Range Of Defocus Research Articles

Prediction of visual outcomes using virtual implantation of a trifocal intraocular lens in presbyopic lens exchange patients.

To assess the reliability of a novel virtual IOL implantation device to predict the outcomes of a trifocal IOL. Clinical sites in Spain and Germany. Prospective multicenter study. Preoperative measurements obtained by the virtual implantation of AT LISA tri 839MP IOL (Carl Zeiss Meditec AG, Jena, Germany) with VirtIOL device (10Lens S.L.U., Terrassa, Spain) were compared to postoperative (month 3) outcomes following the IOL implantation. Evaluated metrics were defocus curve, contrast sensitivity (both in photopic conditions), and visual phenomena (visual angle size of burst and annular pattern) in mesopic conditions. The study included 45 presbyopic non-cataract patients (mean age 56.16±5.03 years). VirtIOL device reasonably predicted the shape of the defocus curve, especially in the intermediate vision range, but underestimated postoperative visual acuities mainly at the defocus range between +1.0D and -3.5D. The difference between predicted and achieved visual acuity was -0.11±0.13 logMAR (p<0.001) for 0.0D defocus and -0.16±0.15D logMAR (p<0.001) for -2.50D defocus. The shape of the contrast sensitivity curve was almost identical for predicted and achieved measurements, but the device underestimated the values by ≈0.3 logCS units for each spatial frequency. Visual phenomena were similar between the predicted and achieved outcome (predicted vs. achieved: burst pattern 2.65±0.97° vs. 2.74°±0.95°, p=0.63; annular pattern: 0.88±0.42° vs. 0.93±0.49°, p=0.59). The device reasonably predicted the pattern of measured variables. Visual acuity/contrast sensitivity reduction might be attributed to viewing the objects through a more complex optical system and would need to be accounted for in clinical studies.

Q-value-guided femtosecond laser-assisted in situ keratomileusis for low-to-moderate myopia with age-related accommodation deficiency

Objective: To evaluate clinical outcomes and visual quality after femtosecond laser-assisted in situ keratomileusis (FS-LASIK) performed with the Q-value-guided optimized monocular vision protocol (Custom-Q) for correction of low-to-moderate myopia and compensation for age-related accommodation deficiency. Methods: A prospective study was performed based on patients with myopia and age-related accommodation deficiency, who underwent Custom-Q FS-LASIK in the Peking University Third Hospital from October 2022 to October 2023. Monocular and binocular distance, intermediate, and near visual acuities, simulated whole-course visual acuity (binocular defocus curve), objective and subjective refractions, anterior corneal Q factor, anterior corneal higher-order aberrations and a subjective questionnaire assessing near visual acuity and visual quality were evaluated at 3 months postoperatively. Visual acuity was recorded using the logarithm of the minimum angle of resolution. The data were analyzed using the t-test and the Wilcoxon rank-sum test. Results: A total of 45 patients (90 eyes) who met the inclusion criteria and completed the 3-month follow-up were included in the study. The mean age of the 21 men (42 eyes) and 24 women (48 eyes) was (42.82±2.72) years. During the 3-month follow-up, all the patients achieved binocular uncorrected distance visual acuity not less than 0.00 and uncorrected near visual acuity not less than 0.20. Defocus curves revealed better results at 3 months postoperatively [0.00 (-0.08, 0.00), -0.08 (-0.08, 0.00)] at intermediate and near vergence (-1.50 to -1.00 D) compared to the preoperative values [0.00 (-0.08, 0.05), -0.08 (-0.08, 0.00)] (P<0.05). All the 45 patients maintained 0.10 or better vision at the defocus range from -2.50 to 0.00 D. The Q value in the dominant eyes was more positive postoperatively (0.01±0.26 vs.-0.15±0.14, P<0.05), while in the nondominant eyes, the Q value and corneal spherical aberration coefficient became more negative than those before surgery (-0.27±0.32 vs.-0.14±0.11, P<0.05; 0.08±0.05 vs. 0.12±0.03, P<0.05). The questionnaire demonstrated 42 (93.3%) patients were satisfied with near vision. The three most commonly reported visual discomforts after surgery were blurred vision, glare and halos. These symptoms were all mild to moderate in severity and did not interfere with daily life. Conclusion: For myopic patients with age-related accommodation deficiency, the Custom-Q algorithm proved to be a safe and effective way to achieve acceptable near vision and visual quality without compromising distance vision.

Wide Dynamic Range Digital Aberration Measurement and Fast Anterior-Segment OCT Imaging †.

Ocular aberrometry with a wide dynamic range for assessing vision performance and anterior segment imaging that provides anatomical details of the eye are both essential for vision research and clinical applications. Defocus error is a major limitation of digital wavefront aberrometry (DWA), as the blurring of the detected point spread function (PSF) significantly reduces the signal-to-noise ratio (SNR) beyond the ±3 D range. With the aid of Badal-like precompensation of defocus, the dynamic defocus range of the captured aberrated PSFs can be effectively extended. We demonstrate a dual-modality MHz VCSEL-based swept-source OCT (SS-OCT) system with easy switching between DWA and OCT imaging modes. The system is capable of measuring aberrations with defocus dynamic range of 20 D as well as providing fast anatomical imaging of the anterior segment at an A-scan rate of 1.6 MHz.

Optical quality in vitro and in vivo of an extended depth-of-focus intraocular lens with isofocal design.

The aim of this study is to compare optical quality results obtained in laboratory analysis (in vitro) versus clinical data (in vivo). The optical quality of ISOPure intraocular lens was assessed both in vitro and in vivo using the modulation transfer function (MTF) for 3.0 and 4.5mm pupil diameters. In vitro measurements were obtained using deflectometer NIMO TRF1504, while in vivo measurements were taken with OPD-Scan III in a set of patients implanted with this lens. Ray tracing techniques were used to determine the MTF and area under MTF curve (MTFa) from the measured wavefront for the isolated lens and for the whole eye. The MTF of the isolated lens obtained under both in vitro and in vivo conditions showed comparable results for both pupil sizes. However, differences were found when comparing the MTF of the whole eye with the lens implanted versus the MTF measured in vitro for 4.5mm pupil size. Also, the MTFa defocus curve was compared with the defocus curve measured in vivo. The defocus curve from the in vivo study aligns closely with the MTFa of the in vitro model, with a useful defocus range of 0.40D. Thus, it is possible to anticipate the visual results of the implanted isofocal lens by using measurements on an optical bench and conducting optical simulations.

Optical Bench Evaluation of the Latest Refractive Enhanced Depth of Focus Intraocular Lens.

Any new intraocular lens (IOL) on the market claims to outperform competitors. We aimed to estimate the modulation transfer function (MTF) for different defocus of a novel refractive enhanced depth of focus (EDoF) IOL and the simulated visual acuity over this range of vision. Further, we analyzed the wavefront pattern produced by this IOL to reveal the function of the IOL's optics. For the novel TECNIS® PureSee® (ZEN00V) IOL, through frequency and through focus MTF were recorded on the optical bench (ISO-2 Cornea 0.28 µm, 546 nm). MTFa and the simulated visual acuity were calculated for different defocus. Apertures of 3 mm and 4.5 mm were applied. Higher order aberrations of the IOLs' optics were recorded and analyzed. PureSee® IOL demonstrated a considerable depth of focus of about 1.7 D at the spectacle plane and a continuous simulated visual acuity over this range of defocus. For the 4.5 mm aperture, near focus depth was reduced, yet far distance MTF was even better. Higher order aberrations revealed increased primary and secondary spherical aberrations. Optical bench results suggest that the new ZEN00V matches the clinical criteria of an EDoF IOL by an increased range of vision and is far distance dominant for an enlarged pupil. This behaviour seems to be due to subtle power changes in the central optics that produce a complex modification of wavefront.

Assessing the interplay of contrast, defocus, and resolution in cryo-EM: a benchmark experiment for limited dataset screening

The selection of defocus ranges for small datasets in cryo-electron microscopy (cryo-EM) is under-researched. We present a comprehensive benchmark experiment that aimed to evaluate the relationship between contrast, defocus, and resolution, particularly in the context of limited datasets. We conducted a detailed analysis of beta-galactosidase, apo-ferritin, and connexin-46/50 datasets to optimize pre-screening strategies for cryo-EM. Our approach involved classifying micrographs based on image contrast using an artificial intelligence (AI) model without considering the defocus level. This method allowed us to investigate the optimal defocus range for pre-screening in a limited dataset and its impact on the overall image processing. The micrographs were categorized into good, moderate, and bad contrast groups. Subsequent analysis revealed that, contrary to the prevailing assumption that lower contrast (associated with lower defocus) leads to higher resolution, in scenarios with limited datasets higher contrast images yield superior resolution. This finding was consistent across all three protein samples, underscoring the critical role of contrast in determining the quality of 3D reconstructions in limited datasets. This significant finding challenges conventional cryo-EM methodologies. In conclusion, our study provides new benchmarks for selecting appropriate contrast and defocus levels in cryo-EM, particularly for screening approaches that use limited datasets. This strategy promises to enhance the data quality and efficiency in structural biology research, particularly in resource-constrained scenarios.

Fabrication and performance evaluation of a design for an extended depth-of-focus intraocular lens based on an improved sinusoidal profile.

This study presents the fabrication and evaluation of a sinusoidal extended depth-of-focus (EDoF) intraocular lens (IOL) based on our previously proposed design approach. The power, through-focus MTF, and surface profile were measured using commercial instruments. Through-focus images of a United States Air Force (USAF) 1951 resolution target formed by the fabricated IOL were compared with Symfony and AR40E under monochromatic and polychromatic light using optical bench testing. Simulations assessed visual acuity (VA) of a pseudophakic model eye with the EDoF IOL, including evaluation of tilt and decentration effects. Results indicate that the base power, add power, and the through-focus MTF@50 lp/mm of the fabricated IOL at a 3 mm pupil size align with the design specifications. The extended-depth-of-focus and imaging performance for the far vision of the fabricated IOL under both monochromatic and polychromatic light conditions at a 3.0 mm pupil diameter is comparable to that of Symfony. In addition, the fabricated IOL exhibits a similar extended-depth-of-focus for three discrete wavelengths. The pseudophakic model eye with the designed EDoF IOL demonstrates a VA exceeding 0.1 logMAR within a defocus range of 2.44 D. The VA is tolerant to both IOL tilt and decentration. These findings demonstrate the promising potential of the sinusoidal EDoF IOL design for future applications in cataract surgery.

Analytical Model of Point Spread Function under Defocused Degradation in Diffraction-Limited Systems: Confluent Hypergeometric Function

Analytical Model of Point Spread Function under Defocused Degradation in Diffraction-Limited Systems: Confluent Hypergeometric Function

Time-domain full-field optical coherence tomography with a digital defocus correction.

Time-domain full-field optical coherence tomography (TD-FF-OCT) is an interferometric technique capable of acquiring high-resolution images deep within the biomedical tissue, utilizing a spatially and temporally incoherent light source. However, optical aberrations, such as sample defocus, can degrade the image quality, thereby limiting the achievable imaging depth. Here we demonstrate that the sample defocus within a highly scattering medium can be digitally corrected over a wide defocus range if the optical path lengths in the sample and reference arms are matched. We showcase the application of digital defocus correction on both reflective and scattering samples, effectively compensating digitally for up to 1 mm of defocus.

Time characteristics of aero-optical imaging degeneration of the ellipsoidal dome under variable operating conditions

As a missile flies at high speed, the index and surface shape of the conformal dome will vary under the influence of the aero-optical effect, which will degenerate the performance of the seeker’s imaging detection system. However, many previous studies on aero-optical imaging deterioration of optical domes were usually carried out under fixed operating conditions, which are not in line with the real flight scene of the missile. In addition, the aero-optical imaging degeneration of the dome is diverse as the flight time increases. Therefore, it is of great significance to study the time characteristics of aero-optical imaging degradation of optical domes under variable work conditions. In this study, taking an air-to-air missile as an example, the Zernike polynomials, wavefront aberration, Strehl ratio, and image simulation are applied to evaluate the aero-optical imaging deterioration of an ellipsoidal dome in the flight time range of 0–10 s under variable working conditions. The simulation results show that, as the flight time increases, (1) the dynamic range of tilt, defocus, astigmatism, coma, and wavefront aberration increase; and (2) the Strehl ratio and the peak signal-to-noise ratio (PSNR) of the simulated images decrease. Therefore, the influence of flight time on the aero-optical image degradation of the ellipsoidal dome gradually becomes more serious.

Clinical Outcomes of a New Hydrophobic Trifocal Intraocular Lens with Hydroxyethyl Methacrylate in Cataract Surgery: A Prospective Multicenter Study.

To investigate the clinical outcomes of new hydrophobic trifocal intraocular lens with hydroxyethyl methacrylate in the Korean population. This prospective, multicenter, and observational study evaluated the clinical outcomes of 80 eyes of 40 patients with age-related cataract underwent cataract surgery using CNWT (Clareon PanOptix). Assessment included monocular and binocular uncorrected distance visual acuity, corrected distance visual acuity, uncorrected intermediate visual acuity (at 60cm), near visual acuity (at 40 and 33 cm), uncorrected defocus curves, questionnaires evaluating photic phenomena, spectacle independence, and spectacle free satisfaction. At postoperative 3 months, mean uncorrected binocular visual acuities were 0.04, 0.04, 0.03 logarithm of the minimum angle of resolution (logMAR) at far, intermediate, and near distances, respectively. All patients achieved uncorrected binocular visual acuity of 0.2 logMAR or better. Monocular and binocular defocus curve indicated a mean visual acuity of 0.2 logMAR or better at the defocus range of +1.0 to - 3.0 diopters (100 to 33 cm) and +1.0 to - 3.5 diopters (100 to 28 cm). High spectacle independence was observed at all distances, with 37.5% patients reporting photic phenomena. The Clareon PanOptix intraocular lens has shown positive clinical outcomes, providing a viable option for cataract surgery. These lenses effectively address patients' visual needs, especially in intermediate and near distance tasks, reducing dependence on glasses.

Optical-Quality Analysis and Defocus-Curve Simulations of a Novel Hydrophobic Trifocal Intraocular Lens.

The optical function of a novel refractive-diffractive trifocal intraocular lens (IOL) was tested in vitro to provide preclinical metrics that predict postoperative performance and may guide patient selection. Fundamental optical characteristics of a trifocal hydrophobic-acrylic IOL with a C-loop haptic configuration (AT ELANA 841P, Carl Zeiss Meditec) were assessed using a fully automated optical test device under both monochromatic and polychromatic conditions combined with increased or compensated spherical aberration (SA). The area under the modulation transfer function (MTFa) was calculated across a defocus range from +1D to -3.5D and used to simulate visual acuity (VA). A polychromatic point spread function (PSF) was employed to assess the light distribution and identify photic phenomena. The highest MTFa values were obtained under monochromatic conditions using an SA-neutral corneal model. Nevertheless, after introducing SA and polychromatic light, the IOL performance remained good. Simulated VA values were 0.00 logMAR for distance, 0.1 logMAR at 100 cm, and progressively improving to 0.05 logMAR at 40 cm from the intermediate point. The light-spread analysis confirmed halos around the PSF center, which is a characteristic of trifocal technology. AT ELANA 841P demonstrated good optical performance across various distances, independently of spectral and SA conditions, resulting in good simulated VA. Although light spread resembles standard trifocal IOLs, clinical studies are essential to confirm these laboratory results.

Optical performance of a new design of a trifocal intraocular lens based on the Devil's diffractive lens.

In this work, we propose a new diffractive trifocal intraocular lens design with focus extension, conceived to provide a high visual performance at intermediate distances. This design is based on a fractal structure known as the "Devil's staircase". To assess its optical performance, numerical simulations have been performed with a ray tracing program using the Liou-Brennan model eye under polychromatic illumination. The simulated through the focus visual acuity was the merit function employed to test its pupil-dependence and its behavior against decentering. A qualitative assessment of the multifocal intraocular lens (MIOL) was also performed experimentally with an adaptive optics visual simulator. The experimental results confirm our numerical predictions. We found that our MIOL design has a trifocal profile, which is very robust to decentration and has low degree of pupil dependence. It performs better at intermediate distances than at near distances and, for a pupil diameter of 3 mm, it works like an EDoF lens over almost the entire defocus range.

Effectiveness of SMILE Combined with Micro-Monovision in Presbyopic Patients: A Pilot Study

Binocular summation along all defocus range after a micro-monovision procedure has scarcely been studied. The aim of this pilot study was to evaluate the efficacy of SMILE combined with different levels of micro-monovision in presbyopic patients and to assess the binocular summation effect on contrast sensitivity defocus curves (CSDC) at the 6-month follow-up. Efficacy was assessed on the basis of visual acuity (VA) and stereopsis at far, intermediate, and near distances. Patient-reported outcomes (PROs) and binocular CSDC were also evaluated. Six patients completed the study with a programmed median anisometropia of 0.81 Diopter. The median binocular uncorrected VA was better than 0 logMAR at the three evaluated distances, and stereopsis was not impaired in any patient, achieving a median of ≤119 arcsec at any distance. CSDC increased binocularly after surgery, significantly in the range of -2 to -3 D (p < 0.05). No clinically relevant changes were observed in PROs compared with the preoperative period, and all patients achieved spectacle independence at intermediate/near distance and were likely or very likely to undergo the same surgery. In conclusion, micro-monovision with SMILE could be an effective procedure, with results that might be comparable to other laser correction techniques specifically designed for presbyopia correction.

Preliminary results obtained by a new intraocular lens based on accommodative technology for the treatment of cataract and presbyopia

AbstractPurpose: The aim of this study was to report the clinical results obtained by a new accommodative intraocular lens (AIOL) in terms of visual acuity, refraction, defocus curve, contrast sensitivity and complications incidence for multiple follow‐up phases.Methods: This is a prospective and experimental study composed by patients interested in an AIOL implantation (Lumina, Akkolens) to improve their visual performance. An exhaustive postoperative follow‐up (1 week, 1 month, 3 months, 6 months, 1 year) was performed including the measurements of visual acuity for multiple distances in decimal notation, subjective refraction, accommodative evaluation by defocus curve, contrast sensitivity and a slit lamp and fundus exploration.Results: The study included 42 eyes of 21 patients (mean age of 61.4 ± 10.9 years; 52% females, 48% males). The mean uncorrected distance visual acuity at week was 0.71 ± 0.28, but it improved to 0.85 ± 0.27 a year after the surgery. Similarly, the mean uncorrected near visual acuity improved for 0.48 ± 0.23 at 1 week to 0.60 ± 0.17 at 1 year. The mean equivalent sphere was −0.39 ± 0.60 diopters and the mean corrected distance visual acuity was 1.04 ± 0.16 at 1 year. For a defocus range comprised between 0.00 and −2.00 diopters the mean visual acuity was better than 0.50. The contrast sensitivity assessment showed values higher than 1.10 log units for all frequencies. Capsule opacification with YAG laser requirement was present in 21% of cases (N = 9). At the end of the follow‐up all minimal complications were resolved.Conclusions: The AIOL Lumina Akkolens provided suitable distance vision and functional near vision improving its performance over time. Contrast sensitivity was good being comparable with a monofocal design, but the Lumina IOL shows better near visual performance as revealed in the defocus curve. Significant persistent complications were not observed. These results will be updated with more patients and will be compared with a control group.

Extension of focal depth by electron quasi-Bessel beam in atomic-resolution scanning transmission electron microscopy

Extension of the focal depth of a sub-nanometer-sized electron probe in a scanning transmission electron microscope was demonstrated using an electron Bessel beam. We observed atomically-resolved annular dark-field scanning transmission electron microscope images of SrTiO3 in the [001] direction with defocus using an electron quasi-Bessel beam generated by a ring-shaped aperture in an aberration-corrected probe-forming system. The experimental results show that the defocus range over which images with a 0.2 nm spatial resolution can be acquired using the electron quasi-Bessel beam is three times longer than the corresponding defocus range for a conventional beam.

Observation of Visual Quality after Femtosecond Laser-Assisted Cataract Surgery Combined with Trifocal Intraocular Lens Implantation.

Objective This study is the first observation of Alcon's PanOptix trifocal intraocular lens (IOL) implanted in 55 cataract patients with femtosecond laser-assisted cataract surgery. Methods Fifty-five patients (63 eyes) with cataract were treated with femtosecond laser-assisted cataract surgery combined with trifocal IOL implantation. Visual acuity, defocus curve, higher order aberration (HOA), refractive stability, eyeglass removal rate, and satisfaction were evaluated and analyzed. Results We found that the visual acuity of patients with near, intermediate, and distance vision was better than 0.1 LogMAR at 1, 3, and 6 months after the completion of surgery. The uncorrected near visual acuity (UCNVA), uncorrected intermediate visual acuity (UCIVA), and uncorrected distance visual acuity (UCDVA) of patients at 1, 3, and 6 months after surgery were compared with those before operation, showing statistical significance. Six months after the operation, all patients' surgical eyes had a smooth transition in the defocus range from +0D to -2.5D, and the visual acuity of the surgical eyes reached a level better than 0.1 LogMAR. The statistical results of 6-month follow-up showed that the eyeglass removal rate at near, intermediate, and far distances was 100%. At 6 months postoperatively, only 1 case had nocturnal glare, which affected life; 3 cases developed glare and halo but did not affect life. The patient satisfaction rate was 98.18%. Conclusions Femtosecond laser-assisted cataract surgery with trifocal IOL implantation can remove the lens from the patient with satisfactory visual quality and significantly improve the postoperative satisfaction of the patient.

Through-focus EUV multilayer defect compensation considering optical proximity correction.

Extreme ultraviolet (EUV) multilayer defects result in the degradation of through-focus imaging quality. The optical proximity effect is another crucial factor that degrades the imaging quality. Both the impacts of the defects and the optical proximity effects could be mitigated by modifying the original mask patterns. A heuristic-based defect compensation method considering optical proximity correction and through-focus optimization is proposed in this paper. The edge of the mask pattern and the insertion of sub-resolution assist features (SRAFs) are optimized by covariance matrix adaptation evolution strategy (CMA-ES) to compensate for the degradation of the imaging quality with a certain defocus range. New encoding strategies for the edge pixels of the mask pattern and the SRAFs are proposed and utilized in this paper to ensure the manufacturability of the mask and the efficiency of the optimization at the same time. The rigorous database approach based on the scattering matrix is adopted to simulate the mask diffraction spectrum efficiently. Simulations verify that the through-focus imaging quality of both the defective masks with bump defects and pit defects could be obviously improved by the proposed defect compensation method.

Optimising curve fitting techniques to look for standardisation of the analysis of defocus curves derived from multifocal intraocular lenses.

IntroductionTo establish the most appropriate curve fitting method to allow accurate comparison of defocus curves derived from intraocular lenses (IOLs).MethodsDefocus curves were plotted in five IOL groups (monofocal, extended depth of focus, refractive bifocal, diffractive bifocal and trifocal). Polynomial curves from 2nd to 11th order and cubic splines were fitted. Goodness of fit (GOF) was assessed using five methods: least squares, coefficient of determination (R 2 adj), Akaike information criteria (AIC), visual inspection and Snedecor and Cochran. Additional defocus steps at −2.25 D and −2.75 D were measured and compared to the calculated visual acuity (VA) values. Area under the defocus curve and range of focus were also compared.ResultsGoodness of fit demonstrated variable results, with more lenient methods such as R 2 adj leading to overfitting and conservative methods such as AIC resulting in underfitting. Furthermore, conservative methods diminished the inflection points resulting in an underestimation of VA. Polynomial of at least 8th order was required for comparison of area methods, but overfitted the EDoF and monofocal groups; the spline curve was consistent for all IOLs and methods.ConclusionsThis study demonstrates the inherent difficulty of selecting a single polynomial function. The R 2 method can be used cautiously along with visual inspection to guard against overfitting. Spline curves are suitable for all IOLs, guarding against the issues of overfitting. Therefore, for analysis of the defocus profile of IOLs, the fitting of a spline curves is advocated and should be used wherever possible.

Video-rate remote refocusing through continuous oscillation of a membrane deformable mirror

This paper presents the use of a deformable mirror (DM) configured to rapidly refocus a microscope employing a high numerical aperture (NA) objective lens. An Alpao DM97-15 membrane DM was used to refocus a 40×/0.80 NA water-immersion objective through a defocus range of −50–50 μm at 26.3 sweeps s−1. We achieved imaging with a mean Strehl metric of >0.6 over a field of view in the sample of 200 × 200 μm2 over a defocus range of 77 μm. We describe an optimisation procedure where the mirror is swept continuously in order to avoid known problems of hysteresis associated with the membrane DM employed. This work demonstrates that a DM-based refocusing system could in the future be used in light-sheet fluorescence microscopes to achieve video-rate volumetric imaging.