Measurements – Welch Allyn VS100 Welch Allyn Vision Screener - User Manual User Manual

Page 30

P/N 20146 Rev A

Page 30

Measurements

Refraction

Spherical Equivalent:

• Range:

-7.50D to +7.50D in 0.25D increments

• Accuracy:

-3.50D to 3.50D,

0.50D

-7.50D to < -3.50D,

1.00D

> 3.50D to 6.00D,

1.00D

Cylindrical:

• Range:

0.00D to +3.00D in 0.25D increments

• Accuracy:

0.00D to 1.50D,

0.50D

> 1.50D to 3.00D,

1.00D

Cylindrical Axis:

• Range:

1 to 180 degrees in 1-degree increments

• Accuracy:

± 5 degrees (for cylinder values > 0.5D)

Pupil size:

• Range:

4.0 mm to 9.0 mm in 0.1 mm increments

• Accuracy:

± 0.1mm

Pupil distance:

• Range:

35mm to 80 mm in 1 mm increments

• Accuracy:

± 1 mm

Time per measurement: 1 s

Measuring distance:

1 m ± 5 cm

Fixation target:

Random visual pattern and audible sound

Measurement principal: Optical reflex