Fabrication commercial vision correction lenses
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Seeing Through the Lens: American-made Eyewear
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The lens shapes often need modification to optimally fit corneas of individual test subjects. However, the choices from commercially available contact lenses are rather limited.
Here, we report a flexible method to fabricate customized hydrogel contact lenses. We showed that the fabricated hydrogel is highly transparent, with refractive indices ranging from 1. Retinal imaging using optical coherence tomography in rats wearing our customized contact lenses has the quality comparable to the control case without the contact lens.
Our method could significantly reduce the cost and the lead time for fabricating soft contact lenses with customized shapes, and benefit the laboratorial-used contact lenses in pre-clinical studies. While contact lenses are commonly used as consumer medical devices for vision correction, they have been increasingly applied in laboratories for in vivo animal retinal imaging and pre-clinical studies 1 , 2 , 3 , 4 , 5 , 6 , 7. Retinal diseases affect millions of people worldwide, resulting in loss of vision and diminished quality of life.
In the path to fully understand the disease development mechanisms and to find the best treatment, in vivo retinal imaging of animal models has gained its popularity in studying retinal diseases 8 , 9 , It provides a cost-efficient solution to comprehensively investigate retinal disease pathophysiology and therapeutic effects of possible treatments.
Custom-shaped contact lenses have been used on animal eyes to 1 minimize optical aberrations and 2 prevent corneal dehydration 11 , Eyeball optical aberration in species such as rats and mice is about five times higher compared with human eyes, which is one of the major factors limiting the resolution of animal retinal image A plano-concave contact lens can be used to reduce the geometrical aberration caused by cornea and thus improve image resolution in optical coherence tomography OCT , fundus photography, two-photon retinal imaging, and confocal retinal imaging 1 , 2 , 3 , 4 , 5.
On the other hand, corneal dehydration is a potential side effect during animal retinal imaging when animals are under anesthesia and stop blink reflex. Corneal dehydration could cause corneal clouding which affects the imaging quality and even cause permanent corneal damage Thus, the contact lens covering the cornea will help to keep it moist to ensure consistent imaging results from various animal studies 14 , Those applications, however, often require modifying the shape of the contact lenses in order to achieve optimal fitting to the cornea of each individual test subject, but the choices from commercially available contact lenses are rather limited.
Thus, it calls for the need for a flexible fabrication method to customize contact lenses that can be conveniently implemented in research laboratories.
While one would expect contact lenses to exhibit excellent optical transparency to accomplish the intended optical functions, they also need to be biologically compatible to maintain the corneal and general eyeball physiological conditions Currently, most contact lenses used in research imaging applications were made of poly methyl methacrylate PMMA 1 , 3 , 5 , 15 , PMMA is rigid and has poor oxygen permeability.
Although PMMA contact lens preserves the water content of anterior ocular media for a short time, the limited oxygen permeability can cause corneal hypoxia, corneal edema, and corneal transparency deterioration in extended wearing, which is not desirable for in vivo studies 16 , Hydrogel is found to be a more suitable material to construct contact lens for in vivo studies.
It is soft and highly permeable to oxygen compared with PMMA Hydrogel contact lens can greatly improve wearing comfort, and potentially prevent physiological changes in cornea while providing a good optical transparency during retinal imaging.
Although not frequently used in laboratorial retinal imaging, hydrogel has gained its success in the commercial contact lens market as the material of soft contact lens Despite the advantages, commercial hydrogel contact lenses for laboratorial use are rarely seen, due to the prohibitive cost for customization from leading manufacturers.
Laboratory-use contact lenses often require unique shapes to fit both specific animal corneal curvature and imaging system, e. It is difficult to mass produce commercial hydrogel contact lenses to fulfill those requirements, due to the high cost for customization and small quantity in demand. Currently, only few rigid polymer PMMA animal contact lenses are in the market and no customizable hydrogel contact lens is commercially available Here, we developed a lab-friendly method for fabricating customized hydrogel contact lenses, which is simple, rapid, and highly adjustable for particular needs in animal retinal imaging.
We further tested the biological compatibility of our customized hydrogel contact lenses using live rats and quantified the imaging quality through the contact lens via in vivo OCT retinal imaging. We chose well-studied hydrogel as the material for soft contact lens to minimize the uncertainty in the imaging experiments.
The procedure for hydrogel synthesis is adopted and simplified from previous reports to better fit the laboratorial uses 21 , After filtering out the beads, we added 0. The mixture was then stirred until clear. The thin slabs were fabricated by photopolymerizing the HEMA hydrogel solution sandwiched between two glass slides. The slab thickness was controlled by using spacers between the glass slides.
Hydrogel cylinders were fabricated by polymerizing the solution in cylindrical molds, such as glass beakers. The fabrication of plano-concave contact lenses are shown in Fig. After placing the steel balls in hydrogel solution, we polymerized the second layer. At the end, we peeled the molded hydrogel from the petri dish, and removed the steel balls. The indented sections of hydrogel were cut out for in vivo rat retinal imaging tests.
Schematic of fabrication of hydrogel contact lens using petri dish and steel balls as eyeball molds. Steel balls were placed in the petri dish as rat eyeball mold. Panel b is the magnified view of one eyeball mold highlighted by black dashed box in a.
Hydrogel was polymerized. The petri dish and the steel balls were then removed; Indented sections of hydrogel were punch cut c to form round-shape, plano-concave hydrogel contact lenses d. Optical refractive index is essential to lens materials.
A high refractive index could reduce lens thickness and improve wearing comfort We determined the refractive index of our hydrogel by measuring the light refraction in the material.
The angle of refraction was measured six times for each wavelength to calculate the mean value. As shown in Fig. The transparency is a fundamental requirement for contact lens materials.
We measured the transmission spectrum of our fabricated hydrogel using a commercial microscope DMIM, Leica equipped with a spectrometer Shamrock i, Andor Technology.
White illumination light was weakly focused on the hydrogel thin slabs. The transmitted light was collected by the objective lens and relayed to the spectrometer to measure the transmission spectra.
The latter two determine the actual attenuation caused by the hydrogel material. We first estimated the optical loss from the hydrogel surface. Thus, to determine the actual optical attenuation induced by the hydrogel, we estimated the reflection from two air-hydrogel interfaces using our experimentally measured refractive index in Fig. When the slab thickness is comparable to that of commercial contact lenses, e.
Low modulus could increase wearing comfort, while the material also needs to be sufficiently stiff to maintain the shape during wearing. Thus, the modulus of commercial contact lenses is commonly found within the range from 0.
The result of the stress vs. Noticeably, the test is on a bulk material. It may explain why our value is relatively larger than the reported values of other hydrogel materials with the similar water content, which are normally obtained from thin slabs.
Black dots: experimental data. Red line: linear fitting. R 2 : adjusted coefficient of determination. It shows how easy water can spread on a solid surface.
For contact lenses, hydrophilic surfaces with small contact angles are desired to support a ocular tear film between the lens and the cornea, and to increase the wearing safety and comfort We repeated the measurement three times and calculated the mean value. The contact angle of our hydrogel is measured to be A representative image of sessile drop measurement is shown in Fig.
Our contact angle is smaller than that of senofilcon A and balafilcon A, comparable to lotrafilcon A, and larger than etafilcon A, showing a hydrophobicity comparable to commercial hydrogel materials Details of the OCT system was described previously When imaging the retina without using the contact lens or using the PMMA lens, we used a relay-lens group to focus the light onto the retina.
When imaging the rat retina through the hydrogel contact lens, as the result of the plano-concave contact lens, most dioptric power of the rat eyeball was cancelled and a scanning lens can be directly used to image the retina. To achieve a fair comparison, we set the same numerical apertures for both the lens-relay system and the scanning lens system to be 0. With the similar imaging power, the scanning lens system could inspect the opacity of the contact lens material and eyeball condition changes e.
The acquisition time was about 2 seconds per image. We used wild-type pigmented rats for OCT imaging. Pictures of a hydrogel contact lens and a rat wearing the hydrogel contact lens are shown in Fig. The lens fitted the rat eyeball well and covered the whole cornea. No bubble was observed between the cornea and contact lens.
The retinal images from the rat eyes with and without the contact lenses are shown in Fig. All images clearly show retinal vessel cross sections and different layers of the retina, indicating that the contact lens did not deteriorate the axial resolution of the OCT.
The en face OCT images shown in Fig. Main vessels are clearly shown in all images, and some retinal arterioles and venules can also be seen but not clearly resolved, which is due to the limited contrast of blood within the NIR spectral range. White dash lines in panels d,f,h are the locations of the B-scan images in panels c,e,g , respectively.
QI evaluates the OCT image quality from reflectivity values in each B-scan, which is more direct and accurate than analyzing from en face images, since en face images are derived from B-scans and some information might be lost during mean-value projection.
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Fabricating customized hydrogel contact lens
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The leading vendors are launching new variants with advanced features, which include advanced technologies providing the best visual acuity and ocular comfort to consumers in the market. The global contact lenses market is driven by the launch of specialized products with advanced features, which provide high optical comfort, better oxygen permeability, high visual acuity, and minimal or no risk of lenses-related adverse effects. The market research report provides in-depth market analysis and segmental analysis of the global contact lenses market by design, usage, application, distribution channels, and geography. The report considers the present scenario of the global contact lenses market and its market dynamics for the period ?
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Да-да, конечно, - быстро проговорил немец, натужно улыбаясь. Он подошел к туалетному столику, где лежал бумажник. - Сколько. Беккер изобразил крайнюю степень негодования.
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The global contact lenses market is estimated to reach revenues of more than $12 billion by 2024
Две эти команды разделяло меньше одной минуты, но она была уверена, что разговаривала с коммандером больше минуты. Сьюзан просмотрела все команды. То, что она увидела, привело ее в ужас. С интервалом в три минуты была зарегистрирована вторая серия команд запирания-отпирания.
Согласно регистру, кто-то открывал ее компьютер, пока ее не было в комнате. Но это невозможно.
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Сьюзан ничего не ответила. - Я вижу, ты выдающийся командный игрок. Может быть, можно взглянуть? - Он встал и начал обходить круг терминалов, двигаясь по направлению к. Сьюзан понимала, что сегодня любопытство Хейла может привести к большим неприятностям, поэтому быстро приняла решение.
О его существовании знали только три процента американцев. - АНБ, - пошутил приятель, - означает Агентство, которого Никогда не Было. Со смешанным чувством тревоги и любопытства Беккер принял приглашение загадочного агентства.
- Но он знал, что сказанного не вернешь.
Испанская церковь гордится тем, что ей принадлежат его останки. Испанская церковь. Беккер отлично знал, что в Испании только одна церковь - римско-католическая. Католицизм здесь посильнее, чем в самом Ватикане.
- У нас, конечно, не все его тело, - добавил лейтенант.
Но не искалеченная рука привлекла внимание Беккера. Он увидел кое-что другое. И повернулся к офицеру. - Вы уверены, что в коробке все его вещи. - Да, конечно, - подтвердил лейтенант.
Чтобы увидеть, как какой-то молодой профессор украл его мечту. Стратмор холил и лелеял Сьюзан, оберегал. Он заслужил. И теперь наконец ее получит.