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Chapter 8: Flattening, Steepening and Torque of Incisions

Incision Flattening & Steepening

Chapter 8 looks at flat and steep corneal meridian and methods of incision flattening as well as planning toric IOL surgery.

Practical Astigmatism: Planning and Analysis book order -

Flattening, Steepening and Torque, Incision flattening, steepening, rotation, Corneal astigmatism, flat corneal meridian, steep corneal meridian The terms of flattening, steepening and torque. Please describe those for us as far as incisional surgery goes. The SIA is a composite parameter that includes how much the astigmatism has been reduced by flattening effect or how much it has been increased by steepening at the intended meridian or axis of astigmatic treatment. It also includes torque, how much it has been rotated in a clockwise or anti-clockwise sense. In a practical sense, if you get a keratometer and measure at the intended meridian and then you do the surgery, and measure at that point again with the same keratometer it shows you how much flattening or steepening happened at that axis. So the flattening effect is how much affect the SIA is having at the treatment meridian and what’s happened to the rest of the SIA which is the torsional effect. So SIA is a composite of flattening and torsion How much reduction in effect is achieved when an astigmatic treatment is misaligned? Using vector analysis and not just comparing magnitudes, an astigmatic treatment that is 15 degrees off-axis loses approximately 15% of the flattening effect and 30 degrees off axis results in a 50% loss of effect. It is not until the misalignment is 45 degrees that there is a 100% loss in flattening effect. This was shown in a recent paper by Dr Tognetto in the JCRS.



ASSORT® offers a comprehensive and informative guide, software and resources to better understand astigmatism analysis. Our guide can help you better understand how to ensure you have the right data and practices when performing incision flattening or planning toric IOL surgery.

Learn More About Incision Flattening & Steepening with Us

Our book, software and resources are built to help you improve your services and better understand steep and flat corneal meridian. We aim to give you a comprehensive, well rounded knowledge that will give you the tools to understand groundbreaking theory and put it into practice.

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