Higher-order aberrations and their association with axial elongation in highly myopic children and adolescents

BackgroundVision-dependent mechanisms play a role in myopia progression in childhood. Thus, we investigated the distribution of ocular and corneal higher-order aberrations (HOAs) in highly myopic Chinese children and adolescents and the relationship between HOA components and 1-year axial eye growth.MethodsBaseline cycloplegic ocular and corneal HOAs, axial length (AL), spherical equivalent (SE), astigmatism and interpupillary distance (IPD) were determined for the right eyes of 458 highly myopic (SE ≤−5.0D) subjects. HOAs were compared among baseline age groups (≤12 years, 13–15 years and 16–18 years). Ninety-nine subjects completed the 1-year follow-up. Linear mixed model analyses were applied to determine the association between HOA components, other known confounding variables (age, gender, SE, astigmatism and IPD) and axial growth. A comparison with data from an early study of moderate myopia were conducted.ResultsAlmost all ocular HOAs and few corneal HOAs exhibited significant differences between different age groups (all p<0.05). After 1 year, only ocular HOA components was significantly negative associated with a longer AL, including secondary horizontal comatic aberration (p=0.019), primary spherical aberration (p<0.001) and spherical HOA (p=0.026). Comparing with the moderate myopia data, the association of comatic aberration with AL growth was only found in high myopia.ConclusionIn highly myopic children and adolescents, lower levels of annual ocular secondary horizontal comatic aberration changes, besides spherical aberrations, were associated with axial elongation. This suggests that ocular HOA plays a potential role in refractive development in high myopia.

High-Entropy-Stabilized Polyanionic Cathodes with Multiple Redox Reactions for Sodium-Ion Battery Applications

High-entropy (HE) materials containing multiple elements have created a growing interest in exploring the property limits of electrodes in energy storage and understanding the underlying chemical/physical mechanisms. Here, we show a substantial improvement in performance of HE-based cathodes in sodium-ion batteries (SIBs). Polyanionic structure has a large compositional flexibility and can incorporate many active transition-metal (TM) species, which is an ideal platform to design HE cathode materials. As a proof of concept, we show that HE sodium superionic conductor (HE-NASICON) materials can be synthesized via a facile sol-gel method. By comparing a group of HE-NASICON cathodes containing different contents of TM species, we demonstrate that the multi-Na-ions intercalation/deintercalation process is highly reversible, whereas capacity and cycling stability are improved. The HE-NASICON cathode with equal molarity of five TM species achieves a high capacity of 161 mA h g−1 and capacity retention of 85% when cycling at a high rate of 5 C over 1000 cycles. In-situ XRD and spherical-aberration-corrected transmission electron microscope (ACTEM) also demonstrate a robust trigonal phase with a volume change of merely 4.07% during the multi-Na-ions storage. These results reveal the effectiveness of HE concept in expediting high-performance polyanionic cathodes for real SIBs applications.

Repeatability and reproducibility of corneal higher-order aberrations measurements after small incision lenticule extraction using the Scheimpflug-Placido topographer

Background To evaluate the precision of corneal higher-order aberrations measurements after small incision lenticule extraction (SMILE) using the Sirius Scheimpflug-Placido topographer (CSO, Italy). Methods Seventy-five eyes from 75 postoperative subjects were included in this prospective study. Three consecutive corneal aberrometric measurements were obtained with the Scheimpflug-Placido topographer by two experienced operators to assess intra- and inter-observer reproducibility. The within-subject standard deviation (Sw), test-retest repeatability (TRT) and the intraclass correlation coefficient (ICC) were calculated. Results For intraobserver repeatability of anterior and total corneal aberrations, all ICCs were more than 0.922, except for trefoil (0.722 to 0.768). The ICCs of total root mean square (RMS), coma Z (3, ± 1), and spherical aberration Z (4, 0) were over 0.810 while higher-order RMS, trefoil Z (3, ± 3), and astigmatism II Z (4, ± 2) were below 0.634 for posterior corneal surface aberrations. All Sw values for all types of aberrations were equal to or below 0.07 μm. Regarding interobserver reproducibility, all TRT values were no more than 0.12 μm, 0.05 μm, and 0.11 μm for anterior, posterior, and total corneal aberrations, respectively. The ICC values ranged from 0.875 to 0.989, from 0.686 to 0.976 and over 0.834 for anterior, posterior, and total corneal aberrations, respectively. Conclusions The repeatability of measurements of anterior and total corneal aberrations with the Sirius system in corneas after SMILE surgery was high, except for trefoil. There was some variability in posterior corneal aberrometric measurements. High reproducibility of corneal aberrometric measurements was observed between measurements of both examiners, except for trefoil, with poor to moderate reproducibility.

Short-Term Effect of Wearing of Extended Depth-of-Focus Contact Lenses in Myopic Children: A Pilot Study

This pseudo-experimental, prospective, and longitudinal pilot study was conducted to characterize the optical and visual changes occurring in the short-term wear of a hydrophilic contact lens (CL) based on extended focus technology (EDOF). A total of 30 eyes of 15 children (age, 6–16 years) were fitted with the EDOF CL Mylo (Mark’ennovy Care SL), performing an exhaustive follow-up for one month evaluating changes in visual acuity (VA), accommodation, binocularity, ocular aberrometry, visual quality, pupillometry, keratometry and biometry. Far and near VA with the CL improved progressively (p < 0.001), obtaining mean final binocular values of −0.08 ± 0.01 and −0.07 ± 0.01 LogMAR, respectively. There was a mean reduction in the accommodative LAG of 0.30 D (p < 0.001), without associated alterations in the magnitude of the phoria and fusional vergences (p ≥ 0.066). A controlled but statistically significant increase (p ≤ 0.005) of ocular high order aberration (HOA) root mean square (RMS), primary coma RMS, primary spherical aberration Zernike term and secondary astigmatism RMS was found with the CL wear. In conclusion, the EDOF CL evaluated provides adequate visual acuity and quality, with associated increased of several HOAs and a trend to reduction in the accommodative LAG that should be confirmed in future studies.

Evaluation of the B/F Ratio Distribution of Cataract Patients Without Corneal Abnormalities and Its Effect on Ocular Parameters

Purpose: To evaluate the distribution of the posterior-anterior corneal radius ratio (B/F ratio; posterior corneal radius/anterior corneal radius) in patients without corneal abnormalities, and to investigate which parameters affect this ratio. Methods: Five thousand eyes from 5,000 patients who underwent cataract surgery were recruited to this study. We explored the linear relationship between B/F ratio and 13 variables using Principal Component-Multivariate Linear Regression Analysis. Results: The B/F ratio was negatively correlated with the difference between simulated keratometry (SimK) and true net power (TNP), central corneal thickness, spherical aberration (SA), and posterior corneal astigmatism and positively correlated with posterior corneal radius, corneal posterior surface, axial length (AL) and anterior corneal radius. Several variables (central corneal thickness, difference between SimK and TNP and asphericity coefficient (Q-value) of the posterior corneal surface) had the highest loading on the final score. B/F ratio reflects the refractive state and anatomical structure of the cornea: thus, higher B/F ratios were associated with larger posterior corneal surface curvature radius, longer axial length, thinner central corneal thickness, lower high order aberrations of the cornea and SA, and the numerical difference between simK and TNP gradually reduced. In clinical practice, for patients with lower B/F ratio, special care should be taken in the choice of system used for intraocular lens (IOL) measurements.

Evaluation of Corneal Higher- Order Aberrations in Adults with Different Refractive Status: تقييم الزّوغانات القرنيّة عالية التّرتيب عند البالغين في مختلف الحالات الانكساريّة

Purpose: The aim of this study is to evaluate the root mean square error (RMS) of corneal higher- order aberrations in Syrian adult population in different refractive status (emmetropia, myopia, hyperopia and simple myopic astigmatism). Methods: This cross- sectional study was conducted at Tishreen University Hospital in Latakia, Syrian Arab Republic. A total of 420 patients (840 eyes), ages 18- 40 years, participated in the study. Refraction was measured with an autorefractor keratometer and expressed as a spherical equivalent. Total corneal higher- order aberrations (Coma, Spherical Aberration, Trefoil) were measured using Sirius Corneal Topography at a pupil diameter of 5 mm. Results: RMS of Coma and Spherical aberrations peaked in the hyperopia group (0.18 ± 0.08, 0.11 ± 0.02) respectively. Whereas, Trefoil was higher in the severe myopia and simple myopic astigmatism groups (0.25 ± 0.05, 0.25 ± 0.08) respectively. Conclusions: Among a Syrian population, some types of refractive status were associated with certain types of higher- order aberrations, with a significant increase in trefoil in severe myopia and simple myopic astigmatism.

First Results after Implantation of Hydrophilic and Hydrophobic Trifocal Intraocular Lenses: Visual and Optical Performance

Purpose. To compare postcataract surgery visual and optical performance between two trifocal intraocular lenses (IOLs) with the same optical design: a hydrophobic acrylic glistening-free IOL and a hydrophilic acrylic IOL. Methods. Patients were bilaterally implanted with either the hydrophobic or the hydrophilic IOL. The data of the patients’ right eyes were evaluated. Visual quality assessments included refractive outcomes, monocular visual acuity (VA) at far, intermediate, and near distances, defocus curve, aberrations (spherical aberration (SA)), root mean square (RMS) of corneal, internal, and total higher-order aberrations (HOAs)), and tilt of IOL. Results. Fifty-one patients were included in the analysis: 26 patients implanted with the hydrophobic IOL and 25 patients implanted with the hydrophilic IOL. At 1 month, no statistically significant differences were found for monocular uncorrected and corrected VA at distance, distance-corrected VA at intermediate and near, defocus curve, manifest spherical equivalent, total SA, and RMS of the total, internal, and corneal HOA. The defocus curve of both groups showed a visual acuity of 0.3 logMAR or better in the intermediate range from 0.5 to −2.5 D of vergence level with no significant differences between the groups. Compared to the hydrophilic group, y-direction tilt was significantly higher in the hydrophobic group ( p = 0.027 ). The total tilt and x-axis tilt did not differ between the groups. Conclusion. Both IOLs demonstrated an excellent quality of vision and provided the patient with a wide range of vision.

On the Relationship between Corneal Biomechanics, Macrostructure, and Optical Properties

Optical properties of the cornea are responsible for correct vision; the ultrastructure allows optical transparency, and the biomechanical properties govern the shape, elasticity, or stiffness of the cornea, affecting ocular integrity and intraocular pressure. Therefore, the optical aberrations, corneal transparency, structure, and biomechanics play a fundamental role in the optical quality of human vision, ocular health, and refractive surgery outcomes. However, the inter-relationships of those properties are not yet reported at a macroscopic scale within the hierarchical structure of the cornea. This work explores the relationships between the biomechanics, structure, and optical properties (corneal aberrations and optical density) at a macro-structural level of the cornea through dual Placido–Scheimpflug imaging and air-puff tonometry systems in a healthy young adult population. Results showed correlation between optical transparency, corneal macrostructure, and biomechanics, whereas corneal aberrations and in particular spherical terms remained independent. A compensation mechanism for the spherical aberration is proposed through corneal shape and biomechanics.

Optical bench simulation for intraocular lenses using field-tracing technology

Purpose To evaluate the image quality of intraocular lenses (IOLs) using field-tracing optical simulation and then compare it with the image quality using conventional ray-tracing simulation. Methods We simulated aspheric IOLs with a decenter, tilt, and no misalignment using an aspheric corneal eye model with a positive spherical aberration. The retinal image, Strehl ratio, and modulation transfer function (MTF) were compared between the ray-tracing and field-tracing optical simulation and confirmed by the results reported in an in vitro experiment using the same eye model. Results The retinal image showed interference fringes from target due to diffraction from the object in a field-tracing simulation. When compared with the experimental results, the field tracing represented the experimental results more precisely than ray tracing after passing over 400 μm of the decentration and 4 degrees of the tilt of the IOLs. The MTF values showed similar results for the case of no IOL misalignment in both the field tracing and ray tracing. In the case of the 200-μm decentration or 8-degree tilt of IOL, the field-traced MTF shows lower values than the ray-traced one. Conclusions The field-tracing optical bench simulation is a reliable method to evaluate IOL performance according to the IOL misalignment. It can provide retinal image quality close to real by taking into account the wave nature of light, interference and diffraction to explain to patients having the IOL misalignment.