Lens Surface Research Articles

Comparing the images formed by uses of lens surfaces

In this study, university students’ experiences with conventional and novel applications for the surfaces of biconvex and biconcave lenses were examined. This work used practical tools to depict refraction and reflection processes that occur on lens surfaces. In the main activity, the surfaces of each lens were used by the students to examine a single image created by refracted light rays and then two images created by reflected light rays. When the students compared the properties of virtual and real images, they discovered that viewing both real and virtual images at the same time is more beneficial and simulating than viewing each image type separately.

Deep learning-based weak micro-defect detection on an optical lens surface with micro vision.

To solve limited efficiency and reliability issues caused by current manual quality control processes in optical lens (OL) production environments, we propose an automatic micro vision-based inspection system named MVIS used to capture the surface defect images and make the OL dataset and predictive inference. Because of low resolution and recognition, OL defects are weak, due to their ambiguous morphology and micro size, making a poor detection effect for the existing method. A deep-learning algorithm for a weak micro-defect detector named ISE-YOLO is proposed, making the best for deep layers, utilizing the ISE attention mechanism module in the neck, and introducing a novel class loss function to extract richer semantics from convolution layers and learning more information. Experimental results on the OL dataset show that ISE-YOLO demonstrates a better performance, with the mean average precision, recall, and F1 score increasing by 3.62%, 6.12% and 3.07% respectively, compared to the YOLOv5. In addition, compared with YOLOv7, which is the latest version of YOLO serials, the mean average precision of ISE-YOLO is improved by 2.58%, the weight size is decreased by more than 30% and the speed is increased by 16%.

New perforated radiation shield for anesthesiologists: Monte Carlo simulation of effects.

Catheterization for structural heart disease (SHD) requires fluoroscopic guidance, which exposes health care professionals to radiation exposure risk. Nevertheless, existing freestanding radiation shields for anesthesiologists are typically simple, uncomfortable rectangles. Therefore, we devised a new perforated radiation shield that allows anesthesiologists and echocardiographers to access a patient through its apertures during SHD catheterization. No report of the relevant literature has described the degree to which the anesthesiologist's radiation dose can be reduced by installing radiation shields. For estimating whole-body doses to anesthesiologists and air dose distributions in the operating room, we used a Monte Carlo system for a rapid dose-estimation system used with interventional radiology. The simulations were performed under four conditions: no radiation shield, large apertures, small apertures and without apertures. With small apertures, the doses to the lens, waist and neck surfaces were found to be comparable to those of a protective plate without an aperture, indicating that our new radiation shield copes with radiation protection and work efficiency. To simulate the air-absorbed dose distribution, results indicated that a fan-shaped area of the dose rate decrease was generated in the area behind the shield, as seen from the tube sphere. For the aperture, radiation was found to wrap around the backside of the shield, even at a height that did not match the aperture height. The data presented herein are expected to be of interest to all anesthesiologists who might be involved in SHD catheterization. The data are also expected to enhance their understanding of radiation exposure protection.

Pre-hyperglycemia immune cell trafficking underlies subclinical diabetic cataractogenesis

BackgroundThis work elucidates the first cellular and molecular causes of cataractogenesis. Current paradigm presupposes elevated blood glucose as a prerequisite in diabetic cataractogenesis. Novel evidence in our model of diabetic cataract challenges this notion and introduces immune cell migration to the lens and epithelial-mesenchymal transformation (EMT) of lens epithelial cells (LECs) as underlying causes.MethodsPaucity of suitable animal models has hampered mechanistic studies of diabetic cataract, as most studies were traditionally carried out in acutely induced hyperglycemic animals. We introduced diabetic cataract in the Nile grass rat (NGR) that spontaneously develops type 2 diabetes (T2D) and showed its closeness to the human condition. Specialized stereo microscopy with dual bright-field illumination revealed novel hyperreflective dot-like microlesions in the inner cortical regions of the lens. To study immune cell migration to the lens, we developed a unique in situ microscopy technique of the inner eye globe in combination with immunohistochemistry.ResultsContrary to the existing paradigm, in about half of the animals, the newly introduced hyper reflective dot-like microlesions preceded hyperglycemia. Even though the animals were normoglycemic, we found significant changes in their oral glucose tolerance test (OGTT), indicative of the prediabetic stage. The microlesions were accompanied with significant immune cell migration from the ciliary bodies to the lens, as revealed in our novel in situ microscopy technique. Immune cells adhered to the lens surface, some traversed the lens capsule, and colocalized with apoptotic nuclei of the lens epithelial cells (LECs). Extracellular degradations, amorphous material accumulations, and changes in E-cadherin expressions showed epithelial-mesenchymal transformation (EMT) in LECs. Subsequently, lens fiber disintegration and cataract progression extended into cortical, posterior, and anterior subcapsular cataracts.ConclusionsOur results establish a novel role for immune cells in LEC transformation and death. The fact that cataract formation precedes hyperglycemia challenges the prevailing paradigm that glucose initiates or is necessary for initiation of the pathogenesis. Novel evidence shows that molecular and cellular complications of diabetes start during the prediabetic state. These results have foreseeable ramifications for early diagnosis, prevention and development of new treatment strategies in patients with diabetes.

Transferability of Diffractive Structure in the Compression Molding of Chalcogenide Glass

This study investigates the use of Ge28Sb12Se60 chalcogenide glass for the compression molding of an infrared optical lens with a diffractive structure. Firstly, a mold core was prepared through ultra-precision grinding of tungsten carbide, and a chalcogenide glass preform was crafted through a polishing process and designed with a radius that would prevent gas isolation during the molding process. The test lens was then molded at various temperature conditions using the prepared mold core and preform. The diffractive structures of both the mold core and the resulting molded lens were analyzed using a microscope and white light interferometer. The comparison of these diffractive structures revealed that the molding temperature had an effect on the transferability of the diffractive structure during the molding of the chalcogenide glass lens. Furthermore, it was determined that, when the molding temperature was properly adjusted, the diffractive structure of the core could be fully transferred to the surface of the chalcogenide lens. Optimized chalcogenide glass-based lenses have the potential to serve as cost-effective yet high-performance IR optics.

A visual defect detection for optics lens based on the YOLOv5 -C3CA-SPPF network model.

Defects in the optical lens directly affect the scattering properties of the optical lens and decrease the performance of the optical element. Although machine vision instead of manual detection has been widely valued, the feature fusion technique of series operation and edge detection cannot recognize low-contrast and multi-scale targets in the lens. To address these challenges, in this study, an improved YOLOv5-C3CA-SPPF network model is proposed to detect defects on the surface and inside of the lens. The hybrid module combining the coordinate attention and CSPNet (C3) is incorporated into YOLOv5-C3CA for improving the extraction of target feature information and detection accuracy. Furthermore, an SPPF features fusion module is inserted into the neck of the network model to improve the detection accuracy of the network. To enhance the performance of supervised learning algorithms, a dataset containing a total of 3800 images is created, more than 600 images for each type of defect samples. The outcome of the experiment manifests that the mean average precision (mAP) of the YOLOv5-C3CA-SPPF algorithm is 97.1%, and the detection speed FPS is 41 f/s. Contrast to the traditional lens surface defects detection algorithms, YOLOv5-C3CA-SPPF can detect the types of optical lens surface and inside defects more accurately and quickly, the experimental results show that the YOLOv5-C3CA-SPPF model for identifying optical lens defects has good generalizability and robustness, which is favorable for on-line quality automatic detection of optical lens defects and provide an important guarantee for the quality consistency of finished products.

Characteristics and factors associated with the position of the haptic after ICL V4C implantation.

To assess the position of implantable collamer lens (ICL) haptic after ICL V4C implantation using standardized panoramic ultrasound bimicroscopy (UBM), to analyze its characteristics, associated factors, and the relationship with the clinical vault quantitatively. Hankou Aier Eye Hospital, Wuhan, Hubei, China. Cross-sectional study. 167 subjects (323 eyes) implanted with ICL V4C who had a 3-month follow-up with UBM examination were included in this study. The relative position of ICL to the adjacent structure and ICL haptic-related parameters (the final tip point of ICL haptic [ftICL haptic], measured from the scleral spur to the final tip of the ICL haptic, the posterior of the ICL to ICL haptic [ICL arc], measured from the posterior surface of the ICL to the ICL haptic plane, and the height of the crystalline lens from the ICL haptic (lens arc), measured from the anterior surface of the crystalline lens to the ICL haptic plane and other parameters), were estimated on the UBM image. Eyes were divided into 3 subgroups according to the ftICL haptic (Group 1: ≤0.5 mm; Group 2: 0.5 to 1.0 mm; and Group 3:≥1.0 mm, respectively), and the factors associated with the ICL haptic-related parameters and their impact on the clinical vault were evaluated. The haptics could be imaged in the ciliary sulcus, on the ciliary body, and under the ciliary body in 629 (48.7%), 525 (40.6%), and 138 (10.7%) eyes, respectively. The ftICL haptic and the summation of ICL arc and lens arc showed a correlation with the clinical vault ( r = -0.34, P = .00; r = 0.87, P = .00). When the ftICL haptic results were divided into 3 groups, the percentage of eyes that exhibited clinical vault >750 μm were lowest in Group 3. Multivariate regression analysis showed spherical equivalent, white-to-white (WTW), anterior chamber volume (ACV) and iris-ciliary angle (ICA); the difference between the implanted ICL size and horizontal sulcus-to-sulcus (ICL size-STS) were associated with the ftICL haptic. The IOP, WTW, ACV, and the ICL size-STS were significantly associated with ICL arc, while the ICA and lens rise were associated with lens arc. The position of ICL haptic was associated with the clinical vault. Its quantitative evaluation may provide valuable information to help clinicians to select the best ICL size before surgery and understand the formation of clinical vault after surgery.

The growth and shape of the eyeball and crystalline lens in utero documented by fetal MR imaging

PurposeTo study the growth model, shape, and developmental relationship of lens and eyeball, we used two-dimensional Magnetic Resonance (MR) imaging to investigate gestationally age-related changes in the selected ocular parameters in vivo. Materials and methodsWe retrospectively reviewed the MR images from 126 fetuses ranging from 21 to 39 weeks' gestation. Ocular parameters on MR imaging of transverse plane were measured including lens diameter (LD), anteroposterior lens diameter (APLD), lens surface area (LS), globe diameter (GD), anteroposterior globe diameter (APGD), globe surface area (GS). The growth model of each biometric against gestational age (GA), aspect ratio of lens and globe (LD/APLD and GD/APGD), and growing relationship between the ratio of lens and globe surface area (LS/GS) were studied by statistical analysis. ResultsThe growth model of most biometry for gestational age is logarithmic, except for the diameter of the ocular globe (GD and APGD) showing a quadratic growth pattern. Our study showed that the lens was consistently larger in the transverse than the anteroposterior diameters during 21–39 weeks(P < 0.001). Besides, the ratio of surface area (LS/GS) was not significantly changing with GA(P = 0.4908), while the increase of LS was significantly accorded with that of GS(P < 0.001). ConclusionThe lens shape throughout fetal life may take part in the process, shape changing from vertical ellipsoid, spherical to transversal ellipsoid, based on the logarithmically increased ratio of lens transverse and anteroposterior diameters. In the meanwhile, the aspect ratio of eyeball in late fetal life may imply a gradually spherical shape during gestation. Nomogram data from this study may provide appropriate information about morphological changes in the fetal lens and the synchronous relationship between lens and eyeball.

Reduction of Surface Reflection on Dielectric Lens Antenna by Matching Periodic Square-Pillars in 300-GHz Band

This study proposes a dielectric lens antenna that implements an impedance matching layer comprising square-pillar periodic structures on the lens surface to reduce the surface reflection formed in the lens from a high-permittivity dielectric material. To ease the fabrication process, the matching structures (MS) implemented on the lens surface are made of the same dielectric material as the dielectric lens through microfabrication structure. The dimensions of the square-pillar periodic MS unit cell are optimized for its period, space occupancy ratio, and height using periodic boundary simulation, considering the plane wave incident. Electromagnetic simulations and experiments to evaluate the effectiveness of the optimized square-pillar periodic MS were conducted. Implementing the square-pillar periodic MS to a lens composed of modified-polyphenylene ether (modified-PPE) with a relative permittivity of 5.34 assists in reducing the surface reflection inside the lens compared with the lens without anti-reflection and improves the peak gain by approximately 2 dB from 250 to 290 GHz.

Correlation between retinal nerve fiber layer thickness and anterior segment parameters in patients with pseudoexfoliation: A cross-sectional comparative study.

The purpose of this study was to assess the retinal nerve fiber layer (RNFL) thickness in patients with pseudoexfoliation (PXF) and to correlate it with anterior segment parameters such as intraocular pressure (IOP), central corneal thickness (CCT), pigments in angle structures, and grades of PXF. This was a cross-sectional comparative study in a tertiary care center. Patients having unilateral PXF were categorized as group 1. Age- and sex-matched healthy controls were categorized as group 2. All subjects underwent IOP measurement, CCT measurement, and retinal nerve fiber thickness measurement. Subjects in group 1 also underwent gonioscopy and perimetry. Data were entered and analyzed using the IBM-SPSS program (version 20.0); Chicago, IL. Mean RNFL thickness in group 1 was 85.91 ± 22.237 μ and in group 2 was 106.65 ± 6.1 μ. The mean RNFL thickness in patients with PXF syndrome was 103.38 ± 5.815 μ and in patients with PXF glaucoma was 67.82 ± 17.984 μ. The mean CCT in patients with PXF syndrome was 516.41 ± 23.03 μ and in patients with PXF glaucoma was 507 ± 33.05 μ and control group was 526.6 m. The mean IOP in patients with PXF syndrome was 8 ± 6.01 mmHg; in patients with PXF glaucoma was 17.21 ± 7.33 mmHg; and in the control group was 14.12 ± 2.693 mmHg. There was a negative correlation between IOP and RNFL thickness, and a positive correlation between CCT and RNFL thickness, but it was not statistically significant. A statistically significant correlation was found between grades of PXF and RNFL thinning with a correlation coefficient of 0.437 (P = 0.001). Patients with PXF have a lower CCT, higher mean IOP, and RNFL thinning compared to normal subjects. The presence of grade 3 PXF (on the lens surface edge) showed a statistically significant correlation with RNFL thinning.

Improved Faster R-CNN-Based Contact Lens Surface Defect Detection

Improved Faster R-CNN-Based Contact Lens Surface Defect Detection

Mechanical Removal of Calcifications on a Silicone Intraocular Lens with a Shielded Light Pipe in Asteroid Hyalosis

Calcific deposits on the posterior surface of a silicone intraocular lens (IOL) are a rare visually significant complication of asteroid hyalosis (AH). We report the novel use of a shielded light pipe to remove calcifications on a silicone lens.

Advances in interdisciplinary medical and engineering research of intraocular lens surface modifications to prevent posterior capsule opacification.

Posterior capsule opacification (PCO), a common complication after cataract surgery, impacts a patient's long-term visual quality to various degrees. Although a neodymium:yttrium aluminum garnet (Nd:YAG) laser posterior capsulotomy is a very effective treatment, it may lead to a serial of complications. Accordingly, the search for simple, safe, and effective methods to prevent PCO has received widespread attention. Various researchers are committed to the interdisciplinary collaboration between medicine and engineering fields, such as functionalizing the surface of the intraocular lens (IOL) via supercritical fluid impregnation, coating the surface of the IOL, high-concentration drug immersion, and application of a drug delivery system, to effectively reduce the incidence and severity of PCO.

Treatment approaches to postoperative fibrinoid syndrome after phacoemulsification

BACKGROUND: Postoperative fibrinoid syndrome (PFS) is an early complication of phacoemulsification, manifested by fibrin deposition on the iris and the intraocular lens surface, which leads to visual acuity decrease.&#x0D; AIM: To assess the rate and the treatment efficacy (by YAG laser, enzymatic, medicalmentous) in PFS after phacoemulsification.&#x0D; MATERIALS AND METHODS: Retrospective analysis of 56,019 cataract surgery cases of 20172021. There were 49 patients with PFS divided into 3 groups according to treatment approaches: 1st group medicamentous treatment (MT) + YAG laser destruction of the fibrin film (n = 6); 2nd MT + prourokinase injection into the anterior chamber (n = 6); 3rd MT only (n = 37).&#x0D; RESULTS: There was no difference between groups in best-corrected visual acuity (BCVA) before the PFS development. There was a more rapid increase in BCVA in the 1st and the 2nd groups compared with the 3rd one on the third day (0.20 0.09 and 0.21 0.08 versus 0.09 0.08 for groups respectively, p = 0.001) and on the fifth day of treatment (0.25 0.10 and 0.27 0.13 versus 0.16 0.14, p = 0.029). Nevertheless, in one week, there was no difference in BCVA between groups. Unfortunately, BCVA did not return to baseline in any group.&#x0D; CONCLUSION: The incidence of PFS after phacoemulsification is relatively low and amounts to 0.093%. The most rapid BCVA recovery was observed in the 1st and the 2nd groups.

Analysis of using Newton’s ring to test lens surface radius of curvature

When using Newton’s ring to test lens surface radius of curvature, the air gap in between the master plate and the lens can have either a positive or a negative meniscus shape. The optics for the negative meniscus shape air gap has been widely analyzed and the results are assumed to be valid for the positive meniscus shape air gap. Accurate and approximate analysis are performed in this paper for the positive meniscus shape air gap. Analysis results of this paper show that for the same parameters involved, the Newton’s ring number for the positive meniscus shape air gap is larger than the Newton’s ring number for the negative meniscus shape air gap. The difference between these two Newton’s ring numbers increases as the value of h / r increases, where h is the lens half diameter and r is the master plate surface radius of curvature. For h / r = 0.87, the ratio of these two numbers can be as large as 2.

Anti-Acanthamoeba activity of a semi-synthetic mangostin derivative and its ability in removal of Acanthamoeba triangularis WU19001 on contact lens.

Garcinia mangostana L., also known as the mangosteen tree, is a native medicinal plant in Southeast Asia having a wide variety of pharmacologically active compounds, including xanthonoid mangostin. In this study, we examined the pharmacological activities of the selected semi-synthetic mangostin derivative, namely, amoebicidal activity, encystation inhibition, excystation activity, and removal capacity of adhesive Acanthamoeba from the surface of contact lens (CL). Among the three derivatives, C1 exhibited promising anti-Acanthamoeba activity against Acanthamoeba triangularis WU19001 trophozoites and cysts. SEM images displayed morphological changes in Acanthamoeba trophozoites, including the loss of acanthopodia, pore formation in the cell membrane, and membrane damage. In addition, the treated cyst was shrunken and adopted an irregular flat cyst shape. Under a fluorescence microscope, acridine orange and propidium iodide (AO/PI) staining revealed C1 induced condensation of cytoplasm and chromatin with the loss of cell volume in the treated trophozoites, while calcofluor white staining demonstrated the leakage of cell wall in treated cysts, leading to cell death. Interestingly, at the concentration ranges in which C1 showed the anti-Acanthamoeba effects (IC50 values ranging from 0.035-0.056 mg/mL), they were not toxic to Vero cells. C1 displayed the highest inhibitory effect on A. triangularis encystation at 1/16×MIC value (0.004 mg/mL). While C1 demonstrated the excystation activity at 1/128×MIC value with a high rate of 89.47%. Furthermore, C1 exhibited the removal capacity of adhesive Acanthamoeba from the surface of CL comparable with commercial multipurpose solutions (MPSs). Based on the results obtained, C1 may be a promising lead agent to develop a therapeutic for the treatment of Acanthamoeba infections and disinfectant solutions for CL.

Multifunctional glycoprotein coatings improve the surface properties of highly oxygen permeable contact lenses

To achieve and maintain good operability of medical devices while reducing putative side effects for the patient, a promising strategy is to tailor the surface properties of such devices as they critically dictate the tissue compatibility and the biofouling behavior. Indeed, those properties can be strongly improved by generating mucin coatings on such medical devices. However, using coatings on optical systems, e.g., contact lenses, comes with various challenges: here, the geometrical and optical characteristics of the lens may not be compromised by either the coating process or the coating itself. In this study, we show how mucin macromolecules can be attached onto the surfaces of rigid, gas permeable contact lenses while maintaining all critical lens parameters. We demonstrate that the generated coatings improve the surface wettability (contact angles are reduced from 105° to 40° and liquid film break-up times are increased from <1 s to 31 s) and prevent tribological damage to corneal tissue. Additionally, such coatings are highly transparent (transmission values above 98 % compared to an uncoated sample are reached) and efficiently reduce lipid deposition to the lens surface by 90 % but fully maintain the geometrical and mechanical properties of the lenses. Thus, such mucin coatings could also be highly beneficial for other optical systems that are used in direct contact with tissues or body fluids.

The silent beast – a case of late‐onset postoperative endophalmitis

AbstractLate‐onset postoperative cataract surgery endophthalmitis remains a rare but sight‐threatening complication usually caused by slow‐growing pathogenic agents: bacterial or fungus. The delayed diagnosis and the potential irreversible ocular damage make this condition a challenging case for ophthalmologists.Herein, we present a 71‐year‐old woman with late‐onset fungal endophthalmitis after cataract surgery caused by candida parapsilopsis, a rare etiologic agent. This diagnosis should be taken into consideration in every late‐onset postoperative persistent panuveitis with no response to antibiotics and partial response to topical steroids, even after negative vitreous or tap culture. White deposits on the surface of the intraocular lens or the capsule are a crucial sign. Systemic and intraocular antifungal therapy along with vitrectomy and intraocular lens removal—if necessary—are the main therapy to ensure the best visual prognosis.

Reduction in the Volumetric Wear of a Ball Polishing Tool Using Ultrasonic-Vibration-Assisted Polishing Process

Ultraprecision freeform polishing using a bonnet or a felt ball mounted on a polishing head plays an important role in the mold and lens production industries. The volumetric wear of a bonnet or a felt polishing ball is still a problem to be solved. The objective of this study was to develop an ultrasonic-vibration-assisted ball polishing process on a CNC machining center to improve the surface roughness of a STAVAX mold steel and to reduce the volumetric wear of the polishing ball. The optimal combination of the ultrasonic-vibration-assisted ball polishing parameters for a plane surface was determined by conducting the Taguchi L18 matrix experiments, ANOVA analysis, and verification experiments. The surface roughness of the polished specimens was improved from the burnished surface roughness of Ra 0.122 μm to Ra 0.022 μm. In applying the optimal plane surface ball burnishing and vibration-assisted spherical polishing parameters sequentially to a fine-milled and burnished aspherical lens surface carrier on a five-axis machining center, the surface roughness of Ra 0.014 μm was obtainable. The improvement in the volumetric wear of the polishing ball was about 62% using the vibration-assisted polishing process compared with the nonvibrated polishing process.

3D Electrohydrodynamic Printing of Contact Lens‐Like Chloramphenicol‐Loaded Patches for Corneal Abrasions Treatment

Corneal abrasion is a common traumatic emergency, which can cause eyelid photophobia, tearing, and obvious foreign body sensation and pain. Herein, the 3D contact lens‐like chloramphenicol‐loaded patches composed of well‐organized micrometer fibers are prepared via electrohydrodynamic (EHD) printing to treat corneal abrasions. The main material of these patches is cellulose acetate (CA), and chloramphenicol (CAM) is loaded in the patches. EHD printing can realize micrometer fibers stacked layer by layer to form a customizable shape suitable for eye wear. Herein, the surface morphology, chemical as well as physical properties, transparency, drug release behaviors, and biocompatibility of the patches loading various concentrations of CAM are studied. It is found that the CAM‐loaded patches have 3D hemispherical shape similar to contact lens and smooth surface morphology. Moreover, patches loaded with different concentrations of CAM all maintain good water absorption, hydrophilicity, light transmittance, and biocompatibility. The drug release curves of CAM‐loaded patches show that the contact lens‐like patches have high loading efficiency and can achieve sustained release of CAM, indicating clinical potential in the treatment of corneal abrasions.