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Background and Purpose: The effect of lens decentration and tilt on retinal image quality has been extensively studied in the past in simulations and clinical studies. The purpose of this study was to analyze the effect of combined lens decentration and tilt on the induction of defocus, astigmatism and coma in phakic and pseudophakic eyes., Methods: Simulations were performed with Zemax on the Liou-Brennan schematic model eye. Based on the position of the gradient lens the image plane was determined (best focus). The lens was decentered horizontally from -1.0 mm to 1.0 mm in steps of 0.2 mm and tilted with respect to the vertical axis from -10° to 10° in steps of 2° (in total 121 combinations of decentration and tilt). For each combination of decentration and tilt defocus, astigmatism (in 0/180°) and horizontal coma was extracted from wave front error and recorded for a pupil size of 4 mm. After replacement of the gradient lens with an aberration correcting artificial lens implant model with the equatorial plane of the artificial lens aligned to the equatorial plane of the gradient lens, the simulations were repeated for the pseudophakic eye model., Results: For the lens positioned according to the Liou-Brennan schematic model eye the simulation yielded a defocus of 0.026 dpt/-0.001 dpt, astigmatism of -0.045 dpt/-0.018 dpt, and a coma of -0.015 µm/0.047 µm for phakic/pseudophakic eyes. Maximum values were observed for a horizontal decentration of 1.0 mm and a tilt with respect to the vertical axis of 10° with 1.547 dpt/2.982 dpt for defocus, 0.971 dpt/1.871 dpt for astigmatism, and 0.441 µm/1.209 µm for coma. Maximum negative values occurred in phakic/pseudophakic eyes with -0.293 dpt/-1.224 dpt for defocus, for astigmatism -0.625 dpt/-0.663 dpt and for coma -0.491 µm /-0.559 µm, respectively., Conclusion: In this simulation study the effect of a combination of lens decentration in horizontal direction and tilt with respect to the vertical axis on defocus, astigmatism and horizontal coma was analyzed. The results may help to describe in clinical routine if with a decentered or tilted artificial lens implant the postoperative refraction does not match the target refraction or the resulting astigmatism after cataract surgery is not fully explained by measurement of corneal astigmatism., (© 2020. The Author(s).)

Background The Haigis formula uses a linear regression with three IOL constants for the prediction of the effective lens position (ELP) of the intraocular lens (IOL), ELP ≈ a 0  + a 1  ACD + a 2  L. It is based on the preoperative anterior chamber depth (ACD) and axial length (L). Material and Methods Differences between IOL constant triplets can be judged based on their statistical measurement uncertainty. To investigate, if the estimation of the average ELP with the help of the average ACD and average L according to 〈ELP〉 ≈ a 0  + a 1  〈ACD〉 + a 2  〈L〉 provides a possible alternative, we have compared both methods. The results based on two different strategies for optimisation of the IOL constants a 0 , a 1 , a 2 are used for illustration. Results The estimation of the average ELP is suitable for basic categorisation of the IOL constants. The confidence-volumes in shape of ellipsoids based on the statistical measurement uncertainties of the IOL constant optimisations allow a better comparison between IOL constant triplets a 0 , a 1 , a 2 ., Competing Interests: Interessenkonflikt: Die Autoren geben an, dass kein Interessenkonflikt besteht., (Georg Thieme Verlag KG Stuttgart · New York.)

Cataract surgery has tremendously evolved in recent years. Innovations include micro-incision cataract surgery through incisions smaller than 2mm, high-fluidics phacoaspiration and laser phacoemulsification to minimize or replace the use of ultrasound, the advent of femtolasers for high-precision incisions in the cornea, the lens capsule and the cataractous lens, aspheric intraocular lenses (IOLs) to enhance the quality and contrast of the image, multifocal and enhanced-depth-of-focus IOLs to correct presbyopia, advancements in biometry and IOL power calculation, prevention of secondary capsule opacification by improvements in the design and material of the IOLs and surgical techniques like capsule polishing and posterior capsulorhexis, and pharmacological prophylaxis and possible future treatment of the cataract itself. Finally, cost-effectiveness and future potential of same-session bilateral cataract surgery are discussed.