Soft Lenses Research Articles

Intraocular devices associated adverse events reporting system in India.

Intraocular devices associated adverse events reporting system in India.

Design of Efficient Power Supply for the Proper Operation of Bio-Mimetic Soft Lens

Soft Robotics is one of the emerging and top-notched researched fields in Robotics which collaborate and Interact with Human Machine Interface (HMI). Several power electronics and electrical devices are used for the proper operation of these robots, among them high voltage power supply plays a vital role. Several approaches are used for the design of the high voltage power supply but still there is a deficiency in the design of the power supply which fulfill our desires level (highly efficient and less complex). This paper presents the efficient power supply for the control of bio-mimetic lens. The proposed power supply is designed by the use of boost converter, single phase inverter and the cock-croft Walton Voltage Multiplier. The work employs the use of power electronics for the achievement of the efficient high voltage power supply and boost the level of voltage up to 5 kV. Numerical simulations are performed for the comprehensive testing of the proposed model. Simulink is used for designing of the high voltage supply for simulation work. More-over the results are verified with the designing of laboratory setup. The experimental results are close to the simulation results with an error less than 3%. This proof the validity of proposed high voltage power supply.

일일착용 고함수율 소프트렌즈 착용 시 정상안과 건성안의 눈물량과 렌즈움직임 비교

일일착용 고함수율 소프트렌즈 착용 시 정상안과 건성안의 눈물량과 렌즈움직임 비교

Cytomorphological assessment of the lid margin in relation to symptoms, contact lens wear and lid wiper epitheliopathy

Purpose: Lid wiper epitheliopathy (LWE) is insufficiently understood from a cytological perspective. This study explored the relationship between lid margin cytomorphology, LWE, contact lens wear, and lens-related symptoms.Methods: Habitual, symptomatic (n = 20) and asymptomatic (n = 20) soft, rigid gas permeable (n = 18) and non-contact lens wearers (n = 19) were enrolled. LWE was graded using lissamine green and the Korb scale. Subjective symptoms were assessed using the Ocular Surface Disease Index and the Contact Lens Dryness Evaluation Questionnaire. Impression cytology samples obtained from the central upper and lower lid margins of both eyes stained histologically to highlight keratinization and imaged using high-resolution microscopy. A masked investigator digitally delimited and measured the average sagittal width of the lid wiper conjunctiva and mucocutaneous junction using ImageJ. Results:The upper lid wiper conjunctiva measured 424 ± 171 μm, 404 ± 75, 667 ± 219 and 266 ± 64 in asymptomatic soft, symptomatic soft, rigid and non-contact lens wearers, respectively. The corresponding lower lid wiper conjunctivae measured 141 ± 57 μm, 232 ± 150, 519 ± 212 and 225 ± 102, which was significantly narrower than that of the upper eyelid in most cases (p < 0.05). Symptoms were not associated with lid margin changes; however, rigid lens wear and clinical LWE were associated with histologically enlarged lid wiper conjunctival areas and increased keratinization.Conclusion: A novel, exploratory account of histological measures of LWE and cytomorphological change associated with contact lens wear suggests mechanical or frictional cellular insult is occurring at the lid wiper conjunctiva.

Ocular thermography in contact lens wearers

AbstractThe infra‐red thermal images have been used in the past for measuring the ocular surface temperature, its main advantage being the non‐invasive means. It is well‐known for its ability to detect the pathological and physiological changes in the eye.There are a few studies about ocular surface temperature and contact lenses. Some authors found that insignificant changes in ocular surface. temperature in soft contact lenses did occur, but other authors described that the pre‐lens tear film in soft lens wearers is cooler than that of the non‐CL‐wearing eye, while the temperature of the post‐lens tear film beneath the CL is higher. Regarding hard and gas permeable corneal contact lenses, the changes are between 0.5–1.5°C compared to the naked eyes. However, gas permeable scleral contact lens seems not to modify the ocular surface temperature despite the presence of the tear film stagnation under the lens.This presentation will navigate in the scientific literature about the usability and applicability of ocular thermography in contact lens wearers.

Technology of contact lenses coloring

The technology of contact lenses coloring is viewed as a way of giving soft contact lenses the tone that is differ-ent from the usual one. Various methods for coloring soft lenses are reviewed; their advantages and disadvantages are outlined. Application features depending on the desired result are described. Differences between tinted, colored and decorative lenses are given.

Dewetting of different soft lens materials before and after stress test with lipid containing rewetting eye drops using Non-Invasive Keratograph Drying Up Time (NIK-DUT)

Purpose The primary objective of the study was to determine differences between surface dewetting of SCL materials out of PBS before and after treatment with lipid containing rewetting drops in vitro using a modified corneal topographer K5 M (Non-Invasive Keratograph – Drying-Up Time [NIK-DUT]).

A piecewise controllable tunable lens with large aperture for eyewear application

Here, we present a piecewise controllable tunable lens with large aperture which is composed of a soft polymer lens, an shape memory alloy (SMA) driven iris diaphragm and an SMA driven latch. The SMA driven diaphragm expands the soft polymer lens in the radial direction, thereby varying the focal length. The soft lens has the large aperture of 35 mm in diameter and shows focal length tunability of 31.7% (175–230 mm) under current signal control. The solid characteristics of the polymer lens assure robustness against gravitational force. In addition, the locking mechanism enables the tunable lens to be piecewise controllable and provides high energy efficiency. Due to these advantages, the fabricated tunable lens module can be implemented in various eyewear applications.

A one-year prospective study on scleral lens wear success

PurposeTo report the success rate of scleral lens wear and the lens handling learning curve from the wearers perspective. MethodsNinety-five participants were consecutively screened for enrollment in a prospective study. Participants were divided into two groups: ICGroup (71 participants with irregular corneas) and RCGroup (24 participants with regular corneas). Participants attended several visits: Baseline, Lens Dispense Visit (LDV), 1-month, 3-month, 6-month and 12-month follow-ups. The number and causes of scleral lens discontinuation and the time to correctly apply the lens for the first time at the LDV were evaluated. During follow-ups, participants answered a questionnaire regarding scleral lens wear (mean number of hours/day and days/week of lens wear, methods used for handling, number of attempts to correctly apply and remove the lenses). ResultsSixty-nine participants (73 %) successfully completed the 12-month period. Twenty-six participants (27 %) discontinued scleral lens wear. None of the discontinuations were due to adverse events. The success rate (number of participants that wore the lenses for the 12 months) was 77 % in ICGroup and 58 % in RCGroup. The main reasons for scleral lens discontinuation were handling issues (35 %) and discomfort (19 %). 36 % of participants required <15 min to correctly apply the lens at the LDV, however 13 % required >60 min (participants that wore spectacles, soft lenses or had no correction method at Baseline). The mean wearing time (hours/day and days/week) increased significantly from 1-month to 12-month appointments: from 9.8–11.1 h and 5.1–5.6 days in new scleral lens wearers, while the number of attempts to correctly apply and remove the lenses decreased significantly. ConclusionsThe success rate was 73 % during this prospective 12-month follow-up study. The main reasons for drop-out were handling issues and discomfort. Participants who continued scleral lens demonstrated increased handling skills.

Smart Lenses with Electrically Tuneable Astigmatism

The holy grail of reconfigurable optics for microscopy, machine vision and other imaging technologies is a compact, in-line, low cost, refractive device that could dynamically tune optical aberrations within a range of about 2–5 wavelengths. This paper presents the first electrically reconfigurable, fully elastomeric, tuneable optical lenses with motor-less electrical controllability of astigmatism in the visible range. By applying different voltage combinations to thin dielectric elastomer actuator segments surrounding a soft silicone lens, we show that the latter can be electrically deformed either radially or along selectable directions, so as to tune defocus or astigmatism, up to about 3 wavelengths. By mounting the new lenses on a commercial camera, we demonstrate their functionality, showing how electrically reconfiguring their shape can be used to dynamically control directional blurring while taking images of different targets, so as to emphasize directional features having orthogonal spatial orientations. Results suggest that the possibility of electrically controlling aberrations inherent to these smart lenses holds promise to develop highly versatile new components for adaptive optics.

Wavefront shaping in underwater with soft gradient-index metasurfaces at ultrasonic frequencies

Metasurfaces are planar metamaterials with a subwavelength thickness that allows wavefront shaping by introducing in-plane variations, namely, gradients, in the spatial wave response of these flat structures. Most of the recently reported acoustic metasurfaces were designed to control air-borne waves. Here, we report a new class of acoustic gradient-index (GRIN) metasurfaces engineered from soft graded-porous silicone rubber with a high and tunable acoustic index for broadband ultrasonic 3-D wavefront shaping in aqueous media. The functionalities of these soft flat lenses are illustrated through various experiments, which demonstrate beam steering and beam focusing, as well as vortex beam generation in free water. These new GRIN metasurfaces may have important applications in various domains using designed ultrasonic fields (biomedical imaging, industrial non-destructive testing, contactless particle manipulation), since their fabrication is very straightforward with common polymer science engineering. Y. Jin, R. Kumar, O. Poncelet, O. Mondain-Monval, and T. Brunet, Nat. Commun. 10, 143 (2019).

Acanthamoeba keratitis related to contact lens use in a tertiary hospital in China

BackgroundTo report the clinical and microbiological features of Acanthamoeba keratitis (AK) related to contact lens use in a tertiary hospital in China.MethodsIn this retrospective study, the medical results of 61 cases of AK related to contact lens use from January 2000 to December 2017 were reviewed. The data included patients’ demographics, lens type, history, risk factors, disease stages, corneal scraping and culture reports, and treatments. Moreover, genotypic identification of some of the isolates was carried out with a PCR assay and sequence analysis of the 18S ribosomal DNA gene.ResultsThere were 64 eyes included in the study. A total of 32.8% of the patients wore soft contact lenses, and 67.2% of patients used overnight orthokeratology. In the cases (20 eyes) in the early stage, 65% (13 eyes) had positive results according to Giemsa-stained smears, and 0.9% sodium chloride (NaCl) wet mounts revealed trophozoites in 7 eyes (35%). Six eyes (30%) were diagnosed by confocal microscopy combined with clinical signs. In the orthokeratology patients, 87.8% (36/41) rinsed their lenses and/or cases with tap water; 55% of soft-lens wearers wore their lenses while showering. The genotype of 9 isolates was determined, and all the strains belonged to genotype T4. In the orthokeratology group, the number of patients who required therapeutic penetrating keratoplasty after 2005 was less than that before 2005 (chi-square test, χ2 = 4.209, P = 0.04).ConclusionsMore than two-thirds of the cases were associated with orthokeratology. Examinations with Giemsa-stained smears, 0.9% NaCl wet mounts and confocal microscopy should be performed for patients who are highly suspected of having early-stage AK to help with early diagnosis. In the orthokeratology group, the rate of therapeutic keratoplasty after 2005 was less than that before 2005.

A Biomimetic Soft Lens Controlled by Electrooculographic Signal

AbstractThanks to many unique features, soft robots or soft machines have been recently explored intensively to work collaboratively with human beings. Most of the previously developed soft robots are either controlled manually or by prewritten programs. In the current work, a novel human–machine interface is developed to use electrooculographic signals generated by eye movements to control the motions and the change of focal length of a biomimetic soft lens. The motion and deformation of the soft lens are achieved by the actuation of different areas of dielectric elastomer films, mimicking the working mechanisms of the eyes of human and most mammals. The system developed in the current study has the potential to be used in visual prostheses, adjustable glasses, and remotely operated robotics in the future.

International survey of contact lens fitting for myopia control in children

PurposeTo determine the extent of contact lens fitting for myopia control (MC) in children (defined as ≤ 17 years of age) worldwide and to characterize the associated demographics and fitting patterns. MethodsSurvey forms were sent to contact lens fitters in 66 countries between January and March every year for eight consecutive years (2011–2018, inclusive). Practitioners were asked to record data relating to the first 10 contact lens fits performed after receiving the survey form. Data were analysed for those countries reporting ≥ 100 contact lens fits to children. ResultsData were analysed for 535 MC fits and 23,295 other (non-MC) lens fits undertaken in 31 countries reporting ≥ 100 contact lens fits to children, with 52.1% of MC fits and 12.0% of non-MC fits being with rigid lenses (p < 0.0001). Overall, MC lenses represented 2.3% of all contact lens fits to children, with significant differences between nations (p < 0.0001), ranging from no MC fits recorded in the Czech Republic, Greece, Japan, South Korea and Puerto Rico, to 24.9% in Austria. There has been an increase in contact lens fitting for MC over the survey period (p < 0.0001). MC contact lenses were fitted to younger children compared to non-MC lenses (MC, median 13 years vs. non-MC, median 15 years) (p < 0.0001). There was no sex bias in the fitting of MC lenses (p = 0.89). ConclusionsMC lenses are currently being prescribed for younger children in equal measure in terms of soft vs. rigid lenses and males vs. females. The extent of MC fitting is low and varies between nations. The gradual increase in MC fitting throughout the survey period perhaps reflects growing concerns among practitioners over the myopia epidemic.

Effect of age and contact lens wear on corneal epithelial dendritic cell distribution, density, and morphology

PurposeContact lens wearers aged 15–25 years are at higher risk of corneal inflammation, yet little is known about corneal inflammatory state in this group. Previous investigations show density of corneal epithelial dendritic cells (CEDC) may increase with contact lens wear. However, it is not known how corneal distribution or morphology of CEDC alters with lens wear or whether these markers are affected by age. This study characterised CEDC in adolescent and young adult contact lens wearers to determine effects of contact lens wear and age on CEDC density, distribution and morphology. MethodForty participants (20 contact lens wearers, 20 healthy non-wearers; age 16–36 years; 16M:24F) completed this pilot study. Corneal images were captured using in vivo confocal microscopy (HRTII, Rostock). CEDC were manually counted in a 1 mm2 area of the central and mid-peripheral cornea, and ratio of central to midperipheral density was calculated. CEDC morphology and dendrite length were graded. Differences between groups and between regions, and associations with age were examined. Significance was determined at P < 0.05. ResultsA lower ratio of central to mid-peripheral CEDC density was found with younger age (ρ = 0.42, P = 0.01). CEDC morphology was not associated with age or contact lens wear. CEDC density in the mid-peripheral cornea was higher in soft lens wearers than non-wearers (P = 0.04), but central density did not differ. CEDC density and morphology were not significantly different between centre (median density 11 cells/mm2, range 0–120) and mid-periphery (10 cells/mm2, 0–58). ConclusionDensity, distribution and morphology of CEDC do not differ in established contact lens wearers. A relatively lower density of CEDC in the central cornea of younger patients may allude to a more naive immune status in this group and warrants further study. Decreased central CEDC density identified in orthokeratology lens wear requires confirmation in a larger group.

Influence of Scleral Lens on Intraocular Pressure

Purpose&#x0D; Since Scleral Lenses (SL) rest entirely on the sclera and may affect underlying anatomical structures that may influence aqueous humor flow, it is important to determine the effect of SL wear on intra-ocular pressure (IOP).&#x0D; &#x0D; Methods&#x0D; Nine subjects with normal corneas were recruited for an Institutional Review Board-approved study. Best fit SL from a 15.8 mm diameter 0.4mm thick diagnostic-lens set was fitted on a randomly selected eye, with a silicone-hydrogel soft lens (soft lens) on the other eye. Three IOP measurements were taken with rebound iCare tonometer prior to lens application (baseline data measured at about 9:30AM), and immediately after lens removal (final data measured at about 5:30PM). Baseline and final lens vault was determined with anterior segment Zeiss optical coherence tomography (OCT). Mean baseline and final IOP for each eye was analyzed with a Student-t-test, 2-way repeated ANOVA, and the Bland-Altman plot.&#x0D; &#x0D; RESULTS&#x0D; IOP was elevated with SL wear for all subjects. Soft lens eyes showed a slight elevation for some but decreased in others. Mean IOP change was 5.81 ± 1.62 mm Hg for SL and -0.62 ± 0.88 mm Hg for soft lens eyes. When mean IOP in SL eyes was compared to soft lens eyes, unpaired t-test showed a significant difference (p &lt;0.05) between the means. Bland-Altman bias was 6.43 (SD of bias 3.139). Repeated ANOVA also showed a significant difference between baseline and final IOP.&#x0D; &#x0D; CONCLUSIONS&#x0D; The results indicate that SL wear can elevate IOP. Eye care practitioners (ECP) must consider this possible outcome in treating patients wearing SL. Additional studies are needed to determine the clinical implications of SL wear on IOP.

Late Night Study 2: End-of-Day Assessment of Asymptomatic and Symptomatic Soft Lens Wearers

Late Night Study 2: End-of-Day Assessment of Asymptomatic and Symptomatic Soft Lens Wearers

Remote hydrodissection.

We describe a technique for performing hydrodissection in which the cannula tip is not advanced beyond the capsulorhexis edge, nor embedded into the cortex, but instead is placed within the capsulorhexis boundaries, pointing to the capsulorhexis edge, and angled slightly posterior to it. The fluid stream squirted from the cannula creates a cleavage plane between the capsule and cortex (hydrodissection), with a distinct wave dissecting the posterior capsule off the overlying cortex. By later rotating the angle slightly more posteriorly, hydrodelineation occurs, with the resultant "golden ring," and often, multiple "golden rings." The cleavage planes obtained using this technique may be more precise than when embedding the cannula tip under and beyond the capsulorhexis edge. This "remote hydrodissection" technique is easy and reproducible with soft and medium lenses, becoming more difficult to perform with harder cataracts. Hence, we recommend that this modification should initially be learned/tried on softer lenses.

Flat acoustics with soft gradient-index metasurfaces

Recently, metasurfaces have been proven to be effective and compact devices for the design of arbitrary wavefronts. Metasurfaces are planar metamaterials with a subwavelength thickness that allows wavefront shaping by introducing in-plane variations, namely, gradients, in the spatial wave response of these flat structures. Here we report a new class of acoustic gradient-index (GRIN) metasurfaces engineered from soft graded-porous silicone rubber with a high acoustic index for broadband ultrasonic three-dimensional wavefront shaping in water. The functionalities of these soft flat lenses are illustrated through various experiments, which demonstrate beam steering and beam focusing, as well as vortex beam generation in free space. These new GRIN metasurfaces may have important applications in various domains using designed ultrasonic fields (biomedical imaging, industrial non-destructive testing, contactless particle manipulation), since their fabrication is very straightforward with common polymer science engineering.

Predictability of intraocular lens power calculation in eyes with average axial lengths: optical versus ultrasonic biometry

Objective The aim of this study was to compare the partial coherence interferometry to ultrasound (US)-based biometry in intraocular lens (IOL) power calculation in eyes with average axial length (AL). Patients and methods One hundred eyes with AL of 21–24 mm having cataract as the only ocular pathology were included in the study from November 2016 to October 2018. Fifty eyes were subjected to US biometry and 50 eyes were subjected to Zeiss IOL-Master optical biometry followed by IOL power calculation. All patients underwent phacoemulsification by experienced surgeons with intra-bagal implantation of one-piece soft hydrophilic intraocular lens. AL, keratometric reading, anterior chamber depth, and intraocular lens power were compared. Actual postoperative spherical equivalent (SE), mean absolute error, and predicted error were calculated. Results No statistically significant difference was found between the two groups regarding the AL, keratometric reading, anterior chamber depth, IOLs power, predicted postoperative SE, and actual postoperative SE (P=0.36, 0.20, 0.57, 0.39, 0.31, and 0.09, respectively). The US group had significantly higher predicted error and mean absolute error than IOL-Master group (P=0.03 and 0.01, respectively). Conclusion IOL-Master optical biometry is slightly more accurate than US biometry for intraocular lens power calculation in eyes with average AL, whereas A-scan biometry is still a cost-effective method.