Mm In Axial Length Research Articles

Estimation of pupil size at iris plane and its magnification after cataract surgery.

To estimate the pupil size (at the iris plane) under photopic (P PH ) and scotopic (P S ) conditions after phacoemulsification with intraocular lens (IOL) implantation. 190 virgin eyes from 190 patients who underwent cataract surgery with IOL implantation. Data collected with Aladdin (Topcon), AS-OCT MS-39 (CSO), and iTrace (Tracey) were SimK, mean pupillary power at 6 mm (MPP), anterior chamber depth (ACD), lens thickness (LT), axial length (AL), lens rise (LR), P PH and P S before and after surgery at 30 days, dysfunctional lens index, and opacity grade. The position of the postoperative iris plane (PIP) was measured manually with MS-39, and a multivariate regression formula was developed to predict it. Statistical analysis was performed using Statistical Package for Social Science (SPSS) (IBM). The mean and standard deviations were 42.61 ± 3.20 D for MMP at 6 mm, 3.35 ± 0.37 mm for ACD, 3.89 ± 0.18 mm for PIP ( P < 0.01), 4.55 ± 0.42 mm for LT, 0.43 ± 0.24 mm for LR, and 25.91 ± 3.03 mm for AL. The mean preoperative and postoperative topographic pupil magnification was 12% and 14.22%, respectively ( P < 0.01). Despite an increase in magnification, the postoperative pupil was smaller than the preoperative one both for scotopic and photopic conditions: The larger the preoperative pupil, the more it tends to reduce in the postoperative period. Analysis of the preoperative topographic pupil alone is not sufficient for a correct indication of the optical zone and total diameter of IOL to be implanted but must be correlated with biometric data. The topographic pupil, therefore, undergoes a change in magnification from the preoperative period to the postoperative period. Furthermore, the real pupil presents a modification and, in most cases, tends to be smaller postoperatively in both photopic and scotopic conditions.

Evaluation of repeatability and agreement of two optical biometers for intraocular lens power calculation.

The repeatability of two biometers (Lenstar-LS900 and Eyestar-900) to measure ocular parameters and intraocular lens (IOL) power calculation, and their agreement were evaluated. 134 eyes of 134 participants were measured thrice with each biometer. Axial length (AL), anterior chamber depth (ACD), lens thickness (LT) and keratometry (K) were evaluated. The IOL power was calculated using different formulas. The repeatability limit (RLimit), the mean differences (MD) and the limits of agreement (LoA) were calculated. The RLimits for all parameters were higher with Lenstar compared to Eyestar. RLimits were lower than 0.50 D except for Barrett Universal II (0.54 D) and Haigis (0.51 D) formulas with the Lenstar. Mean differences were lower than 0.01mm for AL, ACD and LT, and lower than 0.03 D for K. MD ranged from 0 to 0.02 D for all formulas except for Barrett and Hill. When dividing the sample into subgroups (short, normal and long eyes), the MDs were similar for the IOL power and were lower than 0.03 D, except for the Barrett and Hill formulas. Both biometers provide repeatable biometry and IOL power calculations. The LoA interval for the IOL power calculation was between 0.75 and 1.50D, which was similar among the subgroups.

Introduction and Validation of Low-Cost Ocular Biometry in Healthy and Cataractous Eyes Using a Thermally Tunable Swept-Source Laser

To introduce and validate a novel substantially lower-priced and rapid swept-source investigational optical biometer in healthy and cataractous eyes, using a thermally tuned laser diode used extensively in cell phones and data communication as an alternative swept source. Prospective accuracy, validity, and reliability analysis. A total of 60 eyes of 59 subjects (29 eyes of 29 healthy subjects and 31 eyes of 30 cataract patients) were enrolled in a prospective comparative study at the Vienna General Hospital between August 2021 and April 2023. Averaged intraocular distances were acquired in 2.5 seconds from datasets consisting of 5000 consecutive A-scans at a single position by a low-cost swept-source optical biometry (SSOB) system. Instrument repeatability was assessed via standard deviations (SDs) and coefficients of variation (CoVs) of parameters such as axial length (AL), anterior chamber depth (ACD), lens thickness (LT), and central corneal thickness (CCT). Healthy subjects and cataract patients were subsequently measured on the same day with the SSOB and a referential partial coherence interferometry (PCI) biometer (IOLMaster 500) to establish AL inter-device correlation (r) for instrument calibration. AL and ACD as shared parameters between both biometers were evaluated for their limits of agreements (LoA) using Bland-Altman analysis. Repeated measurements of AL, ACD, LT, and CCT revealed SDs of 18 µm, 12 µm, 12 µm, and 10 µm, respectively. All parameters except for CCT had a COV <1%. Except for 1 eye with white cataract, 59 eyes of 59 study participants with various degrees and types of cataract could be measured with both devices. The AL inter-device correlation was excellent (r > 0.99). The 95% LoAs between both biometers were -0.14 to 0.13 mm for AL and -0.28 to 0.25 mm for ACD. Optical biometry using a thermally tunable VCSEL swept-source light source has the potential to provide clinically relevant biometric parameters at an unprecedented 100-fold lower price point than currently used state-of-the-art optical biometers, paving the way for compact devices in remote care settings.

A Flexural Ultrasonic Transducer for Inducing Acoustic Cavitation on Material Surfaces

Abstract Purpose This paper proposes a flexural ultrasonic transducer specifically designed for surface treatment of materials with delicate surfaces such as skin by acoustic cavitation at low frequencies. The goal of this preliminary study is to assess the resonance frequencies and the output sound pressure of the proposed transducer and confirm generation of acoustic cavitation on the surface of an artificial skin phantom. Methods A transducer prototype was designed based on structural-acoustic simulation and fabricated. The proposed design employs a concave-shaped acoustic resonator with a spherical cavity, which is driven by flexural vibration of a piezoelectric ceramic disk actuator. The transducer prototype has compact dimensions of 15 mm in diameter and 8 mm in axial length, working at frequencies around flexural vibration modes of the piezoelectric disk with a thickness of 1 mm. Results The maximum sound pressure amplitude reached 125 kPa with an input voltage amplitude of 10 V at the second resonance frequency of 167 kHz, where the third axisymmetric eigenmode was excited. Despite enhancing the maximum pressure, the sound pressure outside the resonator attenuates because the near-field distance of the irradiated sound wave is smaller than the height of the resonator. This implies that the proposed method provides the cavitation effect on material surfaces, possibly minimizing the side effect of ultrasound irradiation on the underlying structure. Cavitation generation on a urethane gel surface was directly observed by using a high-speed video camera. Conclusion We confirmed that acoustic cavitation was generated and propelled to the target surface. It concludes that ultrasound irradiation using the proposed ultrasonic transducer could be a promising alternative for effective and safe ultrasound treatment of material surfaces.

Clinical Evaluation of a New Spectral-Domain Optical Coherence Tomography-Based Biometer.

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.

Longitudinal analysis of refraction and ocular biometrics in preschool children with early-onset high myopia

We investigated changes in refraction and ocular biometrics in preschool children with early-onset high myopia. Sixty eyes of 60 children with a mean follow-up time of 58.5 months were included in this study. At baseline, mean age of children was 55.6 ± 13.1 months, mean spherical equivalent (SE) was − 8.59 ± 2.66 D, and 25.64 ± 1.16 mm for axial length (AL). The total annual rate of myopic progression and axial elongation were − 0.37 ± 0.39 D/year and 0.33 ± 0.18 mm/year, respectively. During follow-up period, there was a trend toward less myopic progression and axial elongation over time. Of the total participants, 24 children (40%) were in the myopia progression group and the remaining 36 children (60%) were in the myopia stability group. In multiple linear regression analysis, baseline SE and AL were independently associated with myopic progression, while age, sex, and baseline AL-to-CR ratio were not related to myopic progression. According to the model, more myopic SE (β = − 0.186, P = 0.035) and longer AL (β = − 0.391, P = 0.008) at baseline were significantly associated with myopic progression. Myopia progression in preschoolers with high myopia tended to be relatively modest, with 60% of subjects exhibited myopic stability. Higher myopic SE, and longer AL at baseline were associated with myopic progression in preschool children with high myopia.

Comparison between IOL MASTER 500 and MYAH with vector analysis in low and mild anterior corneal astigmatism.

Evaluate the agreement between IOL Master 500 (Carl Zeiss Meditec AG, Germany) and MYAH (Topcon EU, Visia Imaging, Japan) in measuring axial length, keratometry, and anterior corneal astigmatism. Department of Biomedical and Dental Sciences and Morphofunctional Imaging, Ophthalmology Clinic, University of Messina, Messina, Italy. In this prospective study, 40 eyes (right eye 25, left eye 15) of 40 patients were included. Axial length (AL), keratometry (K1, K2), and anterior corneal astigmatism (ACA) were measured. AL, mean K (Kavg) and magnitude of ACA were compared using Bland - Altman plot analysis, parametric and nonparametric statistical analysis. The difference vector and angle of error of the ACA measured by the two devices were evaluated by vector analysis using polar diagrams. Mean and standard deviation with IOL Master and with MYAH device was for AL 24.25 ± 1.22 mm and 24.25 ± 1.22 mm (p = .99), for Kavg 42.75 ± 1.53 D and 42.85 ± 1.52 D (p = .78), for Magnitude of ACA 1.00 ± 0.58 D and 0.89 ± 0.56 D (p = .38) respectively. High correlations were found for AL (R² = 0.999), Kavg (R² = 0.996), and ACA Magnitude (R² = 0.889). Bland-Altman analysis of the two devices found high agreement and absence of proportional bias (MYAH-IOL MASTER) were found between the two assessments for AL (bias = -0.0005 mm, p = .93), Kavg (bias = 0.0955 D, p = .76) and ACA (bias = 0.11 D, p = .41). Limit of agreement (upper/lower LoA, 95%CI) were respectively +0.057/-0.058 mm for AL, + 0.29/-0.09 D for Kavg and +0.49/-0.27 D for ACA. No statistical difference was found between the x-component and y-component of the ACA vector (p > .01), the difference vector (IOL MASTER-MYAH) was +0.14 D axis 159 with an absolute mean angle of error of 7.2 ± 7.5 degree. The instruments appear to be interchangeable for measurements of AL, keratometry, and magnitude of ACA with high agreement between the two devices. Also, in the presence of low astigmatism, the two instruments give the same results in terms of ACA.

Agreement between a Spectral-Domain Ocular Coherence Tomography Biometer with a Swept-Source Ocular Coherence Tomography Biometer and an Optical Low-Coherence Reflectometry Biometer in Eyes with Cataract.

To assess the agreement between biometric parameters measured by a spectral-domain optical coherence tomography optical biometer device (Optopol Revo NX) with a validated swept-source biometer (IOLMaster 700) and a validated optical low-coherence reflectometry biometer (Lenstar LS 900), in cataract surgery candidates. In this prospective comparative study, 100 patients (100 eyes) who were eligible for cataract surgery were involved. Bland-Altman plots were used to assess agreement between devices for biometric parameters including axial length (AL), anterior chamber depth (ACD), lens thickness (LT), and central corneal thickness (CCT). AL measurements were successful in 82 eyes (82.0%) with Revo NX, in 91 eyes (91.0%) with Lenstar LS 900, and in 97 eyes (97.0%) with IOLMaster 700. When Revo NX was compared to IOL Master 700 and Lenstar LS 900, the mean differences were as follows: -0.02 ± 0.02 mm and -0.02 ± 0.03 mm (P = 0.313, P = 0.525) for AL, 0.01 ± 0.03 mm and 0.10 ± 0.03 mm (P = 0.691, P = 0.002) for ACD, -0.15 ± 0.03 mm and 0.001 ± 0.04 mm (P < 0.001, P = 0.95) for LT, and -2.29 ± 0.92 μm, and 0.73 ± 1.43 μm (P = 0.015, P = 0.612) for CCT. Three devices were highly correlated for AL, ACD, LT, and CCT (interclass correlation coefficient > 0.75). Bland-Altman plots showed a narrower 95% limit of agreement (-0.35 to 0.31) between Revo NX and IOLMaster 700 in measuring AL. Despite the higher measurement failure rate in eyes with cataract, the Revo NX showed very good agreement with the IOLMaster 700 and Lenstar LS 900 optical biometers in measuring AL, ACD, LT, and CCT. However, ACD and LT measurements cannot be considered interchangeable between these devices.

Addition of Auricular Acupoint Stimulation to 0.01% Atropine for Myopia: 12-Month Results from a Randomized Trial.

Introduction: A previous 6-month report showed that adjunctive auricular acupoint stimulation (AAS) slowed myopia progression compared with 0.01% atropine (0.01% A) alone. This 12-month report was to determine whether the antimyopic effect of AAS, when added to 0.01% A, continued beyond treatment cessation, and explore the mode of action of AAS from the accommodative response. Design and Interventions: One hundred four children were randomly assigned to either a 0.01% A group or a 0.01% A + AAS group. Participants in the 0.01% A + AAS group received AAS in addition to 0.01% A for 6 months, and then kept using 0.01% A for the following 6 months. Participants in the 0.01% A group only used 0.01% A. The primary outcome was the difference in the mean cycloplegic spherical equivalent refraction (SER) from the baseline to the 12-month visit. Secondary outcomes included axial length (AL) and accommodative lag assessments. Results: The adjusted mean change from baseline to month 12 in the SER was -0.62 D for 0.01% A and -0.46 D for 0.01% A + AAS (difference, 0.16 D; p = 0.01), with a respective mean increase of 0.37 and 0.31 mm in AL (difference, -0.05 mm; p = 0.05). For the 5D near target, there was a reduction in the accommodative lag in children receiving add-on AAS relative to 0.01% A alone at 1 and 6 months (both p = 0.002). Conclusions: AAS treatment produced additional benefits >0.01% A in slowing myopia progression over the 12-month period, where the efficacy was sustained after the cessation of AAS. An effect of add-on AAS on reducing accommodative lag in response to 5D stimulus was found, but its role in mediating therapeutic response remained unclear. Chinese Clinical Trial Registry, ChiCTR1900021316.

Prevalence and Characteristics of Myopia in Adult Rhesus Macaques in Southwest China.

To investigate the prevalence of myopia in a large cohort of adult rhesus macaques at Yunnan Province in southwest China and describe the characteristics of myopic rhesus macaque eyes. A total of 219 rhesus macaques 14.07 ± 2.72 years old (range, 8-21) were randomly recruited for this study. We performed fundus photography and measurements of cycloplegic refractive error (RE) and axial length (AL) on macaques. A total of 429 eyes of 219 macaques were examined. The median RE was -1.25 diopters (D), and the median AL was 18.69 mm. The prevalence of myopia was 62.47%, and one-third of the myopic eyes were highly myopic. The presence of fundus tessellations was higher in myopic eyes than non-myopic eyes (42.54% vs. 6.21%). The cutoff value for the presence of tessellations was -3.52 D for RE and 19.38 mm for AL. In myopic eyes, there were significant differences between grade 1 and grade 3 fundus tessellations on RE (-5.57 ± 2.97 D vs. -8.13 ± 3.51 D) and AL (19.66 ± 0.55 mm vs. 20.60 ± 1.06 mm). Beta-peripapillary atrophy (β-PPA) was found in 48.10% of myopic eyes and 6.83% of non-myopic eyes. The presence of β-PPA is associated with the presence of fundus tessellations, AL, and RE. The presence of β-PPA was higher in grade 3 than grade 1 fundus tessellations (94.4% vs. 76%). More than half of adult rhesus macaques in southwest China are myopic, and one-third of the myopic ones are highly myopic. Similar to humans, tessellated fundi and β-PPA are the characteristic signs of myopic rhesus macaques. Adult rhesus macaques are optimal animal models for research on the pathogenesis of myopia. This study not only provides a reference for the refractive state and AL in myopic rhesus macaques but also indicates that adult rhesus macaques with spontaneous myopia are optimal animal models for research on the pathogenesis of myopia.

Effect of atropine 0.01% on myopia control in children aged 6-13 years during the 2022 lockdown in Shanghai.

To compare the myopic progression in children treated with 0. 01% atropine and those who discontinued atropine during the 2022-home quarantine in Shanghai. In this retrospective study, children aged 6-13 years with follow-up visits before (between January 2022 and February 2022) and after the lockdown (between July 2022 and August 2022) were included. Cycloplegic refraction and axial length (AL) were measured at both visits. The atropine group had continuous medication during the lockdown while the control group discontinued. The 0.01% atropine eyedrops were administered daily before bedtime. The types of spectacle lens were recorded: single vision (SV) spectacles or defocus incorporated multiple segments lenses (DIMS). In total, 41 children (81 eyes) in the atropine group and 32 children (64 eyes) in the control group were enrolled. No significant difference was found in the demographic characteristics, spherical diopter, spherical equivalent (SE), AL, and follow-up time between the two groups before the lockdown in 2022 (all p > 0.1). After the home confinement, a greater myopia progression was observed in the control group (-0.46 ± 0.42 D) compared to atropine group (-0.26 ± 0.37 D; p = 0.0023). Axial elongation was also longer in the control group than that in children sustained with atropine (0.21 ± 0.17 vs. 0.13 ± 0.15 mm, p = 0.0035). Moreover, there was no significant change of spherical diopter and SE during lockdown in the atropine + DIMS combined subgroup (0.03 ± 0.033 D for spherical diopter, p = 0.7261 and 0.08 ± 0.27 D for SE, p = 0.2042, respectively). However, significant myopic shift was observed in the atropine + SV subgroup during the quarantine time (-0.31 ± 0.39 D for SE and 0.15 ± 0.16 mm for AL, both p < 0.001). Children treated with 0.01% atropine had slower myopia progression during the lockdown period in Shanghai compared with children discontinued. Moreover, the effect of atropine on myopic prevention can be strengthened with DIMS lenses.

Clinical Validation of a New Optical Biometer for Myopia Control in a Healthy Pediatric Population.

To assess the clinical validation of the Myah device in a pediatric population by evaluating the repeatability of biometric evaluations and analyzing its agreement with the Myopia Master system. A total of 51 children (51 eyes) were enrolled. Repeated measurements of flat (K1) and steep (K2) corneal radius, white-to-white (WTW) distance and axial length (AL) were performed with the Myah device. The same parameters were obtained from a subgroup (30 eyes) with the Myopia Master for the agreement analysis. The repeatability was assessed using the intrasubject standard deviation (Sw) and the intraclass correlation coefficient (ICC). The agreement was analyzed using the Bland−Altman method and the paired Student t-test. The Sw was 0.018 D, 0.021 D, 0.071 mm and 0.017 mm for K1, K2, WTW and AL, respectively (ICC ≥ 0.971). The mean difference and limits of agreement when comparing instruments were −0.013 (−0.102/0.077) for K1 (p = 0.16), −0.058 (−0.127/0.012) for K2 (p < 0.001), 0.151 (−0.370/0.673) for WTW (p < 0.001) and 0.030 (−0.091/0.151) for AL (p = 0.009). In conclusion, the Myah device provides consistent measurements of corneal radius, WTW distance and AL in a healthy pediatric population, validating their usefulness in clinical practice. These measurements could be used interchangeably with those provided by the Myopia Master device, although with some caution.

Short-term effect of orthokeratology lens wear on choroidal blood flow in children with low and moderate myopia

We investigated changes in choroidal vascularity and choriocapillaris blood perfusion during orthokeratology (Ortho-K) lens wear. Sixty-two children with low to moderate myopia were enrolled. The Ortho-K group (n = 42) continuously wore Ortho-K lenses for 3 months, and the controls (n = 20) wore single-vision distance spectacles. All of the patients were instructed to return for follow-up visits after 1 day, 1 week and 1 month and 3 months of treatment. The subfoveal choroidal thickness (SFChT), choroidal vascularity [including the total choroidal area, luminal area, stromal area, and choroidal vascularity index (CVI)] and percentage of choriocapillaris flow voids (FV%) were determined with a Cirrus HD-OCT instrument. Additionally, ocular parameters were measured. In the Ortho-K group, the SFChT significantly increased by 12.61 ± 5.90 μm, the CVI was significantly increased by 2.99 ± 2.07% and 3.01 ± 2.32% on the horizontal and vertical scans respectively, and the FV% was significantly decreased by 0.89 ± 0.34% from baseline at the 1-week visit (all p < 0.001). The choroidal parameters remained unchanged at the 1-month and 3-month follow-ups with respect to the 1-week follow-up. In the control group, the choroidal parameters did not change significantly at 1 month (all p > 0.05). At the 3-month visit, the changes in the axial length (AL) and vitreous chamber depth (VCD) were significantly greater in the control group than in the Ortho-K group (0.14 ± 0.23 and 0.03 ± 0.05 mm in AL, 0.15 ± 0.23 and 0.06 ± 0.03 mm in VCD respectively). Our longitudinal study showed several choroidal parameter changes in the early stage in Ortho-K lens wearers with low to moderate myopia, and these changes persisted over 3 months. We speculate that Ortho-K lenses regulate choroidal thickness and blood perfusion, affecting myopia development.

Longitudinal Changes and Predictive Value of Choroidal Thickness for Myopia Control after Repeated Low-Level Red-Light Therapy

To evaluate longitudinal changes in macular choroidal thickness (mCT) in myopic children treated for 1 year with repeated low-level red-light (RLRL) therapy and their predictive value for treatment efficacy on myopia control. A secondary analysis of data from a multicenter, randomized controlled trial (RCT; NCT04073238). Myopic children aged 8-13 years who participated in the RCT at 2 of 5 sites where mCT measurements were available. Repeated low-level red-light therapy was delivered using a home-use desktop light device that emitted red-light at 650 nm. Choroidal thickness was measured by SS-OCT at baseline and 1-, 3-, 6-, and 12-month follow-ups. Visual acuity, axial length (AL), cycloplegic spherical equivalent refraction (SER), and treatment compliance were measured. Changes in mCT at 1, 3, 6, and 12 months relative to baseline, and their associations with myopia control. A total of 120 children were included in the analysis (RLRL group: n= 60; single-vision spectacle [SVS] group: n= 60). Baseline characteristics were well balanced between the 2 groups. In the RLRL group, changes in mCT from baseline remained positive over 1 year, with a maximal increase of 14.755 μm at 1 month and gradually decreasing from 5.286 μm at 3 months to 1.543 μm at 6 months, finally reaching 9.089 μm at 12 months. In the SVS group, mCT thinning was observed, with changes from baseline of -1.111, -8.212, -10.190, and -10.407 μm at 1, 3, 6, and 12 months, respectively. Satisfactory myopia control was defined as annual progression rates of less than 0, 0.05, or 0.10 mm for AL and less than 0, 0.25, or 0.50 diopters for SER. Models that included mCT changes at 3 months alone had acceptable predictive discrimination of satisfactory myopia control over 12 months, with areas under the curve of 0.710-0.786. The predictive performance of the models did not significantly improve after adding age, gender, and baseline AL or SER. This analysis from a multicenter RCT found RLRL induced sustained choroidal thickening over the full course of treatment. Macular choroidal thickness changes at 3 months alone can predict 12-month myopia control efficacy with reasonable accuracy. Proprietary or commercial disclosure may be found after the references.

Ocular biometric parameters of mild hyperopia to mild myopia children aged 6-14 years from Wenzhou optometry center: A cross-sectional study.

IntroductionMyopia is the most common visual disorder in school-aged children and adolescents worldwide. This study aimed to explore the ocular biometric characteristics of children aged 6–14 years from the Wenzhou optometry center and to determine the relationship between spherical equivalent refraction (SER) and macular pigment optical density (MPOD).Subjects and methodsParticipants underwent a full-scale ophthalmic examination anteriorly and posteriorly. Relevant parameters were documented, such as axial length (AL), anterior chamber depth (ACD), SER and lens thickness (LT), corneal curvature radius (CCR), and MPOD. Lens power (LP) was calculated using Bennett’s formula. Shapiro–Wilk tests and histograms were used to check the normality of the distribution of refractive and ocular biometric parameters. Scatter diagrams were adopted to analyze the relationships between refraction and parameters of ocular biometry. Multiple linear regression models were employed to fit the associated factors of AL, AL/CCR, and LP.ResultsA total of 902 mild hyperopia to mild myopia (+3.00 D ≤ SE ≤ −3.00 D) children aged 6–14 years were included. The mean age of participants was 10.03 ± 2.47 years, and the prevalence of mild hyperopia, emmetropia, and myopia was 5.65, 27.05, and 67.30%, respectively. The prevalence of mild myopia increased from 30.53% at 6 years of age to 93.62% at 14 years of age. Overall, AL, ACD, and AL/CCR increased, but LP declined from 6 to 14 years of age, whereas CCR and MPOD remained stable. An increase of 1 mm in AL was associated with −0.69 D of myopic change. A unit increase in AL/CCR was associated with −7.87 D in SER. As for the SER variance, AL explained 30.5% and AL/CCR explained 51.1%, whereas AL/CCR and LP accounted for 59.2%.DiscussionIn this work, we have studied the distributions of ocular biometric characteristics of mild hyperopia to mild myopia children from the perspective of an optometry center rather than a sampling survey. In addition, we found that children from the optometry center had a slower progression toward myopia than those from previous sampling surveys, which was an informative finding for future myopia prevention. In addition, we have made a correlation analysis between the macular pigment optical density and spherical equivalent refraction. Though, no correlation was found.

Biometry and intraocular power calculation using a swept-source optical coherence tomography: A repeatability and agreement study.

To evaluate the repeatability of biometry and intraocular lens (IOL) power using Galilei G6 and to determine the agreement of its measurements with those of IOL Master 700 and IOL Master 500. Hundred mature cataract eyes were examined twice with Galilei G6 and the results were compared with those of other two devices. Axial length (AL), minimum (K1), maximum (K2), and mean keratometry, anterior chamber depth (ACD), white-to-white (WTW) diameter, lens thickness (LT), and the calculated IOL power were the studied parameters. The correlation coefficient, within-subject standard deviation (Sw), Bland-Altman method, and 95% limits of agreement (LoA) were used for statistical analysis. The intraclass correlation coefficient (ICC) was above 0.9 for all indices, and the LoA ranged from a minimum of 0.08 mm for AL to a maximum of 0.50 D for K1. Sw also ranged between a minimum of 0.02 for AL, ACD, and WTW and a maximum of 0.13 for K1. In the Galilei G6-IOL Master 700 pair, the narrowest and widest LoA were calculated for AL (0.07 mm) and K2 (0.49 D), respectively. In the Galilei G6-IOL Master 500 pair, the narrowest and widest widths of LoA were calculated for AL (0.17 mm) and K2 (0.92 D), respectively. In the first pair, the LoA of IOL power (0.57 D) were the best for Haigis formula and in the second pair, the best agreement (LoA: 0.35 D) was observed for Holladay-1. Galilei G6 provided repeatable biometric measurements. The agreement between biometry and IOL power calculation was better in the Galilei G6-IOL Master 700 pair compared to the Galilei G6-IOL Master 500.

Sealing mechanism of large size and large deformation rubber cylinder for pipeline intelligent plugging robot under multiple factors

Large-volume rubber cylinder is a core component of pipeline intelligent plugging robot (PIPR). It is used for plug pipe section during pipeline rerouting, maintenance, and repair operations to prevent large-area leakage of pipeline oil and gas. This paper studies the sealing mechanism of large size and large deformation rubber cylinder of the PIPR under the influence of different rubber materials, axial length, radial length and inclined angle. Based on large deformation characteristics of rubber material, the theoretical mechanics of rubber cylinder were deduced and analyzed. Constitutive test of rubber material was carried out, and constitutive relationship parameters of rubber material were obtained. The finite element simulation model of rubber cylinder sealing mechanism analysis is established, and the influence of various system parameters and working conditions on the model is considered. In addition, visible indoor tests were established to verify the simulation model. It showed that stress concentrated on the apex and shoulder inside the rubber cylinder directly affected the deformation damage of rubber cylinder. After comparing the analysis result of the sealing effect of rubber cylinder under various parameters, it is concluded that the optimal rubber cylinder structure is 180 mm in axial length, 55 mm in radial thickness, 28° inclination angle, and hardness of rubber material is 85HA. This study provides a reference for the optimization design of rubber cylinder of PIPR. It has important engineering significance for the successful implementation of the plugging operation.

Predicted Refraction Variability Due to Reliability of Nine Optical Biometers for Intraocular Lens Power Calculation.

To assess the influence of reliability (repeatability and reproducibility) of eye parameter measurements on the prediction refraction by using the outcomes of nine optical biometers reported in the literature. A search was conducted in PubMed focused on the outcomes from original studies regarding reliability. The mean population of within-subject standard deviation (Sw) was estimated from the mean samples reported in the included studies. Repeatability coefficients (R) for the mean population were computed as 2.77 × Sw. The influence of reliability on the prediction refraction for eye biometric parameters, such as mean corneal power in diopters (D) (Km), anterior chamber depth (ACD), and axial length (AXL), were evaluated using a thick lens formula. The lens thickness (LT), central corneal thickness (CCT), and white-to-white (WTW) distance were also evaluated. The repeatability of optical biometers ranged from 0.19 to 0.42 D for Km, from 0.04 to 0.13 mm for ACD, from 0.03 to 0.22 mm for AXL, from 0.06 to 0.13 mm for LT, from 5.5 to 17.7 µm for CCT, and from 0.18 to 0.48 mm for WTW distance. Total prediction refraction due to repeatability ranged from 0.21 to 0.61 D, with Km the variable that caused the major part of total prediction refraction variability, followed by AXL and ACD. Reproducibility for the evaluated variables was generally inside the repeatability ranges. New optical biometers are equally reliable as earlier technologies. Special attention should be focused on Km and AXL, which explain the major part of prediction refraction variability. [J Refract Surg. 2022;38(2):120-127.].

RELATIONSHIP BETWEEN MYOPIC CHOROIDAL NEOVASCULARIZATION ACTIVITY AND PERFORATING SCLERAL VESSELS IN HIGH MYOPIA.

To study perforating scleral vessels (PSVs) in patients with high myopia using swept-source optical coherence tomography and to determine their relationship with myopic choroidal neovascularization (mCNV) and its activity. Retrospective analysis of patients with high myopia (≥-6 D or ≥26 mm of axial length) using multimodal imaging. The presence of PSVs and mCNV was assessed using swept-source optical coherence tomography images (TRITON; Topcon Corporation, Japan). Five hundred sixty-four eyes from 297 highly myopic patients were studied. One hundred fifty-five eyes (27.5%) showed signs of mCNV while PSVs were found in 500 eyes (88.6%). Perforating scleral vessels were found in 93.5% (145/155) of eyes with mCNV, and they were under or in contact with the mCNV in 80.6% (117/145). The mean number of intravitreal injections received by patients with mCNV was 4.06 ± 4.17 along 66.9 ± 4.1 months of follow-up. The number of injections per year was 1.32 ± 1.56, the mean number of relapses was 1.11 ± 1.83, and the mean number of relapses per year was 0.25 ± 0.41. Perforating scleral vessels are more common among highly myopic patients suffering from neovascular complications. Myopic CNV complexes that are coincident with PSVs on optical coherence tomography show higher rates of activity, needing more injections to control them and being more prone to relapses.

Comparison of biometric methods in young children with congenital cataracts in their eyes

BACKGROUND: Relevant keratometric and biometric indicators are necessary for intraocular lens (IOL) power calculation, which is difficult to verify in young children.&#x0D; AIM: Evaluation of the accuracy of various ultrasound methods and optical biometry for axial length measurement in young children with congenital cataracts.&#x0D; MATERIAL AND METHODS: Forty-six children (74 eyes) with congenital cataracts (43 eyes) and pseudophakia (31 eyes) at the age of 6 months to 4 years were examined. Various methods measured the axial length: ultrasound A-scan under general anesthesia by US-4000, ultrasound B-scan without general anesthesia by Voluson E8, and optical biometry by AL-Scan in cases of transparent optics.&#x0D; RESULTS: The greater axial length difference was observed between A-scan and optical biometry (less by 0,78 mm) than between B-scan and optical biometry (more by 0,27 mm). The median axial length difference between A-scan and B-scan was equal for infants and young children with congenital cataracts (0,525 mm and 0,535 mm, respectively).&#x0D; CONCLUSION: Axial length should be measured by different methods in young children with their further comparison to obtaining more accurate biometric indicators for IOL power calculation. The decrease of 12 mm in axial length, which occurs during the A-scan, can lead to errors in the IOL calculation of 36 diopters and unplanned refraction in the long-term period.