Advances in Single-optic Accommodating Intraocular Lenses Akkommodative 1-CU
The most recent clinical data on this accommodative IOL were published in August 2010 in the American Journal of Ophthalmology. In this non-randomized, prospective clinical study, the 1-CU was compared with three other types of IOL: a refractive multifocal IOL (ReZoom, Abbott Medical Optics), a diffractive multifocal IOL (Tecnis, AMO), and a monofocal IOL (AcrySof, Alcon).
This study enrolled 87 patients (87 eyes) with 24 patients implanted with the monofocal (group 1), 21 patients had the accommodating IOL (group 2), 22 patients had the diffractive multifocal (group 3), and 20 patients had the refractive multifocal (group 4). The patients were followed for 18 months and monitored for subjective refractions, monocular and binocular distance, intermediate and near uncorrected visual acuities, monocular distance and near best-corrected visual acuities, monocular distance-corrected intermediate and near visual acuities, stereopsis, visual complaints, and spectacle dependency.
The results found that there was no difference between the near and distance best-corrected visual acuity in all groups, while there was also no difference in the intermediate visual acuities in groups 2, 3, and 4 (p<0.05). The number of patients with better stereoscopic function, spectacle independence, and complaints of halo in groups 3 and 4 was significantly higher than in other groups (p<0.05). Based on these results, the authors concluded that the multifocal IOL patients had better visual function compared with the accommodative IOL (Akkommodative 1-CU) and monofocal IOL groups.10
The Importance of Quality of Vision With ever-increasing numbers of cataract patients opting for presbyopia- correcting IOLs, more scrutiny will be placed on the visual outcomes and quality of vision provided by these lenses. As mentioned in this article’s introduction, the visual trade-offs experienced by patients implanted with multifocal IOLs have been well documented.2
On the other hand, none of
the matters, such as glare, halos, or reduced contrast sensitivity, have been seen in patients implanted with accommodative IOLs. This is attributable to the moving single point of focus in these lenses. Or, in the case of the Crystalens AO, an aberration-neutral, aspheric optic. This design should provide better quality of vision, with no reduction in contrast sensitivity following surgery.11
The Crystalens AO is designed so that the aspheric anterior and posterior surfaces create no spherical aberration. In addition, due to the aberration neutrality of the optic, this IOL is suitable for all patient types; and, whereas visual performance of multifocal IOLs can be compromised by optical
1. Attitudes and Expectations. January 2010. Website of the American Association for Homes and Services for the Aging.
2. Leyland M, Pringle E, Multifocal versus monofocal intraocular lenses after cataract extraction, Cochrane Database Syst Rev, 2006;(4):CD003169.
3. Cumming JS, Kammann J, Experience with an accommodating IOL (letter), J Cataract Refract Surg, 1996;22:1001.
4. Laboratory data on file at Bausch & Lomb Incorporated. 5. Altmann GE, Nichamin LD, Lane SS, et al., Optical performance of 3 intraocular lens designs in the presence of decentration, J Cataract Refract Surg, 2005:31(3):574–85.
misalignment or pupil decentration, the performance of the Crystalens AO is not impacted by less-than-optimal conditions. What this also means is that when patients are implanted with this single-optic accommodating IOL, 100% of available light rays are available at all distances—so patients see near, intermediate, and at distance with equal clarity as the IOL moves forward and changes its radius of curvature as a patient accommodates at near or performs a visual task at a greater distance.
When the performance of a single-optic accommodative IOL is compared with multifocal IOLs, the advantages of this approach for correcting presbyopia become clear. In a study of modulation transfer function (MTF) using a 3mm aperture, the Crystalens AO demonstrated enhanced improved MTF performance over two multifocal lenses (AcrySof ReSTOR® and ReSTOR® Aspheric). In a separate study, using Air Force target photos to compare quality of vision also demonstrated better quality of vision with this accommodative IOL compared with two types of multifocal IOLs (ReSTOR and Tecnis) (see Figure 2).
Pre-operatively, this means careful biometry and IOL calculations, as well as assessing what Pepose calls the “total ocular characteristics” before operating. This includes corneal topography and careful slit-lamp examinations to identify any corneal irregularities.12
The
pre-operative work should also ensure that any ocular surface disease is diagnosed and addressed prior to surgery. Lastly, if there is more than 0.75 diopters of astigmatism, than either limbal-relaxing incisions or astigmatic LASIK should be planned in order to ensure the best possible outcome.
After surgery, the use of low- and high-contrast visual acuity provides a more accurate picture of a patient’s vision and can better pinpoint any issues should a patient refract to 20/20, but express dissatisfaction with the visual result.
Our clinical experience with the Crystalens AO, as well as the earlier models of this single-optic accommodating IOL, has been positive due to the fact that we are able to reduce or eliminate the need for glasses, particularly for reading, following cataract surgery. The added benefit of providing patients with a good range of vision, without any visual trade-offs, is an important reason for encouraging use of these presbyopia- correcting IOLs. n
6. Wolffsohn JS, Hunt OA, Naroo S, et al., Objective accommodative amplitude and dynamics with the 1CU accommodative intraocular lens, Invest Ophthalmol Vis Sci, 2006;47(3):1230–5.
7. Data on file, Surgivision® DataLink. 8. Colvard D, Doane JF, Kandavel R, Near, Intermediate, and Distance Vision 7 Years After Accommodating IOL Implantation. Annual Symposium of the ASCRS Abstract. 2011.
9. Sanders DR, Sanders ML, Tetraflex Presbyopic IOL Study Group. US FDA clinical trial of the tetraflex potentially accommodating IOL: comparison to concurrent age- matched monofocal controls, J Refract Surg,
2010;26(10):723–30.
10. Mesci C, Erbil HH, Olgun A, Yaylali SA, Visual performances with monofocal, accommodating, and multifocal intraocular lenses in patients with unilateral cataract, Am J Ophthalmol, 2010;150(5):609–18.
11. Pepose JS, Qazi MA, Edwards KH, et al., Comparison of contrast sensitivity, depth of field and ocular wavefront aberrations in eyes with an IOL with zero versus positive spherical aberration, Graefes Arch Clin Exp Ophthalmol, 2009;247(7):965–73.
12. Pepose JS, The impact of high-quality vision in patients with accommodating IOLs, Advanced Ocular Care, 2010;21–4.
The use of these two tests—modular transfer function and the Air Force target tests—raises other points that are important when discussing any type of presbyopia-correcting IOL: ensuring a quality visual outcome using careful pre-operative planning, as well as in the post-operative assessment. In a recently published article, Pepose makes the point that the use of presbyopia-correcting IOLs requires more than standard Snellen acuity assessment.12
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