Chart Calibration scale, for Eye Exam Rooms

[Energy Conservation in Housing]

Chart Calibration scale, for Eye Exam Rooms

The attached PDF shows the size that 20/200 letters should measure, for various size eye exam rooms.

Measure the chair to chart distance.

Then adjust the height of the 20/200 letter to correspond to the matching chair to chart distance.

For more clarification, watch this video to show the process.

https://vimeo.com/129494305 

Chart Calibration for Eye Exam Rooms, 2015

[Energy Conservation in Housing]

If you don’t have access to this type of calibration scale, you can do it by calculation.  If you remember that the letter size for a 20/200 letter should be 87.25 mm, you can calculate for a specific room.

Say the chair to chart distance is 16 feet.  16 feet divided by 20 feet, times 87.24 mm will give the correct size of the 20/200 letter  -- about 70 mm.

Say the chair to chart distance is 22 feet.  22 feet divided by 20 feet, times 87.24 mm will give the correct size of the 20/200 letter  -- about 96 mm.

 ALSO, I have attached the M&S (computer screen) Chart Instruction Manual

(see the attachment, below)