Purpose Accurate biometry is an obligatory preoperative measurement for refractive surgery as well cataract surgery. A new device based on partial coherence interferometry was compared with 2 currently used devices. Setting Department of Ophthalmology, Saarland University Medical Center, Homburg, Germany. Design Prospective case series. Methods Eyes patients were examined a functional prototype the optical low-coherence reflectometry (OLCR) biometer OA-2000, standard OLCR Lenstar, and (PCI)...

To explain the concept of Castrop lens power calculation formula and show application results from a large dataset compared to classical formulae.The vergence is based on pseudophakic model eye with 4 refractive surfaces. This was against SRKT, Hoffer-Q, Holladay1, simplified Haigis 1 optimized constant 3 constants. A preoperative biometric values, data postoperative refraction split into training test sets. The were used for optimization, cross-validation. Constant optimization performed...

To study the effects of corneal imaging and focusing using a raytracing simulation with 2 3 surface models based on customized representations tomography data . Raytracing for epithelium (S1), stroma (S2) endothelium (S3) extracted from MS-39 anterior segment tomographer CSV export files. Customized were derived Gaussian Process Predictors, rays traced through cornea 3.5 mm aperture stop located 3.66 behind apex. 4 clinical examples evaluated: A) after hyperopic LASIK, B) myopic C)...

To analyse the optical effect of an artificial hole in optic centre posterior chamber phakic intraocular lenses.Institute Experimental Ophthalmology, Saarland University, Homburg/Saar, Germany.Experimental simulation study.Four eye models with ametropia -4 D, -8 +4 and +8 D were created ray tracing software ASAP. Refractive correction these was implemented a model Implantable Collamer Lens (ICL). Each set up twice 1 receiving conventional ICL without central second hole. Ray bundles traced...

The aim of this study is to present strategies for optimization lens power (IOLP) formula constants and show options how the results adequately.A dataset N = 1,601 preoperative biometric values, IOLP data postoperative refraction was split into a training set test using random sequence. Based on set, we calculated established calculation formulae with different methods. derived prediction error (PE) as difference achieved from predicted refraction.For 1 constant, it possible back-calculate...

Surgically induced astigmatism (SIA) has been widely discussed in the literature as change corneal resulting from incision. The purpose of this study was to investigate refractive power preoperative postoperative using a vector analysis keratometry, total and back surface data modern optical biometer.The based on dataset 122 eyes patients with one month measurements performed IOLMaster 700 biometer 1 clinical center standardized surgical technique involving 2.5 mm 45°-incision made superior...

Abstract Background Intraocular lenses (IOLs) require proper positioning in the eye to provide good imaging performance. This is especially important for premium IOLs. The purpose of this study was develop prediction models estimating IOL decentration, tilt and axial equator position (IOLEQ) based on preoperative biometric tomographic measures. Methods Based a dataset ( N = 250) containing IOLMaster 700 pre-/postoperative Casia2 measurements from cataractous population, we implemented...

To investigate modern nonlinear iterative strategies for formula constant optimisation and show the application results from a large dataset using set of disclosed theoretical-optical lens power calculation concepts.Nonlinear algorithms were implemented optimising root mean squared (SoSPE), absolute (SoAPE), (MPE), standard deviation (SDPE), median (MEDPE), as well 90% confidence interval (CLPE) prediction error (PE), defined difference between postoperative achieved predicted spherical...

To investigate the effect of formula constants on predicted refraction and limitations constant optimization for classical modern intraocular lens (IOL) power calculation formulae.

Purpose The purpose of this study was to investigate the repeatability biometric measures and also assess interactions between uncertainties in these for use an error propagation model, using data from a large patient cohort. Methods In cross-sectional non-randomised we evaluated dataset containing 3379 IOLMaster 700 measurements taken prior cataract surgery. Only complete scans with at least 3 successful each eye performed on same day were considered. mean (Mean) standard deviations (SD)...

To investigate surrogate optimisation (SO) as a modern, purely data-driven, nonlinear adaptive iterative strategy for lens formula constant in intraocular power calculation.

To investigate the effect of severity keratoconus on corneal endothelium using specular microscopy.Seven hundred and twelve eyes from Homburg Keratoconus Center (HKC) database were included in this retrospective study. Corneal was evaluated Tomey EM-3000 microscope. Keratoconus-related topographic tomographic data obtained Scheimpflug-based tomography (Oculus Pentacam® HR). Eyes classified into stages 0 (healthy) to 4 (severe keratoconus) according Topographic Classification (TKC). Subgroups...

To investigate whether variation of the keratometer/corneal refractive index nK/nC improves performance (prediction error PE) classical and a modern intraocular lens (IOL) power calculation formula further, to establish any trend PE for corneal radius R could be eliminated using constant optimisation.Based on 2 large datasets (1: N = 888 Hoya Vivinex aberration-correcting 2: 822 Alcon SA60AT spherical lens) optimisation has been performed Hoffer Q, Holladay 1, Haigis Castrop formulae,...

Abstract Purpose The purpose of this study was to investigate the uncertainty in formula predicted refractive outcome REFU after cataract surgery resulting from measurement uncertainties modern optical biometers using literature data for within‐subject standard deviation S w . Methods This Monte–Carlo simulation used a large dataset containing 16 667 preoperative IOLMaster 700 biometric measurements. Based on values, derived both Haigis and Castrop formulae error propagation strategies....

Abstract Background To compare results from different corneal astigmatism measurement instruments; to reconstruct the postimplantation spectacle refraction and toric intraocular lens (IOL) power; derive models for mapping measured reconstructed astigmatism. Methods Retrospective single centre study involving 150 eyes treated with a IOL (Alcon SN6AT, DFT or TFNT). Measurements included IOLMaster 700 keratometry (IOLMK) total (IOLMTK), Pentacam (PK) refractive power in 3 4 mm zones (PTCRP3...

Abstract Purpose The purpose of this study is to compare the reconstructed corneal power (RCP) by working backwards from post‐implantation spectacle refraction and toric intraocular lens develop models for mapping preoperative keratometry total RCP. Methods Retrospective single‐centre involving 442 eyes treated with a monofocal trifocal IOL (Zeiss TORBI LISA). Keratometry were measured preoperatively postoperatively using IOLMaster 700. Feedforward neural network multilinear regression...

Abstract Background The purpose of this study was to simulate the impact biometric measure uncertainties, lens equivalent and toric power labelling tolerances axis alignment errors on refractive outcome after cataract surgery with implantation. Methods In retrospective non‐randomised cross sectional Monte‐Carlo simulation we evaluated a dataset containing 7458 LenStar 900 preoperative measurements. uncertainties from literature, according ISO 11979, modern (Hoya Vivinex) were taken be...

Purpose To investigate different measures for corneal astigmatism in the context of reconstructed (recCP) as required to correct pseudophakic eye, and derive prediction models map measured recCP. Methods Retrospective single centre study 509 eyes cataract patients with monofocal (MX60P) IOL. Corneal power IOLMaster 700 keratometry (IOLMK), Galilei G4 (GK), total (TCP2), Alpin’s integrated front (CorT) (CorTTP). Feedforward shallow neural network (NET) linear regression (REG) were derived C0...

Abstract Purpose To design a vergence‐based lens power formula based on the classical Haigis for better outcomes while retaining original architecture. Methods Four new variants (A–D) incorporating sum of segments correction axial length, harmonic mean corneal radii instead arithmetic (all variants), and differing combinations lower keratometer index (C, D) an additional term (a3) representing thickness in effective position (B, were assessed analysis four datasets IOLMaster 700 biometric...

Purpose: To present a concept for inter-converting constants of disclosed lens power formulae and to simplify these conversions linear prediction models clinical use. Setting: Augen- und Laserklinik Castrop-Rauxel, Germany. Design: Retrospective single centre case series. Methods: Analysis based on dataset with biometric measurements 19,472 eyes in cataractous population performed the IOLMaster 700. The formula constant conversion from A B includes 2 steps: calculation using variation...

Purpose To investigate the repeatability of biometric measures and assess interactions between their uncertainties for use in an error propagation model, using patient data. Methods Cross-sectional non-randomised study evaluating a dataset containing 969 LenStar 900 measurements taken before cataract surgery. Only complete scans with at least 3 successful each eye performed on same day were considered. For sequence, aggregated mean (AMEAN) population standard deviations (ASD) derived. The...

Abstract Purpose The purpose of this study was to develop a method for evaluating intraocular lens (IOL) formula constant uncertainties using two modern statistical techniques—jackknife and bootstrap resampling. Methods Using datasets (dataset 1: 888 eyes treated with the aberration correcting Hoya Vivinex IOL, dataset 2: 821 spherical Alcon SA60AT/SN60AT IOL), SRK/T (Aconst), Hoffer‐Q (pACD), Holladay 1 (SF), simplified Haigis (a0) preset a1/a2, (triplet a0/a1/a2), Castrop C/H/R) Olsen...