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John Retzlaff MD


Dr. John Retzlaff was born on August 12, 1932 in Harlingen, TX and later moved to Jamestown, ND. As a young man he worked in his father’s Pharmacy (White Drugs) and aspired to become a pharmacist. After his 1st year in pharmacy school, his father suggested he consider becoming a physician and he changed course and in 1953, he began medical school at the University of North Dakota which at the time was a 2-year school. Then in 1955, he transferred to Harvard Medical School where he finished his last 2 years and received his MD degree in 1957.

He then took his internship at Washington University King County Hospital followed by a 3 year residency in internal medicine at the Mayo Clinic. After residency, he served 2 years in the US Army from 1962-63 and then moved to Medford, OR to practice internal medicine. In 1965, he returned to the Mayo Clinic for a residency in ophthalmology which he completed in 1968. He then joined the practice of John Weisel MD in Medford.

He took the Sinskey-Kratz phacoemulsification course at St. John’s Hospital in Santa Monica in 1973 and later performed his 1st lens implantation in 1976. He began working on IOL power calculation using linear regression analysis and felt that the answer just couldn’t be a straight line for calculating IOL power. But after many attempts to make adjustments to the Binkhorst formula he discovered he just could not fix it and settled on his Retzlaff regression formula. He first presented his results at the Thirty-Eighth Annual Convention of the Oregon Academy of Ophthalmology at the University of Oregon in Portland, OR on March 16, 1979. In attendance was Dr. Kenneth J Hoffer who was so impressed, he invited him to present his formula at the 1980 meeting of the American Intra-Ocular Implant Society (AIOIS, now ASCRS) in Los Angeles and to publish his work in the AIOIS Journal (now JCRS) in 19801. In preparing his paper, he discovered that Tom Lloyd and James Gills had already published their regression formula in the Contact Lens Medical Journal previously then in JCRS in 1978.

After meeting Drs. Manus Kraff and Donald Sanders at the Hoffer IOL Power Course that Fall at AAO, the 3 of them decided to collaborate and came out with the Sander-Retzlaff-Kraff (SRK) formula2 in 1981. To fix the problems in long and short eyes they later developed the SRK II3. After the success of the Holladay formula4 in 1988, Retzlaff used that theoretic formula to allow use of the familiar A constant and the SRK/T formula5 was published in 1990. The rest, as they say, is history.

John resides with his wife Tommi in Medford Oregon.

1. Retzlaff J. A new intraocular lens calculation formula. J Cataract Refract Surg 1980;6:148.

2. Sanders DR, Retzlaff J, Kraff MC. Comparison of the accuracy of the Binkhorst, Colenbrander and SRK implant power prediction formulas. J Cataract Refract Surg 1981;7:337-340.

3. Sanders DR, Retzlaff J, Kraff MC. Comparison of the SRK II™ formula and other second generation formulas. J Cataract Refract Surg 1988;14(2):136-141.

4. Holladay JT, Prager TC, Chandler TY, et al. A three-part system for refining intraocular lens power calculations. J Cataract Refract Surg 1988;14:17–24.

5. Retzlaff JA, Sanders DR, Kraff MC. Development of the SRK/T intraocular lens implant power calculation formula. J Cataract Refract Surg 1990;16(3):333–340; erratum, 1990;16(4):528