High success rates are achievable with presbyopia-correcting intraocular lenses (IOLs). Patient selection and expectations—as well as good intraoperative technique and postoperative follow-up—lay the groundwork for positive outcomes with multifocal and accommodating IOLs.
In my group practice, between 15% and 20% of cataract patients elect to have presbyopia-correcting intraocular lenses (IOLs) implanted. Candidacy for a presbyopia-correcting IOL is based primarily on the patient’s ocular health and desire for reduced reliance on spectacles after cataract surgery.
My patient selection focuses on ensuring that an individual’s optical system can take full advantage of a presbyopia-correcting lens’ precise optics. I do not consider any particular psychological profile to be predictive for success with presbyopia-correcting IOLs, and I do not screen out patients who seem demanding. I do, however, make sure patients fully understand what to expect. If a patient has appropriate expectations, adequate corneal and retinal health, and no significant mental issues, it has been my experience that patients will in general be happy with a presbyopia-correcting IOL.
The Preoperative Exam
The key parts of my preoperative screening are the corneal topography, retinal ocular coherence tomography (OCT), and ocular surface evaluation. The corneal topography is one of the most helpful preoperative tests, as it can identify patients with conditions that suggest against implanting a presbyopia-correcting IOL. These conditions include frank or form fruste keratoconus, mild to moderate pellucid marginal degeneration, and nonspecific corneal asymmetry. Topography is of course critical for patients with previous laser vision correction, as it is important to ensure that the cornea remains symmetrical.
Corneal topography is also useful in evaluating patients with significant astigmatism, to see whether the astigmatism can be reduced with corneal procedures (ranging from limbal relaxing incisions to laser vision correction). Since patients with presbyopia-correcting IOLS are very sensitive to residual astigmatism, the topography helps determine whether the astigmatism can be safely reduced intraoperatively or postoperatively to help optimize the visual result.
OCT examination will make sure that no macular abnormality, such as epiretinal membranes or vitreomacular traction syndrome, is present which may affect postoperative vision. With the caveat that every case must be decided on its own merits, significant retinal and corneal topographic pathology will generally militate against the use of a presbyopia-correcting IOL.
The Ocular Surface
Compared to retinal pathology, the treatment of ocular surface issues is relatively straightforward; and treatment of ocular surface problems will typically enable implantation of a presbyopia-correcting IOL.
If the patient shows signs or symptoms of dry eye disease, I will first try to determine whether the condition is due to aqueous deficiency, meibomian gland dysfunction, or both. If the primary issue is aqueous deficiency, I will often treat with punctal plugs and start patients on a short course of topical steroid plus long-term cyclosporine. I will then bring the patient back in 7 to 14 days and reevaluate.
For evaporative dry eye, I favor heat and massage. The LipiFlow® Thermal Pulsation System (TearScience), which combines gentle compression with warming of the lids, is a very promising way to provide this. If successful, it may prove excellent ocular surgery preparation for many patients. In the absence of LipiFlow or a similar device, I make use of warm compresses, topical steroid, and azithromycin.
There are many reasons to optimize the ocular surface prior to surgery; one of the most important is to ensure accurate biometry. Success with presbyopia-correcting lenses, especially multifocals, requires a plano or near-plano postoperative refraction. That, in turn, requires accurate biometry.
Excessive variance in measurements of the same parameter—either from a single device or between devices—is a sign that something is amiss. For example, the keratometry value from topography should match the value produced by the IOLMaster (Carl Zeiss Meditec), and multiple readings with either instrument should be tightly grouped. When that isn’t the case, often the issue is ocular surface drying between readings. If the numbers do not look reliable, I typically treat the ocular surface condition and bring the patient back another day for repeat measurements.
Once the ocular surface appears healthy and the biometry values look trustworthy, I examine the patient’s astigmatism. If it is mild or easily correctable, I will implant a presbyopia-correcting IOL. Surgeons will determine their own cutoff values for corneal astigmatism; I consider presbyopia-correcting IOLs in patients with astigmatism of less than 2.00 D. Greater amounts of corneal astigmatism will likely lead me to suggest the patient consider toric IOLs and blended vision.
What I have learned from my own and from colleagues’ experience is that all of the available presbyopia-correcting IOLs can work. All three—the accommodating Crystalens® (Bausch + Lomb), and the multifocal AcrySof® IQ ReSTOR® (Alcon) and Tecnis® (Abbott)—represent good technology. Although each has specific strengths and weaknesses, a surgeon can succeed with any of them.
With experience, surgeons become familiar with their lens of choice and become adept at helping patients form appropriate expectations. This greatly increases the chances of patients making the right decision and being happy with the outcome.
For example, I most often use the Tecnis multifocal. I explain to patients that it provides very high quality vision for distance and for near. The intermediate vision, while usually strong enough to function well with, can be less crisp. Some patients may find that they have to hold things slightly closer than before to keep them in perfect focus. In addition, I educate patients that they may see halos around lights at night. This is rarely a significant problem and it almost always improves over time, but patients should be made aware of the possibility preoperatively.
Even when one is planning to use a multifocal IOL, there are intraoperative situations in which it is wise to change one’s plan and implant a monofocal lens instead. Any type of complication that makes it impossible to center the multifocal lens is cause to consider a change. If, for example, loose zonules are encountered, or if the capsular bag is not intact enough to keep the lens centered, then a monofocal IOL may be the better alternative. Presbyopia-correcting IOLs are a wonderful technology, but not every patient loves them; and complications during surgery can significantly lower the chances for success.
Intraoperative aberrometry, because it allows us to correct small miscalculations and improve refractive results, can potentially be helpful with multifocal IOLs.
Cystoid macular edema (CME) that develops after surgery can affect vision and reduce patient satisfaction. Thus, it is important to use both a steroid and a nonsteroidal anti-inflammatory drug (NSAID) after surgery, and to continue the NSAID long enough to reduce the risk of CME.
After surgery it is important to continue monitoring for dry eye, as it can degrade vision and lead patients to be unhappy with their lens. If there are signs or symptoms of ocular surface dryness after surgery, I will treat with artificial tears, cyclosporine, punctal occlusions, and other modalities as appropriate. The key thing is to keep the ocular surface healthy so as to maximize the quality of the vision.
Finally, if there is sufficient postoperative refractive error, and if the patient is unhappy with his or her vision, I will use laser refractive surgery or limbal relaxing incisions to achieve the desired refractive result. Typically, laser enhancement will take place 2 to 3 months after surgery. If a YAG capsulotomy is to be performed, I will do it before I use the excimer laser, as the capsulotomy can affect the refractive error.
In the end, almost all of my presbyopia-correcting IOL patients are happy with their vision. The satisfaction rate is not 100%, but it is high enough to make implanting presbyopia-correcting IOLs an important and satisfying part of my practice.
THE BOTTOM LINE
Success with presbyopia-correcting IOLs begins with the selection of patients who have good retinal function, low (and regular) corneal astigmatism, and a healthy ocular surface. Because a good tear film is critical for accurate biometry, ocular surface conditions should be treated before surgery, with treatment continued afterwards to ensure good postoperative vision. All current presbyopia-correcting IOLs can work well; the key is that patients know to expect the kind of vision each can provide. After surgery, CME prophylaxis and continued treatment of ocular surface disease help ensure patient satisfaction. If needed, laser vision correction can be used to eliminate residual refractive error.
William B. Trattler, MD, specializes in refractive, corneal, and cataract surgery at the Center For Excellence In Eye Care, Miami, FL. He is a consultant for Abbott Medical Optics, Allergan, and Bausch + Lomb. Medical writer Tony Hampton assisted in the preparation of this manuscript.