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Visual Quality After Femtosecond Laser Small Incision Lenticule Extraction
摘要： Femtosecond laser small incision lenticule extraction (SMILE) is a newly developed form of “flapless” corneal refractive surgery with all-in-one technology. Femtosecond laser SMILE is increasingly attractive for both doctors and patients because it is minimally invasive and does not require a flap to be lifted during surgery. It exhibits many advantages in terms of morphology, biomechanical effects, corneal wound healing, and nerve rehabilitation. However, visual quality assessment after refractive surgeries is just as important as these advantages and correlates with patient satisfaction. Evaluation indexes for visual quality include visual acuity, contrast sensitivity, aberration, intraocular scattering, and so on. This paper reviewed visual quality and patient satisfaction after SMILE for myopia correction.
关键词： aberration,contrast sensitivity,lenticule extraction,myopia,femtosecond laser,scattering,small incision,visual quality
更新于2025-09-11 14:15:04
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The Field of View, the Field of Resolution, and the Field of Contrast Sensitivity
摘要： The Field of View (FoV), the Field of Resolution, and the Field of Contrast Sensitivity describe three progressively more detailed descriptions of human spatial sensitivity at angles relative to fixation. The FoV is the range of visual angles that can be sensed by an eye. The Field of Resolution describes the highest spatial frequency that can be sensed at each angle. The Field of Contrast Sensitivity describes contrast sensitivity at each spatial frequency, at each visual angle. These three concepts can be unified with the aid of the Pyramid of Visibility, a simplified model of contrast sensitivity as a function of spatial frequency, temporal frequency, and luminance or retinal illuminance. This unified model provides simple yet powerful observations about the Field of Contrast Sensitivity. I have fit this model to a number of published measurements of peripheral contrast sensitivity. This allows us to test the validity of the model, and to estimate its parameters. Although the model is a simplification, I believe it provides an invaluable guide in a range of applications in visual technology.
关键词： Pyramid of Visibility,retinal illuminance,Field of Contrast Sensitivity,spatial frequency,luminance,Field of Resolution,Field of View,contrast sensitivity,temporal frequency
更新于2025-09-10 09:29:36
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Radiographic Evaluation of Gas Tungsten Arc Welded Joints Used in Nuclear Applications by X- and Gamma-rays
摘要： Radiographic inspection of welds in non-standard industrial components often require development of new techniques or modifications to existing ones on the basis of geometry, size, sensitivity requirements, accessibility, nature of defects expected etc. This paper proposes a modified Double Wall Technique (DWT) for evaluation of a weldment in cylindrical component fabricated by Gas Tungsten Arc Welding (GTAW) for use in nuclear facility. The technique has been validated by experimental measurements using film-based gamma radiography with Iridium-192 source. The study also includes evaluation of other joints of the component by X-ray computed radiography (CR) modality. The experimental results show that the proposed technique has met ASME Section V code requirements and yields contrast sensitivity of about 2%.
关键词： gamma radiography,X-ray Computed Radiography (CR),contrast sensitivity,Double Wall Technique (DWT),Gas Tungsten Arc Welding (GTAW)
更新于2025-09-10 09:29:36
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Full-Reference Image Quality Assessment by Combining Features in Spatial and Frequency Domains
摘要： Objective employs mathematical and computational theory to objectively assess the quality of output images based on the human visual system (HVS). In this paper, a novel approach based on multifeature extraction in the spatial and frequency domains is proposed. We combine the gradient magnitude and phase congruency maps to generate a local structure (LS) map, which can perceive local structural distortions. The LS matches well with HVS and highlights differences with details. For complex visual information, such as texture and contrast sensitivity, we deploy the log-Gabor filter, and spatial frequency, respectively, to effectively capture their variations. Moreover, we employ the random forest (RF) to overcome the limitations of existing pooling methods. Compared with support vector regression, RF can obtain better prediction results. Extensive experimental results on the five benchmark databases indicate that the proposed method precedes all the state-of-the-art image quality assessment metrics in terms of prediction accuracy. In addition, the proposed method is in compliance with the subjective evaluations.
关键词： log-Gabor filter,random forest (RF),contrast sensitivity function (CSF),full-reference,Image quality assessment (IQA)
更新于2025-09-09 09:28:46
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Neutral-Density Filters Are Not a Patch on Occlusion
摘要： A number of studies over the past decade have shown that a neutral-density (ND) ?lter placed in front of an eye of a healthy adult can mimic certain aspects of amblyopic function, particularly those related to contrast sensitivity loss, binocular summation, and interocular imbalance. Furthermore, wearing a ND ?lter over the fellow eye of an amblyope can rebalance the dominance and, in some cases, recover stereoscopic function. Neutral-density ?lters reduce the mean luminance of scenes without perturbing the physical contrast. However, the contrast gain of visual neurons from retinal to cortex is dependent on the mean luminance. What this means is that the visual systems’ contrast sensitivity is modulated by the mean luminance even though the physical contrast is itself unaltered. Because it has recently been demonstrated that a rebalancing of the contrast between the eyes of amblyopes can lead to a restoration of binocular function, one might reasonably conclude that the rebalancing effects reported in amblyopes as a result of changes in interocular mean luminance (i.e., use of ND ?lters) are simply due to indirect changes in contrast sensitivity. This leads to the expectation that occlusion with a ND ?lter might provide a way to treat amblyopia and recover binocular function based on the contrast rebalancing principle. This could provide a simple alternative to that of lens blur if occlusion was the preferred approach over the alternative of contrast rebalancing using the dichoptic videogame training.
关键词： binocular function,amblyopia,ocular dominance,contrast sensitivity,neutral-density filters
更新于2025-09-09 09:28:46
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Macular Inner Retinal Layer Thickness in Relation to Photopic and Mesopic Contrast Sensitivity in Healthy Young and Older Subjects
摘要： PURPOSE. To examine relationships between the thicknesses of ganglion cell (GC)-related macular layers and central photopic or mesopic contrast sensitivity (CS) in healthy eyes. METHODS. Measurements were made in 38 young and 38 older healthy individuals. Total, inner, layer (IRL) thicknesses were measured in the macula region through and outer retinal spectral-domain optical coherence tomography (SD-OCT) across three sub?elds, or rings, centered at the fovea: central foveal, pericentral, and peripheral. Ganglion cell complex and circumpapillary retinal nerve ?ber layer thicknesses were also measured. Low-spatial-frequency CS for gratings presented at the central 108 visual ?eld were measured through computerized psychophysical tests under photopic and mesopic conditions. Relationships were examined by uni- and multivariate regression analysis. RESULTS. Peripheral IRL thickness emerged as the only independent predictor of photopic CS (P ? 0.001) in the young group and of photopic (P ? 0.026) and mesopic CS (P ? 0.001) in the older group. The slopes of regression lines used to predict CS from peripheral IRL thickness were signi?cantly different for pair-wise comparisons of both photopic CS and age group (P ? 0.0001) and mesopic CS (P ? 0.0001) and age group. These models explained 37% of the variability in photopic CS and 36% of the variability in mesopic CS. CONCLUSIONS. Macular IRL thinning likely due to GC loss was related to reduced photopic and mesopic CS in older healthy eyes. In contrast, in the young eyes, a thicker macular IRL, possibly indicating transient gliosis, was associated with reduced CS.
关键词： contrast sensitivity,optical coherence tomography,retinal ganglion cells,macular inner retinal layer thickness,mesopic vision,glial cells
更新于2025-09-04 15:30:14
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Comparison between Toric and Non-Toric Intraocular Lenses in Patients with Corneal Astigmatism: A One-Year Multicenter Study
摘要： Objective: To compare the clinical results obtained with a toric intraocular lens (IOL) and non-toric IOL in eyes with corneal astigmatism. Methods: This multicenter retrospective study included eyes with corneal astigmatism ranging from 0.75 diopter (D) to 3.00 D that were implanted with a toric IOL and a non-toric IOL. Non-toric IOLs were implanted before toric IOLs were approved, and the eyes were divided into three groups (T3, T4, or T5) depending on the preoperative degree of corneal astigmatism. Residual refractive cylinder, uncorrected distance visual acuity (UDVA), and contrast sensitivity were compared more than 1 year after implantation. Results: The toric group included 149 eyes (mean patient age, 73.7 ± 7.9 years standard deviation, SD) and the non-toric group included 121 eyes (mean patient age, 76.2 ± 5.9 years). One year postoperatively, the respective residual refractive cylinder values and ± SD of the toric/non-toric groups were -0.61 ± 0.43/-1.45 ± 0.98 D (all eyes), -0.58 ± 0.42/-1.14 ± 0.70 D (T3), -0.59 ± 0.42/-1.63 ± 0.99 D (T4), and -0.67 ± 0.47/-2.18 ± 1.27 D (T5). The respective logarithm of the minimum angle of resolution UDVA values was 0.00 ± 0.12/0.16 ± 0.20 (all eyes), 0.00 ± 0.11/0.13 ± 0.18 (T3), 0.00 ± 0.13/0.25 ± 0.23 (T4), and 0.00 ± 0.11/0.17 ± 0.16 (T5). The toric group had better cylinder and UDVA outcome values; the difference between the groups reached significance (p<0.0001). In the toric group, the IOL rotation after implantation was 4.3 ± 4.0 degrees. Conclusion: Toric IOLs reduced the residual refractive cylinder in cases with corneal astigmatism between 0.75 and 3.00 D, and this effect was similar among different toric models. Toric IOLs are useful to improve the UDVA after cataract surgery.
关键词： Uncorrected visual acuity,Cataract surgery,Contrast sensitivity,Toric intraocular lens,Corneal astigmatism
更新于2025-09-04 15:30:14
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Standard Automated Perimetry: Determining Spatial Summation and Its Effect on Contrast Sensitivity Across the Visual Field
摘要： PURPOSE. To establish Ricco’s critical area (Ac) using the 30-2 Humphrey visual ?eld analyzer (HVFA) and thereby identify Goldmann test sizes that are within or outside complete spatial summation at all visual ?eld testing locations. We also determined the suitability of using age normative data for different test sizes. Finally, by modifying current output measures (dB values), we provide a new method that allows comparison of contrast sensitivity when testing with different Goldmann test sizes within complete spatial summation. METHODS. We used the HVFA in full threshold mode and measured thresholds for all ?ve Goldmann test sizes in 12 observers. Normative data of Heijl et al. were used for age transformation and comparison. RESULTS. All the data converted to a 50-year-old equivalent lie within 1 SD of expected variance for all test locations of the 30-2 paradigm. We established Ac values at all locations of the 30-2 paradigm and showed a systematic increase in Ac as a function of increased visual ?eld eccentricity, consistent with previous studies. Age does not appear to affect Ac or the slope of partial summation for a wide range of visual ?eld eccentricities tested using the HVFA. By equating spatial summation, we propose a new metric, dB*, that returns a uniform sensitivity value for different test sizes that are operating within complete spatial summation (i.e., follow Ricco’s law). CONCLUSIONS. We established that converting to age-equivalent thresholds and application of dB* principle advantageously allows comparison of data sets across age and test size at different locations of the visual ?eld. By identifying the Ac across the visual ?eld, it is now possible to systematically determine threshold changes across the 30-2 locations in ocular disease and further characterize the importance of testing within complete spatial summation in standard automated perimetry.
关键词： retinal eccentricity,contrast sensitivity,Ac,Ricco’s Law,Humphrey visual ?eld analyzer
更新于2025-09-04 15:30:14
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Clinical Results and Optical Quality of Diffractive Multifocal Intraocular Lens
摘要： Purpose: To compare postoperative clinical outcomes, optical quality, and patient satisfaction between two types of diffractive multifocal intraocular lens (IOL, Acri Lisa 366D and Acrysof ReSTOR +3.00 D). Methods: In a total of 68 eyes, one of two diffractive multifocal IOL (Acri Lisa 366D and Acrysof ReSTOR +3.00 D) was implanted after cataract extraction. Visual acuity was measured postoperatively at one week, 1 month, and 6 months. Contrast sensitivity, wavefront aberration, and visual function were determined via questionnaire at postoperative 1 month. Results: Intermediate visual acuity of Acri Lisa 366D and Acrysof ReSTOR at 6 months were 0.31 ± 0.14, and 0.24 ± 0.11 (log MAR), respectively. At 6 months, near and distant visual acuity results showed no significant differences between the two groups. The photopic contrast sensitivity of Acri Lisa 366D at 6 cycles/degree was 55.36 ± 7.40 and showed significant differences with Acrysof ReSTOR (47.25 ± 9.67). The mesopic contrast sensitivity values of Acri Lisa 366D and Acrysof ReSTOR were 40.26 ± 11.38 and 28.97 ± 10.45, respectively, and the spherical aberration values were 0.037 ± 0.039 μm and 0.105 ± 0.066 μm. The spherical aberration of Acri Lisa 366D was significantly lower than that of Acrysof ReSTOR. Total and high order aberration, coma, and trefoil show no significant differences between the two groups. Conclusions: The Acri Lisa 366D multifocal IOL showed better contrast sensitivity and spherical aberration compared to Acrysof ReSTOR multifocal IOL, which had an effective intermediate visual acuity.
关键词： Contrast sensitivity,Multifocal intraocular lens,Patient satisfaction,Spherical aberration
更新于2025-09-04 15:30:14