DOI: 10.1097/IIO.0b013e3181c552c9

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PMID: 20057300

Issn Print: 0020-8167

Publication Date: 2010/01/01


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Accommodating Intraocular Lenses: Theory and Practice

Jason Comander; Roberto Pineda

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Excerpt

Because of the challenges of the current presbyopic intraocular lenses (IOLs) as well as the increased cost to patients, many ophthalmologists do not recommend presbyopic IOLs to their patients. Despite the fact that ciliary muscle is still functional after cataract surgery,1 most patients undergoing cataract surgery are left with uncorrected presbyopia, which currently has no solution that approaches the elegance or effectiveness of the prepresbyopic crystalline lens and its accommodative system. In practice, many patients, especially the elderly, live with their presbyopia uncorrected other than with bifocal spectacles, impeding the vision that their cataract surgery potentially could have restored.2 One might argue that if a technique for cataract surgery becomes available that could preserve or even restore accommodation to its original level, it would create the largest improvement in the final visual outcomes of cataract surgery since the invention of the IOL itself. Fortunately, progress toward this “Holy Grail” is currently underway. This review will discuss the advantages of the accommodative approach over other treatments for presbyopia, the types of accommodating lenses that are currently available with their mechanism of action and empirical results, as well as discussing the many evolving technologies for restoring accommodation.
There are currently 5 fundamental approaches to treating presbyopia: spectacles, monovision, multifocal approaches, surgery on the accommodating structures of the eye, and accommodating IOLs. As simple a solution as spectacles seem from the perspective of an active ophthalmic surgeon, it can be a significant burden for the elderly, the disabled, or the poor.2 Using spectacles for near work (bifocals, progressives, or dedicated readers) places enough of a burden on patients that their presbyopia can sometimes go uncorrected.2 Bifocals themselves can contribute to falls in the elderly.3 Similarly, monovision is not tolerated by about one quarter of the population, is difficult to trial preoperatively in the presence of cataract, and reduces binocularity and depth perception.4,5 Multifocal approaches to presbyopia include multifocal contacts, multifocal corneal refractive procedures,6 and multifocal IOLs. Although there have been significant advances with these technologies, they all divide the incoming light into multiple images, some of which are out of focus at any given time. This reduces contrast sensitivity and can lead to unwanted photic symptoms such as glare and halos, and may not be ideal for patients with previously reduced contrast sensitivity like glaucoma patients.7 There are certainly patients satisfied with their vision after implantation of multifocal IOLs, though in 1 study, a comparison of 2 multifocal IOLs and an accommodating IOL showed greater satisfaction with the accommodative IOL.8 However, the fundamental limitations imposed by the multifocal approaches should help motivate the search for a truly accommodating solution. Surgery on the accommodative system, such as scleral implants, do not have the fundamental limitations described above, but have yet to show large and reproducible published effects, perhaps because their hypothesized mechanism of action plays a limited role in accommodation.9 Similarly, accommodating IOLs provide an opportunity to restore the native accommodation of the eye without the limitations of multifocal approaches. For this reason, accommodating IOLs may be the ultimate solution for presbyopia after cataract surgery.
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