IOLMaster — Axial Length Measurement
Mild to Moderate Cataract.
Measuring a Cataract of Mild to Moderate Density
In measuring a cataract of mild to moderate density, the
IOL Master axial length display
should show the above characteristics. However, with increasing
cataract density, and decreasing signal-to-noise ratio, the secondary
maxima often disappear into the baseline. As long as the primary
maxima is narrow, and has a well-defined and centered terminal peak,
the measurement is considered valid.
If the signal-to-noise ratio of the eye to be measured is borderline
(2.0 to 1.6), focusing in, or focusing out, in such a way that
that focusing spot enlarges to about the same size as the measurement
reticule, will sometimes significantly improve the quality of the
axial length display. This is possible with the IOL Master because
axial length measurements by partial coherence interferometry are
Remember to use the Best Measurement Technique and
sample several areas around the center of the measurement reticule
until the best display is obtained. The important components of
accuracy with the IOL Master are: correct
alignment with the fixation light, measurement consistency, and
a correct display pattern. Experience has shown that this general
rule applies to signal-to-noise ratios as low as 1.6.