FEB 2014

EyeWorld is the official news magazine of the American Society of Cataract & Refractive Surgery.

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Page 24 of 114

E W NEWS & OPINION 22 February 2014 I nstead of using average human biometric measurements in determining correct IOL power, Kenneth J. Hoffer, MD, clinical professor of ophthalmology, by Ellen Stodola EyeWorld Staff Writer The Hoffer H-5 formula incorporates gender and racial differences U CLA, has created a new formula, named the Hoffer H-5, that uses gender and race specific averages to obtain more accurate measurements. This is quite different from all previ- o us formulas, and it even differs from the Holladay 2 and Hoffer H formulas, which use an average for axial length, corneal power, ACD, and other factors. The "H" in the n ame is in honor of Jack T. Holladay, MD, on whose formula it is based. Differences in averages for gender and race D r. Hoffer presented this Hoffer H-5 formula, which is the first fifth generation formula, at the 2013 American Academy of Ophthalmol- ogy meeting. "I realized that average values for human biometric meas- urements are only used in fourth generation formulas, like the Holladay 2 formula and the Hoffer H ," he said. "Most are not familiar with the Holladay 2 formula because it's never been published, and the Hoffer H formula, I never bothered to publish either." Dr. Hoffer said that one thought that came to mind when he was considering this formula was that the average biometry of women and men is different. "The average male axial length is about half a millime- ter longer and the average K is half a diopter flatter than in women," Dr. Hoffer said in his presentation. "There are also racial differences in these means of axial length, ACD and K." In order to come up with his new formula, Dr. Hoffer did thor- ough research (with the help of Giacomo Savini, Bologna, Italy) of the literature for the past 20 years, looking at biometry studies that had been done on large groups of pa- tients. It took him three months in all to collate the research. This was done in order to calculate the averages for the two genders and for various racial differences. He then utilized his 2004 Hoffer H formula (which is a copy of the Holladay 2 formula). "I replaced the average biometric values with gen- der and race specific values," he said. Following the input of gender and racial specific values, Dr. Hoffer did a study to determine how this would impact results. In the original formula, the patient's axial length would be a ratio of the average axial length, and the same thing would be done for other factors like K, corneal diameter, anterior chamber depth, and lens thickness. "What I've decided to do is ignore the patient's preoperative refractive error (in the Holladay 2) continued on page 24 13-25 News_EW February 2014-DL2-ALT-OIS-ad_Layout 1 1/30/14 3:58 PM Page 22

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