![]() However, if it’s decentered, which commonly occurs with hyperopia, a zero aberration lens makes the most sense. “If the topography shows that the center of the cornea is steepest along the line of sight, a positive spherical aberration lens can actually give better quality of vision. “For these patients I would either implant a zero-aberration lens or a positive spherical aberration lens,” he says. Donnenfeld notes that hyperopic LASIK leaves the cornea steeper, inducing negative spherical aberration. But for special circumstances, having the full armamentarium of lenses available is helpful for matching the patient’s preoperative status and achieving the best postoperative surgical result.”ĭr. For routine cases, I generally choose a negative spherical aberration lens, unless the eye is unusual for the overwhelming number of patients, negative spherical aberration lenses yield better quality of vision. All of these play a role in my surgical armamentarium when managing patients undergoing cataract surgery. “There are negative spherical aberration lenses, low-negative spherical aberration lenses, zero spherical aberration lenses and positive spherical aberration lenses. “Today, these lenses are commonplace, and there are several different lenses that are available,” he says. These lenses achieved New Technology IOL status from the Centers for Medicare & Medicaid Services and were reimbursed at a higher rate than other lenses because it was proven that they improved people’s ability to function in tests such as driving ability. “The negative spherical aberration offsets the positive spherical aberration of the average cornea, resulting in better contrast sensitivity. “The advent of new-generation lenses occurred about 10 years ago when Pharmacia developed the aspheric IOL, which has negative spherical aberration,” he continues. ![]() Those aberrations led to glare and halo, a loss of contrast sensitivity and an overall loss of vision quality. “Previous generations of lenses had positive spherical aberration that added to the net spherical aberration of the cornea, resulting in patients having significant higher-order aberrations. Donnenfeld, MD, clinical professor of ophthalmology at New York University Medical Center and a partner at Ophthalmic Consultants of Long Island. “Intraocular lens design has been one of the great innovations in ophthalmology over the past decade,” says Eric D. (In fact, this strategy is now common-ly used to try to produce the best possible vision in eyes with virgin corneas, which normally have some spherical aberration as well.) Many surgeons try to counteract the alteration by choosing an IOL with a level of positive or negative asphericity that may offset it. But today, that’s not the only concern modern lens technology has made it possible to address the spherical aberration of the cornea, which may have been altered by that surgery. Here, three experienced surgeons share their insights about choosing an intraocular lens when a standard choice might not be ideal.Īs every cataract surgeon knows, determining the ideal power for an intraocular lens can be challenging in eyes that have previously undergone refractive surgery. ![]() In cataract surgery, this is often the case when the eye undergoing surgery is nonstandard. Surgery is a lot like life, in at least one respect: The greatest challenges we face are not the situations we encounter most often, but the ones that are exceptional in some way-the situations that require us to alter our strategy to achieve the best outcome. However, hyperopic ablations are often decentered then the positive asphericity could backfire and a zero-aberration lens would be preferable (bottom scans). When an eye has undergone previous hyperopic LASIK, an intraocular lens with positive spherical aberration may help to improve the patient’s vision-if the ablation is well-centered (above, top).
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