Lens Replacement Eye Surgery vs. LASIK: New Study Favors LASIK as Safer Choice in Many Cases

Cataract Surgery Shown to Raise Long Term Risk of AMD, Suggesting Benefit to LASIK and PRK over Refractive Lens Exchange or Clear Lens Extraction in Many Cases. Many patients, particularly those with very early, mild, and slow growing cataracts, have the option of having either laser eye surgery (LASIK or PRK) or lens replacement surgery to lessen their need for glasses or contact lenses. Some patients with no cataracts at all also have an option of lens replacement surgery instead of LASIK or PRK. Often having laser vision correction is the more conservative and more prudent choice.

LASIK and PRK are laser eye surgery procedures which use the excimer laser beam to precisely reshape the cornea to correct vision. As such, they do not enter the eye but work on the outer layer of the eye, which improves their safety profile.

Lens replacement surgery is a procedure in which the natural lens (located inside the eye, behind the pupil) is removed and a replacement plastic lens, called an “implant,” is put in the eye in its place. The implant can be adjusted in its strength to correct nearsightedness, farsightedness, and astigmatism without the use of LASIK or PRK. In this way, lens replacement surgery can accomplish the goals of LASIK without the use of LASIK. However, because it enters inside the eye, lens replacement surgery is inherently more invasive than LASIK. This risk needs to be considered both in terms of the immediate risk of doing lens replacement surgery — as well as the long term consequences of having permanently changed the interior of the eye.

Today, lens replacement patients have the additional option of a new generation of “premium” implants whose goal goes one step beyond correcting nearsightedness, farsightedness, or astigmatism: the additional correction of presbyopia, or the age-related loss of close vision. These presbyopia correcting lenses include a flexible lens (the Crystalens) as well as multifocal lenses (e.g. the Technis Multifocal IOL and the ReSTOR Implant).

Lens replacement surgery typically (but not always) is cataract surgery — surgery in which a cloudy lens is replaced by a clear plastic implant. A cataract is a cloudy lens which interferes with vision. At the time of cataract surgery, therefore, a patient’s nearsightedness, farsightedness, or astigmatism can be corrected without the use of LASIK by choosing the appropriate implant strength. If a presbyopia correcting implant is used, then the addtional benefit of improved close vision can be obtained. Typically cataract surgery is performed when the cloudiness of the lens is inhibiting vision and the patient really has no other option for removing this cloudiness. In this way, cataract surgery actually accomplishes two goals: 1) the removal of the cloudy lens and 2) the correction of nearsightedness, farsightedness, and even presbyopia — all without LASIK.

If lens replacement surgery is performed on a lens that is clear and not cloudy, then technically this is not cataract surgery (there is no cataract yet), but is called “refractive lens exchange” or “clear lens extraction” instead. A presbyopia correcting premium implant such as the Crystalens, ReSTOR, or Technis Multifocal lens also can be used in this setting.

If someone truly has a cloudy lens — a cataract – that is interfering with vision, the best option for that patient is cataract surgery and not LASIK. The issue becomes a bit more complex, however, if the patient has a very minimal, slow growing cataract which is not significantly affecting vision. A patient like this who wants to lessen or eliminate dependency on glasses or contacts has the option of having LASIK like anyone else or simply having “premature” cataract surgery — in other words, having cataract surgery before it is visually necessary to remove the cataract in order to help relieve the burden of glasses and contacts. Some surgeons will advise “killing two birds with one stone” and advancing to cataract surgery to a much sooner date than would otherwise be necessary. Others recommend a more cautious approach and recommend LASIK instead — with the idea of pushing cataract surgery off into the future, only once it really becomes necessary.

Some surgeons take things even a step further and recommend lens replacement surgery even if there is no cataract or cloudiness at all, given that this approach ultimately will “kill two birds with one stone” and will also give the patient the additional potential benefit of presbyopia correction, or at least improvement.

The argument against jumping into lens replacement/cataract surgery before it is necessary — instead of doing LASIK — is that lens replacement surgery is inherently a more invasive surgery — and therefore carries a higher risk than LASIK. Lens replacement surgery is surgery performed inside the eye in which one structure is permanently removed (the natural lens) and a new structure (the implant) permanently is put inside the eye. LASIK, by contrast, does not enter into the eye and, as such, carries a lower risk of sight threatening complications. I personally tend to be quite conservative and try to avoid jumping into cataract surgery before it is necessary.

When thinking about the risk of lens replacement surgery, one needs to think both about the immediate risk of the surgery — but also about the long term risk of lens replacement surgery since the interior of the eye is permanently altered. A recent study published this month drives the cautionary issue of the long term risk of lens replacement surgery home. A study in the August 2012 issue of Ophthalmology showed that lens replacement surgery patients have a higher risk of developing macular degeneration (AMD) beginning 5 years after surgery — even if the surgery itself went perfectly and without any complications. Macular degeneration is the leading cause of blindess in the United States and involves degeneration of the macula, the central part of the retina. The researchers’ findings were based on 20 years of data following 5000 patients in a longitudinal study of the residents of Beaver Dam, Wisconsin. The researchers found this was a long term risk: they found that having cataracts or cataract surgery did not affect the chances of having macular degeneration within the first 5 years after surgery. After that, however, patients who had undergone cataract surgery had nearly double the chances of developing macular degeneration compared to those that chose not to have cataract lens replacement surgery (1.8 times).

In practical terms, there are long terms downsides to lens replacement surgery — one of which has now been shown to be a doubling of risk for macular degeneration down the road. By contrast, no association has ever been made to my knowledge between LASIK and an increased risk of macular degeneration. If someone has visual impairment from a cataract, then of course it still makes sense to have cataract surgery as modern cataract surgery is a wonderful, even miraculous procedure which can remove the burdensome cloudiness. However, lens replacement surgery is not, in my opinion, a good alternative to LASIK if the patient doesn’t really need the lens removed due to visually significant cataract change (or impending visually significant cataract change).

The take home message from this study, of course, is that it is better to delay lens replacement surgery as long as possible and, if a patient with a very mild, early, and slow growing cataract faces a choice between LASIK laser eye surgery now or lens replacement surgery now, I think LASIK is the more prudent and less invasive choice. In my own practice, I explain both options to patients (along with the option, of course, of simply doing nothing and continuing to wear glasses or contacts). I tend to be conservative in how I practice, however, and if the patient wishes to improve his or her vision in this type of situation, I recommend LASIK over lens replacement surgery. Of course, LASIK won’t stop the progression of the cataract, but the hope would be that the cataract continues to grow slowly and that the patient can enjoy many years of improved vision before ultimately needing cataract surgery. If the cataract is rapidly growing, but not yet visually significant, then I will typically recommend no surgery until cataract surgery becomes necessary. Often it can be difficult to determine the rate of growth of lens change — and no one really has a crystal ball — but it is always better to err on the side of conservatism.

Lens Replacement Eye Surgery vs. LASIK: New Study Favors LASIK as Safer Choice in Many Cases

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