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1.
J Optom ; 17(4): 100520, 2024 Sep 03.
Artículo en Inglés | MEDLINE | ID: mdl-39232422
2.
J Ophthalmol ; 2024: 5586202, 2024.
Artículo en Inglés | MEDLINE | ID: mdl-39109251

RESUMEN

Objective: To investigate if the use of vision therapy (VT) in convergence insufficiency (CI) has a significant neural impact and how it correlates with the clinical changes occurring with this option of treatment. Methods: A systematic review of the scientific literature was carried out in the PubMed and Scopus databases, where all the scientific literature on the neural impact of VT in CI was analyzed. A total of 17 articles were initially found and a detailed analysis was carried out. After full-text reading, only four studies met the defined inclusion criteria. The following data from them were extracted: CI cases and controls, clinical and neural parameters evaluated, the neural response to VT observed, type of study, and VT performed. The quality of the studies was assessed using the GRADE tool. Results: Some neural changes have been reported after VT in CI with the use of functional magnetic resonance imaging (fMRI). Specifically, a modification of the functional activity of some brain areas (especially front fields, oculomotor vermis, and cerebellum) was found. However, contradictory findings in terms of the change in functional activity (increase or decrease) were found that might be associated to differences in fMRI protocols. In the GRADE analysis, serious concerns were found in the categories of risk of bias, inconsistency, indirectness, and imprecision, so the certainty of evidence for each outcome was very low. Conclusion: The research performed to this date does not allow confirming if there are neural changes occurring after vision therapy in patients with CI because the quality of the research performed on this issue is very low, with several methodological concerns.

3.
Artículo en Inglés | MEDLINE | ID: mdl-39104038

RESUMEN

PURPOSE: To evaluate and compare the dynamic vault range (DVR) as well as the asymmetry of the vault during a 3-month follow-up after the implantation of two posterior chamber phakic intraocular lenses (pIOLs). SETTING: Aver Clinic, Madrid, Spain. DESIGN: Prospective comparative study. METHODS: One hundred and nineteen eyes (65 patients) that underwent refractive surgical correction with implantation of one of two distinct pIOLs were enrolled: Eyecryl Phakic from Biotech Vision Care (Eyecryl group, 72 eyes) and Evo Visian Implantable Contact Lens from Staar Surgical (ICL group, 47 eyes). Besides evaluation of visual acuity, refraction, and ocular integrity, the pIOL vault was measured centrally and at 2 mm nasally and temporally as well as the DVR from photopic (50 lux) to mesopic (10 lux) illuminations conditions. RESULTS: No significant differences were found between pIOL groups in visual and refractive outcomes (p≥0.454). No significant differences between groups were found in central (523.72±168.4 vs. 494.16±156.7 µm, p=0.248) and temporal vault (499.43±155.8 vs. 431.28±150.5 µm, p=0.067). However, nasal vault was significantly lower in ICL group (465.6±149.1 vs. 375.4±144.0 µm, p=0.045). A trend to a larger DVR was observed in the ICL group, although differences between groups did not reach statistical significance (54.00±36.39 vs. 86.5±57.9 µm p=0.070). The pIOL diameter only correlated significantly with vault measurements in ICL group (r≥0.650, p<0.001). CONCLUSIONS: The Eyecryl pIOL shows more symmetric vaults and a trend to fewer light-induced changes in the central vault compared to the ICL pIOL. The clinical relevance of this finding should be investigated further.

4.
Children (Basel) ; 11(8)2024 Aug 17.
Artículo en Inglés | MEDLINE | ID: mdl-39201941

RESUMEN

OBJECTIVES: This study was aimed at analyzing the efficacy on the improvement of the visual function of a dichoptic online cloud-based platform for the treatment of amblyopia in anisometropic children. METHODS: A quasi-experimental (pretest-post-test) study was conducted in 23 subjects with ages from 5 to 15 years old with anisometropic amblyopia combined with additional presence (2 subjects) or not (21 subjects) of microtropia. A total of 30 home-based training sessions of 30 min per session with Bynocs® platform were prescribed for 6 weeks. RESULTS: Amblyopic eye logMAR visual acuity (VA) significantly improved from 0.28 ± 0.24 to 0.13 ± 0.20 after the 6-week treatment (p < 0.001). At baseline, 60.9% of participants had VA in amblyopic eye of 0.20 logMAR or worse, whereas this percentage decreased to 21.7% after treatment. Binocular function (BF) significantly improved from 2.82 ± 1.11 to 2.32 ± 0.94 (p < 0.001). Mean compliance was 92%, 87% and 93% at 2, 4 and 6 weeks of treatment, respectively. CONCLUSIONS: In conclusion, home-based dichoptic training with the digital platform evaluated is an effective method to improve amblyopic VA and stereoacuity in children with anisometropic amblyopia combined or not with microtropia.

5.
Brain Sci ; 14(8)2024 Jul 26.
Artículo en Inglés | MEDLINE | ID: mdl-39199445

RESUMEN

An efficient mode of evaluation for eye movements is the use of objective eye tracking systems combined with subjective tests (NSUCO or DEM), which are easily applicable across all age groups and in eye care clinical settings. The objective of this study was to characterize fixations during reading in two groups: a group of children with neurodevelopmental disorders (NDDG, 24 children, age: 6-12 years) and a group of children with oculomotor anomalies but without NDD (OAG, 24 children, age: 6-12 years). The results obtained were compared with those from a control group (CG, 20 children, age: 6-12 years). Specifically, the outcomes obtained with two subjective score systems, the Northeastern State University College of Optometry's Oculomotor (NSUCO) test and the Developmental Eye Movement (DEM) test, were compared with the objective analysis obtained through a commercially available eye tracker (Tobii Eye X, Tobii, Stockholm, Sweden). Specialized analysis software, namely Clinical Eye Tracker 2020 (Thomson Software Solutions, Welham Green, UK), was used. It was found that children with NDD had impaired oculomotor skills. A higher number of regressions, more fixations, and longer durations of fixations appear to be characteristic signs of this population group. Additionally, children with NDD took longer to complete the DEM test, as well as exhibiting more errors. The use of objective videoculographic systems for eye tracking and subjective tests like the NSUCO or DEM are good tools to assess saccadic movements, allowing the detection of oculomotor abnormalities in children with NDD.

6.
J Clin Med ; 13(14)2024 Jul 15.
Artículo en Inglés | MEDLINE | ID: mdl-39064176

RESUMEN

Background/Objectives: To evaluate the clinical and patient-reported outcomes (PROMs) obtained with an optimized version of a previously investigated trifocal IOL. Methods: Prospective non-comparative single-center study enrolling 29 patients (55-71 years) undergoing bilateral cataract surgery with implantation of the trifocal diffractive IOL Liberty 677CMY (Medicontur Medical Engineering Ltd., Zsámbék, Hungary). Visual and refractive outcomes as well as PROMs were evaluated during a 3-month follow-up: measurement of uncorrected and corrected distance (UDVA, CDVA), intermediate (UIVA, DCIVA) and near visual acuities (UNVA, DCNVA), defocus curve, patient satisfaction, photic phenomena perception, spectacle independence, and difficulty in performing some vision-related activities. Results: A total of 100%, 92%, and 80% of patients achieved a postoperative binocular UDVA, UIVA, and UNVA of 20/25 or better, respectively. Likewise, 100%, 80%, and 84% of patients achieved a postoperative binocular CDVA, DCIVA, and DCNVA of 20/25 or better, respectively. In the defocus curve, all mean visual acuity values were better than 0.15 logMAR for all defocus levels. A total of 95.8%, 95.8%, and 91.7% of patients referred to be satisfied with their distance, intermediate, and near visual vision, respectively. Mean overall Catquest Rasch calibrated score was -3.12 ± 0.98. Most of the patients were spectacle independent: far (95.8%), intermediate (95.8%) or near vision (91.7%). No bothersome or minimal to moderately bothersome halo, starburst, and glare was perceived by 83.3%, 83.4%, and 83.3% of patients, respectively. Conclusions: The trifocal IOL evaluated provides a visual acuity improvement, with high levels of spectacle independence, patient satisfaction, and perceived visual quality associated.

7.
Diagnostics (Basel) ; 14(13)2024 Jun 28.
Artículo en Inglés | MEDLINE | ID: mdl-39001266

RESUMEN

Our purpose is to develop and validate a new iPad-based contrast sensitivity (CS) test for measuring the contrast sensitivity function at near vision (Optopad-CSF). A total of 200 eyes of 100 healthy subjects (ages 17-63) were evaluated in a comparative study between the Optopad-CSF test (near vision) and the CSV-1000E test (distance vision). The agreement between tests was assessed with the index of contrast sensitivity (ICS) and the area under the curve (AUC). CS for all the spatial frequencies in both eyes showed a negative significant correlation with age, and corrected distance, and near visual acuities (r ≤ -0.512, p ≤ 0.013). A significantly lower CS was found with the Optopad-CSF test in the over-40-year-old subgroup for all the spatial frequencies evaluated compared to the below-40 subgroup (p ≤ 0.008). The mean AUC of the Optopad-CSF test (5.84) was twice that of the CSV-1000E test (2.76). The mean ICS of the Optopad-CSF (-0.019) and CSV-1000E (-0.075) tests showed similar values, both close to 0 (p = 0.3). There was a weak but significant correlation between the Optopad-CSF and CSV-1000E ICS tests (r = 0.246, p < 0.02). A range of normality for the values obtained with the Optopad-CSF test was calculated. The mean CS values in 16 bilateral cataract patients were out of the normal range for all the spatial frequencies evaluated (p < 0.001). Optopad-CSF is a valid portable system for measuring CS at near vision for five spatial frequencies, allowing the detection of age-related changes in CSF with age and CSF loss in cataracts, with no ceiling effect.

8.
Clin Exp Optom ; : 1-8, 2024 Jul 16.
Artículo en Inglés | MEDLINE | ID: mdl-39013551

RESUMEN

CLINICAL RELEVANCE: Perception of optometrists and ophthalmologists of vision therapy (VT) as well as their methods for performing the sessions is of great importance for understanding the problems that professionals face and what should be improved in their clinical practice. BACKGROUND: The objective of this study was to determine the perception of VT and protocols used by eye care professionals globally. METHODS: A cross-sectional study was performed among eye care professionals internationally. The participants completed via online (Google Forms) a questionnaire of 40 questions on their perception and clinical practice of VT. The survey only permitted one answer per email address and was only collected if professionals gave their consent to participate. RESULTS: A total of 205 professionals from 43 countries answered the questionnaire (171 optometrists and 34 ophthalmologists). Accommodation and convergence problems were the main indication reported for VT (47.8%), followed by amblyopia (26.3%). The principal negative factor associated to VT was the limited number of professionals dedicated to this field (55.6%). The most common program of VT was the combination of VT sessions at home and at office (85.5%), with a great variability in terms of duration. Few professionals made use of the new technologies when programming VT, such as eye trackers (2.7%) or virtual reality (6.4%). European professionals surveyed had a more negative perception of VT (p < 0.031). CONCLUSIONS: Eye care professionals globally perceive VT as a scientifically based procedure. Overall, they believe that it has low recognition and prestige, especially ophthalmologists. A great variability in the programming of VT sessions was found, which highlights the need for standardised protocols that professionals could follow in their clinical practice.

10.
Eye Contact Lens ; 50(9): 395-400, 2024 Sep 01.
Artículo en Inglés | MEDLINE | ID: mdl-38886923

RESUMEN

PURPOSE: This study aimed to evaluate the efficacy, safety, and participant compliance of orthokeratology treatment for the correction of myopic refractive errors over a six-month prospective study and to define the potential reasons for early treatment discontinuation. METHODS: A total of 32 participants with low-to-moderate myopia were fitted with the spherical model of corneal refractive therapy (CRT) orthokeratology lenses (Paragon Vision Sciences) and followed over six months, with specific attention to alterations in refractive error, corneal topography, and epithelial thickness. Concurrently, participant feedback and reasons for any treatment discontinuation were documented. RESULTS: Significant changes in refractive error and in corneal topography were observed, with approximately 50% of the refractive error being corrected on the first night of use and 100% by the first two weeks ( P <0.001). Central epithelial thickness experienced substantial thinning, reducing to 15.65±4.49 µm (67.38%) ( P <0.001) after 6 months of lens use. Six participants withdrew from this study for varied reasons, including unmet visual expectations and difficulty adhering to the lens-wearing regimen. Notably, the dropout group exhibited higher baseline low-order aberrations and less prolate corneas than those who persisted with the treatment ( P <0.05). CONCLUSIONS: Orthokeratology with CRT is efficacious and safe for the correction of low-to-moderate myopia in adults, but a portion of patients discontinue the treatment in the first 6 months of contact lens wear. Special care should be taken when recommending orthokeratology in patients with higher levels of myopia and corneas with less prolate shape, providing more realistic expectations and even changing to dual axis or more sophisticated designs.


Asunto(s)
Topografía de la Córnea , Miopía , Procedimientos de Ortoqueratología , Cooperación del Paciente , Refracción Ocular , Agudeza Visual , Humanos , Procedimientos de Ortoqueratología/métodos , Miopía/terapia , Miopía/fisiopatología , Masculino , Estudios Prospectivos , Femenino , Refracción Ocular/fisiología , Adulto Joven , Agudeza Visual/fisiología , Adulto , Lentes de Contacto , Adolescente , Resultado del Tratamiento , Córnea/patología , Estudios de Seguimiento
11.
Semin Ophthalmol ; 39(6): 429-439, 2024 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-38900011

RESUMEN

PURPOSE: The aim of this study is to analyze the scientific literature about the effect of VR on the accommodative and binocular function of healthy subjects with both normal visual conditions and binocular anomalies assessing the quality of the existing studies to detect possible limitations and improve future study designs. METHODS: A search was performed in PubMed, Web of Science and Scopus databases with the search equation (Virtual reality OR head-mounted displays) AND (accommodation OR accommodative) AND (vergence* OR convergence OR divergence OR binocular vision). A limitation was made in terms of the date of publication from 2010 onwards, identifying a total of 198 publications. Finally, 15 publications were included in the quality analysis. After a comprehensive analysis of the publications, a quality assessment was performed using a Quality Appraisal Checklist. RESULTS: Research on effects of immersive VR on accommodative and binocular function to this date was focused on quasi-experimental pre-post studies well written and with results supporting their conclusions. Unfortunately, this scientific evidence provides heterogeneous outcomes, being the results in some cases even contradictory. CONCLUSIONS: Information about the devices, its interpupillary distance adjustment, the software characteristics and type of task performed by users should be better controlled in future studies. Additionally, participants accommodative and binocular baseline characteristics should be better analyzed to obtain firm conclusions about the consequences of the proper immersive VR experience on visual function.


Asunto(s)
Acomodación Ocular , Realidad Virtual , Visión Binocular , Humanos , Acomodación Ocular/fisiología , Visión Binocular/fisiología
13.
Sci Rep ; 14(1): 8592, 2024 04 13.
Artículo en Inglés | MEDLINE | ID: mdl-38615153

RESUMEN

Multifocal contact lenses (MCLs) are one of the solutions to correct presbyopia, but their adoption is not widespread. To address this situation, visual simulators can be used to refine the adaptation process. This study aims to obtain accurate simulations for a visual simulator (SimVis Gekko; 2EyesVision) of daily soft MCL designs from four manufacturers. In-vitro characterization of these MCLs-several powers and additions- was obtained using NIMO TR-1504. From the averaged relative power profiles across powers, phase maps were reconstructed and the Through-Focus Visual Strehl metric was calculated for each MCL design. The SimVis Gekko simulation corresponding to each MCL design was obtained computationally and bench-validated. Finally, the MCL simulations were clinically validated involving presbyopic patients. The clinical validation results show a good agreement between the SimVis Gekko simulations and the real MCLs for through-focus visual acuity (TF-VA) curves and VA at three real distances. All MCL designs showed a partial correlation higher than 0.90 and a Root Mean Square Error below 0.07 logMAR between the TF-VA of simulations and Real MCLs across subjects. The validity of the simulation approach using SimVis Gekko and in-vitro measurements was confirmed in this study, opening the possibility to accelerate the adaptation of MCLs.


Asunto(s)
Lentes de Contacto Hidrofílicos , Lagartos , Presbiopía , Humanos , Animales , Simulación por Computador , Presbiopía/terapia , Agudeza Visual
14.
Graefes Arch Clin Exp Ophthalmol ; 262(9): 3007-3020, 2024 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-38578335

RESUMEN

PURPOSE: To assess the possible benefits of the use of perceptual learning and dichoptic therapy combined with patching in children with amblyopia over the use of only patching. METHODS: Quasi-experimental multicentric study including 52 amblyopic children. Patients who improved their visual acuity (VA) by combining spectacles and patching were included in patching group (PG: 20 subjects), whereas those that did not improved with patching performed visual training (perceptual learning + dichoptic therapy) combined with patching, being assigned to the visual treatment group (VT: 32 subjects). Changes in VA, contrast sensitivity (CS), and stereopsis were monitored during a 6-month follow-up in each group. RESULTS: Significant improvements in VA were found in both groups at 1 month (p < 0.01). The total improvement of VA was 0.18 ± 0.16 and 0.31 ± 0.35 logMAR in PG and VT groups, respectively (p = 0.317). The Wilcoxon effect size was slightly higher in VT (0.48 vs. 0.54) at 6 months. An enhancement in CS was observed in the amblyopic eye of the VT group for all spatial frequencies at 1 month (p < 0.001). Likewise, the binocular function score also increased significantly in VT group (p = 0.002). A prediction equation of VA improvement at 1 month in VT group was obtained by multiple linear regression analysis (p < 0.001, R2 = 0.747). CONCLUSIONS: A combined treatment of visual training and patching is effective for obtaining a predictable improvement of VA, CS, and binocularity in patching-resistant amblyopic children.


Asunto(s)
Ambliopía , Privación Sensorial , Visión Binocular , Agudeza Visual , Humanos , Ambliopía/fisiopatología , Ambliopía/terapia , Agudeza Visual/fisiología , Estudios Prospectivos , Masculino , Femenino , Niño , Visión Binocular/fisiología , Estudios de Seguimiento , Preescolar , Resultado del Tratamiento , Anteojos , Sensibilidad de Contraste/fisiología , Percepción de Profundidad/fisiología
15.
Diagnostics (Basel) ; 14(5)2024 Mar 06.
Artículo en Inglés | MEDLINE | ID: mdl-38473032

RESUMEN

The VEMoS-AXL system is a new optical biometer based on spectral domain optical coherence tomography (SD-OCT) that has been tested in terms of intrasession repeatability and compared with a swept-source optical coherence tomography biometer (SS-OCT), which is recognized as the gold standard for the performance of an agreement analysis. A biometric analysis was performed three consecutive times in 120 healthy eyes of 120 patients aged between 18 and 40 years with the SD-OCT system, and afterwards, a single measurement was obtained with the SS-OCT system. Within-subject standard deviations were 0.004 mm, 4.394 µm, and 0.017 mm for axial length (AL), central corneal thickness (CCT), and anterior chamber depth (ACD) measures obtained with the SD-OCT biometer, respectively. The agreement between devices was good for AL (limits of agreement, LoA: -0.04 to 0.03 mm) and CCT (LoA: -4.36 to 14.38 µm), whereas differences between devices were clinically relevant for ACD (LoA: 0.03 to 0.21 mm). In conclusion, the VEMoS-AXL system provides consistent measures of anatomical parameters, being most of them interchangeable with those provided by the SS-OCT-based gold standard.

16.
J Cataract Refract Surg ; 50(7): 724-732, 2024 Jul 01.
Artículo en Inglés | MEDLINE | ID: mdl-38530027

RESUMEN

PURPOSE: To evaluate the clinical outcomes of the toric version of a presbyopia-correcting intraocular lens (IOL) based on the combination of a diffractive-based extended depth-of-focus (EDOF) pattern and a diffractive multifocal platform. SETTING: Miranza COI Bilbao, Bilbao, Spain. DESIGN: Prospective case series. METHODS: 35 patients (51 to 84 years) with corneal astigmatism ranging from 0.75 to 2.19 diopters (D) undergoing bilateral cataract surgery with implantation of the Synergy Toric II IOL were evaluated during a 3-month follow-up. Visual acuity, refraction, defocus curve, and patient-reported outcomes with the Catquest-9SF questionnaire were analyzed. A vectorial analysis was used to analyze the accuracy of astigmatic correction. RESULTS: Mean 3-month monocular postoperative uncorrected distance, intermediate (80 cm) and near (40 cm) visual acuities were 0.06 ± 0.11 logMAR, 0.13 ± 0.12 logMAR, and 0.13 ± 0.09 logMAR, respectively. Mean monocular distance-corrected intermediate (80 cm) and near visual acuity (40 cm) were 0.11 ± 0.12 logMAR and 0.10 ± 0.10 logMAR, respectively. Mean binocular defocus curve showed visual acuities of 0.10 logMAR or better for defocus levels from +0.50 to -2.50 D. Residual cylinder was within ±0.50 D in 97.0% of eyes. The surgically induced astigmatism prediction error ranged between -0.49 D and 0.50 D, with a mean value of 0.04 ± 0.16 D. Mean absolute IOL rotation was 3.79 ± 2.94 degrees. Significant improvements were found in all Rasch-calibrated scores obtained with Catquest-9SF ( P < .001). CONCLUSIONS: The implantation of the toric presbyopia-correcting IOL evaluated provides an efficacious astigmatic correction while providing a fully restoration of the visual function across different distances.


Asunto(s)
Astigmatismo , Implantación de Lentes Intraoculares , Lentes Intraoculares , Presbiopía , Refracción Ocular , Agudeza Visual , Humanos , Agudeza Visual/fisiología , Presbiopía/cirugía , Presbiopía/fisiopatología , Estudios Prospectivos , Anciano , Refracción Ocular/fisiología , Persona de Mediana Edad , Anciano de 80 o más Años , Masculino , Femenino , Astigmatismo/fisiopatología , Astigmatismo/cirugía , Facoemulsificación , Diseño de Prótesis , Seudofaquia/fisiopatología , Encuestas y Cuestionarios , Resultado del Tratamiento
17.
Semin Ophthalmol ; 39(5): 394-399, 2024 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-38426308

RESUMEN

PURPOSE: To assess the feasibility of the clinical use of a novel Virtual Reality (VR) training software designed to be used for active vision therapy in amblyopic patients by determining its preliminary safety and acceptance on the visual function of healthy adults. METHODS: Pilot study enrolling 10 individuals (3 men, 7 women, mean age: 31.8 ± 6.5 years) with a best-corrected visual acuity (BCVA) of ≥ .90 (decimal) in both eyes were evaluated before and after 20 minutes of exposure to the NEIVATECH VR system using the HTC Vive Pro Eye head mounted display. Visual function assessment included near (40 cm) and distance (6 m) cover test (CT), stereopsis, binocular accommodative facility (BAF), near point of convergence (NPC), near point of accommodation (NPA), accommodative-convergence over accommodation (AC/A) ratio and positive and negative fusional vergences. Safety was assessed using the VR Sickness Questionnaire (VRSQ) and acceptance using the Technology Acceptance Model ;(TAM). Changes in all these variables after VR exposure were analyzed. RESULTS: Short-term exposure to the NEIVATECH VR system only induced statistically significant changes in distance phoria (p = .016), but these changes were not clinically relevant. No significant changes were observed in VRSQ oculo-motricity and disorientation scores after exposure (p = .197 and .317, respectively). TAM scores showed a good acceptance of the system in terms of perceived enjoyment and perceived ease of use, although some concerns were raised in relation to the intention-to-use domain. CONCLUSION: Exposure to the NEIVATECH VR system does not seem to adversely affect the visual function in healthy adults and its safety and acceptance profile seems to be adequate for supporting its potential use in other populations, such as amblyopic patients.


Asunto(s)
Acomodación Ocular , Realidad Virtual , Visión Binocular , Agudeza Visual , Humanos , Masculino , Proyectos Piloto , Femenino , Adulto , Agudeza Visual/fisiología , Acomodación Ocular/fisiología , Visión Binocular/fisiología , Ambliopía/fisiopatología , Ambliopía/terapia , Adulto Joven , Estudios de Factibilidad , Percepción de Profundidad/fisiología , Encuestas y Cuestionarios
18.
Biomimetics (Basel) ; 9(2)2024 Jan 25.
Artículo en Inglés | MEDLINE | ID: mdl-38392119

RESUMEN

Implementing in silico corneal biomechanical models for surgery applications can be boosted by developing patient-specific finite element models adapted to clinical requirements and optimized to reduce computational times. This research proposes a novel corneal multizone-based finite element model with octants and circumferential zones of clinical interest for material definition. The proposed model was applied to four patient-specific physiological geometries of keratoconus-affected corneas. Free-stress geometries were calculated by two iterative methods, the displacements and prestress methods, and the influence of two boundary conditions: embedded and pivoting. The results showed that the displacements, stress and strain fields differed for the stress-free geometry but were similar and strongly depended on the boundary conditions for the estimated physiological geometry when considering both iterative methods. The comparison between the embedded and pivoting boundary conditions showed bigger differences in the posterior limbus zone, which remained closer in the central zone. The computational calculation times for the stress-free geometries were evaluated. The results revealed that the computational time was prolonged with disease severity, and the displacements method was faster in all the analyzed cases. Computational times can be reduced with multicore parallel calculation, which offers the possibility of applying patient-specific finite element models in clinical applications.

19.
J Refract Surg ; 40(2): e98-e107, 2024 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-38346118

RESUMEN

PURPOSE: To determine the prevalence of opacification of a hydrophylic intraocular lens (IOL) with hydrophobic coverage and the percentage of explantations required, determining possible risk factors associated with these opacifications. METHODS: This ambispective study enrolled 575 eyes of 296 patients (age 36 to 87 years) that underwent cataract surgery between 2010 and 2017 with implantation of different models of Lentis Mplus IOLs: LS-312-MF30, LS-313-MF15, LS-313-MF30, LU-313-MF30, and LU-313-MF30T (Oculentis GmbH). Visual, refractive, and slit-lamp biomicroscopic changes were evaluated in a long-term follow-up. The percentage of cases with IOL opacification and the percentage of cases in which IOL explantation was required due to such opacifications were calculated at each visit. Five of the explanted IOLs from this series could be analyzed by scanning electron microscopy (SEM-EDX). RESULTS: IOL opacification developed in 63 eyes (11.0%). With 95% confidence, the prevalence of IOL opacification was between 842 and 1,401 cases per 10,000 eyes. The time elapsed between surgery and the presence of IOL opacification ranged between 0 and 9.3 years (mean: 4.7 ± 2.2 years). No significant differences in terms of IOL opacification rate were found according to gender (P = .378). No significant differences were found in arterial hypertension, diabetes, hypothyroidism, or hyperthyroidism rates between eyes with or without IOL opacification (P ≥ .053). IOL explantation was needed in 9 eyes (1.57%). SEM-EDX analysis confirmed the presence of rough areas on the IOL surface containing different components, such as calcium, phosphorous, copper, or nitrogen. CONCLUSIONS: The prevalence of opacification with time in Lentis Mplus IOLs is high, with no systemic risk factors associated with this complication, suggesting that it may be attributable to the material and/or the manufacturing process. [J Refract Surg. 2024;40(2):e98-e107.].


Asunto(s)
Lentes Intraoculares , Lentes Intraoculares Multifocales , Facoemulsificación , Humanos , Adulto , Persona de Mediana Edad , Anciano , Anciano de 80 o más Años , Implantación de Lentes Intraoculares/efectos adversos , Prevalencia , Refracción Ocular , Lentes Intraoculares/efectos adversos , Complicaciones Posoperatorias/epidemiología
20.
Comput Biol Med ; 170: 107870, 2024 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-38217971

RESUMEN

A biomechanical model that simulates the physiological pressure load on the cornea without considering the stresses in vivo will result in an overstress or underestimation of the stress field and incorrect deformation of the corneal structure. Therefore, it is essential to propose numerical models that consider the stress-free geometry of the cornea. In this study, the Displacement and Pre-stress methods were compared to obtain the stress-free geometry (S-FG) and the physiological estimated geometry (P-EG), based on the patient-specific geometric behavior and the computational time required to reach each geometry. The same shape and contour conditions were considered in the models obtained from both methods for each of the pathological scenarios analyzed. Both methods behaved differently to obtain the free geometry, and this difference increased with the severity grade of the disease. However, they behaved in a similar way to reach the physiological estimated geometry. The Displacement method required a lower computational cost to reach the free geometry, with both methods presenting a similar computational cost to obtain the physiological geometry. The stress-free geometries obtained by both methods allowed to characterize the existing biomechanical decompensation during the progression of the diseases. In conclusion, the calculation of the stress-free corneal geometry associated to the clinically measured intraocular pressure with the Displacement and Prestress Methods in keratoconus eyes allows the development of accurate and useable models in clinical practice in real time. This displacement method shows some benefits in terms of computational cost.


Asunto(s)
Queratocono , Humanos , Fenómenos Biomecánicos , Córnea , Tonometría Ocular , Presión Intraocular
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