Calculation of Equivalent and Toric Power in AddOn Lenses Based on a Monte Carlo Simulation.

INTRODUCTION: Additional lenses implanted in the ciliary sulcus (AddOn) are one option for permanent correction of refractive error or generate pseudoaccommodation in the pseudophakic eye. The purpose of this paper was to model the power and magnification behaviour of toric AddOn and to show the effect sizes with a Monte Carlo simulation. METHODS: Anonymized data of a cataractous population uploaded for formula constant optimization were extracted from the IOLCon platform. After filtering out data with refractive spherical equivalent (RSEQ) between -0.75 and 0.25 dpt and refractive cylinder (RCYL) lower than 0.75, for each of the N = 6,588 records, a toric AddOn was calculated which transfers the refraction error from spectacle plane to AddOn plane using a matrix-based calculation strategy based on linear Gaussian optics. The equivalent (AddOnEQ) and toric (AddOnCYL) power of the AddOn and the overall lateral magnification change and meridional magnification were derived for the situations before and after AddOn implantation, and a linear modelling was fitted for all 4 parameters. RESULTS: RSEQ is the dominant effect size in the prediction of AddOnEQ and overall change in magnification (ΔM), whereas the lens position (LP), corneal thickness (CCT), and mean corneal radius (CPa) play a minor role. In a simplified model, AddOnEQ can be estimated by 0.0179 + 1.4104 RSEQ. RCYL and corneal radius difference (CPad) are the dominant effect sizes in the prediction of AddOnCYL and the change in meridional magnification (ΔMmer), whereas LP, CCT, CPa, and RSEQ play a minor role. In a simplified model, AddOnCYL can be predicted by -0.0005 + 0.0328 CPad + 1.4087 RCYL. Myopic eyes gain in overall magnification, whereas in hyperopic eyes, we observe a loss. Meridional distortion could be in general reduced to 35% on average with a toric AddOn. CONCLUSION: Our simulation shows that with a linear model, the equivalent and toric AddOn power, as well as overall change in magnification, meridional distortion before and after AddOn implantation, and the reduction in meridional distortion, can be easily predicted from the biometric data in pseudophakic eyes with moderate refractive error.

Impact of intraocular lens displacement on the fixation axis.

To investigate the impact of intraocular lens (IOL) decentration ≤±1 mm and IOL tilt ≤±10° on the fixation axis and spherical equivalent refraction (SE), 50 pseudo-phakic eyes were simulated using numerical ray-tracing. We computed the position of the object point whose image ends up at the virtual fovea for each scenario and estimated the corresponding change of fixation axis and SE. The eye turned opposite to the direction of IOL decentration or tilt to compensate for the associated prismatic effect (angle <1.2°). Decentration of the aspheric IOL resulted in a hyperopic shift (<0.57 D), and tilt in a myopic shift (<0.77 D).

Silicone-diffractive versus acrylic-refractive supplementary iols: visual performance and manual handling.

PURPOSE: To compare visual outcome and manual handling of additional multifocal sulcus-fixated intraocular lenses (IOLs) of different materials and lens concepts. METHODS: Visual outcomes after implantation of a monofocal IOL in the capsular bag followed by implantation of a sulcus-fixated multifocal IOL (MIOL) in patients with cataract were assessed. Patients were randomly assigned to receive either the refractive Sulcoflex 653F (Rayner Surgical GmbH, Bamberg, Germany) (35 eyes) or the diffractive MS 714 PB Diff (Dr. Schmidt Intraocularlinsen GmbH, St. Augustin, Germany) (33 eyes) additional MIOL. Three months postoperatively, visual acuity at far, intermediate, and near distance and contrast sensitivity under different conditions were evaluated. Patients with binocular implantation were asked to rate their subjective quality of vision. RESULTS: No complications occurred during or after surgery. No significant differences in uncorrected and corrected distance visual acuity at all distances were found between groups. All eyes achieved uncorrected visual acuity of 0.3 logMAR (20/40 Snellen) or better at all distances. Contrast sensitivity was significantly better in the diffractive MS 714 PB Diff group than in the refractive Sulcoflex 653F group under all conditions. The refractive Sulcoflex 653F group experienced more photic phenomena (81%) than the diffractive MS 714 PB Diff group (25%), but the disturbances were scored as mild to moderate in most cases (93%/100%). The unfolding procedure of the acrylic Sulcoflex 653F IOL was smoother and more controllable than that of the silicone MS 714 PB Diff IOL. CONCLUSIONS: Both additional MIOLs performed well in terms of far, intermediate, and near vision and enabled patients to handle almost all areas of activity without glasses.

Fusarium spp.: infections and intoxications.

The genus Fusarium, member of the Hypocreaceae family, comprises over 500 spp. with an ever-evolving taxonomy. These fungi, some highly pathogenic, primarily affect various plants, including major crops like maize, rice, cereals, and potatoes, leading to significant agricultural losses and contributing to human undernutrition in certain regions. Additionally, Fusarium spp. produce harmful mycotoxins like trichothecenes, fumonisins, zearalenones, etc., posing health risks to animals and humans. These toxins generally transferred to food items can cause diverse issues, including organ failure, cancer, and hormonal disturbances, with effects sometimes appearing years after exposure. The fungi's vast genetic repertoire enables them to produce a range of virulence factors, leading to infections in both animals and humans, particularly in immunocompromised individuals. Fusarium spp. can cause systemic infections and local infections like keratitis. Due to limited antifungal effectiveness and biofilm formation, these infections are often challenging to treat with poor outcomes.

Ophthalmomyiasis Externa due to Oestrus ovis Larvae: A Case Report.

A 23-year-old female presented with redness, itchiness, tearing, and foreign body sensation in her right eye after spending her holiday in Egypt. Slit lamp examination revealed about 15 mobile, whitish maggots that were microbiologically classified as Oestrus ovis larvae. All parasites could be removed without subsequent complications.

[Performance of a new 7 mm intraocular lens with follow-up over 1.5 years]. / Performance einer neuen 7-mm-Intraokularlinse mit Nachbeobachtung über 1,5 Jahre.

BACKGROUND: Good visibility over the entire fundus is mandatory for optimal diagnostics and treatment of retinal pathologies. If an IOL implantation is planned in the context of retinal pathologies, a model with an enlarged optic diameter offers various advantages. The two most important benefits are an enhanced view at the fundus periphery and an improvement of the IOL positional stability especially with combined vitrectomy and the use of gas or silicone oil tamponades. The purpose of this study was to evaluate the performance and positional stability of a new 7 mm IOL. MATERIAL AND METHODS: This prospective study included 55 eyes of 39 patients who were scheduled for standardized cataract surgery and received a monofocal 7.0 mm optic IOL (Aspira-aXA, HumanOptics). An incision size of 2.0 mm was chosen. Follow-up visits were performed 1 week (1W), 1 month (1M), 4 months (4M) and 1.5 years (1.5J) postoperatively. Measurements included subjective refraction, uncorrected and corrected distance visual acuity (UDVA and CDVA) as well as IOL stability regarding decentration, tilt and rotation (IOLs had a pseudomarking on the periphery of the optics). RESULTS: Except for the postoperative occurrence of an Irvine-Gass syndrome in one eye, no intraoperative or postoperative complications were reported. The CDVA did not change significantly (p = 0.40) within the postoperative course from 1 month (median 0.00 logMAR; -0.10 to 0.22 logMAR) to 1.5 years (median 0.00 logMAR; -0.10 to 0.10 logMAR). The IOL was found to be stable over the postoperative course as decentration was < 0.02 mm and tilt < 5.5°. There was a median rotation of 1.8° (0.0-13.4°) within the first postoperative week, which was not significantly different from the rotation between surgery and 1.5 years (median 1.4°; 0.0-10.9°). CONCLUSION: With comparable functional performance and the same small incision size as with usual 6.0 mm IOLs, the Aspira-aXA offers the advantages of a 7.0 mm optic in the diagnostics and treatment of peripheral retinal pathologies. In addition, the lens shows good position stability in the capsular bag.

Ratio of torus and equivalent power to refractive cylinder and spherical equivalent in phakic lenses - a Monte-Carlo simulation study.

BACKGROUND: Spherical and astigmatic powers for phakic intraocular lenses are frequently calculated using fixed ratios of phakic lens refractive power to refractive spherical equivalent, and of phakic lens astigmatism to refractive cylinder. In this study, a Monte-Carlo simulation based on biometric data was used to investigate how variations in biometrics affect these ratios, in order to improve the calculation of implantable lens parameters. METHODS: A data set of over sixteen thousand biometric measurements including axial length, phakic anterior chamber depth, and corneal equivalent and astigmatic power was used to construct a multidimensional probability density distribution. From this, we determined the axial position of the implanted lens and estimated the refractive spherical equivalent and refractive cylinder. A generic data model resampled the density distributions and interactions between variables, and the implantable lens power was determined using vergence propagation. RESULTS: 50 000 artificial data sets were used to calculate the phakic lens spherical equivalent and astigmatism required for emmetropization, and to determine the corresponding ratios for these two values. The spherical ratio ranged from 1.0640 to 1.3723 and the astigmatic ratio from 1.0501 to 1.4340. Both ratios are unaffected by the corneal spherical / astigmatic powers, or the refractive cylinder, but show strong correlation with the refractive spherical equivalent, mild correlation with the lens axial position, and moderate negative correlation with axial length. As a simplification, these ratios could be modelled using a bi-variable linear regression based on the first two of these factors. CONCLUSION: Fixed spherical and astigmatic ratios should not be used when selecting high refractive power phakic IOLs as their variation can result in refractive errors of up to ±0.3 D for a 8 D lens. Both ratios can be estimated with clinically acceptable precision using a linear regression based on the refractive spherical equivalent and the axial position.

[Monte Carlo simulation of biometric effect sizes and their influence on the translational ratio of corneal astigmatism in the cylinders of toric intraocular lenses]. / Monte-Carlo-Simulation biometrischer Effektgrößen und deren Einfluss auf das Übersetzungsverhältnis des Hornhautastigmatismus in den Zylinder torischer Intraokularlinsen.

BACKGROUND AND OBJECTIVE: Toric intraocular lenses (IOL) provide a reliable and predictable option for permanent correction of corneal astigmatism. In order to determine the lens strength necessary for achieving the desired correction, the operator can either use the calculation mode implemented in the biometry device or the calculation service offered by the lens manufacturer; however, in many cases a classical lens calculation from biometric data is not carried out but only a simplified estimation, which translates the corneal astigmatism into the torus of the toric IOL. This translational ratio, which is mostly used as an average standard value, can however show a substantial range of variation, so that in a worst case scenario an undercorrection of the refractive cylinder of up to 12.5 % or an overcorrection of up to 17 % can result. The purpose of this study was to elaborate the biometric effect sizes which determine the relationship between the corneal astigmatism to be corrected and the torus necessary for a full correction of an IOL. METHODS: A total of 16,744 datasets were extracted from the IOLCon web platform and initially the axial position of the IOL implant was derived independent of a formula, based on the preoperative biometric values and the postoperative spherical equivalent. Subsequently, based on a ray propagation strategy for spherocylindrical vergences, the corresponding refractive value of a full correcting toric IOL was calculated. The translational relationship as a ratio between lens toricity and corneal astigmatism was analyzed for potential biometric effect sizes with a Monte Carlo simulation. RESULTS: The Monte Carlo simulation showed that the ratio of lens toricity to corneal astigmatism cannot be assumed as being constant. The analyzed data revealed an average translational ratio of 1.3938 ± 0.0595 (median 1.3921) with a range from 1.2131 to 1.5974. The axial position of the IOL was found to have the greatest influence, whereby the more posterior the lens position the higher the ratio. Due to the correlation of axial eye length and axial lens position, the eye length can be assumed to be an indirect effect size. The corneal equivalent refractive strength and the corneal astigmatism have no noteworthy effect on the translational ratio. CONCLUSION: Many calculation tools on the market simplify toric IOL power calculation by assuming a constant ratio of lens toricity to corneal astigmatism; however, the present simulation study showed that such a simplification can lead to clearly incorrect results. Accordingly, an individual calculation of IOL toricity based on biometric parameters (e.g. based on vergence propagation matrices or full aperture ray tracing) is recommended.

Malignant Keratitis Caused by a Highly-Resistant Strain of Fusarium Tonkinense from the Fusarium Solani Complex.

Fusarium spp. are moulds ubiquitously distributed in nature and only occasionally pathogenic for humans. Species of the Fusarium solani complex are the predominant keratitis-inducing pathogens, because they are endowed with proper virulence factors. These fungi can adhere to the cornea creating a biofilm and, with the help of enzymes and cytotoxins, penetrate the cornea. Whereas an intact cornea is hardly able to be invaded by Fusarium spp. in spite of appropriate virulence factors, these opportunistic fungi may profit from predisposing conditions, for example mechanical injuries. This can lead to a progressive course of corneal infection and may finally affect the whole eye up to the need for enucleation. Here, we present and discuss the clinical, microbiological and histopathological aspects of a particular case due to Fusarium tonkinense of the Fusarium solani complex with severe consequences in a patient without any obvious predisposing factors. A broad portfolio of antifungal agents was applied, both topically and systemically as well as two penetrating keratoplasties were performed. The exact determination of the etiologic agent of the fungal infection proved likewise to be very challenging.

[Crisis management strategies of hospitals during the pandemic]. / Krisenstrategien der Kliniken während der Pandemie.

BACKGROUND: The SARS-CoV­2 pandemic has led worldwide to substantial limitations in healthcare systems. This article describes the recent developments and measures from March through May 2020, which have contributed to the maintenance of ophthalmological care at in-patient departments of ophthalmology. METHODS: PubMed literature search, own data, interhospital survey. RESULTS: The rapid implementation of infection and hygiene control measures and adaptation of standard operating procedures (SOP) to minimize the risk of infection, along with prioritized urgent and emergency care combined with postponement of elective procedures enabled the continuous care of ophthalmological patients. CONCLUSION: Despite the challenge of a significant shift of medical resources during the SARS-CoV­2 pandemic, medically urgently necessary ophthalmological treatments are continuously provided by maximum care clinics; however, based on currently available data, it cannot be ruled out whether treatment of emergency patients was delayed during the pandemic.

Comparison of corneal elevation and pachymetry measurements made by two state of the art corneal tomographers with different measurement principles.

PURPOSE: To compare corneal tomography measurements (elevation and pachymetry) as made by two corneal tomographers: Pentacam AXL and CASIA 2. MATERIAL AND METHODS: The devices were used in a standard measuring mode. 77 normal eyes were measured five times with both devices. The data maps for anterior and posterior corneal elevation and pachymetry were exported and analyzed. Repeatability and average values were calculated for each valid data point on the exported data maps. We also calculated a corrected repeatability of the elevation data maps by removing rotation, tilt, and decentration through realignment of the elevation measurement of each eye prior to analyzing the variations in the measurement usingthe same method as for the repeatability. RESULTS: Pentacam AXL offered the better (corrected) repeatability for anterior corneal elevation measurements. CASIA 2 offered better repeatability for the pachymetry measurements. The tomographers could not be used interchangeably. The central corneal thickness was measured 9 µm ± 3 µm larger when measured with Pentacam AXL compared to CASIA 2.

Keratoconic eyes with stable corneal tomography could benefit more from custom intraocular lens design than normal eyes.

We investigated whether eyes with keratoconic corneal tomography pattern could benefit more from aberration correction with custom intraocular lenses (IOLs) than normal cataractous eyes despite the effect of misalignment on the correction of aberrations. Custom IOLs (cIOLs) were calculated for twelve normal and twelve keratoconic eyes using personalized numerical ray tracing models. The Stiles-Crawford weighted root-mean-square spot-size (wRMS) at the virtual fovea was evaluated for cIOLs and aberration-neutral IOLs (nIOLs) in a simulated clinical study with 500 virtual IOL implantations per eye and per IOL. IOL misalignment (decentration, tilt, rotation) and pupillary ectopia (4.5 mm iris aperture) were varied upon each virtual implantation. The nIOLs achieved average wRMS of 16.4 ± 4.3 µm for normal, and 92.7 ± 34.4 µm for keratoconic eyes (mean ± standard deviation). The cIOLs reduced the average wRMS to 10.3 ± 5.8 µm for normal, and 28.5 ± 18.6 µm for keratoconic eyes. The cIOLs produced smaller wRMS than nIOLs in most virtual implantations (86.7% for normal and 99.4% for keratoconic eyes). IOL misalignment resulted in larger wRMS variations in the keratoconus group than in the normal group. Custom freeform IOL-optics-design may become a promising option for the correction of advanced aberrations in eyes with non-progressive keratoconic corneal tomography pattern.

Individually Customized IOL Versus Standard Spherical Aberration-Correcting IOL.

PURPOSE: To compare the visual performance of an individually customized intraocular lens (IOL) versus a standard spherical aberration-correcting IOL. METHODS: In this prospective comparative study, 74 eyes of 60 patients scheduled for cataract surgery were randomized in a 2:1 ratio to receive either an individually customized IOL (; HumanOptics AG, Erlangen, Germany; customized group) or an aspheric IOL with a standard correction of spherical aberration (SA) (Tecnis ZCB00; Johnson & Johnson Vision Surgical, Inc., Santa Ana, CA; standardized group). In the customized group, IOL calculation was based on a minimum of a merit function that contained terms representing residual refraction, residual SA, and modulation transfer function. In the standardized group, the IOL was calculated with a routine procedure using the Holladay formula and had a standard SA correction of -0.27 µm. Refraction, visual acuity (far, intermediate, near), photopic and mesopic contrast sensitivity, defocus curve, corneal and ocular spherical aberration, and pupil size were measured 4 weeks and 3 months postoperatively. RESULTS: The customized group comprised 48 eyes of 37 patients and the standardized group 26 eyes of 23 patients. At 3 months, mean total ocular SA (5 mm) was 0.04 ± 0.06 µm in the customized group and -0.01 ± 0.05 µm in the standardized group. Uncorrected distance visual acuity and distance-corrected near visual acuity were statistically significantly better in the customized group. Contrast sensitivity testing yielded significantly better results in the customized group under photopic and mesopic conditions for almost all spatial frequencies. Compared to the standardized group, the defocus curve of the customized group showed a wider plateau surrounding the distance focal point. CONCLUSIONS: With the implantation of an individually optimized aspheric IOL visual performance, especially contrast sensitivity, can be significantly improved compared to a standard aberration-correcting IOL. [J Refract Surg. 2019;35(9):565-574.].

First results with a new intraocular lens design for the individual correction of spherical aberration.

PURPOSE: To assess the feasibility of individual compensation of corneal spherical aberration with a custom intraocular lens (IOL). SETTING: Department of Ophthalmology, Rudolf Virchow Klinikum Glauchau, Glauchau, Germany. DESIGN: Prospective case series. METHODS: Cataract patients were randomized to receive an individual aberration-correcting IOL (Invidua-aA; Group A) or a standard aspheric aberration-free IOL of otherwise identical design (Aspira-aA; Group B). In Group A, the IOL was designed according to preoperative calculation of the corneal spherical aberration Z(4,0). The aim was to achieve an overall postoperative ocular spherical aberration close to zero. Four weeks and 3 months postoperatively, the refraction, visual acuity (far, intermediate, and near distance), photopic and mesopic contrast sensitivities (with and without glare), defocus curve, corneal and ocular spherical aberration, and pupil size were measured. RESULTS: Group A, 57 eyes of 42 patients and Group B, 29 eyes of 27 patients. Preoperatively, there was no difference in corneal spherical aberration between groups (P > .05). Three months postoperatively, residual ocular spherical aberration Z(4,0) was significantly lower in Group A (P < .001). Photopic and mesopic contrast sensitivities (with and without glare) were significantly higher in Group A at most spatial frequencies. Monocular defocus curve and distance, intermediate, and near visual acuity outcomes did not differ significantly between groups. CONCLUSIONS: Implantation of a custom monofocal aspheric IOL effectively reduced overall ocular spherical aberration. Clinical outcomes indicate that IOLs with an individual spherical aberration correction improve functional vision, especially contrast sensitivity, compared with standard aberration-free IOLs.

Visual Performance in the Long Term With Secondary Add-on Versus Primary Capsular Bag Multifocal Intraocular Lenses.

PURPOSE: To compare the long-term results of a secondary sulcus-placed, multifocal add-on intraocular lens (IOL) with those of a multifocal IOL implanted in the capsular bag. METHODS: In this prospective clinical trial, 30 pseudophakic eyes were treated with a multifocal add-on IOL and 30 cataractous eyes with a standard multifocal IOL. The main outcome measures comprised manifest refraction, visual acuity, defocus curves, and contrast sensitivity. Patients who had bilateral implantation of the same lens type were asked to complete a questionnaire. RESULTS: One year postoperatively, all eyes from the multifocal add-on IOL group (add-on group) and 97% from the standard multifocal IOL group (standard group) were within ±0.50 diopters (D) of emmetropia. In both groups, median uncorrected distance and intermediate visual acuity were 20/20 and 20/25, respectively. Median uncorrected near visual acuity was 20/20 in the add-on group and 20/25 in the standard group. The survey analysis resulted in a slightly higher patient satisfaction in the standard group regarding distance and near vision without glasses. Contrast sensitivity measures were comparable in both groups. Halos were the most commonly reported visual disturbance, but the perceived impairment by light effects was minimal even in the early postoperative period and the majority of patients got used to it relatively quickly. CONCLUSIONS: Secondary multifocal add-on IOL implantation provides the opportunity for multifocal imaging in already pseudophakic eyes. The functional outcomes are comparable to those achieved after primary multifocal IOL implantation in the capsular bag. [J Refract Surg. 2016:32(11):742-747.].

Additional multifocal sulcus-based intraocular lens: alternative to multifocal intraocular lens in the capsular bag.

PURPOSE: To compare the visual outcomes of additional multifocal intraocular lenses (IOLs) for sulcus fixation with those of standard multifocal IOLs in the capsular bag. SETTING: Department of Ophthalmology, Rudolf-Virchow-Klinikum Glauchau, Glauchau, Germany. DESIGN: Prospective controlled clinical trial. METHODS: Eyes had phacoemulsification and implantation of a monofocal IOL in the capsular bag and an additional aberration-free diffractive IOL in the ciliary sulcus (multifocal add-on IOL group). Measurements of uncorrected and distance-corrected distance, intermediate, and near visual acuities; contrast sensitivity; and defocus curve were performed 3 months postoperatively. Results were compared with those in eyes with an aberration-correcting diffractive posterior chamber IOL (multifocal PC IOL group). RESULTS: The multifocal add-on IOL group comprised 34 eyes of 20 patients and the multifocal PC IOL group, 31 eyes of 17 patients. Cataract surgery, IOL implantation, and the postoperative course were uneventful in all cases. There were no statistically significant differences in uncorrected and distance-corrected distance, intermediate, or near visual acuities between the 2 groups. The median uncorrected distance visual acuity was 0.00 logMAR in both groups, and the median uncorrected near visual acuity was 0.10 logMAR in both groups. Contrast sensitivity testing yielded significantly better results in the multifocal add-on IOL group, especially at spatial frequencies over 1.5 cycles per degree. Defocus curves were similar in the 2 groups. CONCLUSION: Visual performance with a multifocal diffractive add-on IOL was equivalent to that achieved with a commonly used multifocal diffractive PC IOL.

Effect of interface reflection in pseudophakic eyes with an additional refractive intraocular lens.

PURPOSE: To compare the surface reflections in a pseudophakic model eye with and without a monofocal additional refractive intraocular lens (add-on IOL). SETTING: Department of Ophthalmology, Rudolf-Virchow-Klinikum Glauchau, Glauchau, and Experimental Ophthalmology, Saarland University, Homburg, Germany. DESIGN: Experimental study. METHODS: The Liou and Brennan model eye was used to determine the retinal surface reflections in a pseudophakic model eye with and without an add-on IOL. The crystalline lens of the model eye was replaced by (1) a standard posterior chamber IOL (PC IOL) with a refractive power of 22.0 diopters (D) and (2) a PC IOL and an add-on IOL with refractive powers of 19.0 D and 2.5 D, respectively. To theoretically estimate the impact of the reflected images to visual impression, the signal-to-noise ratio (SNR) was calculated under 2 conditions: without and with straylight and double reflection effects. RESULTS: Compared with the pseudophakic model eye without an add-on IOL, the pseudophakic model eye with an add-on IOL showed no relevant differences in the SNR under both conditions. CONCLUSION: Findings indicate that implantation of monofocal add-on IOLs will not induce relevant additional disturbing glare compared with conventional pseudophakia.