International Organization for Standardization (ISO)
Latest
ISO/TR 28980:2007
Scope
The purpose of this Technical Report is to explain the changes relating to power measurements in the revised
editions of ISO 8980-1 [6] and ISO 8980-2 [7].
In order to illustrate the issues raised, an inter-laboratory power measurement study was conducted on ten
different lenses measured by nine organizations worldwide. Twenty-five focimeters of different types were
used. The test lenses were spherically powered allyl diglycol carbonate (ADC)1) hard resin lenses surfaced to
–4,00 D, –2,00 D, 0,00 D, +2,00 D, and +4,00 D, each with an addition power of 2,50 D. Five were D28
bifocals and five were progressive power lenses. The measurements were front distance power, front near
power, back distance power and back near power, for each lens and for each focimeter used. Each lens was
measured nine times: five measurements taken without repositioning the lens and four measurements taken
with the lens repositioned each time.
The assessed parameters were divided into three categories:
discrepancies due to focimeter design and measurement methods;
systematic errors;
random errors.
For each parameter, experimental results are given, as well as theoretical ones when needed. Measurement
data include front distance portion power, front near portion power, back distance portion power and back
near portion power.
NOTE The results of all measurements are available on the ISOTC Server at the address given in the Bibliography[8].
Unless stated otherwise, in order to show relevant information, the results shown are for the D28 bifocals
when no different behaviour was found for the progressive power lenses.