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Achieving emmetropia
For presbyopic IOLs, achieving emmetropia is important in order to fully realize the benefit of the lens. SurgiVision's pooled data for thousands of eyes shows that the best visual results and the widest range of vision result from having the sphere and the cylinder of the postop refraction as close to zero as possible. This applies to multifocal IOLs as well as the newer design accommodating IOLs.
 A postop result after presbyopic IOL implantation shows a plano result with no astigmatism. |
A decade ago, the primary source of postop refractive error was biometry. The axial lengths were measured by ultrasound, and even with immersion techniques, there was variability in the measurements. With the advent of optical methods of axial length biometry, the accuracy of our IOL calculations has improved, and we're closer to getting that desired plano result.
Keratometry is critical for both lens calculations, where 1 D of error in corneal measurement results in about 1 D of IOL power difference, as well as management of astigmatism. With corneal incisional techniques and toric IOLs, treating the pre-existing corneal astigmatism is possible and accurate.
The final frontier may be the modulation of healing so that the effective lens position of the IOL can be controlled. For most patients, achieving a postop refraction that is within 0.5 D of plano for the spherical equivalent, as well as astigmatism within 0.5 D of spherical, maximizes the results from surgery. And sometimes, with a little bit of luck, we're able to nail plano exactly and provide patients with both great vision and satisfaction.
Get more expert perspective from Dr. Devgan live at Hawaiian Eye 2010, to be held January 17-22, 2010 at the Grand Hyatt Kauai. Learn more at OSNHawaiianEye.com.