HOYA aspherical IOL with ABC (Aspheric Balanced Curve) Design

HOYA aspherical IOL with ABC (Aspheric Balanced Curve) Design

Contents Basics of asphericity Visual quality and aspheric IOL Features of HOYA ABC Design 2

What is asphericity? Deviating from the spherical shape or a reflecting surface which by the rotation around a point from the circle by an axial develops. 3

Asphericity The deflect of the sphere form (= spheric) is aspheric form! 4

What is aberration? It is an illusion created by the optical system when viewing an object. We know a lot of different aberrations, e.g. Spherical aberration Chromatic aberration Coma 5

Spherical aberration Abaxial rays outside of the Gaußschen territory (approx. 5 around the axis) will be refracted stronger! Optical axis Spherical aberration Gaußscher territory 6

Chromatic aberration Different index of several mediums determine different chromatic aberrations of the wavelength Chromatic aberration 7

Coma If light rays refract slant on a optical surface, you will get a deformation like the illustration Image Coma 8

Contents Basics of asphericity Visual quality and aspheric IOL Features of HOYA ABC Design 9

Optical system Positive aberration ~ +43 dioptors=2/3 Positive aberration ~+18-26 dioptors=1/3 10

Optical system The abberations of the natural human lens change during life. So the positive abberations of the optical system are increasing with the age. 11

Spherical aberration spheric aberration-free negative aspheric SA = + SA = 0 SA = - +20.4 +20.0 +18.0 +20.0 +20.0 +20.0 +20.4 +20.0 +18.0 Power increases from center to edge Power is uniform for all areas Power decreases from center to edge 12

Concept of aspheric IOLs 13

Influence of aspheric IOL Spherical IOL Good DOF Worse visual Quality ++ + Negative SA IOL +++ Worse DOF Best Image Quality ++ - - 00 14

Effect of pupil size (small pupil) spherical aspheric no difference between the image qualities 15

Effect of pupil size (huge pupil) spherical aspheric Clear image different between booths lenses 16

Simulation 1 with model eye system aspheric vs. spheric aperture:ø 3mm 5mm HOYA ABC Design YA-60BBR With 3mm aperture (pupil diameter), there is no obvious difference between the two charts, but with 5mm there is a significant difference 17

Contents Basics of asphericity Visual quality and aspheric IOL Features of 18

HOYA aspheric ABC Design 19

HOYA aspheric ABC Design 20

HOYA aspheric ABC Design 21

HOYA aspheric ABC Design 22

HOYA aspheric ABC Design 23

HOYA aspheric ABC Design 24

Transmission Aspheric vs. Spheric 100 Comparison of PY-60AD FY-60AD and YA-60BB for transmission of light Transmission (%) 80 60 40 20 0 YA-60BB(+10D) 0.56mm YA-60BB(+20D) 0.76mm YA-60BB(+30D) 1.02mm PY-60AD(+20D) 0.68mm 300 400 500 600 700 800 Wavelength (nm) Comparison PY-60AD (HOYA Aspheric IOL,Yellow) and YA-60BB (HOYA spherical IOL, Yellow) These plots show that the transmission curve is depended on the thickness of the lens. Aspheric lens of the same power has a little bit thinner than the spherical one. Since the thickness of +20 D aspheric lens has thickness between +10 D and +20 D spherical lens, the aspheric transmission curve also lied between these lenses. 25

Edge Technology Sharp edge (electron micrograph: x 100) Posterior optic enhanced 360 o sharp edge and step edge design

Detriment of aspheric optics Shallow depth of focus Strongly influenced by decentration Influenced by tilt Individual asphericity is necessary 27

Depth of focus (4.0 mm pupil) Spherical IOL Good DOF -0.50 D -0.25 D 0 D +0.25 D +0.50 D Negative SA IOL Worse DOF -0.50 D -0.25 D 0 D +0.25 D +0.50 D 28

Effect of decentration Spherical IOL Aspheric IOL Perfectly centered Decentered by 0.5 mm Mean decentration0.37 mm +0.24 mm M. Rynders, B. Lidkea, W. Chisolm, L. N. Thibos, J. Opt. Soc. Am., A, 12, 2348-2357 (1995)

Surface distributions (+20.0 D) 30

HOYA Concept / principle: ABC design is a optimized surface by HOYA Lathe-Cut technology for compensation of the cornea aberration with an asphericityof ~ 0.18 µm HOYA ABC design provides always the best image and contrast quality, also in the case of a pupil offset to the capsular bag. (= USP) 31

PSF in the case of Decentration ~ Simulated by HOYA s original settings ~ On optical axis ABC Design Standard aspheric IOL The aberration can be minimized, and the image is sharp (our design is better, because it is under our optimum condition). Spherical lens 0.5mm decentration There is an aberration also on optical axis, which is bigger than the aberration caused by the decentration HOYA aspheric has sharper vision than the other. 32

Effect of decentration on contrast Recent reports for the decentration, the mean value is 0.24-0.53mm. 1) T. Oshika, G. Sugita, K. Miyata, T. Tokunaga, T. Samejima, C. Okamoto, and Y. Ishii., Influence of tilt and decentration of scleral-sutured intraocular lens on ocular higher-order wavefront aberration, Br. J. Ophthalmol., 2006;(Epub ahead of print) 2) P. Rosales and S. Marcos, Phakometry and lens tilt and decentration using a customdeveloped Purkinje imaging apparatus: validation and measurements, J. Opt. Soc. Am., Opt. Image Sci. Vis., 23(3), 509-520, 2006. 3) M. Baumeister, B. Neidhardt, J. Strobel, T. Kohnen, Tilt and decentration of three-piece foldable high-refractive silicone and hydrophobic acrylic intraocular lenses with 6-mm optics in an intraindividual comparison, Am. J. Ophthalmol., 140 (6), 1051-1058, 2005. Contrast 1 0.8 0.6 0.4 0.2 Spheric A Aperture 4.0 mm HOYA Spatial freq 50 c/mm 0 0 0.2 0.4 0.6 Decentration (mm) Optimum settings for a standard aspheric IOL (under the condition of Z 4 0 = 0.27) A standard aspehric has better contrast if no decentration because setting values are optimum for a standard aspheric. However, over 0.2mm decentration, HOYA aspheric has better visual quality. 33

XX-60AD MTF with tilt Standard aspheric IOL ABC design Spherical IOL 34

Issues of aspheric IOLs Issues 1. Corneal aberration is different among patients. 2. As ages, corneal aberration changes. 3. Standard aspheric IOL is weak to decentration. Solutions 1.and 2. Calculate theological corneal aberration values which can be adapted to many people. 3. Well centered with IOL design. Minimize the effect of decentration with optic design.

Comparison of visual quality spherical and aspheric IOL YA-60BBR ABC Design Pictures in cloudy late afternoon with aperture of 5mm. Signs in right picture seems clearer and sharper. Especially images at the peripheral zones of the lens are affected by the aberration, and the differences between two can be observed easily. 36

Thank you for your attention! 37