Certified Ophthalmic Medical Technologist (COMT) Practice Exam

What wavelength does the IOL Master use to measure axial length?

1. 600 nm (visible light)

2. 780 nm (infrared)

3. 850 nm (near-infrared)

4. 940 nm (infrared)

The correct answer is: 780 nm (infrared)

The IOL Master utilizes a wavelength of 780 nm, which falls into the near-infrared spectrum. This specific wavelength is chosen for several reasons. Near-infrared light is less absorbed by biological tissues than visible light, allowing for more accurate and non-invasive measurements of the eye’s internal structures, such as the axial length. This characteristic is essential in providing precise calculations needed for intraocular lens (IOL) implantation. In contrast, visible light at 600 nm is more easily absorbed, potentially leading to inaccurate readings. Wavelengths like 850 nm and 940 nm, while also in the infrared range, do not match the optimal measurement properties established for the IOL Master. Using a specific wavelength that is best suited for the anatomical and optical properties of the eye ensures the accuracy and reliability of the axial length measurement critical for successful cataract surgery and lens implantation.