Spectacle Lenses Research Articles

In-depth optical characterization of spectacle lenses for myopia progression management

Myopia is one of the most common ocular disorders worldwide and the leading cause of visual impairment in children. The elongation of axial length in the eyes with medium and high levels of myopia can increase the risk of severe ocular pathologies that potentially lead to irreversible blindness. In recent decades, spectacle lenses have been designed, manufactured, and clinically tested to treat myopia progression and abnormal ocular growth in children. However, the optical characterization of those lenses—with and without considering the optics of myopic eyes—has not yet been comprehensively evaluated and compared. Therefore, in this paper, we quantify and compare the focusing and scattering properties of a single vision (SV) lens with two types of spectacle lenses for myopia progression management: defocus incorporated multiple segments (DIMS), and diffusion-optical technology (DOT). To investigate the focusing properties across the eccentricity of the lenses, we have developed an instrument based on spatial light modulation technology that reproduces myopic eyes’ foveal and peripheral aberrations. Our characterization showed an increased contrast and sharpness of images through the DIMS lens at the peripheral retina when inducing myopic defocus with respect to the SV and DOT lenses. On the other hand, the contrast reduction by the DOT lens strongly depends on the luminance at the pupil. The understanding of the imaging properties of the lenses achieved through our results might help optimize future spectacles designs for myopia progression management.

Optical Imaging Deformation Inspection and Quality Level Determination of Multifocal Glasses.

Multifocal glasses are a new type of lens that can fit both nearsighted and farsighted vision on the same lens. This property allows the glass to have various curvatures in distinct regions within the glass during the grinding process. However, when the curvature varies irregularly, the glass is prone to optical deformation during imaging. Most of the previous studies on imaging deformation focus on the deformation correction of optical lenses. Consequently, this research uses an automatic deformation defect detection system for multifocal glasses to replace professional assessors. To quantify the grade of deformation of curved multifocal glasses, we first digitally imaged a pattern of concentric circles through a test glass to generate an imaged image of the glass. Second, we preprocess the image to enhance the clarity of the concentric circles' appearance. A centroid-radius model is used to represent the form variation properties of every circle in the processed image. Third, the deviation of the centroid radius for detecting deformation defects is found by a slight deviation control scheme, and we gain a difference image indicating the detected deformed regions after comparing it with the norm pattern. Fourth, based on the deformation measure and occurrence location of multifocal glasses, we build fuzzy membership functions and inference regulations to quantify the deformation's severity. Finally, a mixed model incorporating a network-based fuzzy inference and a genetic algorithm is applied to determine a quality grade for the deformation severity of detected defects. Testing outcomes show that the proposed methods attain a 94% accuracy rate of the quality levels for deformation severity, an 81% recall rate of deformation defects, and an 11% false positive rate for multifocal glass detection. This research contributes solutions to the problems of imaging deformation inspection and provides computer-aided systems for determining quality levels that meet the demands of inspection and quality control.

Characterization of thick and contact lenses using an adaptive Shack–Hartmann wavefront sensor: Limitations and solutions

Lens characterization is a key challenge for reliable optical and imaging techniques. Shack–Hartmann wavefront sensor (SHWFS) is frequently used as an efficient tool for characterizing optical elements. However, the aberrations arising from the incident wavefront, utilized for the characterization process, cause imprecision in the spherical power measurement. Accordingly, the aim of the present study is to construct an experimental configuration that consists of SHWFS incorporated with a deformable mirror (DM) to provide a correction for the incident wavefront aberrations which yields an ideal plane wave. Different types of thick lenses with a wide range of focal lengths and three single-vision contact lenses were tested before and after aberrations compensation and compared to the reference-based method. The comparison was based on measuring the spherical powers for the tested lenses. The results indicate that the accuracy of measurements is influenced by the incident wavefront aberrations, which has been improved by the proposed compensation system. Finally, the limitations are investigated and it was concluded that the system in its current configuration failed to accurately measure some thick lenses. This issue was solved by suggesting a compound lens correction methodology that extended the measurement range of spherical powers beyond the designated measurable range of the system.

IMI 2023 Digest.

Myopia is a dynamic and rapidly moving field, with ongoing research providing a better understanding of the etiology leading to novel myopia control strategies. In 2019, the International Myopia Institute (IMI) assembled and published a series of white papers across relevant topics and updated the evidence with a digest in 2021. Here, we summarize findings across key topics from the previous 2 years. Studies in animal models have continued to explore how wavelength and intensity of light influence eye growth and have examined new pharmacologic agents and scleral cross-linking as potential strategies for slowing myopia. In children, the term premyopia is gaining interest with increased attention to early implementation of myopia control. Most studies use the IMI definitions of ≤-0.5 diopters (D) for myopia and ≤-6.0 D for high myopia, although categorization and definitions for structural consequences of high myopia remain an issue. Clinical trials have demonstrated that newer spectacle lens designs incorporating multiple segments, lenslets, or diffusion optics exhibit good efficacy. Clinical considerations and factors influencing efficacy for soft multifocal contact lenses and orthokeratology are discussed. Topical atropine remains the only widely accessible pharmacologic treatment. Rebound observed with higher concentration of atropine is not evident with lower concentrations or optical interventions. Overall, myopia control treatments show little adverse effect on visual function and appear generally safe, with longer wear times and combination therapies maximizing outcomes. An emerging category of light-based therapies for children requires comprehensive safety data to enable risk versus benefit analysis. Given the success of myopia control strategies, the ethics of including a control arm in clinical trials is heavily debated. IMI recommendations for clinical trial protocols are discussed.

Multifocal versus modified monovision corrections: A non-dispensing comparison of visual assessment in presbyopic neophytes.

To compare the visual performance of two simultaneous-vision soft multifocal contact lenses and to compare multifocal contact lens and its modified monovision counterpart in presbyopic neophytes. A double-masked, prospective, comparative study was conducted on 19 participants fitted with soft PureVision2 multifocal (PVMF) and clariti multifocal (CMF) lenses in random order. High- and low-contrast distance visual acuity, near visual acuity, stereopsis, contrast sensitivity, and glare acuity were measured. The measurements were conducted using multifocal and modified monovision design with one brand and then repeated with another brand of lens. High-contrast distance visual acuity showed a significant difference between CMF (0.00 [-0.10-0.04]) and PureVision2 modified monovision (PVMMV; -0.10 [-0.14-0.00]) correction (P = 0.003) and also between CMF and clariti modified monovision (CMMV; -0.10 [-0.20-0.00]) correction (P = 0.002). Both modified monovision lenses outperformed CMF. The current study did not show any statistically significant difference between contact lens corrections for low-contrast visual acuity, near visual acuity, and contrast sensitivity (P > 0.01). Stereopsis at near distance was significantly lower with both modified monovision (PVMMV: 70 [50-85]; P = 0.007, CMMV: 70 [70-100]; P = 0.006) and with CMF (50 [40-70]; P = 0.005) when compared to spectacles (50 [30-70]). Glare acuity was significantly lower with multifocal (PVMF: 0.46 [0.40-0.50]; P = 0.001, CMF: 0.40 [0.40-0.46]; P = 0.007) compared with spectacles (0.40 [0.30-0.40]), but no significant difference was noted between the multifocal contact lenses (P = 0.033). Modified monovision provided superior high-contrast vision compared to multifocal correction. Multifocal corrections performed better for stereopsis when compared to modified monovision. In parameters like low-contrast visual acuity, near acuity, and contrast sensitivity, both the corrections performed similarly. Both multifocal designs showed comparable visual performances.

Commentary: Multifocal versus modified monovision contact lens correction for presbyopia - A synopsis.

Commentary: Multifocal versus modified monovision contact lens correction for presbyopia - A synopsis.

Myopia progression in children and adolescents: impact of COVID-19 pandemic and current and future control strategies.

Myopia is a significant and growing public health problem with typical onset or progression during childhood adolescence. High myopia has lifelong impact on ocular health and socio-economic aspects of patients 'lives. COVID-19 lockdown resulted in demonstrable increase in incidence and progression rate of myopia in children and adolescence. Low dose atropine and Orthokeratology contact lenses appear to be most effective in slowing down myopia progression. Rebound progression after stopping both modalities were reported. Defocus modifying spectacle lenses and contact lenses are less effective but possibly better tolerated.

Comparison of vision performance of spectacles prescribed to 0.05D versus 0.25D steps

ABSTRACT Clinical relevance Traditionally, refraction is performed, and spectacles are manufactured in in 0.25D-steps. Trial and spectacle lenses manufactured in smaller increments may allow for a more accurate refraction and prescribed spectacles. Background To determine whether refraction in 0.05D-steps improves the proportion of eyes achieving achieve duochrome equality, and whether spectacles prescribed in 0.05D-steps offer any vision benefits, compared to 0.25D-steps. Methods Myopic young adults were enrolled into two prospective studies conducted at different sites. Study 1 comprised 66 participants (refracted under cycloplegia) while Study 2 comprised 51 participants (not cyclopleged). A standard refraction was performed in both studies and a trial frame and trial lenses were used to determine the spherical endpoint of duochrome equality (0.25D-steps first then 0.05D-steps). In Study 2, the cylindrical component was refined in 0.05D-steps before the spherical endpoint in 0.05D-steps. Monocular high-contrast-visual-acuity (HCVA) was measured while wearing the final refractions. Participants in Study 2 wore spectacles manufactured in 0.25D and 0.05D-steps for 7 days each in a randomized, double-masked study. Both spectacles appeared identical. Outcome measures assessed on dispensing and after 7 days of wear comprised monocular acuity-based measurements (HCVA, low-contrast-visual-acuity, vanishing-optotype-acuity, contrast-sensitivity) and subjective ratings. The Quality-of-Vision questionnaire and subjective preference were assessed after 7 days. Results Both studies showed a higher proportion of eyes achieved duochrome equality (P < 0.001) and better average monocular HCVA (P ≤ 0.006) in 0.05D-steps. Study 2 showed 0.05D-step spectacles provided better average results for all monocular acuity-based measurements (P < 0.006) and were preferred by 65% (P = 0.04) of participants after 7 days (P = 0.04). There were no differences between spectacles for any other measures (P > 0.1). Conclusions Refraction performed, and spectacles manufactured in 0.05D-steps for this study improved average acuity-based outcomes and were preferred by most participants to spectacles in traditional 0.25D-steps.

Prevalence of refractive error in Portugal estimated from ophthalmic lens manufacturing data: Ten-years analysis.

To investigate the prevalence, distribution and trends of refractive error from ophthalmic lens manufacturing data over a ten-year period. Fully anonymized data from ophthalmic lenses, for the years between 2010 and 2020, provided by the leading ophthalmic lens manufacturer operating in Portugal were analysed (no human participants were involved in the research). Prescriptions delivered were divided in single vision prescriptions and progressive/multifocal prescriptions and categorized into 14 spherical equivalent ranges. Given the lack of absolute values, indirect estimates and a qualitative analysis of the current situation and trends on refractive error epidemiology was carried out. Dataset from manufacturer comprises percentage values of ophthalmic lenses dispensed in Portugal. The distribution of ophthalmic prescriptions for single vision prescriptions presents most of the observations in the range [-1.49, -0.50] diopters, in every year from 2010 to 2020. For the progressive prescription's lenses, most of the observations is in an interval of two ranges, [0.50, 1.49] and [1.50, 2.99] diopters. From 2010 to 2020 the proportion of single vision ophthalmic lens prescriptions for myopia increased from 38.13% to 46.21%; the proportion for high myopia increased from 2.76% to 4.45%; and the proportion for hyperopia decreased from 40.85% to 31.36%. Ophthalmic lens manufacturing data can be a valuable source for long-term analysis of refractive error prescription and trends over time. It was possible to observe a trend of increasing prevalence of myopia and high myopia from 40.89% in 2010 to 50.66% in 2020. That increase trend has important implications for public health and in the planning of services.

Symptoms and Satisfaction Levels Associated with Intraocular Lens Implants in the Monofocal and Premium IOL Patient-Reported Outcome Measure Study

To develop a questionnaire with standardized questions and images about visual symptoms and satisfaction administered before and after cataract surgery with monofocal and various (premium) intraocular lenses (IOLs). A prospective, observational study of cataract surgery patients completing a self-administered questionnaire preoperatively and postoperatively at 4 to 6 months. Five hundred fifty-four patients with plans to undergo implantation of the same IOL in both eyes on separate occasions in 20 ophthalmology practices. An 86-item questionnaire with standardized images assessed the following 14 symptoms: glare, blurry vision, starbursts, hazy vision, snowballs, halos, floaters, double images, rings and spider webs, light flashes with eyes closed, distortion, light flashes with eyes open, shimmering images, and dark crescent-shaped shadows. Symptom severity and level of symptom bother, satisfaction with vision, quality of vision, and ability to see without corrective lenses or eyeglasses. Except for dark crescent-shaped shadows, the report of visual symptoms significantly decreased postoperatively. Best uncorrected binocular visual acuity improved from 0.47 (20/59 Snellen visual acuity values) ± 0.35 logarithm of the minimum angle of resolution (logMAR) preoperatively to 0.12 (20/26 Snellen visual acuity values) ± 0.12 logMAR postoperatively. Patients' ratings of intermediate vision as good to excellent improved significantly from 12% preoperatively to 71% postoperatively, and patients' ratings of distance vision improved from 8% preoperatively to 85% postoperatively. After surgery, 84% reported that they were somewhat, very, or completely satisfied with their vision. Most patients (88%) reported that they could see pretty well, very well, or perfectly well without corrective lenses after surgery. The Assessment of IntraOcular Lens Implant Symptoms questionnaire can be used across a wide variety of IOLs to evaluate visual symptoms and satisfaction with a growing segment of the market, premium IOLs, that target intermediate and near vision, in addition to distance vision. Compared to patients receiving monofocal IOLs, patients receiving premium IOLs appear to be more challenging to satisfy because of their requirements for distance, intermediate, and near vision, and their desire to be free of eyeglasses postoperatively. This instrument provides a structured, uniform tool for regulators, researchers, and ophthalmologists in everyday practice to gain insights into patients' experiences. The author(s) have no proprietary or commercial interest in any materials discussed in this article.

Myopia Control Efficacy of Spectacle Lenses With Aspherical Lenslets: Results of a 3-Year Follow-Up Study

To investigate myopia control efficacy in children who continued wearing spectacle lenses with highly aspherical lenslets (HAL) or switched from spectacle lenses with slightly aspherical lenslets (SAL) and single-vision spectacle lenses (SVL) to HAL for 1 year after a 2-year myopia control trial. This was a 1-year extension of a randomized clinical trial. Of 54 children who had worn HAL for 2 years, 52 continued wearing HAL (HAL1 group), and of the 53 and 51 children who had originally worn SAL or SVL, 51 and 48 switched to wearing HAL (HAL2 and HAL3 groups) in year 3, respectively. A new SVL (nSVL) group of 56 children was recruited, matched for age, sex, cycloplegic spherical equivalent refraction (SER), and axial length (AL) of the HAL3 group at extension baseline, and used for a comparison of third-year changes. SER and AL were measured every 6 months in year 3. During year 3, the mean (SE) myopia progression in the nSVL group was -0.56 (0.05) diopters (D). Compared with nSVL, the changes in SER were less in HAL1 (-0.38 [0.05] D, P=.02), HAL2 (-0.36 [0.06] D, P=.01), and HAL3 (-0.33 [0.06] D, P=.005). The mean (SE) AL elongation in the nSVL group was 0.28 (0.02) mm. Compared with nSVL, the elongation in AL was less in the HAL1 (0.17 [0.02] mm, P < .001), HAL2 (0.18 [0.02] mm, P < .001), and HAL3 (0.14 [0.02] mm, P < .001) groups. Myopia progression and axial elongation were comparable in all 3 HAL groups (all P > .05) in year 3. Myopia control efficacy has remained in children who wore HAL in the previous 2 years. Children who switched from SAL or SVL to HAL in year 3 had slower myopia progression and axial elongation than that in the control group.

Long-term myopia control effect and safety in children wearing DIMS spectacle lenses for 6 years

This study evaluated the long-term myopia control effect and safety in children wearing Defocus Incorporated Multiple Segments (DIMS) spectacle lenses. Participants who completed the 2-year RCT were followed for a total of 6 years; their cycloplegic refractions and axial length were measured. Group 1 (n = 36) wore DIMS spectacles for 6 years; Group 2 (n = 14) wore DIMS lens for the first 3.5 years and SV spectacles afterwards; Group 3 (n = 22) wore SV spectacles in the first 2 years and switched to DIMS; Group 4 (n = 18) wore SV spectacles in the first 2 years, switched to DIMS for 1.5 years and then SV spectacles again. Group 1 showed no significant differences in myopia progression (− 0.52 ± 0.66 vs. − 0.40 ± 0.72D) and axial elongation (0.32 ± 0.26 vs. 0.28 ± 0.28 mm, both p > 0.05) between the first and the later 3 years. In the last 2.5 years, DIMS lens groups (Groups 1 and 3) had less myopia progression and axial elongation than the single vision groups (Groups 2 and 4). There was no evidence of rebound after stopping the treatment. Post-wear visual functions in all groups were within norms. The results supported that DIMS lenses provided sustained myopia control without adverse effects over the 6-year study period.Trial registration: clinicaltrials.gov; NCT02206217.

Health-related quality of life for children using orthokeratology (OK), peripheral lenslet designed (PLD) and single-vision (SV) spectacles: based on Child Health Utility 9 Dimensions (CHU9D)

PurposeThis study investigated the health-related quality of life (HRQoL) among children with myopia who used orthokeratology (OK), peripheral lenslet designed (PLD), and single-vision (SV) spectacles. MethodsThis cross-sectional study was conducted between February of 2021 and August of 2022. It involved 211, 231, and 206 respondents with OK, PLD, and SV spectacle lenses, respectively. The HRQoL was presented as utility values using a general preference-based Child Health Utility-nine Dimensions (CHU9D) questionnaire. Descriptive statistical analysis and nonparametric hypothesis testing were used to compare the HRQoL in the OK, PLD, and SV groups. ResultsOf the 648 respondents, the average utility scores was 0.936 (95 % confidence interval (CI): 0.929–0.943). Children who wore the PLD spectacles had a significantly higher utility scores (0.955, 95 % CI: 0.946–0.963) than those who wore the SV spectacles (0.926, 95 % CI: 0.913–0.939) and the OK lenses (0.925, 95 % CI: 0.913–0.937) (p < 0.01). The PLD spectacle wearers were less likely to be worried, sad, tired, or annoyed than those who wore OK and SV spectacles (P < 0.05). Self-reported improved eyesight and lessened eye pain and discomfort from myopia correction using PLD spectacles had higher utility values (P < 0.05). ConclusionsThe PLD spectacles had a significantly higher HRQoL than the OK and SV spectacles among children. Having better eyesight and less eye pain/discomfort from myopia correction could improve the HRQoL of children. This data indicates that PLD spectacles may be considered for myopia management in children and adolescents.

Does visual acuity predict visual preference in progressive addition lenses?

We aimed to determine if visual acuity (VA) could differentiate the quality of vision with two ophthalmic lenses with unwanted astigmatism. Twenty presbyopic subjects (48 to 62 years old; VA better than 0.0 logMAR) graded the magnitude of their preference between two progressive addition lenses (plano addition 2.00D) and their visual acuities were measured with both lenses at various eccentricities from -12 to +12 mm from the near vision point every 3 mm in controlled conditions. The Lens with the least peripheral astigmatism was preferred by 75% of the subjects. VA measured at the near vision point was statistically worse (p<0.01) with this lens whereas the contrary was observed in the periphery (± 12 and -9 mm of eccentricity). The Friedman test shows that the eccentricity (p<0.001) has a significant effect on visual acuity. However, the lens did not show any significant effect (p=0.76). The choice of the favorite lens was predicted for only 35% when considering central VA (up to 6mm) and 80% of the subjects when considering peripheral VA (9 to 12mm). However, the magnitude of the difference could be predicted by peripheral VA in only 60% of the subjects. High contrast Visual acuity was clearly able to differentiate the 2 lens designs tested in our experiment. However, even under the controlled conditions of this study, it was not possible to predict the quality of vision, as measured by a subjective appreciation, through progressive addition lenses at various eccentricities from the near vision with an addition of 2.0D.

PEMERIKSAAN PENDERITA PRESBYOPIA DENGAN STATUS REFRAKSI HYPERMETROPIA, MYOPIA, ASTIGMAT DAN EMETROPIA MASYARAKAT CILANDAK PERIODE JANUARI 2023

The inability of a person to see close objects clearly can occur for several reasons, including presbyopia. Meanwhile, a person's inability to see distant objects clearly can occur for several reasons, including because his eyes have hypermetropic refractive status, myopia, astigmatism and emmetropia. This research was carried out using a descriptive method through a quantitative approach. The results showed that of the 53 Cilandak people who received a subjective refraction examination with optic 688, they were presbyopic patients with right (26.4%) and left (28.3%) hypermetropia refractive status, right and left myopia (41.5%), left com astigmatism (22.6%), right com astigmatism (18.9%), right sim astigmatism (13.2%), left sim astigmatism (15.1%), and right emmetropia (31.1%) and Emmetropia left 28.3%). In the examination of subjective refraction, determining the size of spectacle lenses for far vision for patients with hypermetropia is based on a concept, namely by providing the largest spherical lens that can produce the best vision. Meanwhile, for myopia, the weakest spherical correction lens is provided. For astigmatism, cylindrical correction lenses are given, determining the size of spectacle lenses for near vision for presbyopia sufferers with hypermetropia refractive status, which is the accumulation of lens diopters for far vision and addition. It can be concluded that the ultimate goal of examining subjective refraction in patients with presbyopia with hypermetropia, myopia and astigmatism is to determine the appropriate lens size, so that glasses made with these sizes can function as a visual aid.

Обоснование патогенетической направленности поэтапной световой иммобилизации в макулярной и витреоретинальной хирургии

Purpose. To substantiate the pathogenetic orientation of staged light immobilization in macular and vitreoretinal surgery. Material and methods. Literature data and own longterm clinical observations of the results of vitreoretinal, optoreconstructive, microsurgical and laser therapeutic, optical and refractive operations were analyzed. Particular emphasis was placed on the results of photostress-testing and differential aberrometry in macular and vitreoretinal pathology in combination with ametropia (150 eyes, 96 patients). Results. Studies have shown that changes in the retina and surgical operations for macular and vitreoretinal pathology create conditions, when the usual physiological light load begins to have a damaging effect on the retina and aggravate the course of the disease. The latter indicates the expediency of using various techniques for limiting the light load on the retina. This requires a gradual smooth transition from complete to various options for partial light immobilization. In all cases, optical photoprotection from external UV radiation, complete correction of ametropia and associated optical aberrations were shown This was indicated by a positive correlation between defocus and higher-order aberrations with an increase in visual acuity recovery time after a photostress-test. The timing of such immobilization should take into account the severity of the pathological process and the specific type of surgical intervention. This can be realized with a large arsenal of spectacle, contact, intraocular photochromic and spectral lenses that block the violet rays of visible light and attenuate the flow of rays of the blue spectral range. If full optical correction of ametropia, induced irregular astigmatism and higher order aberrations is impossible, their personalized laser correction is shown according to keratotopography and aberrometry data. This is indicated by the revealed positive correlation between the recovery time of visual acuity after the photostress-test, defocus, and higher-order aberrations. Conclusion. Gradual light immobilization in macular and vitreo-retinal surgery has a pathogenetic focus and should be more widely used in ophthalmic practice. Keywords: light immobilization, deprivation, photoprotection, macular and vitreo-retinal surgery

Highly transparent antibacterial hydrogel‐polymeric contact lenses doped with silver nanoparticles

AbstractBiocompatible polymers such as poly(vinyl alcohol) (PVA) and poly(vinyl pyrrolidone) are used to prepare hydrogels for biomedical applications, including optical applications such as the manufacture of sensing devices, cosmetic and smart, and medical contact lenses, among others. In this study, three contact lenses were prepared by doping PVP‐PVA supportive hydrogel with 0.1, 0.5, and 1 wt% of laboratory‐manufactured Ag NPs. The work demonstrates the evaluation of vision correction through each lens and the effect of changing the concentration of silver on its refractive index. The simulation involved the design and simulation of an aberrated human eye based on the Liou and Brennan model (LBM), and the insertion of the contact lenses for vision correction using the ZEMAX optical design program. This work also included a study of the antimicrobial properties of the resulting hydrogel contact lenses doped with Ag NPs. The resulting refractive index of one PVP‐PVA‐Ag lens was relatively high at 532 nm = 1.604, which made the lens provide the highest image contrast (the lowest MTF curve degradation) of 0.883 ± 0.027 at 20 cycles/mm and an RMS nearly the Airy disc diameter of 3.983 μm. PVA was used in combination with PVP for stabilizing Ag NPs to give the contact lenses an antibacterial property. Finally, the optimum contact lens with a 1 wt% Ag NPs concentration showed the highest inhibition activity.

Bazı Organik Gözlük Camlarının Spektral ve Optik Özelliklerinin İncelenmesi

In this study, the spectral and optical properties of organic spectacle lenses used as visual aids were analyzed using Jasco V-730 UV/VIS spectrophotometer device in the ultraviolet and visible light wavelength ranges. The results obtained showed that the light transmittance in the wavelength (550nm) range to which the human eye is most sensitive in the lens samples examined was over 80% and that Polycarbonate (A3) lenses had a maximum value of 97.87%. The largest cut-off edge wavelength value was found to be 390nm for the A3 lens. At 550 nm for all lenses, the absorption spectrum was below 0.07. In terms of visual quality, it is expected that the visible light transmittance is high and the ultraviolet light transmission is minimal. Our eyes are exposed to ultraviolet rays almost every day, and these rays cause damage to the ocular tissues. The degree of damage caused by the amount of ultraviolet light absorption increases. Among the organic lenses with ultraviolet protection coating, the protection of the A3 lens was relatively higher. Furthermore, optical band gap energies were found to range from 3.145 – 4.155 eV and 2.994 – 3.936 eV for direct and indirect transitions, respectively. The highest optical band gap values were found to be those of the B1 and C1 organic lenses, respectively.

Impact of myopia control spectacle lenses with highly aspherical lenslets on peripheral visual acuity and central visual acuity with peripheral gaze

Myopia control spectacle lenses with peripheral lenslets are gaining popularity because they are non-invasive and easy to manage, and ongoing clinical trials have shown promising results. This study aimed to evaluate peripheral and central visual acuity (VA) with peripheral gaze in conditions where the eyes are turned to look obliquely through the lenslets. High-contrast (100%) VA was measured at 300 cm and 10lx. For each test, two lens designs were evaluated in counterbalanced order: a spectacle lens with highly aspherical lenslets (HALs) and a standard single-vision lens (SVL). The target screen was placed at a visual angle of 21.6° to the nasal side of the right eye. Sixteen adults (27-52 years of age; spherical equivalent refraction (SER), -8.75 D to +0.50 D) wearing their habitual visual correction performed all tests monocularly. Mean (SD) central VAs with peripheral gaze through the SVL and the HAL lens were 0.08 (0.13) and 0.17 (0.12) logMAR, respectively. The HAL lens reduced central VA with peripheral gaze by 0.10 (0.08) logMAR (p= 0.03). No significant correlation was observed between the impact of the HAL lens and other factors, such as age or SER. Peripheral VA was not significantly different through the two lenses (1.09 (0.06) logMAR and 1.09 (0.09) logMAR for the SVL and the HAL lens, respectively; p= 0.86). Under high-contrast and low-luminance conditions, the HAL lens reduced central VA with peripheral gaze by approximately one line compared with the SVL. The impact on central VA did not vary with gaze direction, age or SER. The HAL lens did not affect peripheral VA in this condition.

MesoTIRF: A prism-based Total Internal Reflection Fluorescence illuminator for high resolution, high contrast imaging of large cell populations

Total Internal Reflection Fluorescence (TIRF) illumination bypasses the axial diffraction limit of light by using an evanescent field to excite fluorophores close to a sample substrate. However, standard TIRF imaging through the objective requires a high numerical aperture (NA) to generate the evanescent wave. Available lenses have a high magnification with a correspondingly small field of view—ranging from ∼50 μm to 1 mm in diameter. Switching to the older prism-TIRF configuration introduced by Axelrod in the 1980s might seem to remove the requirement for high objective NA and allow the use of existing large-field objectives. Unfortunately, these lenses are unsuitable because their throughput of light is too low for TIRF imaging. As such, high sensitivity TIRF imaging over a much larger mesoscopic field has yet to be demonstrated. We have developed a prism-based TIRF illuminator for the Mesolens—a highly corrected objective lens with an unparalleled ratio of NA to magnification. The imaging field of the Mesolens is 204 times larger than that of the TIRF objectives previously described, increasing the optical throughput of the optical system by a factor of 25 compared to an off-the-shelf microscope objective of the same magnification. We demonstrate MesoTIRF imaging of cell specimens and show the multi-wavelength capability of the modality across more than 700 cells in a single image.