Publications by authors named "Achim Langenbucher"

240 Publications

Ocular Signs and Ocular Comorbidities in Monoclonal Gammopathy: Analysis of 80 Subjects.

J Ophthalmol 2021 18;2021:9982875. Epub 2021 Jun 18.

Semmelweis University, Department of Ophthalmology, Budapest, Hungary.

Purpose: To examine the ocular signs of monoclonal gammopathy and to evaluate ocular comorbidities in subjects with monoclonal gammopathy. . We analyzed patients from two large referral hematology centers in Budapest, diagnosed and/or treated with monoclonal gammopathy between 1997 and 2020. As a control group, randomly selected individuals of the same age group, without hematological disease, have been included. There were 160 eyes of 80 patients (38.75% males; age 67.61 ± 10.48 (range: 38-85) years) with monoclonal gammopathy and 86 eyes of 43 control subjects (32.56% males; age 62.44 ± 11.89 (range 37-86) years). The hematological diagnosis was MGUS in 9 (11.25%), multiple myeloma in 61 (76.25%), smoldering myeloma in 6 (7.50%), and amyloidosis or Waldenström macroglobulinemia in 2 cases (2.50%-2.50%). Before detailed ophthalmic examination with fundoscopy, 42 subjects with gammopathy (52.50%) and all controls filled the Ocular Surface Disease Index (OSDI) questionnaire.

Results: The OSDI score and best-corrected visual acuity (BCVA) were significantly worse in subjects with monoclonal gammopathy than in controls (=0.02; =0.0005). Among gammopathy subjects, we observed potential corneal immunoglobulin deposition in 6 eyes of 4 (3.75%) patients. Ocular surface disease (=0.0001), posterior cortical cataract (=0.01), and cataract (=0.0001) were significantly more common among gammopathy subjects than in controls ( test).

Conclusions: Ocular surface disease and cataract are more common, and BCVA is worse in patients with monoclonal gammopathy than in age-matched controls. Therefore, and due to the potential ocular signs and comorbidities of monoclonal gammopathy, we suggest a regular, yearly ophthalmic checkup of these patients to improve their quality of life.
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http://dx.doi.org/10.1155/2021/9982875DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8235972PMC
June 2021

[Myopia treatment and prophylaxis with defocus incorporated multiple segments spectacle lenses].

Ophthalmologe 2021 Jul 8. Epub 2021 Jul 8.

Internationale Innovative Ophthalmochirurgie GbR, Theo-Champion-Str. 1, 40549, Düsseldorf, Deutschland.

Excessive axial eye growth in children and adolescents leads to progressive myopia and can result in severe ocular diseases in adulthood. Various strategies have already been developed to inhibit progression of myopia. The novel single vision lens presented in this article features the defocus incorporated multiple segments (DIMS) technology and adds an easy to use, noninvasive option to the portfolio of myopia treatment. Initial studies showed promising results with only a very low side effect profile.
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http://dx.doi.org/10.1007/s00347-021-01452-yDOI Listing
July 2021

The Castrop formula for calculation of toric intraocular lenses.

Graefes Arch Clin Exp Ophthalmol 2021 Jul 8. Epub 2021 Jul 8.

Augen-und Laserklinik Castrop-Rauxel, Castrop-Rauxel, Germany.

Purpose: To explain the concept behind the Castrop toric lens (tIOL) power calculation formula and demonstrate its application in clinical examples.

Methods: The Castrop vergence formula is based on a pseudophakic model eye with four refractive surfaces and three formula constants. All four surfaces (spectacle correction, corneal front and back surface, and toric lens implant) are expressed as spherocylindrical vergences. With tomographic data for the corneal front and back surface, these data are considered to define the thick lens model for the cornea exactly. With front surface data only, the back surface is defined from the front surface and a fixed ratio of radii and corneal thickness as preset. Spectacle correction can be predicted with an inverse calculation.

Results: Three clinical examples are presented to show the applicability of this calculation concept. In the 1st example, we derived the tIOL power for a spherocylindrical target refraction and corneal tomography data of corneal front and back surface. In the 2nd example, we calculated the tIOL power with keratometric data from corneal front surface measurements, and considered a surgically induced astigmatism and a correction for the corneal back surface astigmatism. In the 3rd example, we predicted the spherocylindrical power of spectacle refraction after implantation of any toric lens with an inverse calculation.

Conclusions: The Castrop formula for toric lenses is a generalization of the Castrop formula based on spherocylindrical vergences. The application in clinical studies is needed to prove the potential of this new concept.
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http://dx.doi.org/10.1007/s00417-021-05287-wDOI Listing
July 2021

Benefits and New Features of a Modern International Internet Database "IOLCon" for Updated and Optimized IOL Constants and IOL Specifications.

Klin Monbl Augenheilkd 2021 Jul 1. Epub 2021 Jul 1.

Institut für Experimentelle Ophthalmologie, Universität des Saarlandes, Homburg/Saar, Germany.

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http://dx.doi.org/10.1055/a-1493-5614DOI Listing
July 2021

OCT Application for Sterile Corneal Graft Screening in the Eye Bank.

Klin Monbl Augenheilkd 2021 Jun 22;238(6):688-692. Epub 2021 Jun 22.

Department of Ophthalmology, Saarland University Medical Center (UKS), Homburg/Saar, Germany.

Background And Objective: Sterile donor tomography enables the detection of corneal tissues with refractive anomalies. The aim of this study was to determine the curvature and thickness of donor corneas to support proper selection in the eye bank.

Methods: 704 donor corneas (Klaus Faber Center, LIONS Eye Bank Saar-Lor-Lux, Trier/Westpfalz, in Homburg/Saar) were measured using the anterior segment optical coherence tomograph (AS-OCT) CASIA 2 (Tomey Corp., Nagoya, Japan). The corneoscleral discs were measured in their cell culture flask, which was positioned in a holder on the chin rest of the AS-OCT, after conversion to medium II (with 6% dextran T-500). The measured raw data were analysed and processed in MATLAB (MathWorks Inc., Natick, Massachusetts, USA), after which the refractive power of the steep and flat meridian at the anterior and posterior surface and the central corneal thickness (CCT) of the donor corneas were determined. Results values are expressed as mean x̅ ± standard deviation SD.

Results: The mean refractive power of the steep/flat meridian at the anterior surface was 45.4 ± 1.8 D/44.0 ± 1.3 D, the corresponding values for the posterior surface were - 6.2 ± 0.3 D/- 5.9 ± 0.2 D, and the mean CCT was 616.3 ± 85.1 µm. Of the 704 (100%) measured donor tissues, 590 (83.8%)/670 (95.2%) donor corneas showed no anomaly beyond respectively x̅ ± 2 SD/x̅ ± 3 SD among the 5 examined parameters. 72 (10.3%)/23 (3.3%) donor corneas had only 1 anomaly, 26 (3.7%)/10 (1.4%) had 2 anomalies, 10 (1.4%)/1 (0.1%), 3 anomalies, 5 (0.7%)/0 (0.0%), 4 anomalies, and 1 (0.1%)/0 (0.0%), 5 anomalies.

Conclusions: AS-OCT provides an objective and sterile screening method to identify corneal tissues with curvature anomalies in order to further optimise donor selection in the eye bank. To avoid postoperative refractive surprises, donor corneas with a total refractive power that deviates > ± 3 SD from the mean should not be used for penetrating or anterior lamellar keratoplasty, but may be suitable for posterior lamellar keratoplasty (DMEK or DSAEK). In the future, sterile donor tomography could enable: (1) the harmonisation of donor and recipient tomography, which may minimise residual astigmatism for a particular donor-recipient pair; and (2) the improvement of IOL power calculation in a classical triple procedure by means of regression analysis between pre- and postoperative total refractive power of corneal grafts.
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http://dx.doi.org/10.1055/a-1443-5451DOI Listing
June 2021

Comparison of wash-out properties after use of the vital dye trypan blue in the form of an ophthalmic dye and bound in a sodium hyaluronate by Raman spectroscopy.

Curr Eye Res 2021 Jun 18. Epub 2021 Jun 18.

Experimentelle Ophthalmologie, Universität des Saarlandes, Kirrberger Straße 100, 66421 Homburg Saar, Deutschland.

Purpose: In cataract surgery, viscoelastics protect the corneal endothelium against phacoenergetic and mechanical damage and ensure anterior chamber stability. Vital dyes (trypan blue) are effective aids in anterior segment surgery, especially in challenging cases, but may lead to cytotoxic reactions depending on concentration and dose. A complete removal of the dye is therefore of great importance. Recently, a new viscoelastic colored with Trypan blue (Pe-Ha-Blue®PLUS) was introduced to increase the safety of ophthalmological procedures. The aim of the present work was to determine the residual amount of the dye Trypan Blue that remains on a slide during the routine application of two commercial products (Trypan Blue dye Vision Blue® and Pe-Ha-Blue®PLUS) by Raman spectroscopy.

Materials And Methods: For both products, a test sample (after application of the substance, the slides were flushed according to the clinical procedure) and a reference sample (the substances remained on the slide) were imaged using a Raman spectroscope (LabRam 800 HR spectrometer (Horiba Jobin Yvon GmbH, Bensheim, Germany)) and then analyzed.

Results: The remaining residues of the reference samples of both substances were clearly detected by the spectroscopy measurement. In the mean spectrum of the Vision Blue® test specimen, the Raman bands of Trypan blue were clearly visible at a Raman shift of 1200-1600 cm-1, indicating residues on the test specimen. The test sample of Pe-Ha-Blue®PLUS did not show any Raman bands in the typical Trypan blue Raman shift.

Conclusions: The results of our in-silico experiment showed that a drop of a combination of a vital dye with a viscoelastic could be washed-out more easily with BSS compared to a dye itself without viscoelastics. This suggests that at least in an in silico experiment the removal of both, the viscoelastics and the TB is easier compared to the removal of the TB alone. Further in-vitro experiment in pig cadaver eyes are planned to prove this washout effect. If this concept can be demonstrated, this could further increase the safety of dye-assisted ophthalmic procedures.
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http://dx.doi.org/10.1080/02713683.2021.1942075DOI Listing
June 2021

A retrospective analysis of the therapeutic effects of 0.01% atropine on axial length growth in children in a real-life clinical setting.

Graefes Arch Clin Exp Ophthalmol 2021 Jun 18. Epub 2021 Jun 18.

Internationale Innovative Ophthalmochirurgie GbR c/o Breyer Kaymak and Klabe Augenchirurgie, Duesseldorf, Germany.

Background: Several randomized controlled studies have demonstrated the beneficial effects of 0.01% atropine eye drops on myopia progression in children. However, treatment effects may be different in a routine clinical setting. We performed a retrospective analysis of our clinical data from children to investigate the effect of 0.01% atropine eye drops on myopia progression in a routine clinical setting.

Methods: Atropine-treated children were asked to instill one drop of 0.01% atropine in each eye every evening at 5 days a week. Myopic children who did not undergo atropine treatment served as controls. Objective refraction and ocular biometry of 80 atropine-treated and 103 untreated children at initial visit and 1 year later were retrospectively analyzed.

Results: Myopic refractions in the treated and untreated children at initial visit ranged from -0.625 to -15.25 D (-4.21 ± 2.90 D) and from -0.125 to -9.375 D (-2.92 ± 1.77 D), respectively. Ages at initial visit ranged from 3.2 to 15.5 years (10.1 ± 2.7 years) in the treated and from 3.4 to 15.5 years (11.2 ± 3.0 years) in untreated children. Two-factor ANOVA for age and atropine effects on axial length growth confirmed that axial length growth rates declined with age (p<0.0001) and revealed a significant inhibitory effect of atropine on axial length growth (p<0.0015). The atropine effect on axial length growth averaged to 0.08 mm (28%) inhibition per year. Effects on refraction were not statistically significant.

Conclusion: The observed atropine effects were not very distinctive: Statistical analysis confirmed that atropine reduced axial length growth, but to an extent of minor clinical relevance. It was also shown that beneficial effects of 0.01% atropine may not be obvious in each single case, which should be communicated with parents and resident ophthalmologists.
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http://dx.doi.org/10.1007/s00417-021-05254-5DOI Listing
June 2021

Herpes simplex virus PCR in 2230 explanted corneal buttons.

Acta Ophthalmol 2021 Jun 14. Epub 2021 Jun 14.

Dr. Rolf M. Schwiete Center for Limbal Stem Cell and Congenital Aniridia Research, Saarland University, Homburg/Saar, Germany.

Purpose: To determine herpes simplex virus (HSV) DNA prevalence and mean cycle threshold of polymerase chain reaction (PCR) in corneal tissue of patients with penetrating keratoplasty (PKP), with (HSK+) and without (HSK-) previous clinical herpetic keratitis history.

Methods: Retrospective review of recipient corneal buttons which were explanted through PKP between March 2010 and September 2018 at the Department of Ophthalmology, Saarland University Medical Center in Homburg/Saar, Germany. Corneal tissue samples were analysed by real-time PCR for the presence of HSV DNA. For each subject, clinical data, including patients' demographics and clinical diagnoses, were collected.

Results: In total, 2230 corneal samples (age at the time of the surgery 57.3 ± 19.2 years) of 1860 patients were analysed. HSV PCR was positive in 137 (6.1%) corneal samples, with a 30.57 ± 6.01 (range 14-39) mean cycle threshold (Ct) value. Two hundred ninety-eight (13.4%) corneas of 266 patients were clinically HSK+, and 1932 (86.6%) corneas of 1600 patients were clinically HSK-. HSV DNA was detected significantly more frequently (p < 0.0001) in HSK+ corneal samples (108 corneal samples; 36.2%), than in HSK- corneal samples (29 corneal samples; 1.5%). Ct value was significantly lower in HSK+ than in HSK- corneal samples (29.8 ± 5.8 versus 32.6 ± 5.9; p = 0.008).

Conclusion: Our data demonstrate that a positive clinical history of HSK is related to HSV PCR positivity in about every 2.8th patient. In addition, about every 66th explanted corneal tissue is HSV PCR-positive despite the lack of clinical suspicion. These patients may need additional local/systemic antiviral treatment to avoid newly acquired HSK following penetrating keratoplasty.
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http://dx.doi.org/10.1111/aos.14872DOI Listing
June 2021

Rotational Stability, Tilt and Decentration of a New IOL with a 7.0 mm Optic.

Curr Eye Res 2021 Jun 14:1-8. Epub 2021 Jun 14.

Department of Ophthalmology and Optometry, Kepler University Hospital GmbH, Johannes Kepler University Linz, Linz, Austria.

: To evaluate rotational stability, tilt and decentration of a new monofocal IOL with a 7.0 mm optic and frame haptics. Prospective post-market clinical follow-up study at the Kepler University Hospital Linz, Austria. An Aspira-aXA (HumanOptics, Germany) was implanted in 74 eyes of 42 cataract patients. The lens was manufactured with toric markings. IOL rotational stability was evaluated by comparing its position at the end of surgery (EoS) versus 1 day, 1 week, 1 month and 4 months postoperatively. IOL tilt and decentration were measured using a Scheimpflug camera at 1 week, 1 month and 4 months. Median absolute IOL rotation was 1.42 degrees (n = 52; mean = 2.18 ± 2.23°) within 1 day after surgery and was significantly higher compared to all later intervals (median <1.0 degree; = .001). At the 4 months follow-up, IOL rotation was within 5.0 degrees in 85% of the eyes (n = 40) and within 10.0 degrees in 98% (n = 46) of the eyes. The only eye with an IOL rotation of ≥ 10.ty0 degrees (EoS . 1 day) had an AL of 26.45 mm. At the last follow-up, the IOL vertical and horizontal tilt referenced to the pupillary axis was in average less than 1.5 degrees in both eyes (n = 54; maximum 5.85°). Decentration in both meridians was on average less than 0.10 mm in both eyes (maximum 0.30 mm). The one-piece Aspira-aXA IOL showed good and stable positioning within the capsular bag over a 4 months period.
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http://dx.doi.org/10.1080/02713683.2021.1929329DOI Listing
June 2021

[Optometric eye screening in schools : First epidemiological data for children and adolescents in grades 5-7].

Ophthalmologe 2021 Jun 10. Epub 2021 Jun 10.

Internationale Innovative Ophthalmochirurgie, Breyer Kaymak Klabe Augenchirurgie, Düsseldorf, Deutschland.

Background: Annually recurring optometric screening helps to identify children with increased axial growth and also to create awareness for wearing properly corrected glasses and for spending enough time outdoors, both of which are crucial for healthy eyes. The obtained biometric data help to expand the epidemiological information on myopia in schoolchildren, which is fundamental for the selection of the correct treatment.

Material And Methods: Contact-free biometry of the eye was used to assess central corneal thickness, anterior chamber depth, lens thickness and axial length. Central choroidal thickness was manually assessed using optical coherence tomography (OCT). In addition, the mesopic and photopic pupil sizes were measured.

Results: Biometric data were obtained from 257 (mean age 11.2 ± 1.1 years, 31.9% female, n = 82, 68.1% male, n = 175) out of a total of 274 examined children. Mean corneal radius (mean ± SD, female/male) was 7.74 ± 0.23 mm/7.89 ± 0.22 mm, central corneal thickness was 556.80 ± 31.31 µm/565.68 ± 33.12 µm, anterior chamber depth was 3.62 ± 0.28 mm/3.71 ± 0.25 mm, lens thickness was 3.48 ± 0.18 mm/3.46 ± 0.17 mm and axial length was 23.03 ± 0.88 mm/23.51 ± 0.88 mm. Choroidal thickness was assessed in 240 children and was 335.12 ± 60.5 µm. Mesopic and photopic pupil sizes were 6.38 ± 0.70 mm and 3.11 ± 0.63 mm, respectively.

Conclusion: The axial lengths found are consistent with the normal values for European children. A difference between male and female eyes could be observed. The repetition of these examinations in the future will enable the generation of growth charts.
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http://dx.doi.org/10.1007/s00347-021-01427-zDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8191721PMC
June 2021

Considerations on the Castrop formula for calculation of intraocular lens power.

PLoS One 2021 2;16(6):e0252102. Epub 2021 Jun 2.

Augen- und Laserklinik Castrop-Rauxel, Castrop-Rauxel, Germany.

Background: To explain the concept of the Castrop lens power calculation formula and show the application and results from a large dataset compared to classical formulae.

Methods: The Castrop vergence formula is based on a pseudophakic model eye with 4 refractive surfaces. This was compared against the SRKT, Hoffer-Q, Holladay1, simplified Haigis with 1 optimized constant and Haigis formula with 3 optimized constants. A large dataset of preoperative biometric values, lens power data and postoperative refraction data was split into training and test sets. The training data were used for formula constant optimization, and the test data for cross-validation. Constant optimization was performed for all formulae using nonlinear optimization, minimising root mean squared prediction error.

Results: The constants for all formulae were derived with the Levenberg-Marquardt algorithm. Applying these constants to the test data, the Castrop formula showed a slightly better performance compared to the classical formulae in terms of prediction error and absolute prediction error. Using the Castrop formula, the standard deviation of the prediction error was lowest at 0.45 dpt, and 95% of all eyes in the test data were within the limit of 0.9 dpt of prediction error.

Conclusion: The calculation concept of the Castrop formula and one potential option for optimization of the 3 Castrop formula constants (C, H, and R) are presented. In a large dataset of 1452 data points the performance of the Castrop formula was slightly superior to the respective results of the classical formulae such as SRKT, Hoffer-Q, Holladay1 or Haigis.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0252102PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8172026PMC
June 2021

[Simple method to estimate object to image magnification and aniseikonia following cataract surgery].

Ophthalmologe 2021 Jun 1. Epub 2021 Jun 1.

Dr. Rolf M. Schwiete Zentrum für Limbusstammzellforschung und kongenitale Aniridie, Universität des Saarlandes, 66421, Homburg, Deutschland.

Background And Purpose: Aniseikonia as one of the major risk factors for asthenopic problems is mostly overlooked in modern cataract surgery. The purpose of this study was to develop a simple calculation scheme for clinicians to predict the object to image magnification in a pseudophakic eye with biometric data.

Methods: The calculation scheme for object to image magnification in the pseudophakic eye is based on a vergence calculation of the lens power with theoretical optical formulae. From the biometric data, which are typically derived from both eyes during lens power calculation, the vergences in front of and behind the 3 or 4 refractive surfaces of the pseudophakic eye model are used to predict the magnification for objects at infinity or objects located at a finite measurement distance (e.g. 5 m).

Results: With a formula-based lens power calculation a pseudophakic eye model is set up with 3 or 4 refractive surfaces (postoperative spectacle refraction; thick cornea described by anterior surface or thick cornea characterized by anterior and posterior surfaces; intraocular lens). The vergence in front of and behind each refractive surface is derived by means of linear Gaussian optics. The quotient of the product of all vergences in front of the surfaces and the product of all vergences behind the respective surfaces describes the object to image magnification of the eye. A comparison of the object to image magnification of both eyes yields the retinal image size disparity or aniseikonia. This calculation strategy is shown in a step-by-step approach exemplarily for the Haigis and Hoffer‑Q formulae (3 surfaces) and the Castrop formula (4 surfaces).

Conclusion: If during planning and lens power calculation biometry is performed for both eyes, ocular magnification of both eyes can be easily derived with this calculation scheme and aniseikonia can be extracted from a comparison of magnification of both eyes. Such a simple prediction should be established as a standard for precataract biometry and lens power calculation for early detection and avoidance of asthenopic complaints after cataract surgery.
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http://dx.doi.org/10.1007/s00347-021-01412-6DOI Listing
June 2021

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

Acta Ophthalmol 2021 May 20. Epub 2021 May 20.

Department of Ophthalmology, Semmelweis-University, Budapest, Hungary.

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.
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http://dx.doi.org/10.1111/aos.14902DOI Listing
May 2021

Impact of Pre- and Intraoperative Factors on Endothelial Cell Density in the Early and Late Stage after Penetrating Keratoplasty.

Klin Monbl Augenheilkd 2021 May 17. Epub 2021 May 17.

Dr. Rolf M. Schwiete Zentrum für Limbusstammzellforschung und kongenitale Aniridie, Universität des Saarlandes, Homburg/Saar, Deutschland.

Aim: This retrospective investigated the impact of donor age, recipient age, donor endothelial cell density, vis-à-tergo, and additional intraoperative lens exchange (triple-procedure) on overall early and late phase postoperative endothelial cell density (ECD) following penetrating keratoplasty (PKP) in various diagnosis groups.

Patients And Methods: In 590 cases with diagnosed keratoconus (KC), Fuchs dystrophy (FD) and herpes simplex virus infection (HSV) who underwent PKP or triple surgery, the ECD in cells/mm was analysed, both preoperatively, with all-sutures-in (early postoperative stage), and after last suture removal. The factors were tested by Mann-Whitney U-test, correlation analysis and linear regression analysis.

Outcome: Correlation analysis demonstrated a weak negative correlation between the patient's ECD and donor age (early postoperative stage: r = - 0.25, p < 0.001; after last suture removal: r = - 0.16; p = 0.003). Regression analysis revealed that donor age did not impact postoperative patient ECD. There was a weak negative correlation between postoperative ECD and recipient age (early postoperative stage: r = - 0.31, p < 0.001; after last suture removal: r = - 0.34, p < 0.001). Regression analysis confirmed the negative impact of recipient age on patient ECD (early postoperative stage: β = - 13.2, p = 0.001; after last suture removal: β = - 4.6, p < 0.001). Correlation analysis determined a weak positive correlation between postoperative ECD and donor endothelial cell density (early postoperative stage: r = 0.37, p < 0.001; after last suture removal: r = 0.32, p < 0.001). Regression analysis also determined that donor endothelial cell density had a positive impact on postoperative ECD following last suture removal (β = 0.4, p < 0.001). Vis-à-tergo and additional lens exchange (triple procedure) had no significant effect on postoperative ECD (p > 0.05). This was also confirmed by the results of the regression analysis after last suture removal.

Conclusion: Recipient age and donor endothelial cell density have a significant impact on postoperative ECD following PKP. Not all of the statistical tests proved donor age to be a significant influencing factor. Vis-à-tergo and additional lens exchange (triple procedure) had no significant effect on postoperative ECD following PKP.
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http://dx.doi.org/10.1055/a-1333-2723DOI Listing
May 2021

Calculation of ocular magnification in phakic and pseudophakic eyes based on anterior segment OCT data.

Ophthalmic Physiol Opt 2021 Jul 4;41(4):831-841. Epub 2021 May 4.

Department of Ophthalmology, Vienna University, Vienna, Austria.

Purpose: The purpose of this study is to develop a straightforward mathematical concept for determination of object to image magnification in both phakic and pseudophakic eyes, based on biometric measures, refractometry and data from an anterior segment optical coherence tomography (OCT).

Methods: We have developed a strategy for calculating ocular magnification based on axial length measurement, phakic anterior chamber and lens thickness, keratometry and crystalline lens front and back surface curvatures for the phakic eye, and axial length measurement, anterior chamber and lens thickness, keratometry and intraocular lens power, refractive index and shape factor for the pseudophakic eye. Comparing the magnification of both eyes of one individual yields aniseikonia, while comparing the preoperative and postoperative situation of one eye provides the gain or loss in ocular magnification. The applicability of this strategy is shown using a clinical example and a small case series in 78 eyes of 39 patients before and after cataract surgery.

Results: For the phakic eye, the refractive index of the crystalline lens was adjusted to balance the optical system. The pseudophakic eye is fully determined and we proposed three strategies for considering a potential mismatch of the data: (A) with spherical equivalent refraction, (B) with intraocular lens power and (C) with the shape factor of the lens. Magnification in the phakic eye was -0.00319 ± 0.00014 and with (A) was -0.00327 ± 0.00013, with (B) was -0.00323 ± 0.00014 and with (C) was -0.00326 ± 0.00013. With A/B/C, the magnification of the pseudophakic eye was on average 2.52 ± 2.83%/1.31 ± 2.84%/2.14 ± 2.80% larger compared with the phakic eye. Magnification changes were within a range of ±10%.

Conclusions: On average, ocular magnification does not change greatly after cataract surgery with implantation of an artificial lens, but in some cases, the change could be up to ±10%. If the changes are not consistent between the left and right eyes, then this could lead to post-cataract aniseikonia.
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http://dx.doi.org/10.1111/opo.12822DOI Listing
July 2021

[Optometric eye screening in schools : First results of a pilot project on logistical feasibility].

Ophthalmologe 2021 May 3. Epub 2021 May 3.

Internationale Innovative Ophthalmochirurgie, Breyer Kaymak Klabe Augenchirurgie, Düsseldorf, Deutschland.

Background: We present a pilot project to improve eye health in schoolchildren: annual optometric screening with a focus on early detection of school myopia. The logistical proof-of-concept is illustrated by way of a pilot project at a state high school in North Rhine-Westphalia. The collected biometric parameters also contribute to the collection of epidemiological data.

Material And Methods: On organized examination days objective and subjective refractions of schoolchildren in grades 5-7 (ages 9-16 years) were determined, children were tested for abnormalities in binocular vision and the photopic and mesopic pupil diameters were determined. Noncontact biometry was used to measure the corneal radius, central corneal thickness, anterior chamber depth, lens thickness and axial length of the eyes. Optical coherence tomography (OCT) was used to also determine the central choroidal thickness of the eyes. Questionnaires were employed to inquire about the visual habits of the schoolchildren.

Results: In the fall of 2019 a total of 274 schoolchildren (11.2 ± 1.2 years) voluntarily participated in the examinations: 22% (61) showed myopia (spherical equivalent ≤ -0.50 D), of which 11% (7) were previously uncorrected (uncorrected distance visual acuity < 0.8). Of the schoolchildren 8% (5) showed an increase in myopia of more than -0.5 D compared to their actual spectacle values (distance visual acuity with ophthalmic lens < 0.8). A class of about 25 pupils can be examined within 2 regular periods.

Conclusion: There is an actual need for optometric screening because a total of 4.4% (12) myopic schoolchildren could be identified who had a distance visual acuity of less than 0.8 even with the correction. By determining the axial length and classifying this value depending on age in the literature can help to predict the individual risk of myopia and to raise awareness among parents and children to address this problem. The planned repetition of these examinations enables a better understanding of eye growth in schoolchildren.
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http://dx.doi.org/10.1007/s00347-021-01394-5DOI Listing
May 2021

Clinical Comparison of the Performance of Two Marketed Ophthalmic Viscoelastic Devices (OVDs): The Bacterially Derived Healon PRO OVD and Animal-Derived Healon OVD.

J Ophthalmol 2020 18;2020:8874850. Epub 2020 Nov 18.

Department of Ophthalmology, Saarland University Medical Center UKS, Homburg, Saar, Germany.

This clinical investigation compared the clinical performance of two marketed ophthalmic viscoelastic devices (OVDs): the bacterially derived Healon PRO OVD (test) and the animal-derived Healon OVD (control) under normal use conditions during cataract removal and lens implantation. This prospective, multicenter, randomized, parallel, participant/evaluator masked, postmarket investigation enrolled 139 subjects (170 eyes), 116 (143 eyes) of which were treated (73 test; 70 control group). Both test and control OVDs were used, at a minimum, to inflate the anterior chamber and protect the endothelium prior to cataract extraction according to the standard procedure. The surgeon completed a postsurgery OVD clinical performance questionnaire, and intraocular pressure (IOP) was measured before surgery and at the 1 day postoperative visit with Goldmann applanation tonometry. Any IOP measurement of 30 mmHg or higher was considered a "spike" and recorded as a study-specific, serious adverse event. The bacterially derived Healon PRO OVD was found to be statistically noninferior to the overall clinical performance of the animal-derived Healon OVD control; thus, the primary hypothesis was satisfied. There were no statistically significant differences between OVD groups for any of the additional endpoints relating to IOP changes or to safety, thus satisfying additional hypotheses. The Healon PRO OVD showed statistically significant improvements in surgeon ratings for ease of injectability, transparency/visibility, and ease of IOL placement. The safety profile was also similar between OVD groups with regards to serious and/or device-related adverse events, as well as medical and lens findings. The results of this clinical investigation support the safety and effectiveness of the bacterially derived, currently marketed Healon PRO OVD and indicate that the intraocular surgical performance was similar between the two OVDs.
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http://dx.doi.org/10.1155/2020/8874850DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8028729PMC
November 2020

Large-Diameter Penetrating Keratoplasties are Mostly Due to Very Severe Infectious Keratitis and Cannot Always Prevent Secondary Enucleation.

Klin Monbl Augenheilkd 2021 Apr 14. Epub 2021 Apr 14.

Augenheilkunde, Universitätsklinikum des Saarlandes und Medizinische Fakultät der Universität des Saarlandes, Homburg (Saar), Germany.

Purpose: To report the indications and outcomes of penetrating keratoplasties with a graft diameter > 8.5 mm in severe corneal diseases at the Department of Ophthalmology at Saarland University Medical Centre.

Study Design: Retrospective (6 years), descriptive, and observational.

Methods: Thirty-five large-diameter penetrating keratoplasties (LDPKPs) in 27 patients (mean age, 62 ± 22 years) were performed from March 2010 to December 2016. The indication for surgery, number of previous corneal transplantations, best-corrected visual acuity (BCVA) before surgery, intraocular pressure, graft status, and BCVA at last follow-up were recorded.

Results: Infectious keratitis represented 83% of the indications (of those, 45% fungal). The mean corneal graft diameter was 10.8 ± 1.7 (min 8.75, max 15.0) mm. Twenty-three eyes (65% absolute) had at least one previous penetrating keratoplasty (mean graft size, 9.2 ± 1.6 mm). The mean pre-surgery BCVA was 1.96 ± 0.23 logMAR. With a mean follow-up period of 20.2 ± 13.4 months, the mean BCVA was 1.57 ± 0.57 logMAR at last follow-up. Overall, 12 grafts (35%) remained clear until the last follow-up, and in 23 grafts (65%), the primary disease recurred, or corneal decompensation developed. Up to the last follow-up, 6 eyes (17%) had to be enucleated.

Conclusions: In complex cases of infectious keratitis requiring a LDPKP to remove the complete pathology and preserve eye integrity, the visual outcomes are generally expected to be poor, not only because of the well-known risks of LDPKP but also because of the consequences of the infectious disease itself. This knowledge is important for adequate counselling of the patient preoperatively.
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http://dx.doi.org/10.1055/a-1396-4787DOI Listing
April 2021

Graft survival using cadaver and multiorgan donors between 2008 and 2017 in our department

Orv Hetil 2021 03 28;162(13):488-496. Epub 2021 Mar 28.

1 Semmelweis Egyetem, Általános Orvostudományi Kar, Szemészeti Klinika, Budapest, Mária u. 39., 1085.

Összefoglaló. Bevezetés: Az első szaruhártya-bank 1944-es alapítása óta jelentős változásokon ment át. A szaruhártya túlélését számos tényező befolyásolja, így a tárolási mód, melynek a szövet lejárati ideje szerint rövid, közép és hosszú távú módszereit fejlesztették ki. Célkitűzés: Retrospektív vizsgálatunk célja a 2008. január 1. és 2017. december 31. között perforáló és lamelláris keratoplasztika során felhasznált cadaverből és multiorgan donorból származó szaruhártyák túlélésének vizsgálata volt a Semmelweis Egyetem Szemészeti Klinikáján. Módszer: Feljegyeztük a recipiens nemét, életkorát, a műtétet indikáló klinikai diagnózist, a műtét időpontját, a szövettani vizsgálat eredményét, valamint, hogy a beültetett szaruhártya cadaverből vagy multiorgan donorból származott. Meghatároztuk, hogy a recipiens életkora korrelált-e a rekeratoplasztikáig eltelt idővel. Eredmények: 1451 szaruhártya-átültetés történt 1088 beteg (44,6% férfi) 1159 szemén (életkor 62,8 ± 18,5 év), melyek között 938 (64,6%) cadaver és 262 (18,0%) multiorgan donor került felhasználásra, 251 esetben (17,2%) nem állt rendelkezésre adat. A leggyakoribb primer diagnózis a szaruhártya-dekompenzáció volt (325 eset, 28%). A primer keratoplasztikák során felhasznált szaruhártyák 740 esetben (63,8%) cadaverből, 212 esetben (18,2%) multiorgan donorból származtak, 207 esetben (17,8%) nem állt rendelkezésre adat. Első rekeratoplasztika a primer keratoplasztikák közül 217 esetben (18,7%) történt. A leggyakoribb szövettani diagnózis az endothelsejt-degeneráció volt (130 esetben, 60,4%). 146 esetben (67,2%) korábban cadaver, 31 esetben (14,2%) multiorgan donor esetén került sor ismételt műtétre, 40 esetben (18,4%) nem állt rendelkezésre adat. Következtetés: Klinikánkon elsősorban cadaverből származó donorok biztosítják a szaruhártya átültetésekhez szükséges szövetet. Cadaverből vagy multiorgan donorból származó szaruhártyák esetén nem kerül gyakrabban sor rekeratoplasztikára. A szaruhártya-banki tevékenység további fejlesztésével növelhető a donorok túlélése hazánkban. Orv Hetil. 2021; 162(13): 488-496.

Summary:

Introduction: Corneal banking methods have been changing since the foundation of the first corneal bank in 1944. Corneal graft survival may be affected by several factors, among others the storage method, which may be short-, middle- and long-term storage.

Objective: To investigate corneal graft survival at the Department of Ophthalmology, Semmelweis University between 1 January 2008 and 31 December 2017, using cadaver and multiorgan donors for penetrating and lamellar keratoplasty, retrospectively.

Method: Recipient sex, age, clinical diagnosis, date of surgery, histological examination results and origin of donors (cadaver or multiorgan donor) were recorded. Correlation between recipient age and time to repeat keratoplasty was also analyzed.

Results: There were 1451 keratoplasties in 1159 eyes (age 62.8 ± 18.5 years) of 1088 patients (44.6% male) using 938 (64.6%) cadaver and 262 (18.0%) multiorgan donors, data was not available in 251 (17.2%) cases. There was repeat keratoplasty in 217 patients (18.7% of first keratoplasties). The most common histological diagnosis was endothelial decompensation (130 cases, 60.4%) in these cases. In patients with a first repeat keratoplasty, in 146 cases (67.2%) the first donor originated from cadavers, in 31 cases (14.2%) from multiorgan donors and in 40 cases (18.4%) data were not available.

Conclusion: Corneal donors mainly originate from cadavers at our Department. The necessity of repeat keratoplasties does not differ using cadaver or multiorgan donors. With further development of corneal banking, donor survival may be increased in Hungary. Orv Hetil. 2021; 162(13): 488-496.
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http://dx.doi.org/10.1556/650.2021.32017DOI Listing
March 2021

Reliability analysis of successive Corneal Visualization Scheimpflug Technology measurements in different keratoconus stages.

Acta Ophthalmol 2021 Mar 22. Epub 2021 Mar 22.

Department of Ophthalmology, Saarland University Medical Center, Homburg, Germany.

Background: This study assesses the reliability of successive corneal biomechanical response measurements by the Corneal Visualization Scheimpflug Technology (CST, Corvis ST , Oculus Optikgeräte, Wetzlar, Germany) in different keratoconus (KC) stages.

Methods: A total of 173 eyes (15 controls: 15 eyes, and 112 KC patients: stages 1|1-2|2|2-3|3|3-4|4, n = 26|16|36|18|31|26|5 according to Topographical KC Classification, TKC) were repeatedly examined five times with the CST, each after repositioning the patient's head and re-adjusting the device. Tomographical analysis (Pentacam HR ; Oculus, Wetzlar, Germany) was performed once before and once after CST measurements. Outcome measures included (1) A1 velocity, (2) deformation amplitude (DA) ratio 2 mm, (3) integrated radius, (4) stiffness parameter A1 and (5) Ambrósio relational thickness to the horizontal profile (ARTh). The Corvis Biomechanical Index (CBI) is reported to be extracted out of these parameters. Mean values of the five measurements and Cronbach's α were calculated as a measure for reliability.

Results: Ambrósio relational thickness to the horizontal profile and SPA1 were significantly higher in controls (534|123) compared to TKC1 (384|88), TKC2 (232|66), TKC3 (152|55) and TKC4 (71|27; p < 0.0001). The other parameters were similar in controls and TKC1 (A1 velocity: 0.148|0.151 m/s; integrated radius: 8.2|8.6 mm ), but significantly higher in TKC stages 2 to 4 (DA ratio 2 mm: 5.5|6.3|8.0; A1 velocity: 0.173|0.174|0.186 m/second; integrated radius: 10.9|12.8|19.0 mm ; p < 0.0001). All parameters proved to be highly reliable (Cronbach's α ≥ 0.834) and the corneal tomography remained unaffected.

Conclusions: The individual parameters included in the CBI (consisting of ARTh, SPA1, DA ratio 2 mm, A1 velocity and integrated radius) are highly reliable but differ KC stage-dependently.
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http://dx.doi.org/10.1111/aos.14857DOI Listing
March 2021

Endothelial Cell Density and Central Corneal Thickness following Penetrating Keratoplasty of Acanthamoeba Keratitis Patients - A Retrospective Cross-Sectional Observational Study.

Klin Monbl Augenheilkd 2021 Mar 17. Epub 2021 Mar 17.

Dr Rolf M. Schwiete Center for Limbal Stem Cell and Congenital Aniridia Research, Saarland University, Homburg/Saar, Germany.

Purpose: To analyze endothelial cell density (ECD) and central corneal thickness (CCT) following penetrating keratoplasty (PKP) in keratitis (AK) patients.

Patients And Methods: In this retrospective, clinical, single-center, cross-sectional, observational study, patients were enrolled who underwent PKP at the Department of Ophthalmology of Saarland University Medical Center, Homburg/Saar, Germany between May 2008 and December 2016 with the diagnosis of AK. In all, 33 eyes of 33 patients (14 males, 42%) were enrolled; their mean age at the time of surgery was 39.5 ± 14.3 years. Postoperatively, AK patients received topical polyhexamethylene biguanide, propamidine isethionate, neomycin sulphate/gramicidin/polymixin B sulfate, and prednisolone acetate eye drops (5 ×/day each), and the topical treatment was tapered sequentially with 1 drop every 6 weeks over 6 months. CCT was recorded using Pentacam HR Scheimpflug tomography and ECD with the EM-3000 specular microscope before surgery and 3 and 6 months after surgery as well as after the first and second (complete) suture removal.

Results: ECD tended to decrease significantly from the time point before surgery (2232 ± 296 cells/mm) to the time point 3 months after surgery (1914 ± 164 cells/mm; p = 0.080) and to the time point after the first suture removal (1886 ± 557 cells/mm; p = 0.066) and decrease significantly to the time point after the second suture removal (1650 ± 446 cells/mm; p = 0.028). CCT did not change significantly over the analyzed time period (p ≥ 0.475).

Conclusion: In AK, endothelial cell loss does not seem to be accelerated following PKP, despite the postoperative use of diamidine and biguanide. A subsequent prospective comparative study should confirm our retrospective longitudinal analysis.
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http://dx.doi.org/10.1055/a-1353-5171DOI Listing
March 2021

How Implementing a Quality Management System at the LIONS Eye Bank Saar-Lor-Lux, Trier/Western Palatinate from 2006 to 2016 Impacted the Rate and Reasons for Discarding Human Organ-Cultured Corneas.

Klin Monbl Augenheilkd 2021 Mar 17. Epub 2021 Mar 17.

Klinik für Augenheilkunde, Universitätsklinikum des Saarlandes und Medizinische Fakultät der Universität des Saarlandes, Homburg, Deutschland.

Background: The aim of this study was to explore how the implementation of the quality management system (QM; according to DIN EN ISO 9001 : 2008) at the LIONS Eye Bank impacted the rate and reasons for discarding donated corneas. The QM system was introduced in November 2010.

Material And Methods: The rate of and reasons for discarding cornea tissues at the LIONS Eye Bank Saar-Lor-Lux,Trier/Western Palatinate from 2006 to 2016 were analysed retrospectively. 4,140 corneas from 2,084 donors were analysed. 1,640 corneas were processed before the QM system had been introduced and 2,500 corneas thereafter. Main reasons for discarding cornea tissues were endothelial quality, contamination of the medium and a positive conjunctival swab. The data was extracted from clinical files and data filing systems, entered into a Microsoft Access database and analysed statistically with SPSS.

Outcome: Following the implementation of a QM system, the discard rate decreased significantly from 50.1% to 39.7% (p < 0.0001). Prior to the implementation of the QM system, 493 (30.1%) cornea tissues had been discarded due to endothelial quality, while this figure improved significantly to 604 (24.2%) after the QM system had been implemented (p < 0.0001). Contamination was the reason for discarding tissue in 173 (10.5%) cases before implementation of the QM system, and in 124 (5.0%) cases thereafter (p < 0.0001). Positive conjunctival swab was the reason for discarding tissue in 10 (0.6%) cases before the QM system had been implemented, and in 53 (2.1%) cases thereafter (p < 0.0001).

Conclusion: Implementation of a QM system significantly reduced the rate of discarded donor tissue in the LIONS Eye Bank. Better management of contamination as a reason for discarding cornea tissues can be attributed to improved standards, protocols and training that are part of this QM system.
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http://dx.doi.org/10.1055/a-1327-3835DOI Listing
March 2021

Wavelength-specific optoacoustic-induced vibrations of the guinea pig tympanic membrane.

J Biomed Opt 2021 Mar;26(3)

Saarland University, Medical Center, Department of Otolaryngology, Homburg, Germany.

Significance: Optoacoustic-induced vibrations of the hearing organ can potentially be used for a hearing device. To increase the efficiency of such a hearing device, the conversion of the light energy into vibration energy within each type of irradiated tissue has to be optimized.

Aim: To analyze the wavelength-dependency of optoacoustic-induced vibrations within the tympanic membrane (TM), and to define the most efficient and best-suited optical stimulation parameters for a novel auditory prosthesis.

Approach: Single nanosecond laser pulses, continuously tunable in a range of visible to near-infrared, were used to excite the guinea pig TM. The induced vibrations of the hearing organ were recorded at the malleus using a laser Doppler vibrometer.

Results: Our results indicate a strong wavelength-dependency of the vibration's amplitude correlating with the superposition of the absorption spectra of the different specific tissue components.

Conclusions: We investigated the spectrum of the vibrations of the hearing organ that were induced optoacoustically within a biological membrane embedded in air, in an animal model. First applications for these results can be envisioned for the optical stimulation of the peripheral hearing organ as well as for research purposes.
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http://dx.doi.org/10.1117/1.JBO.26.3.038001DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7934890PMC
March 2021

Optimal Dataset Sizes for Constant Optimization in Published Theoretical Optical Formulae.

Curr Eye Res 2021 Mar 5. Epub 2021 Mar 5.

Dr. Rolf M. Schwiete Center for Limbal Stem Cell and Aniridia Research, Saarland University, Homburg/Saar, Germany.

: To determine the optimal number of data points required for optimization of formulae for classical lens power calculation.: A large dataset of preoperative biometric values was used to assess the convergence of formula constants in a number of established intraocular lens power calculation formulae.: In formulae with a single constant, 80 to 100 clinical data points are sufficient to obtain convergence. The Haigis formula (3 constants), requires 200 to 300 data points although refractive error converges more rapidly.: In all formulae 80 to 100 clinical data points are sufficient to achieve a stable mean refractive error.
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http://dx.doi.org/10.1080/02713683.2021.1900272DOI Listing
March 2021

Prediction model for best focus, power, and spherical aberration of the cornea: Raytracing on a large dataset of OCT data.

PLoS One 2021 22;16(2):e0247048. Epub 2021 Feb 22.

Augen- und Laserklinik Castrop-Rauxel, Castrop-Rauxel, Germany.

Purpose: To analyse corneal power based on a large optical coherence tomography dataset using raytracing, and to evaluate corneal power with respect to the corneal front apex plane for different definitions of best focus.

Methods: A large OCT dataset (10,218 eyes of 8,430 patients) from the Casia 2 (Tomey, Japan) was post-processed in MATLAB (MathWorks, USA). Using radius of curvature, corneal front and back surface asphericity, central corneal thickness, and pupil size (aperture) a bundle of rays was traced through the cornea. Various best focus definitions were tested: a) minimum wavefront error, b) root mean squared ray scatter, c) mean absolute ray scatter, and d) total spot diameter. All 4 target optimisation criteria were tested with each best focus plane. With the best-fit keratometer index the difference of corneal power and keratometric power was evaluated using a multivariate linear model.

Results: The mean corneal powers for a/b/c/d were 43.02±1.61/42.92±1.58/42.91±1.58/42.94±1.59 dpt respectively. The root mean squared deviations of corneal power from keratometric power (nK = 1.3317/1.3309/1.3308/1.3311 for a/b/c/d) were 0.308/0.185/0.171/0.209 dpt. With the multivariate linear model the respective RMS error was reduced to 0.110/0.052/0.043/0.065 dpt (R² = 0.872/0.921/0.935/0.904).

Conclusions: Raytracing improves on linear Gaussian optics by considering the asphericity of both refracting surfaces and using Snell's law of refraction in preference to paraxial simplifications. However, there is no unique definition of best focus, and therefore the calculated corneal power varies depending on the definition of best focus. The multivariate linear model enabled more precise estimation of corneal power compared to the simple keratometer equation.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0247048PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7899355PMC
February 2021

Herpes Simplex Virus Keratitis in a University Tertiary Referral Centre - Clinical Features and Surgical Approaches.

Klin Monbl Augenheilkd 2021 Feb 19. Epub 2021 Feb 19.

Klinik für Augenheilkunde, Universitätsklinikum des Saarlandes und Medizinische Fakultät der Universität des Saarlandes, Homburg, Germany.

Purpose: To assess prevalence, clinical manifestations, required keratoplasties, follow-up, and outcome in patients with Herpes Simplex Virus Keratitis (HSK) attending a University Tertiary Referral Center.

Design: Retrospective (12 years), descriptive, observational study.

Methods: A total of 817 eyes with clinical diagnosis of HSK from 779 patients were classified by the type of presentation. We gathered data on the visual acuity, refraction, IOP, and required surgical procedures.

Results: Stromal involvement including scars represented the most common diagnosis in our department and the main indication of penetrating keratoplasty (PKP). Epithelial keratitis (16%) presented with the best visual acuity at the first visit. Necrotizing keratitis represented 17% of the patients, 78% of whom required PKP; this group also had the worst visual acuity at first examination and was the main indication for emergency PKP. Among all eyes, 288 (35%) required PKP. A total of 230 (28%) PKPs were elective procedures and 58 (7%) PKPs were performed as emergency procedures. Two patients with quiet endothelial decompensations after recurrent HSV endotheliitis were treated with DMEK and had good visual outcomes without HSV recurrence at last follow-up.

Conclusions: HSK is a prevalent disease with severe consequences when not treated appropriately and on time. Even when making an accurate diagnosis, the disease can be extremely aggressive, with all the implications it brings to the patients and health system. Elective PKP had better outcomes in terms of visual acuity and clear graft percentage compared to emergency PKP.
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http://dx.doi.org/10.1055/a-1306-0896DOI Listing
February 2021

Back-calculation of keratometer index based on OCT data and raytracing - a Monte Carlo simulation.

Acta Ophthalmol 2021 Feb 11. Epub 2021 Feb 11.

Augen- und Laserklinik Castrop-Rauxel, Castrop-Rauxel, Germany.

Purpose: This study aims to develop a raytracing-based strategy for calculating corneal power from anterior segment optical coherence tomography data and extracting the individual keratometer index, which converts the corneal front surface radius to corneal power.

Methods: A large OCT dataset (10,218 eyes of 8,430 patients) from the Casia 2 (Tomey, Japan) was post-processed in MATLAB (MathWorks, USA). Radius of curvature, asphericity of the corneal front and back surface, central corneal thickness and pupil size (aperture) were used to trace a bundle of rays through the cornea and derive the best focus plane. Corneal power was calculated with respect to the corneal front vertex plane, and the keratometer index was back-calculated using corneal power and front surface radius. Keratometer index was analysed in a multivariate linear model.

Results: The averaged resulting keratometer index was 1.3317 ± 0.0017 with a median of 1.3317 and range from 1.3233 to 1.3390. In a univariate model, only the front surface asphericity affected the keratometer index. The multivariate model for modelling the keratometer index using all 6 input parameters performed very well (RMS error: 5.54e-4, R : 0.90, significance vs. constant model: <0.0001).

Conclusions: In the classical calculation, the keratometer index used for converting corneal radius to dioptric power uses several model assumptions. As these assumptions are not generally satisfied, corneal power cannot be calculated from corneal front surface radius alone. Considering all 6 input variables, the linear prediction model performs well and can be used if all input parameters are measured with a tomographer.
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http://dx.doi.org/10.1111/aos.14794DOI Listing
February 2021

IOL formula constants - strategies for optimization and defining standards for presenting data.

Ophthalmic Res 2021 Feb 2. Epub 2021 Feb 2.

Purpose: To present strategies for optimization of lens power formula constants and to show options how to present the results adequately.

Methods: A dataset of N=1601 preoperative biometric values, lens power data and postoperative refraction data was split into a training set and a test set using a random sequence. Based on the training set we calculated the formula constants for established lens calculation formulae with different methods. Based on the test set we derived the formula prediction error as difference of the achieved refraction from the formula predicted refraction.

Results: For formulae with 1 constant it is possible to back-calculate the individual constant for each case using formula inversion. However, this is not possible for formulae with more than 1 constant. In these cases, more advanced concepts such as nonlinear optimization strategies are necessary to derive the formula constants. During cross-validation, measures such as the mean absolute or the root mean squared prediction error or the ratio of cases within mean absolute prediction error limits could be used as quality measures.

Conclusions: Different constant optimization concepts yield different results. To test the performance of optimized formula constants a cross-validation strategy is mandatory. We recommend performance curves, where the ratio of cases within absolute prediction error limits is plotted against the mean absolute prediction error.
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http://dx.doi.org/10.1159/000514916DOI Listing
February 2021

Project hyperopic power prediction: accuracy of 13 different concepts for intraocular lens calculation in short eyes.

Br J Ophthalmol 2021 Jan 27. Epub 2021 Jan 27.

Department of Ophthalmology and Optometry, Kepler University Hospital, Linz, Oberösterreich, Austria.

Purpose: To evaluate the accuracy of intraocular lens (IOL) power calculation in a patient cohort with short axial eye length to assess the performance of IOL power calculation schemes in strong hyperopes.

Methodology: The study was a single centre, single surgeon retrospective consecutive case series at the Augen- und Laserklinik, Castrop-Rauxel, Germany. Inclusion of patients after uneventful cataract surgery implanting either spherical (SA60AT) or aspheric (ZCB00) IOLs. Inclusion criteria were axial eye length <21.5 mm and/or emmetropising IOL power >28.5 D. Lens constants were optimised on a separate patient cohort considering the full bandwidth of axial eye length. Data of one single eye per patient were randomly included. The outcome measures were: mean absolute prediction error (MAE), median absolute prediction error, mean prediction error with SD and median prediction error and the percentage of eyes with an MAE within 0.25 D, 0.5 D, 0.75 D and 1.0 D.

Results: A total of 150 eyes from 150 patients were assessed. Okulix, PEARL-DGS, Kane and Castrop provided a statistically significantly smaller MAE compared with the Hoffer Q and SRK/T formulae.

Conclusion: In our patient cohort with short axial eye length, the use of PEARL-DGS, Okulix, Kane or Castrop formulae showed the lowest MAE. The Castrop formula has not been published before, but will be disclosed with a ready-to-use Excel sheet as an addendum to this paper.
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http://dx.doi.org/10.1136/bjophthalmol-2020-318272DOI Listing
January 2021
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