Complications of multifocal intraocular lenses: What have... : Journal of Cataract & Refractive Surgery (2024)

^{This guest editorial is one of a series looking back at landmark articles published in the JCRS. This special series commemorates the 25th anniversary of the joint Journal of Cataract & Refractive Surgery. This issue: Dissatisfaction after multifocal intraocular lens implantation. Woodward MA, Randleman BJ, Stulting DR. J Cataract Refract Surg 2009;35:992–997; Dissatisfaction after implantation of multifocal intraocular lenses. de Vries NE, Webers CAB, Touwslager WRH, Bauer NJC, de Brabander J, Berendschot TT, Nuijts RMMA. J Cataract Refract Surg 2011;37:859–865; Distance and near contrast sensitivity function after multifocal intraocular lens implantation. Montés-Micó R, Alió JL. J Cataract Refract Surg 2003;29:703–711.1–3}

Multifocal intraocular lenses (IOLs) are designed to offer refractive correction at both near and distance, reducing the dependence on spectacles after cataract surgery. These lenses were introduced almost 3 decades ago. Soon after the widespread use of these IOLs, complications associated with them began to appear.

The first major study looking at the complications associated with multifocal IOLs was published in 2009. Woodward et al. reported on dissatisfaction after multifocal IOL implantation.¹ This group evaluated 43 eyes of 32 patients who had unwanted visual symptoms after implantation with the 2 major multifocal IOLs available at that time. Thirty patients (41 eyes) reported blurred vision, 15 patients (18 eyes) reported photic phenomenon, and 13 patients (16 eyes) reported both. When looking at overall causes of blurred vision, the most common finding was posterior capsule opacification (PCO) in 22 eyes (54%). Other causes of blurred vision included an ametropia (12 eyes [29%]) and dry eyes (6 eyes [15%]). When looking at the causes of photic phenomenon, the most common finding was also PCO (12 eyes [66%]); this was followed by IOL decentration (2 eyes [12%]) and dry-eye syndrome (1 eye [2%]). Photic phenomenon attributed to PCO also caused blurred vision. Overall, 35 eyes (81%) had improvement with conservative treatment. Five eyes (12%) did not have improvement despite different treatment combinations. However, only 3 eyes (7%) required IOL exchange. This study is important as it was one of the first major studies to look closely at complaints of blurred vision and photic phenomenon after IOL implantation. These authors found that most of the complaints were effectively managed with appropriate treatment and very few eyes required IOL exchange. This article also made the important point that YAG capsulotomy should be delayed until it has been determined that IOL exchange will be necessary.

A second major study out of Maastricht University in the Netherlands also reported on a group of patients who were dissatisfied after implantation of multifocal IOLs.² This group reported on 76 eyes of 49 patients with dissatisfaction and complaints after implantation of multifocal IOLs. Blurred vision (with or without photic phenomenon) was reported in 72 eyes (94.7%), and photic phenomenon (with or without blurred vision) was noted in 29 eyes (38.2%). Both symptoms were present in 25 eyes (32.9%). Residual ametropia and astigmatism, PCO, and a large pupil were the 3 most significant etiologies. Sixty-four eyes (84.2%) were amenable to therapy with refractive surgery, spectacles, and YAG laser capsulotomy being the most frequent treatment modalities. IOL exchange was performed in only 3 cases (4.0%). This article has many of the same similarities and echoes the findings noted in the landmark study by Woodward et al. in that the causes of dissatisfaction after implantation of multifocal IOLs can be identified and that greater than 84% of the eyes were amenable to treatment with resolution of their dissatisfaction and symptoms. Similar to the study by Woodward et al., these authors also found that IOL exchange was performed very uncommonly for patients with complaints after multifocal IOL implantation.

Findings of decreased contrast sensitivity after the implantation of a multifocal IOL were not a new phenomenon at the time of the publication of these 2 landmarks studies. Montés-Micò and Aliò reported on distance and near contrast sensitivity function after multifocal IOL implantation in 2003.³ They measured contrast sensitivity at distance and near in a group of 21 patients with a refractive multifocal IOL and compared it with a group with a monofocal IOL. These authors found that the multifocal IOL study provided contrast sensitivity at distance that was comparable with the monofocal IOL between 3 and 6 months after implantation. However, the results at near vision were always lower than at distance, and the multifocal IOL showed lower contrast sensitivity than the monofocal IOL when measured at near.

Multifocal IOLs split the light coming into the eye between multiple focal points to provide distance and near vision and some intermediate vision. This splitting of light can result in increased scattering of light and generation of multiple defocused images on the retina.⁴ This translates into more frequent or pronounced dysphotopsia compared with monofocal IOLs. This can also lead to issues with nighttime halos with the defocusing of the image. Multifocal IOLs can affect contrast sensitivity with increased visual disturbances such as glare and halos. This can be especially prominent in low-light conditions. A Cochrane database review looked at multifocal vs monofocal IOLs after cataract extraction.⁵ An extensive review/update of the efficacy and safety of multifocal IOLs after cataract and refractive lens exchange was published by Rosen et al. in 2016.⁶ These authors provided an extensive review of the literature on patient dissatisfaction with multifocal IOLs and the varying rate of problems with these lenses. An interesting finding from this review was that postoperative visual acuity does not guarantee that a patient will be satisfied with the result and that patient personality significantly affected the perception and tolerance of glare and halos.

Extended depth-of-focus (EDoF) IOLs have been developed to improve the range of vision after cataract surgery, especially at intermediate distances. These IOLs may provide improved visual acuity at intermediate distance and may cause fewer or less severe visual disturbances and fewer problems with contrast sensitivity.⁷ Kohnen and Suryakumar published a review/update on the EDoF technology.⁸ This extensive review went over the various types of EDoF IOLs and different designs of the optics. The clinical performance of these IOLs was also reviewed in this article. Kohnen and Suryakumar followed up this article with another review article measuring visual disturbance in patients receiving EDoF or trifocal IOLs.⁹ These authors reviewed the previous issues of multifocal IOLs associated with greater levels of positive visual disturbances such as halo, glare, and starburst that were presumably due to their inherent light-splitting technology. They concluded that “although EDoF IOLs have been designed to provide an extended visual range without inducing significant visual disturbances, current data suggest that diffractive-based EDoF optics do not achieve this goal.”

Although IOL technology continues to evolve in the quest for providing the best possible uncorrected vision, there is still a long way to go in providing aberration-free distance, intermediate, and near visual acuity after cataract surgery. Ongoing research into IOLs that will provide true accommodation will go a long way toward fulfilling this goal.

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