Trifocal IOL power calculation

Pentacam corneal map best for trifocal IOL power calculation using standard formulas.

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Photo of Roibeard O’hEineachain

Sergey Shukhaev MD
Intraocular lens (IOL) power calculations for trifocal IOLs performed with standard formulas appear to be more predictable when using keratometric data from total corneal power maps obtained using the Pentacam®(Oculus) than when using keratometric data from the IOLMaster, according to a study presented by Sergey Shukhaev MD, S. Fyodorov Eye Microsurgery Federal State Institution, St Petersburg, Russia. The study involved 45 eyes of 30 patients with axial lengths ranging from 23mm to 24mm who underwent femtosecond laser-assisted cataract surgery (FLACS) with a main corneal incision of 2.3mm and implantation of a trifocal diffractive AcrySof IQ PanOptix IOL (Alcon), Dr Shukhaev told the 24th ESCRS Winter Meeting in Marrakech. At one-to-three months postoperative, IOL power was calculated on the IOLMaster 500 (ver. 5.4 Carl Zeiss Meditec AG) using four formulas (Haigis, HofferQ, Holladay 1, SRK / T) and four different types of keratometric data, namely the IOLMaster, the total corneal power in the 4mm zone from the Pentacam Cataract Pre-Op map (map 1), keratometry in the actual zone from the Pentacam EKR Holladay report (map 2) and keratometry (axial/sagittal map) in the actual zone from the Pentacam Power Distribution. Their analysis showed that the deviation of the calculated refraction from the postoperative values of refractometry and subjective correction was significantly lower when using the Hoffer Q and Holladay 1 formula with the Pentacam total power map keratometric data than it was when using IOLMaster keratometric data, Dr Shukaev said. That is, the mean absolute error (MAE) when using the IOLMaster keratometric data was 0.60D with the Hoffer Q formula and 0.87 D with the Holladay 1 formula, compared to respective values of 0.37D and 0.64D when using the Pentacam map 1 data (p<0.05). There were no significant differences between the MAE obtained with the IOLMaster compared with the keratometric data Pentacam EKR Holladay map 2 and the Pentacam power distribution map 3, which had respective values of 0.51D and 0.59D, when using the Hoffer Q formula, and 0.78 and 0.57D, when using the Holladay 1 formula. “When calculating using the keratometric data from the Pentacam Holladay EKR Detail Report and Power Distribution cards, there were no significant differences compared to the IOLMaster data. However, there was a lower average calculation error when using data from the presented Pentacam cards compared to the IOLMaster data,” Dr Shukaev noted. Sergey Shukhaev: shukhaevsv@gmail.com