Tutorial

Slides

The IOLMaster

Warren E. Hill, MD, FACS

Click on each slide to view a larger image.

	Slide 1. Typical interference fringes of alternating light and dark bands produced by a Michelson interferometer.
	Slide 2. The IOLMaster is the equivalent of an upright, noncontact, ultra-high-resolution immersion A-scan, consistently accurate to within 0.01 mm. Photo courtesy of Carl Zeiss Meditec.
	Slide 3. Measuring axial length with the IOLMaster allows a high degree of flexibility. Rather than simply positioning a small, in-focus image in the middle of a video screen, the operator can instead maneuver the focusing spot anywhere within the measurement reticule, and even focus in or focus out until a high-quality axial length display is obtained.
	Slide 4. The ideal IOLMaster axial length display should show a slender and straight primary maxima and a very thin terminal peak. The baseline may be slightly elevated and typically shows a set of secondary maxima. Out of 20 possible axial measurements, at least 4 should be within 0.02 mm of each other to ensure accuracy.
	Slide 5. On rare occasions, reflections from the surface of an IOL in the pseudophakic eye may produce a falsely short axial length reading if the measurement is taken through the IOL reflection. This has been seen with PMMA, silicone, and acrylic IOLs and can be avoided by moving the focusing beam away from the IOL reflection, while at the same time staying within the measuring reticule.