Correcting pseudophakic presbyopia remains one of the great challenges of modern cataract surgery. Existing multifocal IOLs are plagued by optical disadvantages such as poor image contrast, glare, and halos, all of which induce optical aberrations that lead to visual impairment and discomfort and that require IOL explantation in some patients.
IMPROVING ON DESIGN
Visiogen, Inc. (Irvine, California) has developed a dual-optic, silicone, single-piece, foldable, accommodating lens called Synchrony. The IOL features two optics connected by haptics that have a spring-like action. The optical power of the anterior optic is within the range of 30.00 to 35.00 D, and the posterior optic is assigned a variable diverging power in order to produce emmetropia for a given eye.1 The optical principle behind this lens design relies on axial displacement of the anterior optic, previously described by Stewart Cummings, MD, and others as in the range of 0.25 to 1 mm.2,3 This axial displacement is related to accommodative effort and theoretically produces changes of between 1.70 and 2.60 D in the eye's conjugation power. This amount of accommodation theoretically allows functional, unaided near vision in patients who receive the lens implant.
Accommodating IOLs promise to restore functional near, intermediate, and distance vision without inducing aberrations. Theories about how these accomodating IOLs work include the idea that the ciliary body directly causes the IOL to vault forward. According to this thinking, either the ciliary body presses on the lens, or the contraction of the ciliary muscle generates a pressure gradient between the aqueous and vitreous, actions causing anterior displacement of the lens zonule diaphragm and steepening of the anterior central lens curvature. If this theory is correct, then the amount of excursion generated (usually between 0.4 and 0.7 mm) limits the accommodative range of a single-optic design (such as the CrystaLens [Eyeonics, Inc., Aliso Viejo, CA] and the Akkommodative 1CU [HumanOptics, AG, Erlangen, Germany]). A dual-optic system with a highly powered anterior optic, such as that of the Synchrony IOL, does not need such a large excursion to achieve adequate intermediate and near focus. As a result, this design improves image quality at all distances.
EARLY EXPERIENCE
The first six patients to receive the Synchrony implant have achieved promising results. I was the only surgeon to perform the implantation surgery for all patients (six eyes). Each patient underwent endocapsular phacoemulsification through a 2.5-mm clear corneal incision after I performed a well-centered, round, 5.0-mm capsulorhexis. Next, I filled the chamber with viscoelastic, enlarged the clear corneal incision to 4.5 mm, and implanted the Synchrony accommodating IOL. At the conclusion of every procedure, I took special care to remove any viscoelastic remaining between the two optics. I sutured all incisions with an astigmatically neutral x-pattern suture. All patients received prednisolone sulfate 1% and ofloxacin. Researchers at Visiogen, Inc., performed power calculations for the IOLs by means of proprietary algorithms based on axial length, keratometry, anterior chamber depth, and lens thickness.
RESULTS
At the writing of this article, our first six patients had completed at least 1-month postoperative follow-up. Their BCVAs ranged from 20/20 to 20/30 in all cases. The patients' near UCVA ranged from J1 to J7, with five out of six patients (83%) achieving J3 or better. Once we placed the distance correction in the study eyes, five out of six patients (83%) attained J2 or better for near vision and did not need spectacle correction to read the newspaper or work at the computer. The implants are well centered within the capsular bag, and I have observed no signs of posterior capsular opacification at this point. No patient has complained of glare, halos, or other unwanted visual phenomena—a key point when comparing these results with those of refractive multifocal IOLs or even monofocal IOLs. Currently, not enough has been written in the literature regarding diffractive multifocal IOLs in order to compare their results with the outcomes of the Synchrony accommodating IOL.
POSITIVE FEEDBACK
The initial findings with the Synchrony lens are encouraging. To date, I have implanted more than 15 patients with this accommodating IOL, and all their results are similar in the immediate postoperative stages. Patients' satisfaction level with the lens is so high that I have even received an unusual request from a former patient. I implanted a conventional hydrophobic acrylic lens in the husband of one of my Synchrony patients 2 years ago. His surgery was uneventful, and he was happy with his outcome—until his wife received the Synchrony IOL. I have explained at length to the husband about how current protocol constraints prohibit me from using the Synchrony lens for monofocal IOL replacement, much to his displeasure.
Ivan L. Ossma, MD, MPH, is Clinical Professor of Ophthalmology at Fundacion Oftalmologica de Santander, Department of Ophthalmology Universidad Industrial de Santander, and is in private practice at Centro Medico Ardila Lülle in Bucaramanga, Colombia. He holds no financial interest in the technology and company described herein. Dr. Ossma may be reached at +57 76 39 27 27; iossma@foscal.com.co.
1. McLeod SD, Portney V, Ting A. A dual optic accommodating foldable intraocular lens. Br J Ophthalmol. 2003;87:1083-1085.
2. Hardman Lea SJ, Rubinstein MP, Snead MP, et al. Pseudophakic accommodation? A study of the stability of capsular bag supported, one piece, rigid tripod, or soft flexible implants. Br J Ophthalmol. 1990;74:22-25.
3. Lesiewska-Junk H, Kaluzny J. Intraocular lens movement and accommodation in eyes of young patients. J Cataract Refract Surg. 2000;26:562-565.
