What is a good LogMAR score?

The World Health Organization established criteria for low vision using the LogMAR scale. Low vision is defined as a best-corrected visual acuity worse than 0.5 LogMAR but equal or better than 1.3 LogMAR in the better eye. Blindness is defined as a best-corrected visual acuity worse than 1.3 LogMAR.

How is visual acuity rating calculated?

The VAS scale (VAS = Visual Acuity Score) serves the same purpose. Its formula is: 100 – 50 x logMAR or 100 + 50 x log (V). It is more user friendly, since it avoids decimal values and is more intuitive, since higher values indicate better vision.

How do you use a LogMAR chart?

1. Ask patient to read down chart with one eye covered.
2. Note how many letters are read correctly until none of the letters on a line are.
3. read correctly.
4. Read off vision score from chart.
5. Repeat with pinhole if the vision is worse than 0.2.
6. If logMAR vision is worse than 1.0, retest at 2m or 1m (see over page)

How do you calculate LogMAR vision?

The formula: logMAR acuity = x – 0.02y, where x is the logMAR value of line completely read by the subject and y is the number of letters read in the low- er row. Applying this method to the example above (Snellen acuity 6/12+2), the logMAR value of the let- ters read is: 0.3 – 0.02 (2) = 0.26.

What is best corrected visual acuity?

Legal blindness is said to be present when best-corrected visual acuity is 20/200 or less in each eye.

Is LogMAR more accurate than Snellen?

Initially used as a research tool because it is more accurate than other acuity charts, this accuracy is also valuable in the clinical setting and many eye departments now use it routinely….Snellen and LogMAR acuity testing.

Is minus 3.5 eyesight bad?

If your number is between -0.25 and -2.00, you have mild nearsightedness. If your number is between -2.25 and -5.00, you have moderate nearsightedness. If your number is lower than -5.00, you have high nearsightedness.

What is the meaning of 6 36 vision?

Normal distance vision is recorded as 6/6. In the USA, this is known as “20/20” vision (measured in feet). In practical terms, Jane’s acuity of 6/36 means that, at a distance of 6m, she can read the row of letters that a fully sighted person can read at 36m.

What does LogMAR 0.2 mean?

The term LogMAR is an acronym for the Logarithm of the Minimum Angle of Resolution. The letter size is described in LogMAR units where LogMAR 0.00 is equivalent to 6/6 (20/20) and LogMAR 1.00 is equivalent to 6/60 (20/200). The letter size change in units of 0.1 LogMAR from one row to the next.

What is Bailey-Lovie chart?

The Bailey-Lovie chart features a stringent logarithmic progression of optotypes. The chart comes in a set of two panels (W x H 56 x 65 cm). One panel for measuring distance visual acuity at normal contrast, and one for measuring visual acuity at low contrast (contrast value=0.1).

What is the normal visual acuity range?

What does 20/20 vision mean? 20/20 vision is normal vision acuity (the clarity or sharpness of vision) measured at a distance of 20 feet. If you have 20/20 vision, you can see clearly at 20 feet what should normally be seen at a distance.

How to calculate the LogMAR score of a line?

Each letter has a score value of 0.02 log units. Since there are 5 letters per line, the total score for a line on the LogMAR chart represents a change of 0.1 log units. The formula used in calculating the score is: LogMAR VA = 0.1 + LogMAR value of the best line read – 0.02 X (number of optotypes read)

What is the LogMAR score for reduced acuity?

An observer who can resolve details as small as 1 minute of visual angle scores LogMAR 0, since the base-10 logarithm of 1 is 0; an observer who can resolve details as small as 2 minutes of visual angle (i.e., reduced acuity) scores LogMAR 0.3, since the base-10 logarithm of 2 is 0.3; and so on.

Why is LogMAR used in the clinical setting?

More recently, the LogMAR chart has been introduced into clinical practice. Initially used as a research tool because it is more accurate than other acuity charts, this accuracy is also valuable in the clinical setting and many eye departments now use it routinely.

How to read a LogMAR chart with one eye?

Ask patient to read down chart with one eye covered 2. Note how many letters are read correctly until none of the letters on a line are read correctly 3. Read off vision score from chart Repeat with pinhole if the vision is worse than 0.2 If logMAR vision is worse than 1.0, retest at 2m or 1m (see over page) Line Number letters correct logMAR 4m