opto type that follow a 5×5 grid idea. • They include log MAR , decimal , 10 feet , and meters for easy acuity recording. • This sets of opto types consist of 10 specially formed ‘’LETTERS’’ C D H K N O R S V Z.
  17. 17. • Charts comes in 3 scrabled version ( CAT. NO , 2120 A , 2120 B & 2120 C ) or an identical reserved opto type charts. • CAT. NO , 2120 R – used for mirror testing in smaller offices.
  18. 18. LEA’S SYMBOL • Four symbols are used (House, Square, Ball, Apple) • Based on Log MAR progression. • Tested at 4 meters. • Recorded in log units, which can be converted to Snellen fraction. • Key card is available
  19. 19. • The chart is available in simple as well as spiral booklet form . • The main card consist of 5 symbols with one symbols in centre and the rest 4 are located in circular form around the central symbol . • These arrangement is done in particular to develop both crowding and confusing phenomenon for the child difficulty
  20. 20. • The examiner shows normally centre symbol but at the same time he can ask for other symbols too. • The patient is given a key card to point out the symbol . • These symbols are fixed and are kept a standard like apple ,house ,circle ,square etc .. • The size of pictures goes on decreasing from 3/9.5 to 3/2.4 and there are four cards for each size .
  21. 21. ADVANTAGE • Use clinically tested opto type which provide a narrow acuity threshold. • Distance and near vision cards included in one binding. • Show both metric and English measure. • Can be used at 3 or 1.5 meters and near at 16 inch.
  22. 22. LEA PADDLE CHART • It is based on preferentional looking. • Two paddles are shown to the patient, one blank and another with stripes on it. • Thickness of the stripes goes on decreasing • Testing Distance is 1mt. • 0.25, 0.5, 1.0, 2.0, 4.0, and 8.0 cpcm (cycles per centimeter of surface)
  23. 23. • The chart is placed at a distance of 1m from the patient . • It is usually used for the age group of 3 to 9 months . • There are cards available of various thickness of lines .
  24. 24. • At a time two cards are held in front of the patient .The blank in front and the one with lines i.e. , held behind it . • Then immediately the second card is flipped out and we keep on changing the positions. • The patient should appreciate the card with lines . • The test is done at same eye level and the eye movement of patient is seen . • It is necessary to fixate the patients attention. • It give only approximate value and so we can’t.
  25. 25. LEA GREATING • It is based on log MAR chart. • Testing distance is 3 meter. • Used for pre school children.
  26. 26. TELLER CARDS • Almost same as lea paddle or Cardiff. • Based on preferentional looking test. • Testing distance at 3 meters. • Rectangle cards are used. • This can be used as measure of grating acuity. • Preferential looking test proves to be successful in checking visual acuity of children in age group 2 months to 12 months. • The Teller Acuity Test is also useful when testing adult patients who are unable to respond verbally during screening..
  27. 27. • Thickness of the stripes goes on decreasing • Patients fixation is noted by examiner through a peep hole. • Visual acuity from 6/60 to 6/6 is recorded.
  28. 28. ALLEN CARDS • It is same of teller. • Testing distance is 3 meters. • Different pictures like Horse, Car, Cake etc of different sizes are shown to the patient. • Patient has to identify the symbol. • No Key card available. • Visual acuity recorded from 6/60 to 6/6
  29. 29. • It consist of a set of seven card with each card containing a single picture . • It is usually used for 2 yrs old child and older . • The child is first shown cards at close range with both eyes open and is asked to name each picture . • Then one eye of patient is occluded the examiner shuffles the cards and presents them individually over greater distances.
  30. 30. THANK YOU