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00213_Field_213.txt
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1997-10-28
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OPHTHALMOMETER MEASURING TECHNIQUE
Converting from Diopters to Radii
The ophthalmometer power drums marked with both dioptric and radius values and has a range from 35 D. (9.64 mm) to 60 D. (5.62 mm).
The dioptric value is converted to radius by using
the following formula:
(1.3375-1.00)
radius (meters)= -------------
diopters
Usually you want the value in millimeters, to
obtain the millimeter value you can multiply
the above result by 1000 or more easily use
the following formula:
337.5
radius (mm)= ----------
diopters
Most contact lens textbooks and manuals that come with the keratometer provide tables have conversion tables
Contact lens laboratories often supply them.