Klinische Monatsblatter fur Augenheilkunde · 2011
[Accommodative intraocular lenses--principles of clinical evaluation and current results].
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Klaproth O K, Titke C, Baumeister M, Kohnen T
Аннотация
BACKGROUND: A potential option for the correction of presbyopia after cataract extraction or refractive lens exchange is the implantation of accommodative intraocular lenses (IOL). When evaluating these lenses, it is essential to differentiate between accommodative and pseudoaccommodative effects, as both may have a positive impact on near visual acuity and reading performance. Only in this way accommodation can be proved.
MATERIAL AND METHODS: This article provides a brief overview on the principles of accommodation and presbyopia. Furthermore, different tests for testing near visual acuity, reading ability and accommodative processes are described, as well as options to perform these in a manner that allows the differentiation between accommodative and pseudoaccomodative effects. Against this background, the current literature has been reviewed regarding the results of potential accommodative IOLs.
RESULTS: A differentiation between accommodative effects in clinical practice can be performed using defocus curves or better open field aberrometers or refractometers as well as IOL movement measurements under non-pharmacologically stimulated conditions. Reading charts are not suitable. Currently mainly 7 different potential accommodating IOLs can be found in clinical research literature (5 single-optics, 1 gel-optic and one dual-optic). All of them are based on the principle of using ciliary muscle contraction for moving the IOL or changing its thickness and/or surface radii during accommodation in order to change the ocular refractive power. A proof of principle of such lenses under physiological, non-pharmacologically stimulated conditions is still lacking. However, the evaluated implants show significant improvement in terms of visual acuity in near and especially intermediate distances.
CONCLUSION: Using adequate testing procedures it becomes clear that the positive near vision effects achieved with accommodative intraocular lenses are due rather to pseudoaccommodative effects than to accommodative ones.
MATERIAL AND METHODS: This article provides a brief overview on the principles of accommodation and presbyopia. Furthermore, different tests for testing near visual acuity, reading ability and accommodative processes are described, as well as options to perform these in a manner that allows the differentiation between accommodative and pseudoaccomodative effects. Against this background, the current literature has been reviewed regarding the results of potential accommodative IOLs.
RESULTS: A differentiation between accommodative effects in clinical practice can be performed using defocus curves or better open field aberrometers or refractometers as well as IOL movement measurements under non-pharmacologically stimulated conditions. Reading charts are not suitable. Currently mainly 7 different potential accommodating IOLs can be found in clinical research literature (5 single-optics, 1 gel-optic and one dual-optic). All of them are based on the principle of using ciliary muscle contraction for moving the IOL or changing its thickness and/or surface radii during accommodation in order to change the ocular refractive power. A proof of principle of such lenses under physiological, non-pharmacologically stimulated conditions is still lacking. However, the evaluated implants show significant improvement in terms of visual acuity in near and especially intermediate distances.
CONCLUSION: Using adequate testing procedures it becomes clear that the positive near vision effects achieved with accommodative intraocular lenses are due rather to pseudoaccommodative effects than to accommodative ones.