Quantitative assessment of photic phenomena in the presbyopia-correcting intraocular lens.

This was a prospective study to evaluate the feasibility of the photic phenomena test (PPT) for quantifying glare, halo, and starburst. We compared two presbyopia-correcting intraocular lenses (IOLs), the Symfony IOL and the PanOptix IOL, as well as the monofocal Clareon IOL in 111 IOL-implanted eyes of 111 patients who underwent the PPT 1 month postoperatively. The reproducibility of photic phenomena with the PPT was assessed in 39 multifocal IOL-implanted eyes of 20 patients and among the examiners. Patients with ocular diseases, except for refractive errors, were excluded. The mean values of the groups were evaluated. Bland-Altman plots were used to analyze statistical data (Easy R version 1.37; R Foundation for Statistical Computing, Vienna, Austria). The PPT reproducibility assessment revealed no fixed bias or regressive significance. Reproducibility was confirmed. The glare size did not differ significantly between the Symfony, PanOptix, and Clareon groups. The halo size was significantly larger in the Symfony group (p < 0.01) than in the PanOptix group. The halo intensity was significantly brighter in the PanOptix group (p < 0.01) than in the Symfony group. In contrast, no halos were perceived in the Clareon group. The starburst size or intensity did not differ significantly between the Symfony, PanOptix, and Clareon groups. We identified the photic phenomenon related to various IOLs.

Prediction accuracy of conventional and total keratometry for intraocular lens power calculation in femtosecond laser-assisted cataract surgery.

This study evaluated the accuracy of total keratometry (TK) and standard keratometry (K) for intraocular lens (IOL) power calculation in eyes treated with femtosecond laser-assisted cataract surgery. The retrospective study included a retrospective analysis of data from 62 patients (91 eyes) who underwent uneventful femtosecond laser-assisted cataract surgery with Artis PL E (Cristalens Industrie, Lannion, France) IOL implantation by a single surgeon between May 2020 and December 2020 in Severance Hospital, Seoul, South Korea. The new IOLMaster 700 biometry device (Carl Zeiss Meditec, Jena, Germany) was used to calculate TK and K. The mean absolute error (MAE), median absolute error (MedAE), and the percentages of eyes within prediction errors of ± 0.25 D, ± 0.50 D, and ± 1.00 D were calculated for all IOL formulas (SRK/T, Hoffer-Q, Haigis, Holladay 1, Holladay 2, and Barrett Universal II). There was strong agreement between K and TK (intraclass correlation coefficient = 0.99), with a mean difference of 0.04 D. For all formulas, MAE tended to be lower for TK than for K, and relatively lower MAE and MedAE values were observed for SRK/T and Holladay 1. Furthermore, for all formulas, a greater proportion of eyes fell within ± 0.25 D of the predicted postoperative spherical equivalent range in the TK group than in the K group. However, differences in MAEs, MedAEs, and percentages of eyes within the above prediction errors were not statistically significant. In conclusion, TK and K exhibit comparable performance for refractive prediction in eyes undergoing femtosecond laser-assisted cataract surgery.

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

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.

Artificial accommodating intraocular lens powered by an ion polymer-metal composite actuator.

The current method of controlling the focus of an accommodating intraocular lens is based on ciliary muscle contraction and cannot be used in older patients with presbyopia. We aimed to develop a dynamically accommodating intraocular lens powered by a membrane-shaped ion polymer metal composite actuator that is thin enough to be inserted in the eye. This study addresses two key problems identified in our previous accommodating intraocular lens prototype: the lack of repeatability due to the use of swine lenses instead of artificial lenses and the occurrence of a sixth order aberration. Thus, we present a new accommodating intraocular lens design and a method to transfer energy to actuators. To accommodate lens deformation and depth of focus, we used a membrane-shaped ion polymer metal composite actuator, thin enough to be inserted in the eye, and used an artificial silicone lens. To prevent the sixth order aberration, we included a ring between the ion polymer metal composite actuator and the lens. Different voltage patterns were applied to the IPMC actuator and changes in focus were observed. We were able to obtain repeatability and prevent the sixth order aberration. The dioptric power changed to ±0.23 D when ±1.5 V was used; however, at >1.5 V, a large accommodating range occurred, in addition to astigmatic vision. Thus, we have developed a novel prototype that is completely artificial, allowing reproducible and repeatable results. Visual accommodative demands were successfully met; however, although astigmatic vision was lessened, it was not completely eradicated.

Corrección de la presbicia tras cirugía cristaliniana. ¿Dónde nos encontramos en 2020? / Lens-based surgical correction of presbyopia. Where are we in 2020?

INTRODUCCIÓN: La presbicia es la pérdida progresiva e irreversible de la acomodación debido al envejecimiento. Es una de las principales causas de disminución de la calidad de vida en personas a partir de los 45 años derivada de la, muchas veces novedosa, dependencia de las gafas. El afán por corregirla por parte de los oftalmólogos, impulsados por el deseo de millones de personas que la padecen, se ha convertido en uno de los principales motores de desarrollo de la tecnología de las lentes intraoculares (LIO) durante los últimos 20 años. MATERIAL Y MÉTODOS: Esta revisión repasa las distintas alternativas que han permitido ir mejorando el enfoque quirúrgico cristaliniano de la presbicia; desde las lentes monofocales y la técnica de la monovisión, a las lentes acomodativas, pasando por las lentes multifocales refractivas y difractivas y terminando con las más recientes lentes de foco o campo extendido conocidas como EDOF. RESULTADOS: Cada una de estas LIO tiene sus ventajas, limitaciones e inconvenientes; y además, no existe la lente que se adapte a las necesidades de todos los pacientes. CONCLUSIONES: Es necesario conocer la variedad de lentes disponibles, y comprender en profundidad tanto sus propiedades ópticas como el impacto que estas van a tener luego en su rendimiento clínico y en la calidad visual de los pacientes. Esto nos debería ayudar a poder seleccionar la mejor alternativa para cada uno de ellos

INTRODUCTION: Presbyopia is the progressive and irreversible loss of accommodation due to aging. It is one of the main causes of loss of quality of life in people from 45 years of age, due to the, often novel, dependence on spectacles. The eagerness to correct it by ophthalmologists impulsed by the desire of millions of people who suffer from it, has become one of the main drivers for the development of intraocular lens (IOL) technology over the last twenty years. MATERIAL AND METHODS: This review briefly presents the different alternatives that have allowed us to improve the crystalline lens surgical approach of presbyopia; from monofocal lenses and monovision technique, accommodative, refractive, and diffractive multifocal lenses, and finally the most recent extended depth of focus/field lenses known as EDOFs. RESULTS: Each IOL has its advantages, limitations and disadvantages. Furthermore, there is no single lens that suits the needs of all patients. CONCLUSIONS: It is necessary to know the variety of lenses available, and to have an in-depth understanding of their optical properties, as well as the impact that these will have later on their clinical performance and on the visual quality of the patients. This should help us to select the best alternative for each of them

Intraocular cataract lens replacement and light exposure potentially impact procedural learning in older adults.

Procedural learning declines with age and appropriately timed light exposure can improve cognitive performance in older individuals. Because cataract reduces light transmission and is associated with cognitive decline in older adults, we explored whether lens replacement (intraocular blue-blocking [BB] or UV-only blocking) in older patients with cataracts enhances the beneficial effects of light on procedural learning. Healthy older participants (n = 16) and older patients with post-cataract surgery (n = 13 with BB or UV lens replacement) underwent a randomized within-subject crossover laboratory design with three protocols. In each protocol, 3.5 hr dim-dark adaptation was followed by 2 hr evening blue-enriched (6,500K) or non-blue-enriched light exposure (3,000K or 2,500K), 30 min dim post-light, ~8 hr sleep and 2 hr morning dim light. Procedural learning was assessed by the alternating serial reaction time task (ASRT), as part of a larger test battery. Here, ASRT performance was indexed by type of trial (random or sequence) and sequence-specific (high or low probability) measures. During evening light exposure, we observed a significant effect of the interaction of "group" versus "light condition" on the type of trial (p = .04; p = .16; unadjusted and adjusted p-values, respectively) and sequence-specific learning (p = .04; p = .16; unadjusted and adjusted p-values, respectively), whereby patients with UV lens replacement performed better than patients with BB lens or non-cataract controls, during blue-enriched light exposure. Lens replacement in patients with cataracts may potentially be associated with beneficial effects of blue light on procedural learning. Thus, optimizing spectral lens transmission in patients with cataracts may help improve specific aspects of cognitive function, such as procedural learning.

A novel Q-value-based nomogram for single intracorneal ring segment implantation versus standard manufacturer's nomogram combined with accelerated cross-linking for treatment of keratoconus: a randomized controlled trial.

PURPOSE: To compare the efficacy of implanting a single Keraring segment according to a novel Q-value-based nomogram (QN) to that of segment implantation according to the manufacturer's standard nomogram (SN), for keratoconus treatment. METHODS: This was a prospective, randomized controlled trial of 104 patients (104 eyes) with Amsler-Krumeich grade 1 or 2 keratoconus, and type 1 or 2 cone asymmetry determined according to manufacturer's classification. They were randomly distributed into two groups: group A patients (n = 52) underwent Keraring implantation according to the SN, and group B patients (n = 52) underwent implantation of a single (210° arc-length) Keraring segment according to the QN. Both treatments were combined with accelerated transepithelial cross-linking, and follow-up was 6 months. Main outcome measures were preoperative and postoperative visual acuity, subjective refraction and corneal topography. RESULTS: At postoperative month 6, group B exhibited statistically significantly higher values of mean uncorrected distance visual acuity (UDVA), sphere, K2, K-average, K-max and Q-anterior (p = 0.02, 0.01, 0.002, 0.001, 0.0001 and 0.03, respectively) compared to that of group A. However, group A exhibited better refractive cylindrical improvements (p = 0.04). In group A, we documented spontaneous extrusion of one Keraring segment. CONCLUSION: Single 210° arc-length segment implantation using our objective QN was more efficacious for keratoconus treatment than using the subjective SN. The nomograms were comparable when the Q-anterior value was >-1.00; however, the QN was superior to the SN when the Q-anterior value was ≤-1.00. The QN yielded greater postoperative UDVA and smoother corneal remodelling than did the SN for treatment of grade 1 and 2 keratoconic eyes.

Diferencias en la visión intermedia: lente intraocular monofocal vs. lente intraocular monofocal de rango extendido / Differences in intermediate vision: monofocal intraocular lenses vs. monofocal extended depth of focus intraocular lenses

OBJETIVO: El objetivo de este estudio es analizar si una lente intraocular (LIO) monofocal (TECNIS Eyhance®, Johnson&Johnson Surgical Vision, Inc., Santa Ana, CA) de foco extendido proporciona una mejor agudeza visual (AV) intermedia que otras LIO monofocales (TECNIS 1-pieza®, Johnson&Johnson Surgical Vision, Inc., Santa Ana, CA) de la misma plataforma. MÉTODOS: Se realizó un estudio observacional prospectivo y aleatorizado con pacientes que necesitaban cirugía de cataratas en ambos ojos. Un grupo de pacientes recibió el implante con la LIO TECNIS 1-pieza y otro grupo recibió la LIO Eyhance de foco extendido monofocal. Un mes desde la cirugía en el segundo ojo se evaluó la AV intermedia corregida (66 cm) y se obtuvieron las curvas de desenfoque. También se exploró la correlación de aberraciones de orden elevado y esféricas con AV intermedia, tamaño pupilar con AV intermedia y edad con AV intermedia. RESULTADOS: El estudio analizó a 30 pacientes (60 ojos), 15 de ellos en el grupo TECNIS 1-pieza y 15 en el grupo Eyhance. Ambos grupos consiguieron una AV lejana de 0,00 logMAR. En contraste, para la visión intermedia la AV fue mejor con las LIO Eyhance de foco extendido monofocal (0,16 ± 0,12 LogMAR), siendo la diferencia estadísticamente significativa (p < 0,001). Además, se observó que la AV intermedia binocular guardaba una correlación significativa con las aberraciones corneales (6 mm) RMS de alto orden (ρ 0,476) y Z40 (ρ 0,483) con la LIO Eyhance. CONCLUSIONES: La nueva LIO monofocal de foco extendido (Eyhance) ofrece suficiente profundidad de foco para proporcionar a los pacientes una visión confortable sin afectar la visión lejana

PURPOSE: The purpose of this study was to analyse whether an extended depth of focus (EDOF) monofocal intraocular lens (IOL) (TECNIS Eyhance™, Johnson&Johnson Surgical Vision, Inc., Santa Ana, CA) provides better intermediate visual acuity (VA) than another monofocal IOL (TECNIS 1-piece™, Johnson&Johnson Surgical Vision, Inc., Santa Ana, CA) from the same platform. METHODS: Randomised prospective observational study. Patients who required cataract surgery in both eyes were included. Patients in one group were implanted with Tecnis 1-piece IOL and those in the other group with Eyhance EDOF monofocal IOL. One month after surgery in the second eye, we assessed the corrected intermediate VA (66 cm) and obtained defocus curves. We also explored the correlation of: high-order and spherical aberrations with intermediate VA, pupil size with intermediate VA and age with intermediate VA. RESULTS: We analysed 30 patients (60 eyes), 15 patients in the TECNIS 1-piece group and 15 in the Eyhance group. Both groups achieved a far VA of 0.00 logMAR. In contrast, for intermediate vision, VA was better with the Eyhance EDOF monofocal IOLs (0.16 ± 0.12 LogMAR), the difference being statistically significant (p < 0.001). In addition, binocular intermediate VA was found to be significantly correlated with corneal (6 mm) RMS high-order aberrations (ρ 0.476) and Z40 (ρ 0.483) with the Eyhance IOL. CONCLUSIONS: The new EDOF monofocal IOL (Eyhance) offers sufficient depth of focus to provide patients with comfortable vision without impairing far vision

The assessment of the impact of glistening on visual performance in relation to tear film quality.

BACKGROUND: The aim of our case control study was to evaluate the impact of glistening and tear film quality on visual performance after implantation of two different hydrophobic acrylic intraocular lenses (IOLs). MATERIALS AND METHODS: In our retrospective study we included cataract patients operated between January 1, 2011 and December 31, 2012, with follow-up controls between January 2016 and December 2019. Z-Flex 860FAB (Medicontur) and AcrySof IQ SN60WF (Alcon) monofocal IOLs were implanted during standard phacoemulsification. Best corrected distance visual acuity (BCDVA) and contrast sensitivity were monitored over the post-operative period of up to 6 years. Glistening was evaluated semi-quantitatively with slit-lamp biomicroscopy and quantitatively using Pentacam HR (Oculus). Using HD Analyzer OQAS (Visiometrics), total intraocular light diffusion was interpreted with the objective scatter index (OSI) and tear film quality was evaluated with the tear film related objective scatter index (TF-OSI). RESULTS: 26 eyes implanted with the Z-Flex and 25 eyes with the AcrySof IQ IOLs were included in the analysis. The slit-lamp evaluation of patients with the Z-Flex IOL (0.57 ± 0.60) revealed significantly less glistening (p<0.0001), compared to the AcrySof IQ group (1.82 ± 0.90), and these observations were confirmed by the Pentacam HR analyses, as well (Z-Flex group: 35.1 ± 1.63, Acrysof IQ: 39.6 ± 3.69, p<0.0001). TF-OSI differed between the two sets of patients remarkably (1.53 ± 1.03 vs. 2.51 ± 1.76 for AcrySof IQ and Z-Flex groups, respectively, p = 0.043). Both groups of patients provided similar results of BCDVA and contrast sensitivity. CONCLUSION: Glistening and tear film quality both contribute to visual performance outcomes after cataract surgery. In our study the advantage of less glistening in the Z-Flex IOL might have been masked by the adverse effects of the more pronounced tear film insufficiency of these patients, compared to the AcrySof IQ group. Among other factors, tear film quality should also be taken into consideration when comparing the impact of glistening on visual quality of patients implanted with different IOLs.

Sagitta of ophthalmic lenses.

PURPOSE: To propose alternative formulas for the sagitta calculation of ophthalmic lenses. METHODS: Equation factoring. RESULTS: The conventional sagitta formula is algebraically inconsistent when applied to curves with direction-oriented radii. It is possible to correct this problem by factoring it. CONCLUSIONS: The conventional sagitta formula can and should be replaced by unambiguous equations.

Evaluation of the optical performance for aspheric intraocular lenses in relation with tilt and decenter errors.

PURPOSE: To evaluate and compare the effect of misalignment and tilt on the optical performance of different aspheric intraocular lens (IOL) designs. METHODS: Three aspheric IOLs with a different quantity of spherical aberration (SA) have been designed and the effect of IOL misalignment and tilt on the imaging quality of an eye model has been numerically assessed using a commercial optical design software. The prototypes have been manufactured by lathe turning and tested in vitro using the same optical bench (PMTF, Lambda-X) that complies with International Organization for Standardization standard 11979-2 requirements. Image quality was evaluated from the modulation transfer functions (MTFs), through-focus modulation transfer functions (TF-MTFs), root mean square (RMS) values of defocus, astigmatism and coma, and images of the United States Air Force (USAF) target were taken. A comparison with the optical performance of spherical IOLs has also been performed. RESULTS: Intraocular lens misalignment and tilt increased wavefront aberrations; the effect of misalignment on root mean square (RMS) astigmatism and coma was positively correlated with the spherical aberration of the IOL. Aberration-free IOLs showed the highest MTF for all misalignment values and for IOLs with negative SA correction the MTF decays below 0.43 when they are decentered 0.50 mm. CONCLUSIONS: Aspherical IOLs are more sensitive than spherical IOLs to misalignment or tilt, depending on their SA correction. The optical degradation caused by IOL misalignment had a greater effect on IOL designs with a higher amount of negative spherical aberration. In contrast, the effect of tilt on the optical performance was less sensitive to the IOL design.

Accuracy of intraocular lens power calculation formulas using a swept-source optical biometer.

PURPOSE: To compare the accuracy of the five commonly used intraocular lens (IOL) calculation formulas integrated to a swept-source optical biometer, the IOLMaster 700, and evaluate the extent of bias within each formula for different ocular biometric measurements. METHODS: The study included patients undergoing cataract surgery with a ZCB00 IOL implant, using IOLMaster 700 optical biometry. A single eye per patient was included in the final analysis for a total of 324 cases. The SRK/T, Hoffer Q, Haigis, Holladay 2, and Barrett Universal II formulas were evaluated. The correlations between the refractive prediction errors calculated using the five formulas and ocular dimensions such as axial length (AL), anterior chamber depth (ACD), corneal power, and lens thickness (LT) were analyzed. RESULTS: There were significant differences in the median absolute error predicted by the five formulas after the adjustment for mean refractive prediction errors to zero (P = 0.038). The Barrett Universal II formula had the lowest median absolute error (0.263) and resulted in a higher percentage of eyes with prediction errors within ±0.50 D, ±0.75 D, and ±1.00 D (all P < 0.050). The refractive errors predicted by only the Barrett formula showed no significant correlation with the ocular dimensions: AL, ACD, corneal power, and LT. CONCLUSIONS: Overall, the Barrett Universal II formula, integrated to a swept-source optical biometer had the lowest prediction error and appeared to have the least bias for different ocular biometric measurements for the ZCB00 IOL.

Comparison of visual and optical quality of monofocal versus multifocal intraocular lenses.

OBJECTIVE: To compare visual quality in patients implanted with Tecnis® monofocal (ZCB00) and multifocal (ZMB00) intraocular lenses taking into account their optical quality measured in vitro with an eye model. METHODS: In total, 122 patients participated in this study: 44 implanted with monofocal and 78 with multifocal intraocular lenses. Measurements of visual acuity and contrast sensitivity were performed. The optical quality of the intraocular lenses was evaluated in three image planes (distance, intermediate and near) using an eye model on a test bench. The metric considered was the area under the curve of the modulation transfer function. RESULTS: Optical quality at the far focus of the monofocal intraocular lens (area under the curve of the modulation transfer function = 66.97) was considerably better than that with the multifocal lens (area under the curve of the modulation transfer function = 32.54). However, no significant differences were observed between groups at the distance-corrected visual acuity. Distance-corrected near vision was better in the multifocal (0.15 ± 0.20 logMAR) than that in the monofocal group (0.43 ± 0.21 logMAR, p < 0.001), which correlated with the better optical quality at near reached by the multifocal intraocular lens (area under the curve of the modulation transfer function = 29.11) in comparison with the monofocal intraocular lens (area under the curve of the modulation transfer function = 5.0). In intermediate vision, visual acuity was 0.28 ± 0.16 logMAR (multifocal) and 0.36 ± 0.14 logMAR (monofocal) with p = 0.014, also in good agreement with the values measured in the optical quality (area under the curve of the modulation transfer function = 10.69 (multifocal) and 8.86 (monofocal)). The contrast sensitivity was similar in almost all frequencies. Pelli-Robson was slightly better in the monofocal (1.73) than in the multifocal group (1.64; p = 0.023). CONCLUSION: Patients implanted with multifocal ZMB00 achieved a distance visual acuity similar to those implanted with monofocal ZCB00, but showed significantly better intermediate and near visual acuity. A correlation was found between intraocular lenses' optical quality and patients' visual acuity. Contrast sensitivity was very similar between the multifocal and monofocal groups.

Accuracy of Intraocular Lens Formulas in Eyes With Keratoconus.

PURPOSE: To evaluate the refractive accuracy of current intraocular lens (IOL) formulas in eyes with keratoconus. DESIGN: Retrospective case series. METHODS: Preoperative optical biometry, Pentacam topography, and postoperative outcomes were collected from eyes with keratoconus that had uncomplicated cataract surgery between 2014 and 2018 at a single institution. Exclusion criteria include postoperative best-corrected spectacle visual acuity worse than 20/40, multifocal lens, prior ophthalmic surgeries, and prior ocular trauma. The Hoffer Q, SRK/T, Holladay I, Holladay II, Haigis, and Barrett Universal II formulas were analyzed in each eye stratified by keratoconus severity. RESULTS: A total of 73 eyes were included. All formulas had a positive mean predicted error ranging from 0.10 to 4.38 diopters (D). The Barrett Universal II formula had the lowest median absolute error for stage I (n = 46, 0.445 D) and II (n = 22, 0.445 D) eyes, and the highest percentage of eyes with predicted error within ±0.50 D for both stage I (52%) and II (50%) eyes. In stage III eyes (n = 5), the Haigis formula had the lowest median predicated error (1.90 D) and the highest percentage of eyes with predicted error within ±0.50 D (40%). Corneal power measured by optical biometers was higher than measurements by Pentacam keratometry. CONCLUSIONS: All formulas tend to have a hyperopic surprise. The Barrett Universal II formula was the most accurate for mild to moderate disease. Pentacam keratometry may help avoid hyperopic outcomes.

Using Proactive Risk Assessment (HFMEA) to Improve Patient Safety and Quality Associated with Intraocular Lens Selection and Implantation in Cataract Surgery.

BACKGROUND: A proactive risk assessment using the Healthcare Failure Mode and Effect Analysis (HFMEA) process was completed on the intraocular lens (IOL) selection and implantation process to analyze system vulnerabilities that could cause patient harm. The three largest ophthalmology clinics based on patient surgical volume were studied in the analysis. The analysis included in-clinic eye measurements needed for IOL selection through the actual implantation of the lens in the operating room. METHODS: The HFMEA process was used for the analysis. A detailed process and subprocess diagram was created through interviews and observations. A multidisciplinary team met 12 times over a 14-week period, evaluating 170 discrete process and subprocess steps and identifying 177 failure modes and 75 failure mode causes for analysis. RESULTS: A high degree of process variability and lack of a robust quality assurance process was found. Areas for improvement included reducing variability between and within clinics, reducing variability in processes used by surgeons, modifying equipment and software to better support the work processes, and implementing a quality assurance program requiring observation of staff performing their routine work as opposed to relying on self-reports of quality metrics. CONCLUSION: The HFMEA process provided a more complete understanding of all of the processes associated with cataract surgery. This allowed for the identification of a variety of risk factors to patient safety that had not previously been identified by the more traditional reactive analysis methods, which tend to focus only on vulnerabilities identified by a specific event.

The impact of glistenings on the optical quality of a hydrophobic acrylic intraocular lens.

PURPOSE: To study the effect of glistenings on the optical quality of a hydrophobic acrylic intraocular lens (IOL). SETTING: David J. Apple Laboratory, Heidelberg, Germany. DESIGN: An in vitro laboratory study. METHODS: An accelerated aging protocol was used to induce glistenings (microvacuoles) in 38 hydrophobic acrylic IOLs. The IOLs were warmed to 45°C and then cooled to 37°C. Image analysis of light-microcopy photographs determined the number and size of microvacuoles (MV). A classification was applied based on the glistening number per mm2: grade 0 (none), grade 1 (1-100), grade 2 (101-200), grade 3 (201-500) and grade 4 (more than 500). An optical bench was used to measure each IOL's modulation transfer function (MTF) and Strehl ratio to evaluate the impact of glistenings on image quality. RESULTS: Glistenings were observed in all IOLs. The mean glistening numbers ± SD (MV/mm2) in grades 1 through 4 were 74 ± 12.7, 142 ± 22.2, 297 ± 76.2, and 1509 ± 311.9, respectively. The mean glistening sizes in grades 1 through 4 were 13.28 ± 3.85 µm, 15.88 ± 2.08 µm, 16.85 ± 3.23 µm, and 15.27 ± 2.25 µm, respectively. Statistical analysis showed that grades 1 through 3 did not change the optical quality; however, in grade 4, the MTF and the Strehl ratio were significantly affected. CONCLUSION: A limited number of glistenings (<500 MV/mm2) had no effect on the image quality. Although statistically significant deteriorations in the MTF and the Strehl ratio were observed in grade 4, the effects found were small and are unlikely to affect the visual quality.

[Study on the Imaging Quality Evaluation of Aspheric Intraocular Lenses].

The article is to study the objective evaluation method of the imaging quality of aspheric intraocular lens with different design concepts by establishing the model eye which is close to the actual corneal spherical aberration characteristics. Combined with the research data of corneal spherical aberration, the simulated cornea corresponding to Zernike c(4,0) coefficient 0.00 µm, 0.10 µm, 0.20 µm and 0.28 µm was established respectively. The optical quality of the measured simulated corneal lenses basically reached the theoretical design effect, and the deviation between the MTF value and the theoretical design value was equivalent to the MTF test repeatability. The establishment of model eye for artificial lens provides a research tool for the evaluation of aspheric intraocular lens imaging quality.

Analysis between two optical biometric devices in patients with cataract / Análise entre dois dispositivos de biometria óptica em pacientes com catarata

ABSTRACT Objective: To evaluate the correlation of optical biometry and target with variable ages, anterior chamber depth, axial length, R1/K1 and R2/K2 established by two optical biometry devices in patients with cataract. Methods: The study included the analysis of 348 medical records, from which 503 cataract eyes were selected, which underwent evaluation by the optical biometric devices IOL Master 700 and Lenstar LS 900 in the period of April to July 2017. Data collected were: age, anterior chamber depth, axial length, R1/K1 and R2/K2. Results: The average of the biometrics obtained using Lenstar was 21.02, varying 3.46, more or less, with an average target of -0.02, varying 0.45. In relation to the IOL Master it was 21.19, with a variation of 3.40 and average target of -0.01, a variation of 0.11. It can be observed that despite close values in relation to the mean, there was significance (p<0.001). Axial length (p<0.001) and R1/K1 (p<0.001) had an influence on the difference of the biometric values between the devices. Conclusion: A high degree of clinical and statistical correspondence was observed between the results obtained by the biometry devices in patients with cataract.

RESUMO Objetivos: Avaliar a correlação da biometria óptica e target com as variáveis idade, profundidade da câmara anterior, comprimento axial, R1/K1 e R2/K2 estabelecidos por dois dispositivos de biometria óptica em pacientes com catarata. Métodos: O trabalho abrangeu a análise de 348 prontuários dos quais foram selecionados 503 olhos com catarata ,que passaram pela avaliação nos dispositivos de biometria óptica IOL Master 700 e Lenstar LS 900 no período de abril a julho de 2017. Os dados colhidos foram: idade, profundidade da câmara anterior, comprimento axial, R1/K1 e R2/K2 . Resultados: A média da biometria obtida utilizando o Lenstar foi de 21,02, variando 3,46 para mais ou para menos, com target médio de -0,02, variando 0,45. Já em relação ao IOL Master foi de 21,19, com variação de 3,40 e target médio de -0,01, variação de 0,11. Pode-se observar que apesar de valores próximos em relação à média, houve significância (p < 0,001). Houve a concordância da biometria em relação ao comprimento axial (p < 0,001) e R1/K1(p < 0,001). Conclusão: Observou-se alto grau de correspondência clínica e estatística entre os resultados obtidos pelos dispositivos de biometria em pacientes com catarata.

Estimation of intraocular lens position from full crystalline lens geometry: towards a new generation of intraocular lens power calculation formulas.

In a cataract surgery, the opacified crystalline lens is replaced by an artificial intraocular lens (IOL). To optimize the visual quality after surgery, the intraocular lens to be implanted must be selected preoperatively for every individual patient. Different generations of formulas have been proposed for selecting the intraocular lens dioptric power as a function of its estimated postoperative position. However, very few formulas include crystalline lens information, in most cases only one-dimensional. The present study proposes a new formula to preoperatively estimate the postoperative IOL position (ELP) based on information of the 3-dimensional full shape of the crystalline lens, obtained from quantitative eye anterior segment optical coherence tomography imaging. Real patients were measured before and after cataract surgery (IOL implantation). The IOL position and the postoperative refraction estimation errors were calculated by subtracting the preoperative estimations from the actual values measured after surgery. The proposed ELP formula produced lower estimation errors for both parameters -ELP and refraction- than the predictions obtained with standard state-of-the-art methods, and opens new avenues to the development of new generation IOL power calculation formulas that improve refractive and visual outcomes.