Presbyopic Intraocular Lenses for Monocular Cataract

At one time, for the developed nations, the primary goal of cataract surgery was improved visual acuity, with or without the need for spectacles after surgery.

That was then.

Technology has evolved, and in certain settings, patients have come to expect spectacle independence as a desirable consequence of cataract surgery. A number of presbyopic strategies and intraocular lens (IOL) devices have been developed to reduce dependence on reading glasses postoperatively; clinicians may be challenged by decision-making in selecting an intraocular lens that will satisfy patients’ expectations. This is particularly so for the patient desiring freedom from spectacles but with monocular cataract. This specific problem is addressed in this issue of the Journal in an article from Mesci and associates. The authors provide insight to cataract surgeons and their patients regarding the benefits of implanting a presbyopic IOL in cases of monocular cataract for relatively young individuals (their study included patients between 40 and 70 years of age). As the authors designed their investigation, the primary optical goal of the cataract surgery was distance emmetropia as the fellow normal eyes in their study had little to no distance optical error. They assigned approximately 20 patients to each of 4 IOL groups. One group received a monofocal lens (SA60AT; Alcon, Fort Worth, Texas, USA), a second an accommodative lens (1CU; HumanOptics AG, Erlangen, Germany), a third a diffractive multifocal IOL (Tecnis ZM900 multifocal; AMO, Santa Ana, California, USA), and the last group a refractive multifocal IOL (ReZoom; AMO). When viewed at 18 months following surgery, as compared with the monofocal group, the patient groups with presbyopic IOLs achieved a measurable improvement in both uncorrected and distance spectacle-corrected intermediate and near visual acuities. Moreover, near stereopsis was also improved by use of the presbyopic IOLs when compared with the distance monofocal.

As might be expected, there were intergroup differences in optical performance based on the specific IOL design. However, because of relatively low enrollment numbers (87 patients overall), some of the observed differences did not achieve statistical significance. The 2 multifocal IOL groups achieved the best near vision and stereoacuity, albeit with greater degrees of undesired optical images, halos in particular. The accommodative IOL achieved better intermediate vision than did the monofocal IOL, but did not reach the same near acuity as did the 2 multifocal groups. Spectacle dependence was significantly lower in the 2 multifocal groups. These observations are in keeping with what we have come to understand from IOL design, from clinical practice, and from the established literature.

The results of the investigation suggest a definite patient benefit with use of presbyopic IOLs in the setting of a monocular cataract. Unfortunately, however, the results of the present investigation may not be extrapolated to other specific IOLs and the data may be of limited use to surgeons in the United States given that the HumanOptics accommodating IOL has not been studied by or approved for use by the US Food and Drug Administration. Moreover, in the United States the specific model of the Tecnis multifocal (3-piece silicone) employed in the investigation has been replaced by a single-piece acrylic model. Additionally, the most common presbyopic IOL currently implanted in the US, the ReStor (Alcon), was not included for study, nor was the Crystalens (Bausch & Lomb Surgical, San Dimas, California, USA), the only accommodative IOL currently approved for use in the US. Moreover, and curiously, the authors did not include a group of patients with surgically created monovision, employing a monofocal IOL for near vision tasks in the operated eye. The latter is frequently employed as a strategy to reduce spectacle dependence following surgery for monocular cataract.

It was interesting to note that patient satisfaction was high among all groups despite an understandable incidence of undesired optical aberrations associated with multifocal IOLs. However, not mentioned in the investigation was whether patients paid a premium price for their presbyopic IOLs. In common practice an additional fee is paid by patients for these devices. The net result is the potential for consumerism and an altered expectation of IOL performance on the part of the patient. Patient satisfaction in the general population, therefore, may differ from the experience of the patients in the authors’ study. Additionally, the authors did not employ a validated satisfaction survey, making it difficult to compare results of their investigation to other groups of patients or individuals. Nevertheless, in keeping with another recent study, the results of Mesci and associates’ study are very encouraging for outcomes with presbyopic IOLs and the “take-home message” for clinicians is that these devices should be considered when managing patients with monocular cataract. Surgeons should have a comprehensive knowledge base regarding presbyopic IOLs and be able to educate and guide patients in IOL selection. It should go without saying that patients must be good surgical candidates for presbyopic implants and have a strong understanding of their positive and negative attributes.

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Jan 17, 2017 | Posted by in OPHTHALMOLOGY | Comments Off on Presbyopic Intraocular Lenses for Monocular Cataract
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