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Dual-optic Accommodating IOLs

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New generation of accommodating IOLs offers objective forward movement and significant pseudoaccommodative effect 

Many of our patients desire spectacle independence following cataract surgery. Ideally, we could provide them with perfect vision at all distances, in all lighting conditions, without dysphotopsia or any impact on quality of vision. Although no lens available today can do all that, we are getting closer to the ideal with newer accommodative designs. The original single-optic accommodating IOLs, while successful in many eyes, provide limited or inconsistent near vision. Our research measuring movement of these older accommodating IOLs with Scheimpflug photography demonstrated axial movement of less than 0.5 D1. The theory behind dual-optic lenses is that the combination of a high-plus anterior optic with a negatively powered posterior optic should be able to produce a significant amount of pseudo-accommodation with relatively small lens movements. We have been studying the first of these dual-optic lenses, the Synchrony Accommodating IOL (Abbott Medical Optics Inc., Figure 1). Movement of the lens has been objectively demonstrated with both aberrometry and ultrasound biomicroscopy.

Study results

 In the first 48 eyes of 24 patients implanted bilaterally with the Synchrony lens, visual acuity results have been excellent (Figure 2). Many of our patients are completely spectacle-independent or only use spectacles for prolonged reading of fine print. The average spherical equivalent is plano ± 0.70 D. And since light is not divided into multiple zones, contrast sensitivity with Synchrony is comparable to that of monofocal IOLs. 10 per cent of the eyes had very mild posterior capsular opacification (PCO).

Surgical Pearls

The lens is designed to be implanted through a 3.8mm incision. Although I prefer smaller incisions, there is one major advantage to having such a large optic. Like the crystalline lens, it fills the capsular bag completely, which may help to prevent PCO. I make the incision on the steep axis to reduce minor amounts of astigmatism and will occasionally place a temporary suture to reduce the chance of inducing cylinder. As with all accommodating IOLs, it is very important for the capsulorhexis to be round, perfectly centred, intact and free of notches. In order to allow the lens to move correctly, the capsulorhexis should be 5.0 to 5.5mm in diameter. I mark the cornea or use a forceps with a ruler for accurate sizing. One needs to have pristine cortical cleanup. Polishing the underside of the anterior lens capsule with low flow/ low vacuum settings helps prevent capsular contraction and fibrosis. The goal with any accommodative IOL is to ensure that the capsule remains crystal clear and flexible. Before implanting the IOL, I fill the bag with cohesive viscoelastic. Synchrony comes pre-loaded in a disposable injector that ensures the lens unfolds in a slow, controlled fashion inside the bag. OVD removal is best achieved with bimanual I/A to access the space between the two optics.

Patient selection

Although dual-optic accommodating IOLs are an important addition to our armamentarium, we continue to implant a full range of presbyopia-correcting IOLs to meet patients’ needs. For the patient who is most concerned about superb near vision and doesn’t mind the potential for nighttime glare and halo, I might opt for a multifocal IOL. In patients who want good spectacle independence at all distances and the highest possible quality of vision, or those who spend all day at the computer, my preference is a dual-optic accommodating IOL. Because the dual optics are monofocal optics, these lenses may also provide some security to surgeons or patients who are concerned about future macular or retinal developments. I have implanted a Synchrony lens in a healthy eye that later went on to develop an epiretinal membrane. Following macular surgery, the patient is back to 20/20 UCVA and continues to enjoy the benefits of the dual-optic lens without any loss of contrast or light transmission. Dr Marques is head of the Department of Ophthalmology at the Portuguese Red Cross Hospital in Lisbon, Portugal. Contact him at: References: 1. Marques EF. Objective measurement of anterior movement of an accommodating IOL, paper presentation, ASCRS, March 18 2006. 

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