Fine-Tuning Premium IOLs

What you can do to guarantee patients a premium experience

By Scott M. MacRae, MD, Len Zheleznyak, MS, Geunyoung Yoon, PHD

Premium IOLs require premium results. This starts with excellent communication between the staff and the patient. Perhaps the most challenging task is for the surgeon and staff to clearly describe the pros and cons of premium IOLs. In premium practices, the staff is well trained in assessing the patient’s needs and expectations based on their initial patient interactions. They can begin to educate the patient on options even before the doctor meets him or her.

The doctor’s assessment can confirm and add to the staff’s initial impressions and then elaborate on what the staff already discussed with the patient. It is helpful for the patient to hear the doctor confirm these options. If a patient does not have a realistic understanding of potential outcomes, a satisfactory result is less likely.

However, no matter what we do, some patients will be dissatisfied and have problems that will require corrective action. This article looks at some of the actions doctors can take to optimize premium IOL outcomes.

Causes of IOL Dissatisfaction

Understanding the potential pitfalls of premium IOLs helps to avoid them and manage them when they do occur. A Dutch study evaluated 76 multifocal IOLs that left the patients dissatisfied after implantation.¹ Ninety-five percent were dissatisfied because of blurred vision and 33% were dissatisfied because of what the investigators called “photic phenomena.”

The most common causes of dissatisfaction were ametropia, astigmatism, posterior capsular opacification (PCO), large pupils and dry eye. An Emory University study found a similar set of symptoms — plus an additional 15% with decentered IOLs.² In the Dutch study, 84% were successfully treated with refractive surgery, spectacles and laser capsulotomy, while 4% required lens exchange.

Taming Residual Refractive Error

In my experience, residual refractive error is the most common cause of patient dissatisfaction with premium IOLs. Multifocal IOL image quality is more sensitive to defocus and astigmatic errors. Investigators in Japan noted in a group of patients who had AcrySof ReSTOR (Alcon Surgical) multifocal IOLs implanted, most could tolerate up to 1.00 D of astigmatism.³ Another study noted up to 1.00 D of astigmatism and 0.75 mm of decentration is acceptable with the AcrySof ReSTOR IOL.⁴ These studies did not look at higher-order aberrations that can play a major role in patient satisfaction.

Our group has been interested in comparing the optical quality and performance of IOL modalities including multifocal, accommodative and other modified or mini-monovision. We’ve done this using an adaptive optics optical bench system that allows us to directly compare the multitude of premium IOLs available in Europe, Asia and the United States.⁵ We have carefully evaluated how myopia/hyperopia and astigmatism affect premium IOL optics and visual performance. Using the deformable mirror, we have the flexibility to correct these aberrations and add in aberrations to simulate clinical conditions and enable us to create optical designs of our choosing. The power of the adaptive optics system allows us to correct and induce aberrations to optimize these IOLs for distance and near vision.

We have evaluated the effect of sphere, cylinder and higher-order ablations on a number of IOLs, including the IQ ReStor +3 and ReSTOR Aspheric +4 (Alcon Surgical), Tecnis multifocal (Abbott Medical Optics), Lentis MPlus (OcuLentis), FineVision (Micro F) (PhysIOL), Crystalens AO and HD IOLs (Bausch + Lomb) and others (Figure). We used the AcrySof spherical monofocal IOL as a control.

The Lentis Mplus is interesting because it is a rotationally asymmetric refractive multifocal with a 3.00 D near power segment added to the lower half of the implant, similar to a traditional spectacle bifocal. The FineVision (Micro F) is also interesting because it is an apodized diffractive trifocal with adds of 1.75 D and 3.50 D. Unfortunately, the latter two lenses are not yet available in the United States.

Role of Spherical Refractive Error

We found spherical refractive error reduces image quality at distance and essentially shifts the image quality peak to the right (inducing hyperopia) or left (inducing myopia). Most multifocal IOLs have two image quality peaks: one at distance and a second at near at the targeted add power.

The FineVision (Micro F) is unique in that it has an additional intermediate image peak for a total of three peaks. With sphere, even though the image quality peaks shift, the magnitude of the peaks does not decrease. In other words, if we correct out the spherical refractive error, the patient gets the full benefit of the image peak and quality.

Optimizing Outcomes

These are steps you can take to optimize outcomes after implanting premium IOLs:

■ Manage higher-order aberrations. Higher-order aberrations are probably the most problematic preoperative condition. Screen for them carefully with preoperative topography because they can be difficult to treat afterward. We found that moderately increased levels of higher-order aberration above 0.4 m RMS (5 mm pupil) reduces both distance and near image quality.

■ Reposition toric IOLs. Toric IOLs need to be positioned properly and should be checked within the first two weeks after cataract surgery. Carefully marking the cornea at the 3 and 9 o’clock positions and then marking the correct axis with a corneal axis maker can easily reposition illpositioned toric IOLs. One method David Chang, MD, has described involves injecting balanced salt solution (BSS) with a 30-gauge bent tip cannula to reinflate the capsular bag and gently rotating the lens using the cannula tip.⁶ The best time to do this is in the first few weeks after the cataract surgery. Toric IOL eyes that have a combination of sphere and cylinder error will require LASIK or PRK.

■ Consider limbal relaxing incisions for mixed astigmatism. If a patient has 1.50 D or less of mixed astigmatism, LRIs can be effective, but they have limited predictability. LRIs can either be done intraoperatively or postoperatively. Relaxing incisions can be used sequentially in combination with LASIK if additional astigmatism treatment is necessary. A University of Texas Southwestern Medical Center study evaluated 73 eyes that had IQ ReSTOR +3 IOLs and were treated with LRIs, and 21 eyes treated with both LRI and LASIK. The combination group had a greater level of astigmatism, but actually had a greater percentage of 20/25 UCVA eyes (81%) compared to the LRI only group (76%). Nevertheless, LRIs are simple to do either intraoperatively or postoperatively.⁷

■ Treat dry eye. Pseudophakic patients are generally older and may be more susceptible to dry eye. This should be treated with aggressive lid hygiene, artificial tears, oral omega-3 supplementation, Restasis (cyclosporine, Allergan) or punctal plugs. These strategies improve the accuracy of the pretreatment refraction as well as expedite visual recovery after refractive surgery.

■ Revision LASIK and PRK. Laser refractive surgery can effectively treat spherical and cylindrical error. A minimum of three months is recommended after cataract surgery to allow the wound to heal. LASIK using thin flaps (less than 100 μm) allows for less neurotropic-induced dry eye. Clinicians uncomfortable with LASIK can perform PRK. PRK patients can progress with quicker visual recovery using two methods we developed:

► Mini PRK. Because most post-IOL refractive errors are relatively small and pseudophakic patients have relatively small low-mesopic pupil diameters, treatment of refractive errors can often be accomplished using a 7 mm-diameter area of epithelial removal rather than the typical 8.5 mm-diameter zone. This 30% reduction in the area of epithelial removal also reduces postoperative pain, and quickens reepithelization and visual recovery. A 7-mm diameter 20% alcohol well (6.5 × 8 mm elliptical diameter) can be used for treating larger amounts of astigmatism. This involves placing the long meridian of the well on the flat meridian that always has the most peripheral pulses when treating astigmatism. (The author developed the instruments but has no financial interest.)

► Simulate correction before treatment. Apply a −1.25 D therapeutic soft contact lens to the PRK eye immediately postoperatively to compensate for the postoperative myopia. This typically occurs because of the preferential central steepening the corneas have secondary to central edema, which decreases seven to 14 days, postoperatively. If both eyes are treated, I typically place a −1.25 D lens in one eye and a plano therapeutic soft contact lens in the contralateral eye, effectively inducing monovision for the first week until the lens is removed.

Before treating the patient, it is helpful to simulate the refractive error correction in a trial frame and let the patient walk around the clinic and even go outside to see if this helps solve the symptoms. This clarifies whether the treatment will be of benefit. It avoids the frustration of doing relaxing incisions or laser refractive surgery and subsequently leaving the patient disappointed.

When I am uncertain whether or not a patient will benefit from correcting a small amount of refractive error, I will prescribe the correction which can be placed in an old frame and have the patient test the new prescription for a few weeks, particularly under conditions that cause the symptoms. This way I can see if it improves the outcome. If it does not, we need to rule out other causes, including subtle PCO, CME or an epiretinal membrane if not already done.

■ Correct PCO. Patients who have multifocal IOLs typically are more sensitive to PCO. A low threshold for treating these patients is appropriate, but it is critical to clarify whether their vision was good before PCO. If the patient did not have good postoperative vision before the PCO developed, even with an optimal manifest refraction, then carefully consider why the visual quality is poor. Avoid posterior capsulotomy if you’re considering an IOL exchange.

If the patient has a combination of refractive error and PCO, correct the PCO first because the lens position may change. This is particularly true with an accommodative IOL where the lens flexes against the posterior capsule and may shift posteriorly after YAG treatment, thus changing the refraction.

Optimizing Outcomes and Expectations

The goal of premium IOL surgery is a happy patient. The surgeon and his or her team can facilitate this by explaining to the patient the variability of the IOL implantation and the potential need for refinements. If the patient knows this before cataract surgery, he or she will accept the need for additional minor surgery. OM

References

1. de Vries NE, Webers CA, Touwslager WR, et al. Dissatisfaction after implantation of multifocal intraocular lenses. J Cataract Refract Surg. 2011;37:859-865.

2. Woodward MA, Randleman JB, Stulting RD. Dissatisfaction after multifocal intraocular lens implantation. J Cataract Refract Surg. 2009;35:992-997.

3. Hayashi K, Manabe S, Yoshida M, Hayashi H. Effect of astigmatism on visual acuity in eyes with a diffractive multifocal intraocular lens. J Cataract Refract Surg. 2010;36:1323-1329.

4. Ben Yaish S, Zlotnik A, Raveh I, Yehezkel O, Belkin M, Zalevsky Z. Intraocular omni-focal lens with increased tolerance to decentration and astigmatism. J Refract Surg. 2010;26:71-76.

5. Zheleznyak L, Kim MJ, MacRae S, Yoon G. Impact of corneal aberrations on through-focus image quality of presbyopia-correcting intraocular lenses using an adaptive optics bench system. J Cataract Refract Surg. 2012;38:1724-1733.

6. Chang D, Repositioning Technique and Rate For Toric Intraocular Lenses; J. Cataract Refract. Surg. 2009;35:1315-1316.

7. Muftuoglu O, Dao L, Cavanagh HD, McCulley JP, Bowman RW. Limbal relaxing incisions at the time of apodized diffractive multifocal intraocular lens implantation to reduce astigmatism with or without subsequent laser in situ keratomileusis. J Cataract Refract Surg. 2010;3:456-464.

Scott M. MacRae, MD, is a surgeon, a professor of ophthalmology and a professor of visual science at the Flaum Eye Institute, University of Rochester Medical Center, Rochester, N.Y.