Accommodating intraocular lenses: a critical review of present and future concepts
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Significant efforts have been made to develop lens implants or refilling procedures that restore accommodation. Even with monofocal implants, apparent or pseudoaccommodation may provide the patient with substantial though varying spectacle independence. True pseudophakic accommodation with a change of overall refractive power of the eye may be induced either by an anterior shift or a change in curvature of the lens optic.
Materials and methods
Passive-shift lenses were designed to move forward under ciliary muscle contraction. This is the only accommodative lens type currently marketed (43E/S by Morcher; 1CU by HumanOptics; AT-45 by Eyeonics). The working principle relies on various hypothetical assumptions regarding the mechanism of natural accommodation. Dual-optic lenses were designed to increase the dioptric impact of optic shift. They consist of a mobile front optic and a stationary rear optic which are interconnected with spring-type haptics. With active-shift lens systems the driving force is provided by repulsing mini-magnets. Lens refilling procedures replace the lens content by an elastic material and provide accommodation by an increase of surface curvature.
Findings with passive-shift lenses have been contradictory. While uncorrected reading vision results were initially reported to be favorable with the 1CU, and excellent with the AT-45 lens, distant-corrected near vision did not exceed that with standard monofocal lenses in later studies. Mean axial shift from laser interferometric measurements under stimulation with pilocarpine showed a moderate anterior shift with the 1CU, while the AT-45 paradoxically exhibited a small posterior shift. With the 1CU, the shift-induced accommodative effect was calculated to be less than +0.5 D in most cases, while +1 D was achieved in a single case only. Ranges and standard deviations were very large in relation to the mean values. Under physiological near-point stimulation, however, no shift was seen at all. Prevention of capsule fibrosis by extensive capsule polishing did not enhance the functional performance. Dual optic lenses are under clinical investigation and are reported to provide a significant amount of accommodation. However, possible long-term formation of interlenticular opacifications remains to be excluded. Regarding magnet-driven active-shift lens systems, initial clinical experience has been promising. Prevention of fibrotic capsular contraction is crucial, and it has been effectively counteracted with a special capsular tension ring, or lens fixation technique, together with capsule polishing. Lens refilling has been extensively studied in the laboratory and in primates. Though it offers great potential for fully restoring accommodation, a variety of problems must be solved, such as achieving emmetropia in the relaxed state, adequate response to ciliary muscle contraction, satisfying image quality over the entire range of accommodation and sustained functioning. The key problem, however, is again after-cataract prevention.
As opposed to psychophysical evaluation techniques, laser interferometry measures what shift lenses are designed to provide: axial shift on accommodative effort. While under pilocarpine some movement was recorded, no movement at all was found under near-point stimulation with any of the lenses currently marketed. In contrast, magnetic-driven active-shift lens systems carry the potential of sufficiently topping up apparent accommodation to provide for clinically useful accommodation while using conventional lens designs with proven after-cataract performance. Dual optic implants significantly increase the impact of axial optic shift. The main potential problem, however, is delayed formation of interlenticular regenerates. Lens refilling procedures offer the potential of fully restoring accommodation due to the great impact of increase in surface curvature on refractive lens power. However, various problems remain to be solved before clinical use can be envisaged, above all, again, after-cataract prevention. The concept of passive single-optic shift lenses has failed. Concomitant poor capsular bag performance makes these lenses an unacceptable trade-off. Magnet-assisted systems potentially combine clinically useful accommodation with satisfactory after-cataract performance. Dual optic lenses theoretically offer substantial accommodative potential but may allow for interlenticular after-cataract formation. Lens refilling procedures have the greatest potential for fully restoring natural accommodation, but will again require years of extensive laboratory and animal investigations before they may function in the human eye.
KeywordsAccommodative intraocular lenses Working principle and clinical performance of current lenses Future concepts
- 8.Fercher AF, Roth E (1986) Ophthalmic laser interferometer. Proc SPIE 658:48–51Google Scholar
- 18.Haigis W, Auffarth GU, Limberger IJ, Rabsilber TM, Reuland AJ (2005) [Precision measurements of accommodative shift of the 1CU-lens for assessment of resulting refractive changes.] Proceedings 19th Congress of the German-speaking Society of Intraocular Lens Implantation and Refractive Surgery, Magdeburg pp241–255Google Scholar
- 28.Huber C (1981) Planned myopic astigmatism as a substitute for accommodation in pseudophakic eyes. Am Intraocular Implant Soc 3:244–249Google Scholar
- 29.Kessler J (1964) Experiments in refilling the lens. Arch Opthalmol 71:412–417Google Scholar
- 37.Kuechle M, Nguyen NX, Langenbucher A, Gusek-Schneider GC, Seitz B, Hanna KD (2002) Implantation of a new accommodative posterior chamber intraocular lens. J Refract Surg 18:208–216Google Scholar
- 38.Kuechle M, Seitz B, Langenbucher A, Martus P, Nguyen NX (2003) Erlangen Accommodative Intraocular Lens Study Group. Stability of refraction, accommodation, and lens position after implantation of the 1CU accommodating posterior chamber intraocular lens. J Cataract Refract Surg 29:2324–2329CrossRefGoogle Scholar
- 39.Kuechle M, Seitz B, Langenbucher A, Gusek-Schneider GC, Martus P, Nguyen NX (2004) The Erlangen Accommodative Intraocular Lens Study Group. Comparison of 6-month results of implantation of the 1CU accommodative intraocular lens with conventional intraocular lenses. Ophthalmology 111:318–324CrossRefGoogle Scholar
- 45.Maloof AJ. Selective targeting of lens epithelial cells during human cataract surgery using sealed-capsule irrigation with distilled water. ARVO 2004, Fort Lauderdale, Abstract B291Google Scholar
- 47.McDonald JP, Croft MA, Vinje E, Glasser A, Heatley GA, Kaufman P, Sarfarazi FM (2003) Sarfarazi elliptical accommodating intraocular lens (EAIOL) in rhesus monkey eyes in vitro and in vivo. Invest Ophthalmol Vis Sci;44: Abstract 256Google Scholar
- 49.Menapace R (2004) Prevention of after cataract. In: T Kohnen, DD Koch (eds) Cataract and refractive surgery, Series Essentials in Ophthalmology. pp 101–122Google Scholar
- 52.Menapace R (2006) “Aspiration Curette”: an instrument for efficient and safe anterior capsule polishing: laboratory and clinical results. J Cataract Refract Surg, in pressGoogle Scholar
- 57.Niessen AGJE, de Jong LB, van der Heijde GL (1992) Pseudo-accommodation in pseudophakia. Eur J Implant Refract Surg 4:91–94Google Scholar
- 65.Nishi O (2005) [After-cataract prevention and the restitution of accommodation—A new lens-refilling procedure. PPCCC+PBH: Proceedings 19th Congress of the German-speaking Society of Intraocular Lens Implantation and Refractive Surgery, Magdeburg 2005, pp247–250Google Scholar
- 68.Payer H (1997) Ringwulstlinse mit Zoomwirkung zur Verstärkung einer Pseudoakkommodation und deren Erklärung aus erweiterter Akkommodationstheorie. [Posterior chamber lens allowing cases of pseudoaccommodation]. Spektrum Augenheilkd 11:81–89Google Scholar
- 69.Payer H, Reiter J (2003) Five years of experience with the Annular Ring Lens In: Guthoff R, Ludwig K (eds) Current aspects of human accommodation II. Kaden, Heidelberg, pp 179–192Google Scholar
- 71.Sacca Y, Hara T, Yamada Y, Hara T, Hayashi F (1996) Accommodation in primate eyes after implantation of refilled endocapsular balloon. Am J Ophthalmol 121:210–212Google Scholar
- 73.Schaeffel F (2003) Optical techniques to measure the dynamics of accommodation. In: Guthoff R, Ludwig K (eds) Current aspects of human accommodation II. Kaden, Heidelberg, pp 71–94Google Scholar
- 76.Stachs O, Martin H, Kirchhoff A, Stave J, Terwee T, Guthoff R (2002) Monitoring accommodative ciliary muscle function using three-dimensional ultrasound. Arch Clin Exp Ophthalmol 240:906–912Google Scholar
- 78.Verzella F, Colossi A (1993) Multifocal effect of against-the-rule myopic astigmatism in pseudophakic eyes. Refract Corneal Surg 1:58–61Google Scholar
- 81.Yamamoto S, Adachi-Usami E (1992) Apparent accommodation in pseudophakic eyes as measured with visually evoked potentials. Invest Ophthalmol Vi Sci 33:443–446Google Scholar