IOL Power Calculations and Selection: Consider These Best Practices
During the Annual Cutting-Edge Symposium at the American Academy of Ophthalmology’s 2018 annual meeting in Chicago, Warren E Hill, MD, FACS, offered best practice advice about IOL power calculation methods and measurement devices.
Above all, Dr. Hill, Medical Director at East Valley Ophthalmology in Mesa, AZ, urges clinicians to track their outcomes. Not doing so “is a little bit like going to sea without a chart and rudder.” Additionally, “avoid the temptation to ‘automate and delegate’. The surgeon should be the most knowledgeable person in the process and should give guidance to the staff, not simply accept papers from staff and circle an IOL power. Become involved in the process and the outcomes will get better.”
Of the newer IOL formulas, Dr. Hill recommends these three, which perform well with all types of anterior segment anatomy:
- Olsen C formula. This utilizes a ray tracing method. “It is a bit more complicated than the others, so the lens constants need to come from Dr. Olsen, and the measurements need to be bioptical biometry.
- Barrett Universal II formula. “Of the modern formulas, this is probably the single most accurate formula. Those who are not using it really should begin. It works wonderfully in conjunction with optical biometry.”
- Hill RBF artificial intelligence formula.. “The second version was released earlier this year and paid special attention to very short and long eyes.”
“If you have an older biometer with only the older versions for the formulas, then I suggest using Holladay 1 formula, but with appropriate modifications,” for the high to extreme axial myope and axial lengths above 25 mm, explained Dr. Hill.
If you’re in the market for a measurement device, Dr. Hill suggests one that utilizes Swept source optical coherence tomography (SS-OCT) for axial measurements. “It’s going to be the standard in years to come.” The newer devices that use SS-OCT include:
- Zeiss IOL Master 700
- Movu Argos
- Tomey OA 2000
He added that the Zeiss device also measures parts of the cornea with SS-OCT for increased accuracy.
Hill W. Diagnostics and IOL Selection Methodology. Talk presented at: AAO 2018 annual meeting; October, 26-30, 2018; Chicago.