Intraocular Lens Power Calculations
The selection of appropriate formulas and surgical techniques is vitally important to best fulfill each patient's visual needs and expectations. With over 30 years of experience, H. John Shammas, MD clearly explains the importance of intraocular lens (IOL) power calculations during preoperative cataract evaluation and their role in positively improving surgical outcomes.
Intraocular Lens Power Calculations addresses both currently used and the latest, more advanced formulas. To fully understand the application of these formulas in various situations, thorough explanations are provided. Numerous highlighted clinical applications, case reports, figures, and tables are also utilized to illustrate and reinforce key points.
This well-organized text contains the most up-to-date information on axial length measurement, biometry units, constants, and ways to avoid errors. IOL power calculations and selection are included for an array of conditions ranging from the normal phakic eye to the more challenging high myopic and high hyperopic eyes, piggyback implantation, intumescent cataract, and the aphakic eye.
Intraocular Lens Power Calculations updates surgeons, technicians, and students on all the techniques and formulas available to achieve the most accurate and precise calculations, thus paving the way for surgical results that fulfill patients' visual needs.
- New formulas including Holladay, Olsen, and Haigis
- IOL power calculations after corneal refractive surgery
- Calculating for emmetropia and iseikonia
- High precision A-scan biometry
- B-mode guided biometry
- Optical coherence biometry
- Selecting the proper IOL power
About the Author
- Chapter 1: Basic Optics for IOL Power Calculations
- Chapter 2: Historic Overview
- Chapter 3: Modern Formulas for IOL Power Calculations
- Chapter 4: The Olsen Formula
- Thomas Olsen, MD
- Chapter 5: The Haigis Formula
- Wolfgang Haigis, PhD
- Chapter 6: The Refractive Formula
- Chapter 7: Calculating for Iseikonia
- Chapter 8: Physical Principles of A-Scan Ultrasound
- Shane Dunne, PhD
- Chapter 9: The A-Scan Biometer
- Chapter 10: A-Scan Biometry
- Chapter 11: High Precision A-Scan Biometry Using the Kohn Immersion Shell
- Gus Kohn, CRA, COT, ROUB
- Chapter 12: Axial Length Measurement of the Challenging Eye
- Pier Enrico Gallenga, MD, A. Mancini, MD, and A. Di Giovanni, MD
- Chapter 13:Avoiding Errors in Axial Length Measurement
- Chapter 14: Optical Coherence Biometry
- Wolfgang Haigis, PhD
- Chapter 15: B-Mode Guided Biometry
- Olivier Bergès, MD, Kamal Siahmed, MD, Michel Puech, MD, and Francois Perrenoud, MD
- Chapter 16: Measuring the Ultrasound Axial Length in Biphakic Eyes (IOLs in Phakic Eyes)
- Kenneth J. Hoffer, MD
- Chapter 17: Measuring the Corneal Power
- Chapter 18: Intraocular Lens Power Calculations After Corneal Refractive Surgery
- Chapter 19: Selecting the Proper IOL
- Chapter 20: The Unexpected Postoperative Results
"The formulas are presented in a simplistic manner, which allows one to grasp the development of the formulas without having to be lost in the minutiae of the math. I found this book to be excellent in all its aspects. I highly recommend it to all. It would be an asset to residents in training as well as practicing ophthalmologists."
— George H.H. Beiko, BM, BCh, FRSCS, Canadian Journal of Ophthalmology
About the Author
H. John Shammas MD
H. John Shammas, MD is a clinical professor of Ophthalmology at the University of Southern California, The Keck School of Medicine in Los Angeles, California, and the medical director of the Shammas Eye Medical Center and M/S Surgery Center in Lynwood, California.
As an ophthalmologist, Dr. Shammas has two major areas of interest; the first one is ophthalmic ultrasonography. He wrote his first textbook, Atlas of Ophthalmic Ultrasonography and Biometry in 1984, the second one, Three-Dimensional Ultrasound Tomography of the Eye in 1998, and edited his third one, Ultrasound in Ophthalmology, in 2000. His second area of interest is cataract surgery and how to improve its outcome. In 1991, he co-authored Color Atlas of Ophthalmic Surgery: Cataracts with Richard Kratz, MD. The combination of these two areas of interest can only lead to the subject of biometry and IOL power calculations.
Dr. Shammas has published multiple articles in the American and international literature on axial length measurement and intraocular lens power calculations. As an ophthalmic surgeon, patient satisfaction is very important to him, and avoiding errors in IOL power calculations has been a primary focus of his research studies. He self-published a book on the subject in 1996. Lately, he has focused his research on those cases that had previous refractive surgery, and Chapter 18 is dedicated to this subject.
This book represents the latest developments on the subject and the author’s personal experience during the past 25 years.