• Incorrect vertex distance will change effective power of a prescription
• Avoid costly remakes and troubleshooting time by measuring vertex accurately
• With each distometer, you will receive a conversion scale for easy calculations

Directions:

SELECT A NUMBER ON THE MILLIMETER SCALE THAT REPRESENTS THE DISTANCE OF THE TRIAL LENS FROM THE CORNEA, ROTATE TO ALIGN WITH THE POWER OF THE TRIAL LENS ON THE DIOPTER SCALE. THE POWER ON THE DIOPTER SCALE THAT CORRELATES WITH THE MILLIMETER SCALE REPRESENTS THE EFFECTIVE POWER OF THE LENS AT THAT DISTANCE. BE SURE TO USE THE MINUS MILLIMETER SCALE FOR MINUS LENSES AND THE PLUS FOR PLUS LENSES.