Lens Group Research Articles

Large-depth-of-field imaging system using a square aperture overlapped micro-lens array

The application of a light-field camera based on an overlapped square aperture micro-lens array (MLA) is reported. The location and direction of the incident light rays are recorded and reconstructed with a large depth of field by this imaging system. The optimized square MLA for light-field imaging, which increases the fill factor and utilization efficiency of the image sensor, is proposed. The array is fabricated by ultra-precision machining and micro-injection molding, which is economical and ensures that the array remains in high accuracy and consistency. Finally, a light-field imaging system is built with lens groups, an MLA, and an adjustable square stop. A comparative study of the field in-depth and super-resolution image is conducted. The experimental results show that the system significantly increases the range of the depth of the field. The reconstructed image is also enhanced with higher resolution and clarity.

A High-Resolution Microfluidic LAPS Imaging System for 3D Cell Metabolism Monitoring

A High-Resolution Microfluidic LAPS Imaging System for 3D Cell Metabolism Monitoring

Improvement of allograft kidney biopsy yield by using a handheld smartphone microscope as an on-site evaluation device

BackgroundSmart lens is a magnifying device that turns the smartphone into a microscopic exploring instrument. It is a convenient and inexpensive tool as an on-site evaluation device for the kidney biopsy specimen. We demonstrate the benefit of using a handheld smartphone microscope compared to the standard procedure in allograft kidney specimens. Material and methodsThis was a cohort study of allograft kidney biopsies performed between June 2015 and November 2017 in Srinagarind Hospital, Khon Kaen University, Thailand. The clinical utility of the “Chula smart lens” applied to the smartphone as an on-site evaluation device was studied. Clinical data, diagnostic quality, and complications were retrospectively reviewed and compared between the smart lens group and the standard group. ResultsThe study cohort consisted of 93 allograft kidney biopsies (standard:47, smart lens:46). The mean age was 40.6 (18–48) years, and 63 patients (67.7%) were male. By using the smart lens device, the number of obtained tissue cores was higher (3.5 vs 2.9, p = 0.019) and the inadequacy rate for diagnosis was significantly lower (7% vs 21.3%, p = 0.05). ConclusionUsing a handheld smartphone microscope as an on-site evaluation device resulted in more positive glomeruli and diagnostic yield compared to the standard procedure.

Fast versus gradual adaptation of soft monthly contact lenses in neophyte wearers

AimTo determine if a gradual adaptation period is necessary for neophytes when fitted with modern hydrogel or silicone hydrogel reusable disposable contact lenses. MethodAcross four sites, 74 neophytes (18–28 years) were randomly assigned to a reusable lens cleaned nightly with Opti-Free® Puremoist® multi-purpose contact lens solution: Proclear® (hydrogel) or Biofinity® (silicone hydrogel) and an adaptation schedule: fast (10 h wear from the first day) or gradual (4 h on the first day, increasing their wear time by 2 h on each subsequent day until they had reached 10 h). Masked investigators graded ocular surface physiology and non-invasive tear breakup time (NIBUT) and a range of comfort, vision and lens handling subjective ratings (0–100 visual analogue scales) were recorded at the baseline visit and after 10 h of lens wear, 4–6 days and 12–14 days after lens fitting. Subjective scores were also repeated after 7 days. ResultsThere was no difference (p > 0.05) in ocular surface physiology or NIBUT between fast and gradual adaptation groups at any time point in either lens type with the exception of increased corneal staining (p = 0.019) in the silicone hydrogel fast adaptation group after 4–6 days, but was similar by 12–14 days. Subjective scores were also similar across the visits and lens types with the exception of ‘lens awareness’ (p = 0.019) which was less in the gradual versus the fast adaptation silicone hydrogel lens group at 12–14 days. ConclusionThere seems to be no clinical benefit for recommending a gradual adaptation period in new wearers fitted with modern soft reusable disposable contact lenses. The findings of this work add to a growing body of evidence suggesting that such advice is unnecessary in regular soft contact lens wear, which has important ramifications for the initial clinical management of these patients.

The influence of water content and ionicity on the efficacy of soft contact lens care regimens on Pseudomonas aeruginosa

Background: Contact lens care regimens appear to be prescribed based on familiarity or by matching contact lens brands rather than consideration to efficacy.Aim: This study compared the effectiveness of multipurpose and peroxide cleaning solutions on low- and high-water content ionic and non-ionic soft contact lenses, in removing Pseudomonas aeruginosa (P. aeruginosa).Setting: The laboratory work was conducted by health science students in a graduate level programme in the microbiology laboratory at a university in south-eastern South Africa.Methods: A quantitative analytical experimental design was used. Four groups (labelled I, II, III and IV) of soft contact lenses, varied ionicity and water content were inoculated with P. aeruginosa and then exposed to three solutions containing antimicrobial ingredients, polyaminopropyl biguanide (Dymed), hydrogen peroxide (H2O2) and polyquaternium-1 (Polyquad). Each group contained 14 soft contact lenses, with the exception of Group III in which eight lenses were used. Saline served as the control. After 18 h, the remaining colony-forming units were counted using visual inspection as an indicator of efficacy against P. aeruginosa.Results: The solution containing H2O2 was found to be the most effective in removing P. aeruginosa from all Food and Drug Administration (FDA) groups of contact lenses whilst Dymed was found to be comparatively ineffective for this organism. Water content and ionicity had no effect on the efficacy of the solutions.Conclusion: Practitioners should consider the efficacy of the active ingredients against microorganisms when dispensing contact lens solutions, particularly for contact lens wearers at risk for P. aeruginosa infections.

Miniscleral Contact Lens in Pediatric Age Group: Indications, Safety, and Efficacy.

To report indications, fitting feasibility, and safety of miniscleral design (MSD) lenses in children. Medical records of patients aged <18 years at the time of referral to Contact Lens Clinic of Farabi Eye Hospital, because of inadequate spectacle-corrected visual acuity, rigid gas-permeable or soft contact lens intolerance, and ocular surface disease were reviewed. Uncorrected visual acuity (UCVA), best spectacle-corrected visual acuity (BSCVA), best-corrected vision with the lens (CCVA), lens parameters, and comfortable daily wearing time (CDWT) were documented. Seventy-two eyes of 52 pediatric patients were fitted with MSD lens over a 9-year period. The indications for MSD lens fitting were keratoconus (29 eyes), corneal scarring from ocular trauma (16 eyes), ocular surface diseases (25 eyes), and postkeratitis corneal scar (2 eyes). The average UCVA and the mean difference between CCVA and BSCVA were 1.20 and 0.55 logarithm of the minimal angle of resolution, respectively, which shows statistically significant improvement. This significant increase in vision was even seen in those who were referred for the management of ocular surface diseases. The mean CDWT for most patients was 10 hr/day. Miniscleral design lens can be used as a safe and helpful modality to provide good vision and comfort in children experiencing ectatic disorders, traumatic corneal scars, and ocular surface diseases.

Design of projection optical system for 3D defect detection on PCB

According to the practical experience of PCB defect detection in semiconductor industry, a projection optical system suitable for structured light detection device is designed by using a DMD chip. In order to realize the lateral projection of structured light stripe and improve the quality of system projection, the design of tilt back group of projection lens is adopted and the projection size is 57×32mm.The simulation results show that the illumination uniformity of the projection system on the measured surface is more than 85%, the fringe contrast is larger than 0.5, and the maximum height of the measuring device is 5mm, which provides a guarantee for practical application of structured light fringe for 3D defect detection on PCB.

Design and characterization of a thin linear ultrasonic motor for miniature focus systems

We present a miniature linear piezoelectric ultrasonic motor with a thin and hollow design, which can serve as an essential component of autofocusing features in next-generation camera modules. It consists of a thin square stator with a hole and an elastic cylindrical slider with a slit. The motor design, in which the slider inserted into the stator hole expands outward, enables a hollow structure for centering a lens and an optimal preload for enhancing the motor thrust force. In this study, we model the relationship between the dimensions and the preload statically to quantify the preload value and clarify the design methodology of the motor. After optimizing the preload empirically, we evaluate the fundamental characteristics experimentally. The stator with a side length of 4.5 mm and a thickness of less than 1 mm provides a thrust force of 12.9 mN that leads to a quick response, which is a requirement of autofocusing. Finally, the motor drive system with visual feedback control is used to demonstrate the positioning of an actual lens group in front of an image sensor to obtain clearer images.

Coupling system with concave and positive–negative angular cone lenses group for the Cassegrain receiving antenna system

In space optical communication system, the beam received by the Cassegrain receiving antenna needs to be coupled into the single-mode fiber before being detected. In this paper, a concave lens and a set of positive–negative angular cone lenses structure are designed to change the hollow beam generated by the Cassegrain receiving antenna into a solid beam. The coupling efficiencies for the hollow beam and solid beam are analyzed and numerically simulated. The simulation results show that the coupling efficiency can be improved and reaches the optimum value 0.808 after the hollow beam is changed into solid beam. Moreover, when the coupling lens and the fiber are not perfectly aligned, the coupling efficiency of the solid beam is larger than the hollow beam. The research results provide a way to improve the coupling efficiency of the Cassegrain receiving system and have practical application in the space optical communication system.

Quality of Life in Presbyopes with Low and High Myopia Using Single-Vision and Progressive-Lens Correction.

This study evaluates the impact of the severity of myopia and the type of visual correction in presbyopia on vision-related quality of life (QOL), using the refractive status and vision profile (RSVP) questionnaire. A total of 149 subjects aged 41–75 years with myopic presbyopia were recruited: 108 had low myopia and 41 had high myopia. The RSVP questionnaire was administered. Rasch analysis was performed on five subscales: perception, expectation, functionality, symptoms, and problems with glasses. Highly myopic subjects had a significantly lower mean QOL score (51.65), compared to low myopes (65.24) (p < 0.001). They also had a significantly lower functionality score with glasses (49.38), compared to low myopes (57.00) (p = 0.018), and they had a worse functionality score without glasses (29.12), compared to low myopes (36.24) (p = 0.045). Those who wore progressive addition lenses (PAL) in the high-myope group (n = 25) scored significantly better, compared to those who wore single-vision distance (SVD) lenses (n = 14), with perception scores of 61.19 and 46.94, respectively (p = 0.029). Highly myopic presbyopes had worse overall QOL and functionality, both with and without glasses, compared to presbyopes with low myopia. High-myopic PAL users had a better perception outcome than SVD lens wearers. Low-myopic PAL wearers had a better QOL than SVD wearers.

Beam collimation scheme of laser wireless power supply system for high potential monitoring node of power transmission and transformation

Laser wireless power supply technology has the advantages of high energy density, good directionality, small transmitting and receiving aperture, convenient and flexible installation and deployment. It is very suitable for power supply for sensors or mobile electrical equipment in complex high potential environment, such as patrol UAV. Because the beam quality of high-power semiconductor laser is far worse than that of other types of lasers, when it is used as the transmitter of beam shaping system, it must be equipped with corresponding beam shaping system to obtain laser beam with uniform spot, appropriate size and small divergence angle, so as to ensure that the photoelectric cell module has high conversion efficiency and meet the needs of long-distance laser transmission. In this paper, a beam collimation scheme based on aspheric lens group is designed, which integrates optical devices with low cost, reduces the energy loss in the process of laser transmission, and obtains laser beam with certain intensity uniformity. The test shows that the collimator can better meet the parameter requirements of the collimation system.

Visual performance of four types of diffractive multifocal intraocular lenses and a review of articles.

To compare the clinical outcomes of a variety of multifocal intraocular lenses (MIOLs) in patients diagnosed with presbyopia or cataracts. This clinical trial study included 141 patients (282 eyes) with different MIOLs implantation. The Symfony (60 eyes), the ReSTOR (100 eyes), the AT LISAtri (60 eyes), and the PanOptix (62 eyes) intraocular lenses were evaluated in this prospective interventional study. The near, intermediate, and distant visual acuities, contrast sensitivity, and defocus curve were measured as valid criteria. To statistically analyze the results, we used the Statistical Package for Social Science software, the non-parametric Wilcoxon signed-rank t, the one-way analysis of variance and the Tukey's post-hoc test in our analysis. Moreover, we conducted a detailed literature search on the PubMed database in English about MIOLs, in total 59 studies were included in this review article. The four approaches did not show any significant difference in the best-corrected distance visual acuity (P>0.05). The defocus curves at the contrast of 100% showed that trifocal IOLs had better intermediate performance than the bifocal IOL (P<0.05). There were no statistically significant differences between AT LISAtri and PanOptix lenses for visual acuity at all distances. The eyes with PanOptix, Symfony, and AT LISAtri IOL showed better contrast sensitivity than those ReSTOR at spatial frequencies of 1, 3, and 6 cpd in photopic and mesopic conditions (P<0.001). All four groups of the multifocal lenses were satisfying in terms of distance and near vision. Also, the group of trifocal lenses led to satisfactory outcomes in intermediate vision, without degradation in quality of vision.

Wide field of view handheld smart fundus camera for telemedicine applications.

Purpose: We report that a large field-of-view (FOV) retinal image can be acquired by a smart fundus camera. Approach: This handheld system consists of a Raspberry Pi board, a touch screen display, a customized optical lens group, a ring light-emitting diode, and a Li-battery. Results: Wide FOV of is observed with proper lens configuration and can be expanded using image stitching algorithms. Conclusions: This customized handheld fundus camera provides better image quality than cellphone-based fundus imaging solutions and offers more operational features than traditional portable fundus cameras. It may benefit field-portable ophthalmic diagnostic applications.

Astigmatism correction with toric implantable collamer lens in low and high astigmatism groups.

To analyze the target induced astigmatism (TIA), surgically induced astigmatism (SIA), difference vector (DV), and correction index (CI) in the correction of astigmatism with phakic lenses, and its influence on visual acuity, and to analyze the safety and efficacy indexes of the correction of high and low power astigmatism with toric phakic lenses. Retrospective comparative study. The medical records of patients that were operated on at the research center during the period were analyzed. Results were divided into Low Astigmatism Group - LAG (33 eyes) and High Astigmatism Group - HAG (93 eyes) according to the implanted toric ICL lens power. Preoperative refraction and resultant postoperative refraction were analyzed by vector analysis. Visual acuity pre and postop, with and without optical correction, were compared. A total of 126 eyes were studied. The average preop refraction was -5.02 D sphere with -2.61 D cylinder. The average ICL lens power implanted was -8.31 D sphere +2.77 D cylinder. Refractive remaining was -0.01 ± 0.11 D sphere -0.15 ± 0.28 D cylinder. The arithmetic average angle of error in the astigmatism correction was 1.08°. The resultant cylinder was -0.03 ± 0.12 D and -0.19 ± 0.30 D in the low and high astigmatism groups, respectively, with a mean UDVA -0.01 ± 0.10 and 0.01 ± 0.16 and CDVA -0.03 ± 0.08 and -0.01 ± 0.17 for each group. The safety and efficacy indexes for the low astigmatism group were 1.09 ± 0.16 and 1.05 ± 0.17, respectively, with 1.11 ± 0.17 and 1.06 ± 0.16 for the high astigmatism group. The correction of astigmatism by the implantation of toric phakic lenses of the posterior chamber is safe and effective, independently of the amount of cylinder corrected.

Effect of different tinted soft contact lenses on the tear quality and ocular surface properties

Different designs for contact lenses can result in insufficient oxygen permeability of the lenses. Moreover, the contact lens wearing schedule, replacement, lens care systems, and purchase methods are all important considerations for contact lens wearers. To evaluate the influence of tinted contact lenses with the pigment layer in different locations on the tear quality and ocular surface properties, as well as the subjective experience of the wearer In this randomized double-blind study, 30 healthy subjects (60 eyes) were randomly assigned to two groups. The pigment layer of lenses in group I was embedded within the matrix, close to the front surface, while that in group II was located on the front surface of the lens. Subjects wore the contact lenses for 7 days, 8 h a day. In both groups, the frequency of blinking after lens wear increased significantly relative to that before lens wear. The tear-breakup time was significantly shorter in group II than in group I. Temporal bulbar conjunctiva, nasal bulbar conjunctiva, temporal limbal, nasal limbal, and eyelid redness levels in both groups, and corneal staining levels in group II, were significantly increased after 7-day lens wear. Nasal bulbar conjunctiva, temporal limbal, and nasal limbal redness; eyelid smoothness; and corneal staining levels were significantly higher in group II. There was no significant between-group difference in the subjective experience. Ocular surface properties deteriorated while the frequency of blinking increased after wear of both types of tinted contact lenses for 7 days. Both designs resulted in insufficient oxygen permeability of the contact lenses.

Hand-Held Zoom Micro-Imaging System Based on Microfluidic Chip for Point-of-Care Testing (POCT) of Vaginal Inflammation.

Background: Vaginitis is a common and very private disease, and the current diagnosis is a frequent go to the hospital for testing. Objective: In order to improve the convenience and speed of detection, in this paper, we have developed a hand-held zoom micro-imaging system based on a microfluidic chip for point-of-care testing (POCT) of vaginal inflammation. Methods: This system consists of a microfluidic chip, an optical system and a hand-held zoom system assembled with a mobile phone. In terms of hardware, we designed a self-priming microfluidic chip, which can realize automatic sampling and full mixing of samples. We have also developed an optical system that can be adapted to smartphones, which has a lens group with a 37x magnification function and equipped with a zoom system with a focus range of 4mm to 6mm. In terms of software, we proposed an APP that can accurately identify cocci and can determine the inflammation level. Results: Compared with the recognition rate of the observers in the hospital, the detection accuracy of the portable recognition system is 95%, and after testing the clinical samples, the results were completely consistent with the hospital diagnosis results. The detection limit was 500 CFU / ml, which the relative error was (0.9 ± 0.3) %, and recognition time is 7 seconds. Conclusion: This system is definitely suitable for women’s point-of-care testing (POCT).

Effect of sustained-release long-acting intravitreal dexamethasone implant in patients of non-proliferative diabetic retinopathy undergoing phacoemulsification: A randomized controlled trial.

Purpose:Cataract and diabetes, both being a major health care problem, an intervention evaluated for the combination of the two attains paramount importance. The purpose of the study was to determine the role of intraoperative intravitreal dexamethasone implant in patients with diabetic retinopathy with/without macula edema undergoing phacoemulsification.Methods:The study was a two-arm, single-center, randomized, assessor-blinded trial of 151 patients with type-2 diabetes mellitus and cataract. It had two groups: dexamethasone group (DEX) versus standard of care (SOC) group, i.e. phacoemulsification and intraocular lens (IOL) implantation without injection of dexamethasone drug delivery system (DDS). The number of rescue interventions required, central macular thickness by optical coherence tomography (OCT), Early Treatment Diabetic Retinopathy Study (ETDRS) score, laser flare meter (LFM) values, intraocular pressure (IOP), and grade of diabetic retinopathy (DR) were recorded until three months follow up. Macular thickness and number of rescue medications between the treatment groups were the co-primary outcomes.Results:A statistically significant interaction was present between treatment and time on OCT score (P < 0.001). The requirement of rescue interventions in the dexamethasone DDS group [40.2% (33/82)] was lesser as compared to the SOC group [49.3% (34/69)] at the end of 12 weeks [odds ratio (OR), 0.70 (0.36–1.33)] follow up although not statistically significant (P = 0.343). A statistically significant interaction was present between treatment and time on LFM score (P = 0.003). No statistically significant interaction was present between the treatment and time on visual acuity score (P = 0.08) and IOP score (P = 0.375).Conclusion:Dexamethasone implant may have potential as a valuable therapy for patients undergoing cataract surgery with DR with/without macular edema with effects lasting for at least three months.

Effect of High-Order Aberrations and Satisfaction on Cataract Patients Implanted with Four Types of AcrySof Blue Light Filtering Intraocular Lens

Objective: The objective is to evaluate the visual acuity, high-order aberrations and satisfaction in the cataract patients with the implantation of different types of AcrySof blue light filtering intraocular lens, which would provide the clinical guidance for the selection of individualized intraocular lens. Methods: From January 2019 to December 2020, the patients with age-related cataract in Guangzhou Red Cross Hospital were equally randomized to be divided into four groups. 20 patients (20 eyes) were implanted with AcrySof (SN60WF), which was the blue light filtering single focus group; 20 patients (20 eyes) were implanted with blue light filtering aspheric multifocal intraocular lens (AcrySof ReSTOR IOL +3.0D, SN6AD1), which was the multifocal intraocular lens group; 20 patients (20 eyes) were implanted with aspheric astigmatism correction intraocular lens (Toric SN6AT), which was the astigmatism group; 20 patients (20 eyes) were implanted with blue filtering aspheric multifocal astigmatism correction intraocular lens (AcrySof ReSTOR IOL +2.5D IQ, SV25T0), which was the ART group. Three months after the operation, the patients were followed up with slit lamp to check the visual acuity, including uncorrected distance visual acuity (UCDVA), uncorrected near visual acuity (UCNVA), best corrected distance visual acuity, (BCDVA); the questionnaire surveys on the satisfaction of different intraocular lens implantation (far and near vision, glare, halo and abnormal visual symptoms); the iTrace visual function analyzer was used to check the total high-order aberrations (spherical aberration, wisdom aberration and Clover aberration) in the 3 mm pupil diameter. Results: Three months after cataract surgery, American Simplified version of questionnaire survey showed that the scores of near removing glasses in the multifocal group and the ART group were significantly better than those in the single focus group and the astigmatism group (P P > 0.05). Three months after cataract surgery, there were statistically significant differences about UCDVA, BCDVA and UCNVA among the four groups (F = 18.189, P P P > 0.05). Conclusion: Different types of AcrySof blue light filtering intraocular lens implantation could improve the far vision and satisfaction of cataract patients, without different higher-order aberrations. Multifocal intraocular lens and ART intraocular lens could significantly improve the far vision of patients and reduce the dependence on near glasses.

A comparison between anterior chamber intraocular lenses with those of retro-pupillary iris claw lenses: Visual outcome and complications

Purpose: A comparison of the visual outcome and complications in anterior chamber intraocular lenses with those of retropupillary iris fixated lenses. Materials and Methods: A retrospective observational study done at tertiary hospital in South India. Records of patients who underwent small incision cataract surgery with either anterior chamber intraocular lens (ACIOLs) and retropupillary iris fixated lens implantation done between 2009 to 2016 were assessed. Demographic details, and data regarding pre operative status, intraoperative and postoperative events were noted, and compared. Results: Records of 50 patients of retro-pupillary iris fixated lenses and 44 patients of ACIOLs were analysed. Postoperatively, 42% of patients who had an iris claw had visual acuity better than 6/60, and 50% of patients in the ACIOL group had a visual acuity better than 6/60, in the immediate postop period. 33 patients (66%) in the iris claw lens group had a vision improvement of one line or more, while 26(60.4%) in the ACIOL had a vision improvement of one line or more. (p=0.214). The postoperative complications in both groups were similar. Conclusion: Good surgical technique is the main factor in determining the postoperative outcome notwithstanding the type of lens used, especially in the immediate postoperative period. Keywords: ACIOL, Retropupillary Iris-claw lens, Small Incision Cataract surgery, Postoperative complications, Visual outcome.

Liquid lens with adjustable focus for ultrasonic imaging

An acoustic lens is an attractive device due to its superior ability to image and focus acoustic beams. Nevertheless, the limitation of such a solid-phase device is apparent in that once an acoustic lens is made, its focal length remains fixed. On the contrary, the liquid acoustic lens can not only flexibly tune the position of focus, but also avoid greater acoustic impedance. This paper presented a liquid acoustic convex lens with a tunable focus. The focal distance of the liquid acoustic lens is derived from the focal length formula of the optical lens group. The interface curvature of the lens and the dependent focus as a function of the infused liquid volume in the lens were studied theoretically and experimentally. Furthermore, the refraction index of the liquid can be accurately selected as needed by adjusting the concentrations of liquid. This also results in a modification of the lens focal length. The magnification ability of this acoustic lens in combination with a single element 6.8 MHz transducer was evaluated by imaging steel probes which were embedded at different position without performing mechanical axial scanning. The error caused by the difference of sound speed between the liquid in the lens and the host medium is corrected.