I therefore want to know in advance if the patient’s visual axis and limbal center are poorly aligned, not so that I can shift the implant, but so that I can avoid selecting a multifocal IOL.įigure 2. With current haptic technology, the lens has a tendency to center in the middle of the capsular bag, which is most closely correlated with the center of the limbus. It may be impossible, however, to keep an IOL centered on the visual axis if that axis is not closely in line with the anatomical center of the capsule. In the presence of a high angle kappa, for example, it is often recommended to deliberately decenter or “nudge” the IOL nasally in order to keep it on the visual axis. Many strategies have been proposed for clinically estimating the visual axis and optimizing centration of an IOL. The angle alpha is the distance from the visual axis to the center of the limbus (blue cross hair), which is useful for IOL implantation. The iTrace measures the distance between the visual axis, as estimated by the center of the first Purkinje reflex (red cross hair), and the center of the pupil (green cross hair), which is useful for LASIK. 1 Poor alignment of a toric lens with the visual axis may induce astigmatism, reduce the magnitude of the correction, or otherwise affect quality of vision.įigure 1. If a diffractive multifocal IOL is decentered relative to the visual axis, the patient may look through the diffractive rings rather than through the central optical zone as intended, which can induce higher-order aberrations and thus decrease postoperative visual function. Surgeons know that good centration of premium IOLs is critical. Excluding patients with a high angle alpha, using scanned capsule centration, and implanting a more forgiving multifocal IOL have produced excellent refractive results. The author has made measuring angle alpha a routine part of his preoperative workup for refractive cataract patients.Many strategies have been proposed for clinically estimating the visual axis and optimizing centration of an IOL.If a diffractive multifocal IOL is decentered relative to the visual axis, the patient may look through the diffractive rings rather than through the central optical zone as intended, which can cause deterioration of postoperative visual function due to an induction of higher-order aberrations. Good centration of premium IOLs is critical to successful outcomes.If You Could Do It All Again, Would You Choose Ophthalmology? How Three Companies Navigated the FDA Approval ProcessĪn Alternative to ABMS Maintenance of Certification Implantable Miniature Telescope Offers Hope to Patients With Advanced AMD Ten Years Later: Stromal Infiltrate and Lamellar Keratitis IOL Formulas for Refractive Cataract Surgery Using Angle Alpha in Premium IOL Screening The Ophthalmologist’s Role in Caring for Patients With Diabetes Enhancing the Delivery of Topical Ocular Drops
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