Formula for achieving successful multifocal IOL outcomes

Reviewed by Karolinne M. Rocha, MD, PhD

Achieving a successful outcome with multifocal intraocular lens (IOL) implantation depends on a careful preoperative evaluation and nailing refractive error correction, said Karolinne M. Rocha, MD, PhD.

The preoperative evaluation involves gaining an understanding of the patient’s expectations, personality, and visual needs to determine whether the individual is a good candidate for a multifocal IOL and for what technology. A comprehensive ocular examination is also needed with special attention to pathologic conditions that can preclude an optimal visual outcome.

Because the available multifocal IOLs have different performance characteristics, surgeons need a thorough understanding of the different technologies, explained Dr. Rocha, director of cornea service, Storm Eye Institute, Medical University of South Carolina, Charleston.

Characterization of the patient’s lifestyle to understand his or her visual needs is important for guiding IOL selection. There are questionnaires available that can help surgeons gather the proper information.

However, Dr. Rocha cautioned that planning surgery based on the questionnaire responses and patient input does not guarantee good outcomes. She described an experience with her mother as a patient to illustrate this point.

“My mother completed a few questionnaires and indicated she wanted really good uncorrected visual acuity for distance,” Dr. Rocha explained. “When I followed her around to observe her usual activities, I saw that she was often using her cell phone or a tablet.”

Anatomical considerations

Anatomical considerations

Anatomical considerations include conditions affecting the back of the eye and the ocular surface. Dr. Rocha recommended against patients with category 3 or 4 dry age-related macular degeneration, anyone with an epiretinal membrane and thick retina, and glaucoma patients.

“In addition, it may be a good idea to have a plan B in case some anatomical feature that would preclude a good outcome with a multifocal IOL is found intraoperatively,” she added.

Figure 1 and 2: Dynamic measurement of the point-spread-function over a 20-second interval in normal eyes (control group) and mild dry eye syndrome.

Ocular surface optimization is also critical prior to planning surgery because an irregular ocular surface will affect biometry measurements used for surgical planning, as well as higher-order aberrations and visual acuity. In addition to performing standard evaluations for dry eye disease, Dr. Rocha said she conducts a thorough tear film analysis and measures the Ocular Scatter Index (OSI), using double-pass wavefront technology (OQAS, Visiometrics) that provides insight on retinal image quality and tear film stability.

“Double-pass wavefront technology provides a dynamic analysis of the point-spread-function, which is represented as the OSI, while the patient blinks normally over a 20-second interval,” Dr. Rochas explained. “We found that OSI in an eye with a healthy ocular surface will be low and stable, but that it can fluctuate and worsen during the testing period, even in patients with just mild dry eye and no ocular surface staining.”

Intraoperative aberrometry

Because accurate correction of refractive error is key for good visual outcomes with multifocal diffractive bifocal and trifocal IOLs, Dr. Rocha said she uses intraoperative aberrometry to check IOL power and toric IOL alignment.

Figure 3: Intraoperative correction of astigmatism with a toric extended-depth-of-focus IOL guided by intraoperative aberrometry.

In order to reduce astigmatism, intraoperative correction with limbal relaxing incisions is planned in some cases. Depending on the amount of pre-existing astigmatism, some patients may be told they will need a combined-staged procedure with postoperative laser vision correction.

Functionality of IOLs

Understanding the functional outcomes associated with the different multifocal IOLs is also critical so the technology can be matched to the patient’s visual needs. However, surgeons should understand that information obtained from optical bench testing may not translate to the real-life situation.

“Studies using a single wavelength (green light) at one spatial frequency are not necessarily achieved in vivo,” Dr. Rocha said. “Ideally, IOLs should also be analyzed under white light and multiple spatial frequencies.”

Figure 4: Astigmatism management: femtosecond laser limbal relaxing incisions and a combined staged procedure with postoperative laser vision correction.

Dr. Rocha noted that extended-depth-of-focus (EDOF) IOLs (Tecnis Symfony/Symfony Toric, Abbott Medical Optics) represent a new category of presbyopia-correcting IOLs available in the United States. This technology improves intermediate visual performance and near vision to a lesser extent without comprising distance vision.

The EDOF technology has the benefit of causing less glare and halos and less loss of contrast, especially compared to the first generation diffractive multifocal IOLs.

Looking ahead, Dr. Rocha said increased use of in vivo simulation, allowing patients to experience multifocality and compare different IOL designs, will become an important and useful component of the preoperative evaluation.

“This type of simulation is emerging in adaptive optics technologies that are friendly for use in the clinical situation,” Dr. Rocha said. “It should lead to increased confidence for patients and surgeons when choosing an IOL. It might also increase the number of multifocal IOL procedures performed along with overall patient satisfaction.”

Karolinne M. Rocha, MD, PhD

E: karolinnemaia@gmail.com

This article is based on a presentation given by Dr. Rocha at the 2016 Refractive Surgery Subspecialty Day meeting, prior to the American Academy of Ophthalmology meeting. Dr. Rocha is a consultant/advisor for Johnson & Johnson Vision Care (Abbott Medical Optics), Alcon Laboratories, Allergan, and Bausch + Lomb.