Lens Research Articles

Accuracy of intraocular lens formulas in combined phacovitrectomy.

To assess the refractive accuracy of eight intraocular lens (IOL) formulas in eyes that underwent combined phacovitrectomy. A retrospective chart review of 59 eyes that underwent uncomplicated phacovitrectomy between 2017 and 2020 at the Johns Hopkins Wilmer Eye Institute. Inclusion criteria were postoperative best corrected visual acuity of 20/40 or better within 6months of surgery and IOL implantation in the capsular bag. The Barrett Universal II (BUII), Emmetropia Verifying Optical (EVOv2.0), Hill-Radial Basis Function (Hill-RBFv3.0), Hoffer Q, Holladay I, Kane, Ladas Super Formula (LSF), and SRK/T formulas were compared for accuracy in predicting postoperative spherical equivalents (SE) using Wilcoxon rank sum tests. Pearson's correlation coefficients were used to assess correlations between biometric parameters and errors for all formulas. Prediction errors of SE ranged from -1.69 to 1.43 diopters (D), mean absolute errors (MAE) ranged from 0.39 to 0.47 D, and median absolute errors (MedAE) ranged from 0.23 to 0.37 D among all formulas. The BUII had the lowest mean error (-0.043), MAE (0.39) and MedAE (0.23). The BUII also had the highest percentage of eyes with predicted error within ± 0.25 D (51%) and ± 0.50 D (83%). Based on MedAE however, no pairwise comparisons resulted in statistically significant differences. Axial length (AL) was positively correlated with the error from the Hoffer Q and Holladay I formulas (correlation coefficients = 0.34, 0.30, p values < 0.01, 0.02 respectively). While all eight IOL formulas had comparable accuracy in predicting refractive outcomes in eyes undergoing combined phacovitrectomy, the BUII and Kane formulas had a tendency to greater accuracy.

A critical analysis of volunteer tourism in post-socialist China

ABSTRACT This study delves into post-trip transformations among Chinese volunteer tourists, challenging the conventional Western-centric lens. Traditionally, research has focused on international examples in the Western context, but this study explores the less-investigated intra-country practices in China. It employs a simplified transformative learning framework, adopting a collective autoethnographic inquiry that involves the first author’s participation as a volunteer tourist in 2011, followed by an extended advisory role and authors’ cross-cultural reflexivity. The study scrutinizes psychological, convictional, and behavioural shifts while emphasizing the interconnection of transformations with pre-trip motivations, onsite host–guest interactions, post-trip actions, and the pivotal role of local organizations including long-neglected authorities. Significantly, it uncovers the mediating influence of China’s distinct socio-political landscape, contending that volunteer tourism in China serves as a top-down response to counter Western cultural dominance. This research underscores the need for a decolonized and context-specific approach to investigating volunteer tourism practices in non-Western contexts. It highlights the dynamic interplay between tourism experiences and the intricate socio-political environment in China, offering a fresh perspective on the transformative effects of local tourism practices in this unique context.

Choroidal Morphology and Photoreceptor Activity Are Related and Affected by Myopia Development.

The choroid is critical for the regulation of eye growth and is involved in the pathogenesis of myopia-associated ocular complications. This study explores the relationship among choroidal biometry, photoreceptor activity, and myopic growth in marmosets (Callithrix jacchus) with lens-induced myopia. A total of 34 common marmosets aged 92 to 273days old were included in this study. Axial myopia was induced in 17 marmosets using negative soft contact lenses and 17 marmosets served as untreated controls. Cycloplegic refraction (RE) and vitreous chamber depth (VCD) were measured using autorefraction and A-scan ultrasonography, respectively. Choroidal scans were obtained using spectral-domain optical coherence tomography and binarized to calculate subfoveal choroidal thickness (ChT), total choroidal area (TCA), luminal area (LA), stromal area (SA), choroidal vascularity index (CVI), and LA/SA. To assess photoreceptor activity, the a-wave of the full-field electroretinogram was measured. Regression models were used to investigate the relationship between outcome measures. Eyes induced with axial myopia (RE = -7.14 ± 4.03 diopters [D], VCD = 6.86 ± 0.39mm) showed significant reductions (4.92-21.24%) in all choroidal parameters (ChT, TCA, LA, SA, CVI, and LA/SA) compared to controls (RE = -1.25 ± 0.60 D, VCD = 6.58 ± 0.26mm, all P < 0.05), which changed as a function of refraction and vitreous elongation, and were associated with a decrease in the a-wave amplitude. Further, multiple regression showed that a combination of ChT and CVI could well predict RE and VCD. This study reports the existence of significant alterations in choroidal morphology in non-human primate eyes induced with myopia. The changes in choroidal anatomy were associated with reduced light-adapted a-wave amplitude. These findings may represent early markers for reduced visual performance and chorioretinal complications known to occur in eyes with large degrees of myopia.

Comparing subject-specific mastery motivation in Hungary and the Republic of Moldova

Research on mastery motivation has documented its importance in personality development and school achievement, yet there is little research that examines school subject-specific motivation, specifically cross-cultural research. The objective of this study was to investigate the school subject-specific nature of mastery motivation in the context of middle and secondary school grades 5, 7, and 9 in Hungary (N = 1121) and Moldova (N = 939) in Reading, Math, Science, English as a foreign language, Music, and Art. The findings indicated that subject-specific mastery motivation (SSMM) domains in Hungary and Moldova have different paths across grade levels. In Hungary, there was a constant decreasing trajectory across all grades in all domains with the exception of English, whereas in Moldova, the decrease was identified in Math, English, Music, and Art between the fifth and the seventh grades but not between the seventh and the ninth grades, while Reading mastery motivation levels remained stable. Upon conducting a cross-cultural comparison of SSMM levels across the countries and grades, we identified only one statistically significant difference in science mastery motivation. The study attempts to explain the absence of cross-cultural differences not only through a conventional lens focusing on the unique characteristics of individual educational systems but also by considering the cultural values associated with each country.

Broadband Terahertz Metalenses Based on Printed Circuit Board Fabrication

AbstractMetalenses have provided a good solution to the bulkiness of conventional refractive lenses. Due to the subwavelength feature sizes of the metalens structure, the increasing fabrication difficulties at high frequencies limit its application in the terahertz and optical regime. Moreover, the deeply subwavelength features of the metasurface unit cells usually make the cells strongly resonant, which limits the bandwidth of the metalens. In this paper the usage of aggressive discretization in a metalens design is investigated, and it is found that aggressive discretization can lead to the usage of weakly resonant and relatively large unit cells, which leads to excellent broadband performance and dramatically relaxes the feature size tolerance of the metalens. For examples, two terahertz focusing metalenses are designed which feature large numerical apertures (NA = 0.86), diffraction‐limited focusing over a broad bandwidth (240–400 GHz, or 50% bandwidth), and minimum feature sizes of 0.1 mm. These tolerance‐relaxed terahertz metalenses are successfully constructed using conventional printed‐circuit‐board fabrication technology. The experimental measurements validate the simulated performances. Compared to existing terahertz meta‐devices based on micro‐fabrication or nano‐fabrication technologies, this paper opens door to a kind of high‐quality terahertz metasurfaces featuring low‐cost, rapid, and established fabrication.

Comparison of proximal and minus lens autorefraction techniques to measure monocular accommodative amplitude.

This study provides a faster method for objectively measuring accommodative amplitude with an open-field autorefractor in a research setting. Objective measures of accommodative amplitude with an autorefractor take time because of the numerous stimulus demands tested. This study compares protocols using different amounts and types of demands to shorten the process. One hundred participants were recruited for four age bins (5 to 9, 10 to 14, 15 to 19, and 20 to 24 years) and monocular amplitude measured with an autorefractor using three protocols: proximal, proximal-lens (letter), and proximal-lens (picture). For proximal, measurements were taken as participants viewed a 0.9 mm "E" placed at 13 demands (40 to 3.3 cm = 2.5 to 30 D). The other protocols used a target (either the "E" or a detailed picture) placed at 33 and 12.5 cm followed by 12.5 cm with a series of lenses (-2, -4, and -5.5 D). Adjustments were made for lens effectivity for the three lens conditions, which were thus 9.6, 11.1, and 12.0 D for individuals without additional spectacle lenses. Accommodative amplitude was defined as the greatest response measured with each technique. One-way analysis of variance was used to compare group mean amplitudes across protocols and differences between letter protocols by age bin. Amplitudes were significantly different between protocols (p < 0.001), with proximal having higher amplitudes (mean ± standard deviation, 8.04 ± 1.70 D) compared with both proximal-lens protocols (letter, 7.48 ± 1.42 D; picture, 7.43 ± 1.42 D) by post hoc Tukey analysis. Differences in amplitude between the proximal and proximal-lens (letter) protocol were different by age group (p = 0 .003), with the youngest group having larger differences (1.14 ± 1.58 D) than the oldest groups (0.17 ± 0.58 and 0.29 ± 0.48 D, respectively) by post hoc Tukey analysis. The proximal-lens protocols took less time and identified the maximum accommodative amplitude in participants aged 15 to 24 years; however, they may underestimate true amplitude in younger children.

Objective and subjective assessment of accommodative insufficiency.

A variety of subjective and objective procedures are available to measure the amplitude of accommodation. However, it is unclear whether the standard criterion of Hofstetter's minimum minus 2 D can be used to diagnose accommodative insufficiency with each of these techniques. The use of objective dynamic retinoscopy and three subjective techniques to diagnosis accommodative insufficiency was examined. A total of 632 subjects between 8 and 19 years of age were enrolled. Accommodative lag, monocular accommodative facility, and subjective (push-up, modified push-down, and minus lens) and objective (dynamic retinoscopy) amplitude of accommodation were quantified. Accommodative insufficiency was diagnosed based on Hofstetter's minimum minus 2 D for each subjective method, as well as adding an additional subjective criterion (either accommodative lag exceeding 0.75 D or monocular accommodative facility falling below the age-expected norms). The prevalence of accommodative insufficiency was lowest and highest with the push-up (7.9 and 1%) and dynamic retinoscopy (94 and 12%) procedures when measured without and with the additional subjective criteria, respectively. Comparing the validity of dynamic retinoscopy against the traditional criterion, moderate to low sensitivity and high specificity were found. However, adding the additional subjective criteria improved the findings with moderate to high sensitivity and high specificity. Using a cutoff for dynamic retinoscopy of 7.50 D showed moderate diagnostic accuracy based on likelihood ratios. It is clear that a revised definition of accommodative insufficiency is required, which must include the method of assessing accommodation. The various objective and subjective methods for quantifying the amplitude of accommodation are not interchangeable, and subjective assessment does not provide a valid measure of the accommodative response.

Gradient myopic defocus causes scleral tissue reinforcement and structural scleral remodelling

Aims/Purpose: To determine histological effects of lens induced refractive change on scleral remodelling in chicks.Methods: 18 Ross‐Ross chicks were raised for 14 days on a 14 hr light/10 hr dark cycle. 6 chicks were allowed to develop normally. 6 chicks wore conventional ‐10D lenses for the full 14 days. 6 chicks wore conventional ‐10D lenses for the first 7 days and myopia progression control (MPC) lenses or the next 7 days. MPC lenses had a central power of ‐10D and a gradient power rise at pupil edge (+ 2.75D). Birds were euthanized after 14 days and eyes were routinely processed for histopathological evaluation. Whole mount H&amp;E‐stained tissue sections were microscopically analysed using bright field microscopy.Results: All lens treated birds developed significant myopia as expected Total scleral thickness was significantly reduced in the group wearing conventional ‐10 lenses (p &lt; 0.05), but remained comparable to the normal control group for the MPC lenses treated birds. New appositional growth of the cartilaginous sclera was observed in all MPC lenses treated eyes and only in those eyes. The thickness of the cartilaginous component of the sclera was 135 ± 6, 153 ± 5, 125 ± 8 μm for conventional myopic, MPC lenses treated, and control birds respectively. There was a significant increase in the cartilaginous scleral thickness in the MPC lenses treated birds compared to the other two groups (p &lt; 0.03), but not between the conventional ‐10D lens treated and control birds (p &gt; 0.05).Conclusions: It is possible to induce appositional growth in hyaline cartilage in the chick sclera. In our study, this has only been achieved by using MPC lenses to reverse previously induced experimental myopia with conventional minus lenses. Our finding suggests that gradient decrease in peripheral lens power and the resulting differential level of defocus it causes could be a potential trigger of scleral reinforcement through stimulation of cartilage growth in the chick sclera.

Comparative Evaluation of Visual Outcomes in Combined Cataract and Vitrectomy for Idiopathic Epiretinal Membrane with an Advanced or Conventional Intraocular Lens

Introduction: The aim of this study was to investigate the efficacy of new monofocal intraocular lens (IOL) in comparison with conventional monofocal IOL in patients undergoing combined cataract and vitrectomy surgery for epiretinal membrane (ERM). Methods: This prospective non-randomized comparative study included 65 eyes of 65 patients who underwent combined cataract and vitrectomy for ERM with implantation of advanced monofocal IOL (Eyhance ICB00, 33 patients) and standard monofocal IOL (Tecnis ZCB00, 32 patients). Monocular visual acuities were measured 6 months post-operatively, including corrected and uncorrected distance visual acuity (CDVA, UCDVA), uncorrected intermediate visual acuity (UCIVA), and uncorrected near visual acuity (UCNVA). Furthermore, contrast sensitivity and metamorphopsia were measured. Results: There was no significant difference between two groups regarding operation time, post-operative CDVA, UCDVA, UCNVA, and spherical equivalent (p > 0.05). Monocular UCIVA was significantly higher in the Eyhance IOL group than in the Tecnis IOL group (p = 0.005). The photopic and mesopic contrast sensitivities were comparable between each group for any spatial frequency (p > 0.05). The correlation coefficients from correlations between retinal wrinkling ratio and M score did not differ significantly between groups (p = 0.877), and the degree of metamorphopsia was not significantly related to the type of IOL (p = 0.969). Conclusions: In combined cataract and vitrectomy for ERM, Eyhance IOL provided significant better visual performance at intermediate distance than standard monofocal IOL without compromising operation time, distance vision, contrast sensitivity, and evaluating metamorphopsia. Eyhance IOL can be a useful option for both surgeons and patients.

Artificial intelligence in cataract and refractive surgery

Artificial intelligence (AI) technology is proving to be promising in the field of healthcare, especially in the areas relying on big data and image‐based analysis. In Ophthalmology, AI was already tested in majority of subspecialities, including cataract and refractive surgery. There were interesting studies showing the benefits of using AI algorithms in early keratoconus detection, to predict the outcomes of laser refractive surgery, and to cataract surgery training and monitoring. Moreover, AI models using fundus images to diagnose and grade cataract have been developed. New intraocular lens (IOL) formulas are applying big data and computational methodologies to achieve better prediction of targeted refraction and simplify the IOL selection process. Recent developments in AI have shown their potential possibility for the diagnosis and management of paediatric cataract using slit‐lamp images.

Comparative Evaluation of the Defocus Curve of Monofocal IOL, Extended Depth of Focus IOL, and Trifocal IOL

Purpose. Comparative evaluation of the defocus curve (DC) of monofocal IOLs (MIOLs), extended depth of focus IOLs (EDОF) and trifocal IOLs (TIOLs). Patients and methods. We observed 90 patients (average age 57.8 ± 1.8 years) who underwent standard binocular phacoemulsification of cataracts in both eyes with emmetropic “target” refraction and postoperative monocular uncorrected distance visual acuity (UCVA) of at least 1.0 rel. units. All patients were divided into three groups equal in number of patients, age, gender and visual status, corresponding to three options of implantable IOLs: MIOL (“RayOne Aspheric”, model RAO600C); EDOF (RayOne EMV, model RAO200E) and THYOL (RayOne Trifocal). DC was performed binocularly based on a standard BCVA measurement with an optical load for defocusing from +3.0 D to -4.0 D with a “step” of +1.0 D and -0.5 D. Results. Under conditions of optical defocusing with positive lenses (1.0; 2.0; 3.0 D), all three types of IOLs maintained almost the same average BCVA (at +1.0 D, the BCVA range was 0.72–0.76 rel. units; at +2.0 diopters — 0.66–0.72 relative units; at +3.0 diopters — 0.52–0.56 relative units). In relation to the analysis of BCVA in conditions of defocusing with negative lenses, it was found that visual acuity was significantly better with EDOF than with MIOL, with a load from -1.0 to -4.0 diopters, while these differences were statistically significant and ranged from 0.14 to 0.27 relative units (p &lt; 0.01). Along with this, it was determined that UCVA was significantly better in the group with TIOL than in the group with EDOF, with a load from -2.5 to -4.0 D. Moreover, these differences were statistically significant and ranged from 0.09 to 0.14 rel. units (p &lt; 0.01). Conclusion. The design features of IOLs make it possible to consider implantation of EDOF as an option for an individual approach to the selection of IOLs, especially taking into account the possibility of use in patients whose professional activities involve long-term visual work at intermediate distances (for example, users of personal computers).

Development of a microelectrode for simultaneous &lt;i&gt;in vivo&lt;/i&gt; calcium and electrophysiological recording of hippocampal neuronal activity

Calcium (Ca2+) imaging is a commonly utilized neuroscience technique for in vivo recording of neuronal activity. It involves the optical measurement of calcium concentration using genetically encoded calcium indicators (GECI) [1]. However, the kinetics of changes in the fluorescence of GECI are relatively slow and limited by the biophysics of the calcium binding [2]. In response to single action potentials (APs) in pyramidal neurons, most of the widely used GECI have a fluorescence half-life of approximately 100 ms [3]. As a result, GECI cannot provide complete information about the dynamics of neural ensembles. To address this issue, new variants of GECI, such as jGCaMP7 [3], and jGCaMP8 [4], have been developed, or genetically encoded voltage indicators (GEVI), such as JEDI-2P [5], have been utilized. However, the speed of GECI or GEVI is still lower than that of electrophysiological registration methods. Thus, we have designed a microelectrode that can be utilized with a gradient lens for in vivo calcium imaging with a miniscope. The miniscope is a miniature microscope for single photon epifluorescence Ca2+ imaging, which enables recording of neuronal activity in freely moving laboratory animals, unlike the traditionally used two-photon imaging technique. The miniscope utilizes gradient-index (GRIN) lenses that are implanted directly into the brain of a laboratory animal, instead of a conventional lens. The gradient lens is a transparent cylinder with a diameter of 1.8 mm and a length of 3.8 mm. To facilitate electrophysiological recording, we developed a microelectrode that can be aligned with a GRIN lens. The microelectrode is a three-layer structure consisting of: 1) a polyimide film, 2) conductive copper tracks deposited through thermoforming, and 3) a polyimide film with cutouts for pads. On one side of the microelectrode, there are 12 gold-plated conductive contacts for registering local field potentials, while on the other side, a similar number of conductive tracks are present for connecting to a connector that transmits data to the processing board. The flexible microelectrode is wrapped around a gradient lens and fixed using thermoforming, after which it is implanted in the animal's brain. Using the developed microelectrode, our aim is to perform a comparative analysis of the calcium and electrophysiological activity of hippocampal neurons in freely moving wild-type mice and in a mouse model of Alzheimer's disease. This study will enable the identification of any abnormalities in Alzheimer's disease at the level of neural ensembles and may suggest new treatment approaches or mechanisms for the development of the progressive memory loss pathology associated with this disease. We would like to express our gratitude to Anastasia Viktorovna Bolshakova for her administrative assistance, and to the staff of the Laboratory of Molecular Neurodegeneration for their invaluable help and advices.

Accuracy of intraoperative aberrometry versus modern preoperative methods in post-myopic laser vision correction eyes undergoing cataract surgery with capsular tension ring placement

PurposeTo assess the accuracy of intraoperative wavefront aberrometry (IWA) versus modern intraocular lens formulas in post-myopic laser vision correction (LVC) patients undergoing cataract surgery with capsular tension ring placement.MethodsThis is a retrospective chart review conducted at an academic outpatient center. All post-myopic LVC eyes undergoing cataract surgery with IWA from a single surgeon from 05/2017 to 12/2019 were included. All patients received a capsular tension ring (CTR). Mean numerical error (MNE), median numerical error (MedNE), and percentages of prediction error within 0.50D, 0.75D, and 1.00D were calculated for the above formulas.ResultsTwenty-seven post-myopic LVC eyes from 18 patients were included. In post-myopic LVC, MNE with Optiwave Refractive Analysis (ORA), Barrett True K (BTK), Haigis, Haigis-L, Shammas, SRK/T, Hill-RBF v3.0, and W-K AL-adjusted Holladay 1 were + 0.224, − 0.094, + 0.193, − 0.231, − 0.372, + 1.013, + 0.860, and + 0.630 (F = 8.49, p < 0.001). MedNE were + 0.125, − 0.145, + 0.175, + 0.333, + 0.333, + 1.100, + 0.880, and + 0.765 (F = 7.89, p < 0.001), respectively. BTK provided improved accuracy in both MNE (p < 0.001) and MedNE (p = .033) when compared to ORA in pairwise analysis. If the ORA vs. BTK-suggested IOL power were routinely selected, 30% and 15% of eyes would have projected hyperopic outcomes, respectively (p = 0.09).ConclusionsOur study suggests that in post-myopic LVC eyes undergoing cataract surgery with CTRs, BTK performed more accurately than ORA with regard to accuracy and yielded a lower percentage of eyes with hyperopic outcomes. Haigis, Haigis-L, and Shammas yielded similar results to ORA with regard to accuracy and percentage of eyes with hyperopic outcomes. On average, Shammas and Haigis-L suggested IOLs that would yield outcomes more myopic than expected when compared to BTK.

Meta-Lens Particle Image Velocimetry.

Fluid flow behavior is visualized through particle image velocimetry (PIV) for understanding and studying experimental fluid dynamics. However, traditional PIV methods require multiple cameras and conventional lens systems for image acquisition to resolve multi-dimensional velocity fields. In turn, it introduces complexity to the entire system. Meta-lenses are advanced flat optical devices composed of artificial nanoantenna arrays. It can manipulate the wavefront of light with the advantages of ultrathin, compact, and no spherical aberration. Meta-lenses offer novel functionalities and promise to replace traditional optical imaging systems. Here, a binocular meta-lens PIV technique is proposed, where a pair of GaN meta-lenses are fabricated on one substrate and integrated with a imagingsensor to form a compact binocular PIV system. The meta-lens weigh only 116mg, much lighter than commercial lenses. The3Dvelocity field can be obtained by the binocular disparity and particle image displacement information of fluid flow. The measurement error of vortex-ring diameter is ≈1.25% experimentally validates via a Reynolds-number (Re) 2000 vortex-ring. This work demonstrates a new development trend for the PIV technique for rejuvenating traditional flow diagnostic tools toward a more compact, easy-to-deploy technique. It enables further miniaturization and low-power systems for portable, field-use, and space-constrained PIV applications.

Sub-diffraction metalens for generating longitudinal bifoci and optical needles

Lenses are a fundamental component of optical systems. Bifoci and optical needle devices have excellent application potential in many optical systems. Conventional lenses are limited by their diffraction limits, and the spot size has a considerable influence on the resolution of optical and microscopic images. Optical super-oscillation is a novel technique, to the best of our knowledge, for far-field sub-diffraction focusing. In this study, we proposed a binary-amplitude super-oscillatory lens (SOL) approach for generating bifoci and optical needles (ON), and it was based on the angular spectrum method (ASM) and a binary-particle-swarm optimization (BPSO) algorithm. We reported a class of binary-amplitude-based Bifoci- and ON-SOLs that generated sub-diffraction bifoci and optical needles. Sub-diffraction bifoci with a transverse range of 0.401λ−0.522λ were recorded for a work wavelength of λ=632.8nm. The generated optical needle had a sub-diffraction length of 4.122λ, and the super-oscillation region was 2.083λ long. This provides potential applications for further super-resolution imaging, optical communication, and precision manufacturing.

Varifocal diffractive lens based on microfluidics

Conventional flat diffractive lenses possess compact dimensions and exhibit exceptional optical performance. However, the focal length can hardly be adjusted adaptively. In this paper, we demonstrate a novel diffractive lens that achieves switchable focal length based on microfluidic. A multi-level diffractive lens (MDL) is designed and optimized. By filling liquid materials into the tiny gaps between the MDL, the proposed lens operates in different states with switchable focal length. Experimental results demonstrate that the proposed lens enables focal length tuning without mechanical movement, allowing for switching between different focal lengths. The proposed lens is polarization-independent and does not require complex driving mechanisms. The core imaging component has dimensions of only 1.5 mm × 1.5 mm × 0.6 mm. The proposed lens enhances the adjustability of diffractive lenses, showcasing the advantages of liquid materials in diffractive lens design. It holds great potential for applications in compact zoom imaging systems.

Efficacy of corneal curvature on the accuracy of 8 intraocular lens power calculation formulas in 302 highly myopic eyes.

To investigate the effect of corneal curvature (K) on the accuracy of 8 intraocular lens formulas in highly myopic eyes. Eye Hospital and School of Ophthalmology and Optometry, Wenzhou Medical University, Wenzhou, China. Retrospective consecutive case series. 302 eyes (302 patients) were analyzed in subgroups based on the K value. The mean refractive error, mean absolute error (MAE), median absolute error (MedAE), root-mean-square absolute prediction error (RMSAE) and proportions of eyes within ±0.25 diopter (D), ±0.50 D, ±0.75 D, ±1.00 D were statistical analyzed. Emmetropia Verifying Optical (EVO) 2.0, Kane, and Radial Basis Function (RBF) 3.0 had the lower MAE (≤0.28) and RMSAE (≤0.348) and highest percentage of eyes within ±0.50 D (≥83.58%) in the flat (K ≤ 43 D) and steep K (K > 45 D) groups. Hoffer QST had the lowest MedAE (0.19), RMSAE (0.351) and the highest percentage of eyes within ±0.50 D (82.98%) in the normal K group (43 < K ≤ 45 D). When axial length (AL) ≤28 mm, all formulas showed close RMSAE values (0.322 to 0.373) in flat K group. When AL >28 mm, RBF 3.0 achieved the lowest MAE (≤0.24), MedAE (≤0.17) and RMSAE (≤0.337) across all subgroups. EVO 2.0, Kane, and RBF 3.0 were the most accurate in highly myopic eyes with a flat or steep K. Hoffer QST is recommended for long eyes with normal K values. RBF 3.0 showed the highest accuracy when AL >28 mm, independent of corneal curvature.

Neural network-assisted design of GSST-based achromatic metalens with continuously variable focal heights

Recently developed achromatic metalens show great potential to replace conventional lenses. However, current long-wavelength infrared (LWIR) achromatic metalens are limited to fixed functions, severely hampers their integration and application. In order to address this limitation, Ge2Sb2Se4Te1 (GSST) and Silicon (Si) are used as materials for continuously variable focus height broadband achromatic metalens (CVFHBAM) at LWIR. Specifically, the multipole decomposition is performed within the operating band (8–12μm) to avoid undesired resonances and ensure the high degree of linearity of the meta-atoms. A tandem neural network is utilized for parameter optimization. Numerical results show that the CVFHBAM is well-corrected for chromatic aberration within the operating wavelength. By varying the crystalline fraction of GSST, focal length can continuously varied up to five times the center wavelength while maintaining achromatic focus, and the average numerical aperture (NA) is varied from 0.345 to 0.454. In addition, by calculating the Strehl ratio values, the transverse dimensions of the corresponding focal spots almost reach sub-diffractive focusing. The average focusing efficiencies are 57.74%, 64.32%, 68.94% and 71.48% respectively, for the four selected crystalline states. The results show that CVFHBAM has a promising application in developing high-resolution LWIR imaging and spectroscopy systems.

Method for increasing the utilization rate of birefringence in liquid crystal lenses.

We propose a method to increase the utilization rate of birefringence in liquid crystal (LC) lenses. The method involves designing electrode patterns based on the phase response curve of the LC material, enabling the lenses to operate across a wide range of driving voltages while generating the desired phase profile. The underlying principle of this technique is discussed in detail. Electrode patterns have been successfully designed for positive and negative cylindrical LC lenses. The experimental results demonstrate that the designed lenses generate a parabolic phase profile even when the driving voltage exceeds the linear response region. The utilization rate of LC birefringence for the positive lens has increased from 41.3% to 69.7%, indicating a 68.8% increase from the original. For the negative lens, the utilization rate has risen from 41.8% to 68.7%, representing a 64.4% increase from the original.

Optical performance of synthetic aperture metalens based on hybrid unit-cells

In this paper, we introduce a metalens with a hybrid unit-cell arrangement that operates at a wavelength of 0.94 μm. The metalens consists of 0.8 μm unit-cells on the inner and 0.4 μm unit-cells on the outer. The transmittance of 0.8 μm and 0.4 μm unit-cells are about 0.5 and 1, respectively. Therefore, the proposed metalens with hybrid unit-cells, behaving like a synthetic aperture lens, suppresses the low spatial frequency signal and enhances the high spatial frequency one. As a result, the proposed metalens with hybrid unit-cells presents a higher spatial resolution than that with an identical unit-cell size and holds higher transmittance than that of a conventional synthetic aperture lens. Moreover, we comprehensively discuss the optical performance and limitations of pixelate metalens and expand the application prospects of synthetic aperture metalenses in optical imaging.