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Clinical pearls can guide success for using presbyopia-correcting IOLs
Ophthalmologists should have a complete understanding of patient expectations and the functionality of presbyopia-correcting IOLs.
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To ensure patient satisfaction after implantation with presbyopia-correcting IOLs, surgeons must balance device knowledge, surgical technique and patient characteristics.
Design and technique
 Samuel Masket |
Know how the lens works. Understanding the design and functionality of a presbyopia-correcting IOL is critical for proper implantation. The design of an apodized diffractive IOL, for example the AcrySof ReSTOR IOL (Alcon, Inc.), gradually tapers between different diffractive areas to evenly direct light, allowing the eye to easily focus from one vision range to another. There will not be a noticeable difference in distance visual acuity with the AcrySof ReSTOR apodized diffractive IOL compared with a monofocal lens (Figure).2
Bilaterally implant IOLs and capitalize on cortical summation. For optimal visual outcomes, the patient should have the same vision system in each eye. With bilateral implantation, the brain needs to interpret information from only one system, resulting in a clearer image vs. an image produced from an interpretation of information from two vision systems. In general, surgeons should plan to implant an IOL into the second eye as soon as possible after the first eye. My preference is within 1 to 2 weeks after the first eye. The uncorrected near and distance VA improves over time after bilateral implantation vs. monocular implantation.3 At 6 months, approximately 58% of patients with bilateral AcrySof ReSTOR IOLs had 20/20 distance vision or better compared with less than 30% for patients implanted with one AcrySof ReSTOR IOL. For near vision, over 60% of patients with bilateral AcrySof ReSTOR IOLs had near vision that was 20/25 or better compared with approximately 50% for patients implanted with one AcrySof ReSTOR IOL. The mixing and matching approach to presbyopia-correcting IOL implantation risks the adverse effects of both, but the summation factor of neither.
Correct and control astigmatism to less than 0.5 D. Addressing a patient’s astigmatism is imperative. The surgeon should use his or her best medical judgment in determining which options to choose to manage astigmatism. I encourage surgeons to be selective with patients with astigmatism.
Be willing and able to adjust the optical outcome. In my practice, I follow “The Four A Rule” to improve patient VA when implanting presbyopia-correcting IOLs. The first is “astigmatism control” prior to IOL implantation. Perform “accurate biometry” using the Zeiss IOL master or immersion A scan to obtain the correct length of the eye and the thickness of structures inside the eye. Use the “appropriate formulas” to determine IOL power calculations, and finally “adjust the outcome” according to the results from astigmatism control, biometry and formulas.
Perform good surgery, and do not allow surgery to limit the outcome. Good surgery begins preoperatively with proper eye measurements and evaluation of the cornea and macula. Good surgery entails a small precise incision, adjusting astigmatism and centering the IOL on the visual axis. A well-centered 5.0-mm capsulorrhexis is crucial for IOL centration. There should be no surgically induced damage to the zonules. Also, use topical nonsteroidal anti-inflammatory medication postoperatively to avoid cystoid macular edema and inflammation. Due to the multifocality of presbyopia-correcting IOLs, the eye is more sensitive to even low levels of macular edema, which could adversely affect outcomes.
| Binocular Defocus Curve – A Full Range of Vision  Figure. The AcrySof ReSTOR IOL directions for use showing clarity in ranges of vision for ReSTOR compared with monofocal IOLs.1 |
Patient evaluation and education
Perform accurate biometry. Surgeons should employ the Haigis, Holladay II, Hoffer Q and SRK-T formulas. Patients who have undergone laser correction require additional assessments. Often, surgeons overestimate the power of the cornea after myopic ablation and underestimate it after hyperopic ablation. Knowing the amount of ablation performed on the patient when he or she presents for cataract surgery will help determine correct measurements. IOL power usually depends on two factors: length of the eye and corneal power. The latter often poses a problem when determining the correct measurements of the eye in postexcimer cases.4 I developed the regression formula to adjusts the final IOL power: IOL adjustment (from the Zeiss IOL Master calculation) = D (prior laser treatment) x (–0.326) + 0.101.
Evaluate the eyes carefully and assess the patient’s desire for spectacle independence. The majority of patients choose presbyopia-correcting IOLs to become independent of spectacles. In the clinical trial, about 80% of patients implanted with AcrySof ReSTOR IOLs never wear spectacles compared with 8% of patients who received a monofocal IOL.5 Patients with diseases such as maculopathy, age-related macular degeneration, epiretinal membrane peeling or anterior basement membrane dystrophy may not be optimal candidates for multifocal IOLs due to irregularities surrounding the cornea and ocular membranes. The surgeon must be aware of these diseases to know how they could affect the outcomes of presbyopia-correcting IOL implantation.
Explain the benefits and tradeoffs of IOLs to the patient. Patients must have realistic expectations regarding the procedure. Surgeons should review expectations of post-surgical vision, including the possibility of adverse events. Although many presbyopia-correcting IOL options offer excellent vision outcomes, none can supply “seamless vision” over all distances. However, the AcrySof ReSTOR IOL offers most patients excellent distance and near vision and good intermediate vision. Some surgeons mix presbyopia-correcting IOLs to make up for less-than-excellent intermediate vision; however, this could compromise other visual ranges and cortical summation. Patients may experience some adverse effects, such as nighttime halos or glare, but with the AcrySof ReSTOR IOL these tend to diminish over time. In addition, posterior capsule opacification can occur, but this is a common adverse event for standard IOL implantation that should be addressed at an earlier stage than with traditional multifocal IOLs.
Establish credibility with both staff and patients. A consistent and clear message should be sent to patients at all times regarding the procedure and their multifocal IOL options. From a business standpoint, this is standard protocol for success. In a physician’s practice that offers premium procedures to its patients, everyone should be well versed in the entire procedure and its benefits and tradeoffs. The patients are customers paying for a premium service, and they expect to physically see the value of their investment. Implant the IOL, where appropriate, in staff members or family members to let your patients know that you believe in the technology.
Under promise and over deliver. Ensure realistic expectations through proper patient selection. I would avoid hypersensitive patients with unreasonable expectations. Performing impeccable surgery will keep patients satisfied and seeing more clearly. Be a sensitive and concerned patient advocate.
References
- AcrySof ReSTOR Apodized Diffractive Optic Posterior Chamber Intraocular Lenses, Models MA60D3 and SA60D3 - P040020: Summary of Safety and Effectiveness. Available at: http://www.fda.gov/cdrh/pdf4/p040020.html. Accessed December 6, 2006.
- Souza CE, Muccioli C, Soriano ES, et al. Visual performance of AcrySof ReSTOR apodized diffractive IOL: a prospective comparative trial. Am J Ophthalmol. 2006;141:827-832.
- AcrySof ReSTOR IOL. [package insert] Ft. Worth, Tex: Alcon Laboratories.
- Masket S, Masket SE. Simple regression formula for intraocular lens power adjustment in eyes requiring cataract surgery after excimer laser photoablation. J Cataract Refract Surg. 2006;32:430-434.
- AcrySof ReSTOR Clinical Trial Data. Alcon data on file from USFDA submission. December 2001-March 2005.
Dr. Masket is a clinical professor of ophthalmology at Jules Stein Eye Institute, University of California Los Angeles School of Medicine in Los Angeles, Calif. and also is in private practice. He is a consultant for Alcon Laboratories, Visiogen, PowerVision, Othera and Omeros.