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The Effect of Atropine on Human Global Flash mfERG Responses to Retinal Defocus
摘要： PURPOSE. To investigate the action of atropine on global flash multifocal electroretinogram (gmfERG) responses to retinal defocus. METHOD. gmfERG recordings were made monocularly in 19 healthy adults under three lens-imposed defocus conditions (2 diopters myopic, 2 diopters hyperopic, and no defocus) before and 24 hours after instillation of 1 drop of 0.1% atropine. Signals reflecting activity from the outer and inner retina (direct [DC] and induced [IC] components respectively) were analyzed. Responses were grouped into either a central (0°–6°) or peripheral (6°–24°) retinal zone. The gmfERG responses were compared relative to the no defocus, no atropine condition. RESULTS. Within the central zone, atropine had no effect on the amplitudes and peak times of DC or IC responses to defocus. For IC responses in the peripheral zone, there was a significant interaction effect of atropine and defocus (F2,36 = 6.050, P = 0.011) with greater post-atropine amplitudes under myopic defocus (mean increase = 15.5%, 95% confidence interval [CI] = 5.6%–25.4%, P = 0.004). Atropine also had a significant main effect of increasing IC peak times (F1,18 = 9.722, P = 0.006). For DC responses, atropine had a significant main effect of increasing DC amplitudes (F1,18 = 7.821, P = 0.012) and peak times (F1,18 = 15.406, P = 0.001) regardless of sign of defocus. CONCLUSIONS. Our results imply that atropine acts in the inner layers of the peripheral retina to affect neuronal responses to myopic defocus, raising the possibility that atropine may potentiate the effects of myopic defocus in inhibiting eye growth.
关键词： atropine,retina,hyperopic defocus,electrophysiology,myopic defocus
更新于2025-09-23 15:22:29
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Peripheral Defocus of the Monkey Crystalline Lens With Accommodation in a Lens Stretcher
摘要： PURPOSE. To characterize the peripheral defocus of the monkey crystalline lens and its changes with accommodation. METHODS. Experiments were performed on 15 lenses from 11 cynomolgus monkey eyes (age: 3.8–12.4 years, postmortem time: 33.5 6 15.3 hours). The tissue was mounted in a motorized lens stretcher to allow for measurements of the lens in the accommodated (unstretched) and unaccommodated (stretched) states. A custom-built combined laser ray tracing and optical coherence tomography system was used to measure the paraxial on-axis and off-axis lens power for delivery angles ranging from (cid:2)208 to t208 (in air). For each delivery angle, peripheral defocus was quanti?ed as the difference between paraxial off-axis and on-axis power. The peripheral defocus of the lens was compared in the unstretched and stretched states. RESULTS. On average, the paraxial on-axis lens power was 52.0 6 3.4 D in the unstretched state and 32.5 6 5.1 D in the stretched state. In both states, the lens power increased with increasing delivery angle. From 08 to t208, the relative peripheral lens power increased by 10.7 6 1.4 D in the unstretched state and 7.5 6 1.6 D in the stretched state. The change in ?eld curvature with accommodation was statistically signi?cant (P < 0.001), indicating that the unstretched (accommodated) lens has greater curvature or relative peripheral power. CONCLUSIONS. The cynomolgus monkey lens has signi?cant accommodation-dependent curvature of ?eld, which suggests that the lens asserts a signi?cant contribution to the peripheral optical performance of the eye that also varies with the state of accommodation.
关键词： crystalline lens,accommodation,laser ray tracing,peripheral defocus
更新于2025-09-23 15:22:29
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A Fast 2D-to-3D Image Conversion System based on Depth from Defocus
摘要： Blur variation in 2D images caused by camera focus provides a suitable cue for depth estimation. Depth from defocus (DFD) technique calculates the blur amount in images considering that the depth and defocus blur are related to each other. Conventional DFD methods use only defocused images that might yield low-quality depth data and reconstructed infocused image. In this article, a new DFD methodology based on infocused and defocused images is proposed in which using an infocused image can solve the quality degradation problems. In this method, Subbarao’s DFD is combined with a novel edge blur estimation method to obtain an improved depth map. In addition, a saliency map mitigates the ill-posed problem of depth estimation in homogeneous regions. For real-time full high de?nition (Full-HD) image processing, a parallelized graphics processing unit (GPU) implementation is devised to improve execution speed.
关键词： saliency map,GPU implementation,edge blur estimation,Depth from defocus,2D-to-3D conversion
更新于2025-09-23 15:21:01
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Sequential Evolution of Colored Copper Surface Irradiated by Defocused Femtosecond Laser
摘要： An effective method for the fabrication of sequential colors on copper by adjusting femtosecond laser defocusing distance is proposed. The sequential evolution tendency of induced colors by adjusting laser defocusing distance is carried out. Corresponding mechanisms are revealed by different kinds of surface structures. Angle-resolved spectrum and simultaneously derived hydrophobicity are also investigated.
关键词： hydrophobicity,femtosecond laser,sequential colors,defocus-dependent
更新于2025-09-23 15:19:57
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Evaluating the myopia progression control efficacy of defocus incorporated multiple segments (DIMS) lenses and Apollo progressive addition spectacle lenses (PALs) in 6- to 12-year-old children: study protocol for a prospective, multicenter, randomized controlled trial
摘要： Background: Myopia is increasing in prevalence and is currently recognized as a significant public health issue worldwide, particularly in China. Once myopia develops, appropriate clinical interventions need to be prescribed to slow its progression. Currently, several publications indicate that myopic defocus (MD) retards eye growth and myopia progression. However, no clinical trials have compared the outcomes of different MD spectacle lenses in the same observational group, especially in mainland China. The aim of the present study is to compare the myopia control efficiency of two different MD spectacle lenses: defocus incorporated multiple segments (DIMS) lenses and Apollo progressive addition lenses (PALs). Methods: The trial is designed as a 3-year, prospective, randomized, multicenter clinical trial of schoolchildren treated with DIMS lenses and PALs. A total of 600 Chinese primary school children aged 6–12 years will be recruited, and each group is intended to include 300 subjects. The inclusion criteria are myopia between ? 1.00 and ? 5.00 diopters and astigmatism ≤ 1.50 diopters. The follow-up time points will be 1 month (m), 3 m, 6 m, 12 m, 18 m, 24 m, 30 m, and 36 m. The primary outcome will be determined by the difference between the two groups in cycloplegic spherical equivalent refraction between baseline and the last follow-up visit. The secondary outcome is the axial length, and the exploratory outcomes include ocular biometric measures, peripheral refraction, binocular vision, accommodation, compliance, and the results of questionnaires related to wearing experiences.
关键词： Multicenter,Trial,Spectacle lens,Prospective,Myopic defocus,Myopia,Progression
更新于2025-09-23 15:19:57
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4-aperture differential image motion monitor as a new approach for estimating atmospheric turbulence parameters
摘要： The present study aims to evaluate the possibility of simultaneous measurements of Fried parameter and atmospheric Zernike defocus by measuring defocus aberration with 4-aperture differential image motion monitor (DIMM) for a portable telescope. Based on the results, a relation was observed between the variances of the defocus aberration (4-aperture defocus) and Fried parameter for G-tilt and Z-tilt methods. In addition, the variance of the 4-aperture defocus was compared with those of the Zernike defocus and the conventional DIMM and the results indicated a linear relationship. Based on the telescope and 4-aperture specifications, the variance of the 4-aperture defocus was converted into the Zernike defocus or the DIMM variances. Finally, the ability of estimating atmospheric coherence time by measuring the variance of the Zernike defocus velocity or the sum of the variances of two astigmatisms velocities with 4-aperture DIMM was investigated.
关键词： atmospheric defocus aberration,atmospheric turbulence parameters,Optical turbulence
更新于2025-09-19 17:15:36
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The effect of the optical design of multifocal contact lenses on choroidal thickness
摘要： Studies have found reduced myopia progression with multifocal contact lenses, albeit with an unclear mechanism behind their protective effect. It is hypothesized that the induced myopic defocus of the addition zones of the multifocal contact lenses leads to choroidal thickening and therefore inhibits eye growth. In the current study, the effect of the optical design of multifocal contact lenses on choroidal thickness was investigated. Eighteen myopic participants wore four different contact lenses ((1) single-vision lenses corrected for distance, (2) single-vision lenses with +2.50 D full-field defocus, (3) Multifocal center-distance design, (4) Multifocal center-near design, both with addition power +2.50 D) for 30 min each on their right eye. Automated analysis of the macular choroidal thickness and vitreous chamber depth were performed before and after the wear of each of the contact lenses. Peripheral refraction profiles in primary gaze were obtained using eccentric photorefraction prior to contact lens wear. Choroidal thickness and vitreous chamber depth showed no significant differences to baseline with any of the contact lenses (all p > 0.05). Choroidal thickness increased by +2.1 ± 11.1 μm with the Multifocal center-distance design, by +2.0 ± 11.1 μm with the full-field defocus lens, followed by the Multifocal center-near design with +1.6 ± 11.3 μm and the single-vision contact lens correcting for distance with +0.9 ± 11.2 μm. Multifocal contact lenses have no significant influence on choroidal thickness after short-term wear. Therefore, changes in choroidal thickness might not be the main contributor to the protective effect of multifocal contact lenses in myopia control.
关键词： multifocal contact lenses,choroidal thickness,optical design,defocus,myopia control
更新于2025-09-10 09:29:36
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Characterization of optical performance with defocusing curve: Analysis of two refractive intraocular lens models with high and medium addition
摘要： Purpose: To characterize the optical performance of two models of refractive bifocal intraocular lenses, with medium and high addition, using defocus curves. Methods: 20 eyes from 20 subjects were included in this study. 10 eyes underwent cataract surgery with an implant of a medium addition refractive bifocal intraocular lens (IOL) (Lentis LS-313 MF20) and the other 10 eyes underwent cataract surgery with an implant of a high addition refractive bifocal IOL (Lentis LS-313 MF30). Six weeks after surgery, subjective refraction and defocus curve were made. Results: Mean final residual refraction in spherical equivalent was +0.10 ± 0.07 D in the LS-313MF30 group and +0.12 ± 0.10 D in the LS-313MF20 group. Defocus curve showed a different optical performance in intermediate/near distance depending on the IOL model. The medium addition IOL provided good visual acuity (VA) at far and intermediate distance up to 50 cms, and the high addition IOL provided better VA in near distance up to 25 cms. Conclusions: The high addition intraocular lens provides better visual acuity in the spatial range from infinity to the point close to 25 cm. The medium addition intraocular lens provides excellent visual acuity in far and intermediate vision. The defocus curve seems to be a valid and reproducible tool for evaluating the optical behavior of multifocal sector refractive lenses.
关键词： High addition,Intraocular lens,Defocus curve,Bifocal,Medium addition
更新于2025-09-10 09:29:36
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A Local Metric for Defocus Blur Detection Based on CNN Feature Learning
摘要： Defocus blur detection is an important and challenging task in computer vision and digital imaging fields. Previous work on defocus blur detection has put a lot of effort into designing local sharpness metric maps. This paper presents a simple yet effective method to automatically obtain the local metric map for defocus blur detection, which based on the feature learning of multiple convolutional neural networks (ConvNets). The ConvNets automatically learn the most locally relevant features at the super-pixel level of the image in a supervised manner. By extracting convolution kernels from the trained neural network structures and processing it with principal component analysis, we can automatically obtain the local sharpness metric by reshaping the principal component vector. Meanwhile, an effective iterative updating mechanism is proposed to refine the defocus blur detection result from coarse to fine by exploiting the intrinsic peculiarity of the hyperbolic tangent function. The experimental results demonstrate that our proposed method consistently performed better than previous state-of-the-art methods.
关键词： Defocus blur,PCA,local sharpness metric,ConvNets,feature learning
更新于2025-09-10 09:29:36
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An effective method for camera calibration in defocus scene with circular gratings
摘要： Conventional camera calibrations with circular patterns always require sharp target images and thus fail if the images are blurred. In this paper, we present an effective calibration approach using three circular gratings, which can be employed in defocus scene. Rather than using the concentric circles as the targets, the proposed method utilizes circular gratings generated by phase-shifting methods. The intrinsic parameters of the camera can be obtained with the images of circular points, and it works even if the camera is out-of-focus. Numerical simulation and real data experiments have been carried out to validate the method. And the results show that our method can calibrate the camera effectively even under severe defocus. Moreover, the entire process requires no metric measurement of the test pattern, which is very flexible to implement and suitable for people who are not familiar with computer vision.
关键词： Phase-shifting,Camera calibration,Defocus,Concentric circles
更新于2025-09-09 09:28:46