Visual acuity Conversion.pdf

LEARN HOW TO CONVERT VISUAL ACUITY

1. VISUAL ACUITY CONVERSION
KHULESH SAHU
(CONSULTANT OPTOMETRIST)
SAI BABA EYE HOSPITAL RAIPUR

3. HOW TO CONVERT METER TO FEET
1.6/6 6/6 = 20/x (Cross multiplication)
6x = 20*6
6x = 120
x = 120/6
x = 20
Ans. 20/20

4. 2. 6/18 6/18 = 20/X
1/3 = 20/X
X = 20*3
X = 60
Ans. 20/60

5. HOW TO CONVERT METER TO DECIMAL
1.6/12 6/12 = ½ = 0.5
2.6/24 6/24 = ¼ = 0.22
3.6/18 6/18 = 1/3 = 0.33
4.6/60 6/60 = 1/10 = 0.1
5. 6/6 6/6/ = 1/1 = 1

6. HOW TO CONVERT METER TO LOG MAR
•RULE
• CONVERT IN DECIMAL FIRST
•NEED LOG 10 CALCULATOR

7. 1.6/9 6/9 = 2/3 = 0.66 (Change in decimal)
Log (0.66) = 0.18 (Log calculator)
Ans. 0.2 Log MAR
2.6/24 6/24 = ¼ = 0.22
Log (0.22) = 0.65
Ans. 0.6 Log MAR

8. HOW TO CONVERT METER TO MAR
FORMULA

MAR = DENOMINATOR
NUMERATOR

9. 1.6/18 (HERE 6 IS NUMERATOR AND 18 IS DENOMINATOR)
18/6 = 3
Ans. MAR 3 MINUTES OF ARC
2. 6/36 36/6 = 6
Ans. MAR 6 MINUTES OF ARC

10. • ANTO LOG CALCULATOR
•NEED TO RULE OUT MAR VALUE
•FORMULA
MAR = DENOMINATOR
6
HOW TO CONVERT LOG MAR TO METER

11. 1.LOG MAR 0.18 (RULE OUT MAR)
LOG MAR = 0.18
MAR = 0.18/LOG
MAR = LOG-1 0.18
MAR = 1.51 MIN OF ARC
WE KNOW THAT
MAR = DENOMINATOR
6
1.51 = X/6
X = 1.51*6
X = 9.6
Ans. 6/9

12. 2. LOG MAR 0.78
LOG MAR = 0.78
MAR = 0.78/LOG
MAR = LOG-1 0.75
MAR = 6 MIN OF ARC
WE KNOW THAT
MAR = DENOMINATOR
6
6 = X/6
X = 6*6
X = 36
Ans. 6/36

13. VISION TAKING IN LOG MAR CHART

14. •Each line contains 5 optotypes
•Each letter has a score of 0.02 log unite
•Total score of each line is 0.10 log unite
( 0.02 x 5 = 0.10)
• formula
value of line read + 0.02 x No. of letter not read

15. 1
0.78
0.60
0.48
Value of line read + 0.02 x No. of letter not read
1 + 0.02 x 6 , 1 + 0.06 , 1.06
EX – IF A PATIENT MISSED 3 LETTERS FROM 1 LOG LINE AT 4 METER

16. 1
0.78
0.60
0.48
Value of line read + 0.02 x No. of letter not read
0.48 + 0.02 x 2 , 0.48 + 0.04 , 1.06 , 0.52
EX – IF A PATIENT MISSED 2 LETTERS FROM 0.48 LOG LINE AT 4 METER

17. •IF PATIENT CAN’T READ THE ANY LETTERS FROM TOP MOST LINE (1 LOG
UNITE)
•REDUCE THE MEASURING DISTANCE TO 2M OR 1M UNTILL THE TOP LETTERS
CAN BE SEEN
•NOTE FOR EVERY HALF REDUCTION ADD 0.3 TO THE LOG MAR ACUITY
- FOR 2M ADD 0.3
- FOR 1M ADD 0.6
- FOR 0.5M ADD 0.9

18. 1
0.78
0.6
0.48
Value of line read + 0.02 x No. of letter not read + 0.3
0.78 + 0.02 x 3+0.3 , 0.78 +0.06 +0.3 , 1.14
EX – IF A PATIENT MISSED 3 LETTERS FROM 0.78 LOG LINE AT 2 METER

19. Q & A SESSION
1.COVERT 6/24 METER INTO FEET
2. CONVERT 0.5 DECIMAL INTO METER
3.CONVERT 20/80 FEET INTO METER

20. 4. CONVERT 20/40 FEET INTO MAR

5.CONVERT 6/18 METER INTO LOG MAR
6.CONVERT LOG MAR 0.60 INTO METER

21. 1
0.78
0.6
0.48
0.3
6. IF A PATIENT MISSED 4 LETTERS FROM 0.6 LOG LINE AT 4 METER

22. 1
0.78
0.6
0.48
0.3
6. IF A PATIENT MISSED 1 LETTER FROM 0.3 LOG LINE AT 1 METER

23. ANSWER
1.20/80 2. 6/12 3. 6/24 4. 2 MIN OF ARC
5. 0.48 6. 6/24 7. 0.68 8. 1.4

24. REFERENCE
•Anti Log calculator on the basis of 10
https://www.omnicalculator.com/math/antilog