This article is more than 5 years old. Information may no longer be current.
Always use topography to correct astigmatism postop with toric IOLs
Click Here to Manage Email Alerts
KOLOA, Hawaii – When correcting astigmatism after toric IOL implantation, be sure to always capture a patient’s topography, a presenter said here.
“The reason for that is that it’s never regular,” Jack T. Holladay, MD, MSEE, FACS, said during a mini-symposium on astigmatism correction at the Hawaiian Eye meeting. “What you end up with on almost all people is some asymmetric bowtie, which doesn’t change the axis, but makes the magnitude different in 3, 4, 5, and 6 mm and it’s always got a real curl to it so you can never be exactly sure of the axis. That’s why you have to look at the zone somewhere between 3 mm and 4 mm as opposed to looking in a ring, which is what a keratometer does.”
Jack T. Holladay
“In keratometry, if you have against the rule, add a half a diopter to the astigmatism to compensate for the changes,” he continued. “Subtract a half a diopter from with the rule.”
Physicians should also use an exact toric calculator to avoid errors in low and high power IOLs, Holladay said.
“However, if you do end up with a refractive surprise, or an unwanted residual astigmatism, be sure to use exact postop toric back calculation and it will tell you exactly how much to rotate the lens to achieve the minimum residual astigmatism,” he said.
According to Holladay, if the IOL ends up at 130°, by measuring the postoperative refraction, the orientation of the IOL and getting the K-reading, the exact amount of IOL rotation can be calculated. –by Daniel Morgan
Disclosure: Holladay is a consultant for Abbott Medical Optics, AcuFocus, Alcon Laboratories, Carl Zeiss Meditec, Oculus, Visionmetrics and WaveTec Vision Systems.