doctor-hill.com
Carl Zeiss Meditec IOL Master
Cataract Surgery Arizona

IOLMaster — Axial Length Measurement
Results - Example Signal Curves.


Valid Signal Curves

Axial Length Measurement

  • Very good signals (signal-to-noise ratio > 10)
  • Several secondary maxima visible (system specific)
  • Clear media, correctly fixating patient
  • Weak ametropia

Axial Length Measurement

  • Clear signal (SNR > 2.0)
  • Secondary maxima visible
  • Relatively clear media

Axial Length Measurement

  • Valid signal in "Borderline SNR" range of 1.6 ... 2.0
  • Steep rise of measuring signal
  • Such readings are marked on the display by an exclamation mark and the message "Borderline SNR" appears.
IOL Master warning Warning
This reading may be used after verification and comparison with other data from this series of measurements.

Maladjustments on the Graph

Axial Length Measurement

  • Low signal (signal-to-noise ratio 1.6)
  • Error message is displayed.
  • The measuring signal cannot be clearly distinguished from the noise.
Possible reasons:
  • Unsteady (non fixating) patient
  • Strong ametropia
  • Dense medial opacity along the visual axis

Repeat the measurement!

Ask the patient to fixate steadily.