Reproducibility analysis of measurements with a mechanical semiautomatic eye model for evaluation of intraocular lenses

Mechanical eye models are used to validate ex vivo the optical quality of intraocular lenses (IOLs). The quality measurement and test instructions for IOLs are defined in the ISO 11979-2. However, it was mentioned in literature that these test instructions could lead to inaccurate measurements in case of some modern IOL designs. Reproducibility of alignment and measurement processes are presented, performed with a semiautomatic mechanical ex vivo eye model based on optical properties published by Liou and Brennan in the scale 1:1. The cornea, the iris aperture and the IOL itself are separately changeable within the eye model. The adjustment of the IOL can be manipulated by automatic decentration and tilt of the IOL in reference to the optical axis of the whole system, which is defined by the connection line of the central point of the artificial cornea and the iris aperture. With the presented measurement setup two quality criteria are measurable: the modulation transfer function (MTF) and the Strehl ratio. First the reproducibility of the alignment process for definition of initial conditions of the lateral position and tilt in reference to the optical axis of the system is investigated. Furthermore, different IOL holders are tested related to the stable holding of the IOL. The measurement is performed by a before-after comparison of the lens position using a typical decentration and tilt tolerance analysis path. Modulation transfer function MTF and Strehl ratio S before and after this tolerance analysis are compared and requirements for lens holder construction are deduced from the presented results.

[1]  S. Norrby.  ISO eye model not valid for assessing aspherical lenses. , 2008, Journal of cataract and refractive surgery.

[2]  Kirsten Lux,et al.  Mechanical eye model for comparison of optical and physiological imaging properties , 2012, Proceedings of 15th International Conference MECHATRONIKA.

[3]  Edwin J Sarver,et al.  Visual Acuity as a Function of Zernike Mode and Level of Root Mean Square Error , 2003, Optometry and vision science : official publication of the American Academy of Optometry.

[4]  N A Brennan,et al.  Anatomically accurate, finite model eye for optical modeling. , 1997, Journal of the Optical Society of America. A, Optics, image science, and vision.

[5]  Patricia Piers,et al.  Model eyes for evaluation of intraocular lenses. , 2007, Applied optics.

[6]  Jan P. Allebach,et al.  Measuring the modulation transfer function of image capture devices: what do the numbers really mean? , 2012, Electronic Imaging.

[7]  Corina van de Pol,et al.  Normal‐eye Zernike coefficients and root‐mean‐square wavefront errors , 2006, Journal of cataract and refractive surgery.

[8]  Rafael Navarro,et al.  The Optical Design of the Human Eye: a Critical Review , 2009 .

[9]  P Artal,et al.  Modulation transfer functions of eyes implanted with intraocular lenses. , 1993, Applied optics.

[10]  Markus Sticker,et al.  Quantitative performance of bifocal and multifocal intraocular lenses in a model eye: point spread function in multifocal intraocular lenses. , 2002, Archives of ophthalmology.

[11]  Wilhelm Stork,et al.  In vitro strehl ratios with spherical, aberration-free, average, and customized spherical aberration-correcting intraocular lenses. , 2009, Investigative ophthalmology & visual science.

[12]  S. Webb.  The Physics of Medical Imaging , 1990 .

[13]  Mathias Forjan,et al.  Mechanical eye model for the comparison of optical imaging quality and physiology of human vision , 2012 .

[14]  Sowmya Ravikumar,et al.  Visual Impact of Zernike and Seidel Forms of Monochromatic Aberrations , 2010, Optometry and vision science : official publication of the American Academy of Optometry.

[15]  Dietmar Wüller,et al.  Digital camera resolution measurement using sinusoidal Siemens stars , 2007, Electronic Imaging.

[16]  T. Kohnen,et al.  Cataract and refractive surgery , 2005 .

[17]  D. Apple.  Sir Harold Ridley and His Fight for Sight: He Changed the World So That We May Better See It , 2006 .

[18]  L W Grossman,et al.  Minimum resolution specification of intraocular lens implantsusing the modulation transfer function. , 1993, Applied optics.

[19]  D. Malacara-Hernández,et al.  PRINCIPLES OF OPTICS , 2011 .

[20]  J. Haueisen,et al.  Mechanical eye model for evaluation of intraocular pressure measuring under consideration of the biomechanical characteristics , 2011, 2011 10th International Workshop on Biomedical Engineering.

[21]  Mathias Forjan,et al.  Semi-automatic evaluation of intraocular lenses (IOL) using a mechanical eye model , 2013, Photonics West - Biomedical Optics.

[22]  W. Stark.  The Intraocular Lens , 1983 .

[23]  D. Atchison,et al.  Recent advances in measurement of monochromatic aberrations of human eyes , 2005, Clinical & experimental optometry.