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  Zeiss IOLMaster®
Online Users Instruction Manual V.4
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IOL Power Calculations IOL Power Calculations
Optical Biometry Optical Biometry
Lens Constants Lens Constants
Validation Guidelines
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Axial Length (ALM)
Best Technique
Summary of Results
Interpretation of Signals
Signal Curves
Pseudophakic Eyes
Clear Media
Mild Cataract
Moderate Cataract
Dense Cataract
Zooming Display
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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.


IOLMaster Help

Zeiss IOLMaster® Tutorial Version 4

Zeiss IOLMaster®

Optical Biometry

Intraocular Lens Power Calculations

East Valley Ophthalmology
5620 East Broadway Road
Mesa, Arizona 85206

Tel: +1-480-981-6111
FAX: +1-480-985-2426

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