Science topic

Cornea - Science topic

The transparent anterior portion of the fibrous coat of the eye consisting of five layers: stratified squamous CORNEAL EPITHELIUM; BOWMAN MEMBRANE; CORNEAL STROMA; DESCEMET MEMBRANE; and mesenchymal CORNEAL ENDOTHELIUM. It serves as the first refracting medium of the eye. It is structurally continuous with the SCLERA, avascular, receiving its nourishment by permeation through spaces between the lamellae, and is innervated by the ophthalmic division of the TRIGEMINAL NERVE via the ciliary nerves and those of the surrounding conjunctiva which together form plexuses. (Cline et al., Dictionary of Visual Science, 4th ed)
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I want to Immunostain retina vasculature, so I'm looking for a protocol to embed the retina in wax, do I need to embed and section the whole eye or do I have to remove the cornea and the lens and embed the eye cup and is there any tips on how to handle the retina during the embedding????
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Yes, it would be good if you could isolate the lens, since it could break while sectioning, and breaking the rest of the sections.
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Hello everyone.
Are there any resources explaining how Pentacam calculates Zernike coefficients of the cornea?
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Mario Rehnert, thank you very much.
That's a good point.
For the ray-tracing, I used the 'front' and 'back related to front' data from the elevation file rather than the pachymetry data. After your comment, I used pachymetry data, which improved my results.
However, there is still a total of 20% difference between the extracted coefficients and the coefficients provided by Pentacam.
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I am transplanting a polymer (Parylene-C) coated structure in the anterior chamber of the eye and expect it to reside on the iris, however, almost all of them get adhered to the cornea and not the iris. Is there any eye-physiology-related explanation to that?
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Very interesting video Vladimir Siplivy , thanks!
That is right, the iris movement seems predominant. However, we do see tissues being transplanted to the ACE and they all got vascularized. Now, we are aiming to position our device at the angle of the eye where iris movements are minimal.
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I am doing IHC with mouse cornea and after adding Prolong Gold Anti-fade mounting media, there are now bubbles on the slides. How can I remove the bubbles?
Thank you!
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I did some research and found my answer. Thank you!
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The behavior of bacterial/fungal keratitis do not not allow the doctor to wait for laboratory support to start treatment as every moment is crucial in saving the cornea. After having sent the swabs for identification of infecting organism and culture/sensitivity reports, the best option seems in following "Imtiaz's law of inversely proportional hypopyon" which states that in fungal keratitis, hypopyon is less than the size of ulcer in contrast to bacterial ulcer where hypopyon is usually more in size than the ulcer area relatively. Therefore immediately embarking on treatment on the basis of this law seems justified.
Ref: Shah SIA et al: Concise Ophthalmology Text & Atals. 5th ed. Param B (Pvt.) Ltd. 2018: 48-49
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Dear Alejandro Rodriguez-Garcia, your recommendation clearly indicates that you are a transparent researcher with a deep sense of sympathy for humanity and not a researcher like robot who do not have a logical sense of elasticity in assessment and do not possess innate innovative capability. Hats off.
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Bom dia!
O meu artigo " Perfil epidemiológico dos doadores de córneas e doadores de órgãos de cinco hospitais do Estado do Espírito Santo, Brasil " está cadastrado com o ano de 1969, mas o ano correto é 2016. Como eu faço para corrigir?
Att.,
Flávia Marini Paro
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Olá Flavia,
Fiz uma consulta e vi que o artigo está com a citação correta no ano de 2016. Você pode verificar abaixo. Quais foram os procedimentos que você utilizou para atualizar os dados da citação?
Rocon, P. C., Almeida, A. V. de, & Paro, F. M. (2016). Perfil epidemiológico dos doadores de córneas e doadores de órgãos de cinco hospitais do Estado do Espírito Santo, Brasil. Revista Brasileira De Pesquisa Em Saúde/Brazilian Journal of Health Research, 17(1), 56–64. Recuperado de https://periodicos.ufes.br/rbps/article/view/12450
Muito obrigado por compartilhar,
Jean
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Hi everyone,
Could someone please explain how I can reconstruct the cornea shape using elevation data from a topography system? The data is in rectilinear coordinates and depicts the difference in elevation with respect to a reference sphere.
At first, I believed that simply adding the height of the reference sphere to the data at each location (x,y) would suffice. However, the attached article made me ponder by citing complicated methods like Zernike polynomials.
Is there anything I'm overlooking?
Let me know your thoughts.
Thank you,
Payman.
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A distortion will exist or be expected because of dealing with different projections of the same space. A best fit sphere minimizes the error, therefore what I would do is knowing the orientation of the rectilinear coordinate system, determine the center of the sphere and its xyz offsets and orientation, aligning them in that system. Then at a regular angular intervals of choice to cover the required surface area, determine the spherical coordinates.
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hi guys, I am doing experiments with cornea epithelial cell line. In my experiment, I have to wash away the residual drug in cells with PBS, and I use 96 wells plate(flat bottom). After the washing procedure, I always find a lot of cells are washing away along with the drug. The intensity of the cell is about 80%-90% in the well before I do the experiment. And the number of losing is hard to control so it affected the experiment results. I want to ask if there are any tips or suggestions for the washing procedure on 96 well plates? Thank you, guys.
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I am wondering whether you have experienced such cell loss only on the 96-well plate or also on other flasks or dishes. Anyway, given that your cell line can attach and grow well on the plate but in the absence of the drug, pre-coating the bottom of wells, and spinning down the plate before aspiration may help. If detachment from the bottom is due to drug toxicity, its treatment protocol may need to be modified, e.g., at a longer period of time at a lower concentration.
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I’m working on an image processing project with aim of developing A method to differentiate between healthy and diseased cornea. I have images taken from SHG microscopy for the collagen bundles in the human corne. I have used GLCM and I obtained the correlation, energy, homogeneity and contrast of each image but the results are not good enough to use them as a solid evidence to classify the images. please can anyone suggest for me any other method that can be used to classify collagen bundles image that can be done witthin a short time or a method to enhance my glcm results.
Thank you in advance
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For how long period, the cattle remains infective after getting the Pink Eye and when can the animal be safely return to the herd?
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Infectious bovine kerato-conjunctivitis, or IBK:
The bacterium Moraxella bovis (M. bovis) is the main infectious cause of pinkeye in cattle.
M. bovis organism is sensitive to Oxytetracycline and penicillin.
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There are so many different rodent OCT instruments and rodent fundus cameras on the market. Generally, the market is dominated by a Phoenix Lab Micron III/IVsystem however there little information about what performance you can expect from the different instruments. I was thinking of writing a review of the pros and cons of different OCT/Fundus machines so I'm looking for the OCT images of the mouse retina and cornea as well as fundus images to try to understand which instrument having the best resolution on the market. However, it is naturally quite difficult to have all the instruments tested. (I have data for Micron III, IV, OcuScience iVivo). Also, welcome your thoughts on OCT/Fundus user experience. It may result in the review paper, but too early to say. If you provide the OCT/Fundus images I'll contact you if we try to use it in the review.
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Dear, Brent A Bell Well, I have OCT images of the mouse retina on several instruments including Micron IV, Bioptigen, OcuScience with a few more it can be the foundation for the review. I hope to find few more collaborators to complete the set.
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In a primary congenital glaucoma child who has a cloudy cornea that makes it impossible to do a goniotomy what factors (clinical/demographic) influence one to make a decision between a trabeculotomy or a combined trabeculotomy/trabeculectomy?
I am aware that they do these combined procedures in some regions of the world. This would greatly help decision making especially in countries without any data on outcomes.
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Please follow Dr A K Mandal's (LV Prasad Eye Institute, India) work. He has extensively reported his results of Combined Trabeculotomy with Trabeculectomy in children with PCG, Aniridia, SWS. It works best for children <2 years with cloudy corneas (common presentation in developing nations).
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what is the best machine learning method , to segment and extract the length , angle and the size of collagen bundles pictures obtained from the human cornea?
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It will depend on your database. You can start with traditional computing, extracting resources, such as filters, lbp, surfing, etc... and if the result is not what you expected, you can try methods that require more processing, such as artificial neural networks and finally deep learning, if you have a robust database and gpu.
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I am analyzing the tissue damage to the mouse cornea tissue after incubated a kind of medium. The protocol is
1) mouse cornea was incubated in the medium for one day
2) embedding the cornea with OCT compound and snap frozen in liquid nitrogen
3) cryosection
4) HE staining
The control is naïve cornea that embeded with OCT, cryosection and HE staining. In fact, the thickness of incubated cornea should be thicker than the naïve one (3-4 times) from the optical coherence tomography. But the thickness of the incubated and naïve cornea from cryosection HE staining is similar. What the problem is? Should I use paraffin section? Why the thickness of incubated cornea is changed after cryosection and HE staining? Many thanks!
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use cryosectioning in which the tissue is immersed in cryoprotectant, frozen and then cryosectioned
fresh tissues were immersion-fixed by rapidly replacing the PBS with 10% formalin (Fisher Scientific, Pittsburgh, PA) for 1 minute at room temperature, taken out briefly for imaging and then returned to fixative for 24 hours. To study the effects of sectioning, the 24-hour fixed PPONHs were further processed, including immersing in a 30% sucrose solution for cryoprotection and embedding in Optimal Cutting Temperature compound (Fisher Scientific, Pittsburgh, PA) before freezing in liquid nitrogen (−196 °C). Frozen blocks of PPONH tissue were then cryosectioned coronally at 30 µm thickness (Leica CM3050 S, Leica Biosystems Inc., Buffalo Grove, IL)
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With increasing COVID-19 infected cases worldwide, people around the world are practicing strict personal hygiene against infection. Alcohol-based hand sanitizer was one of the best sellers, but will it cause eye injury?
What if it is accidentally split into the eyes?
Will prolonged exposure to the evaporated alcohol cause eye problems?
Have you even encountered such an injury in your life or medical practice?
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If it irritates the eyes then I think it is harmful. It might be better to wear a face shield instead.
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Hi, everyone,
I am looking for a cornea topography (elevation based) source file. Anybody know where can I find cornea topography data to be loaded and opened on a personal computer?
Thank you in advance.
Payman
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Not sure what you are looking for exactly, but you can find some average elevation maps measured with CASIA2 and with Pentacam AXL in the supplementary data of: https://doi.org/10.1371/journal.pone.0223770 .
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How are the patients with severe damage in corneal or retinal surfaces being treated currently? As far as I understand, for such implantation the shortage of donor, poor graft survival and allergenic rejection of natural graft are some of the biggest problems. I am curious if any synthetic implant could successfully pass through FDA channel? Please share if any knowledge on this. Thanks!
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Hi Nadim, For the cornea we have several options. You would want to look at the use of 1. Boston Keratoprosthesis 2. Alphacor (https://dx.doi.org/10.1038%2Feye.2011.122) 3. KeraKlear 4. Dohlmans Artifical Cornea. For the retina, you can look at : 1. Argus family of retinal implants 2.Nanoretina NR600
The FDA approval is usually via the Humanitarian Device Exemption (https://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfhde/hde.cfm?id=H110002)
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What is the role of atropine here?
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No indication for an ocular surface condition like phlyctenular keratoconjunctivitis, which is a type-IV (cell-mediated) hypersensitivity reaction to high-MW bacterial (Staph, mycobacteria) capsule proteins. Phyctenular ulceration may occur, but it usually involves the gelatinous proliferative tissue on its apical portion, rather than the corneal epithelium. On the other hand, AC inflammatory reaction is not a common feature of the disease; therefore, ciliary spasm is not frequently present.
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Hi everyone, I have a question with regards to the cell lysis protocol.
I'm considering to do RNA/protein extraction from cornea cells. As a start, we realised that the cornea morphology between keratoconus patients and normal controls are quite different (in terms of corneal thickness, cell structure, etc.).
As the overall corneal structure are more elastic from other tissues due to the presence of fibroblasts (keratocytes) in the stroma layer, where can I find suitable protocols on cornea tissues/cells lysis to refer on? And are there any other suitable methods to lyse these cells for various downstream applications such as gene expression or western blot?
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I agree with Sebastian. For RNA, just repeat the procedure he mentioned adding trizol to the mortar.
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I was wondering whether it is possible to image transparent tissue like cornea, with dark-field imaging technology? I'd appreciate any help :)!
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I think it is possible but i don't find research about this technical in cornea, just in retina
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It offers some evidence that the concern I express here has some basis. Spray-able after-shaves containing alcohol (or worse!) can deliver undesirable material to a very sensitive part of the body - the corneal surface. Unlike alcohol in the mouth, there is no copious saliva in the eye to dilute and wash down undesired substances. Even if washed down by tiny amounts of tears, they can do further damage down the nasal tract. Calling after-shave solutions external applications and ignoring the risks they pose could be dangerous.
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Additional Remarks on sprayable after-shaves
1) You may wish to refer to FDA's position on cosmetics
2) Recently, I looked through the shelves of a well-known retailer in Maryland, USA, for a sprayable after-shave. I wanted to see what warning, if any, was printed on the product. It turned out that there was no sprayable after-shave on their shelves at all. Is this voluntary restraint? Did the manufacturers suspect that such a product could lead to harm to consumers, and to consequential litigation?
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I am working on a Diagnostic tool to help ophthalmologists diagnose Eye Diseases (like Keratitis) . The idea is to upload a picture of the eye and let the python program isolate the features / Lesions from the uploaded picture and present it as output for the Opthalmologist to consider.
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Dear Amit:
Nice to see the researchers started to pay more attentions about the ophthalmic imaging. I have number of research in such field regrading the keratoconus and some other ophthalmic problems. My advice to you that the ophthalmic diseases such as Keratitis are more clear to be diagnosed by the ophthalmologist as it is surface and clear changes and mostly the time periods for it is not so critical (unless it is severe). All the way I suggest to you the open source program called orange, you can find it on the following website:
Regards
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Can anyone share articles or reviews on the following topics:
a. Management of Posterior Synechiae after Triple procedure (PKP, Cataract extraction and IOL implantation)
b. Management of iris adhesions to the graft-host interface
c. Complications of triple procedure
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you can search your article from google scholars.
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We are investigating how the structure changes after riboflavin and UV illumination for Cross-linking process. Will the structural characteristics (molecules or collagen inside cornea) after CXL process turn to be smaller or bigger.
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I am recommending following article that summarizes the mechanism of CXL: Corneal cross-linking--a review. Meek KM, Hayes S.
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Which device would you use as a gold standard for verification of the project relate real keratometry of the eye. I want to verify the anterior, posterior and the real power, Sim K of the posterior, anterior and true values.
I was thinking about Casia 2000 SS-OCT from Tomey but they do not have FDA. So, what would be the best reference for the prototype software: maybe Pentacam or GALILEI from Ziemer.
Kind regards,
Bart
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If the gold standard assumes a device that is the most prevalent and the one that we can compare the other topographers with, then it is definitely Pentacam, although many other units may be better in one way or another. As mentioned earlier, the future lies in OCT technology, the fanciest of all currently being Anterion by Heidelberg.
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Hi everyone!
In my project we've been grinding equine corneas with mortar and pestle + liquid nitrogen followed by the Qiashredder column and RNeasy kit for RNA extraction. The problem is that we've had very low concentrations (from 4 to 70 ul/dL) of RNA (using Nanodrop). Anyone has had similar issues and knows how to troubleshoot that?
Thank you so much!
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David Farringdon Spencer
The highest we got was 70 ng/dl. I've talked to other researched who have gotten 150 to 600 ng/dl...
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There are various techniques for in vitro culture of various tissues and also cornea.The success for corneal culture across world is still in primitive stage as far as I knew. Then what is your method and at what stage you are.
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Dear Dr Rao
At present we are industrialising a bioreactor dedicated to long term storage of human corneas. By restoring intra ocular pressure (among other things) it allows increasing the viability of endothelial cells (+23% after 4 weeks of storage).
Results will be soon published.
Sincerely yours
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Hi There
Could anyone suggest the most common practice to preserve rabbit corneas for at least 2 weeks? suggestions would be well appreciated.
Thanks
Manish
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Check this link
Hope you good luck
regards
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Hi all,
I have perfused mice with 1% PFA and post fixed eyes in 1% PFA then removed cornea and lens and put the eye cup (containing retina) in OCT for cryosectioning. Th problem is that the protocol requires the retina to be fixed for short time and that makes it challenging to embed it in OCT as the retina is still soft. I am thinking to sections the whole eye without removing cornea and lens. Have you tried sectioning mouse eyes with lens on? Do you have any recommendation to avoid retinal breakage whole I remove the lens for OCT sectioning?
Thank you
Assraa
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You may try
i- 4% bufferized paraformaldehyde for perfusion.
ii- Increase the perfusion time.
iii- Post fix in 10-40% sucrose gradient solutions and finally freeze it in oct compound.
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Samples: cornea of cadaverous donors.
Methods: Procedure for corneal manipulation.
Time of culture.
Culture mediums.
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Thanks!
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Liver part donation is accepted from live donor.
Kidney is accepted from live donor.
Cornea from one eye is not accepted from live donor who has two functioning eyes like two functioning kidneys.
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Binocular function of human eyes will be lost if one cornea is donated. Stereopsis will be lost. Kidneys do not function simultaneously  alike human eye.
Besides in a living donor, you want to evicerate the eye for corneal transplantation? It will lead to risk of sympathetic ophthalmia. However, this risk is negated by enucleation.
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There are most common causes of eye infection in sheep especially corneal opacity. 
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The most common is infection  ,so as dietary deficient , I think
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As we know that variation exists between dimensions and morphology of cornea in different strains of mice. Even the susceptibility and resistance to some group of pathogens has been observed (eg. C57BL/6 susceptible to Pseudomonas aeruginosa and resistant to Staphylococcus aureus etc.). Considering different factors (corneal diameter, thickness, cost effectiveness and handling etc) which mice strain do you prefer for studying Keratitis?
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I think all of them are important, It is better we considering different factors (corneal diameter, thickness, cost effectiveness and handling etc)  in our study.
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I am conducting my research on cornea and I read about endothelial cells. It's very interesting to know that corneal cells are derived from neural crest. I have developed little bit about it. But I want to know the logic. Thanks
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Why do the corneal endothelial cells do not have an ability to proliferate?
Some thinks it´s important to know.
Human embryo, 7 weeks old.
Human Corneal endothelial cells and keratocytes originate from neural crest cells and then differentiate into mesenchymal cells. Human embryo, 7.5 weeks old: Corneal endothelium consists of a double layer of cuboidal or flat cells. These cells starts to form Descemet membrane.
Human fetus, 5 months old
Corneal endothelium appears as a monolayer at the 18th week. The decrease in cellularity of the endothelium is more rapid during the prenatal months than during the first 2 postnatal years. The diameter of the cornea increase from 4.2 to 9.3mm, from 16 weeks gestational age to term. During this time de endothelial surface increases from 14 to 68 mm². This rapid enlargment provides much more space to be covered by the endothelial cells.The decrese in cellularity and the increase in the surface of the corneal endotelium to be covered cause changes in the packing, size, thickness and shape of the endothelial cells.
Barishak,YR. Embriology of the Eye and Its Adnexa. 2nd Ed. 2001
After this phase the cell cycle remains blocked, some believe that due to factors inherent to the aqueous humor, but there is still no clear proof of the real reason.
It is known that its mitosis after birth is rare. The amount of your cells gradually decreases during life. This major decrease occurs in the first 5 to 6 years of life due to corneal growth in diameter. I suggest you study well the cycle of cell division and expand literature review included the article below.
Okumura N, Inoue R, Okazaki Y, Nakano S, Nakagawa H, Kinoshita S, Koizumi N. Effect of the Rho Kinase Inhibitor Y-27632 on Corneal Endothelial Wound Healing. Invest Ophthalmol Vis Sci. 2015 Sep;56(10):6067-74.
 
Abib FC1, Barreto Junior J. Behavior of corneal endothelial density over a lifetime. J Cataract Refract Surg. 2001 Oct;27(10):1574-8.
It is rare to prove clinically significant mitosis. It is believed that they may be related to herpex virus infiltration. In my professional and research experience I have 2 or 3 well documented cases. If you study endothelium by means of specular microscopy, follow the articles below.
Bernard E. McCarey, Henry F. Edelhauser, Michael J. Lynn. Review of Corneal Endothelial Specular Microscopy for FDA Clinical Trials of Refractive Procedures, Surgical Devices and New Intraocular Drugs and Solutions. Cornea. 2008 Jan; 27(1): 1–16.
Abib FC, Holzchuh R, Schaefer A, Godois R. The Endothelial Sample Size Analysis in
Corneal Specular Microscopy Clinical Examinations. Cornea 2012;31:546–550.
Abib FC, Andrade Neto JL, Abib DS. The sampling error from specular microscopy
examinations and their reliability indexes. Cornea 2013;32:377–378.
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This optic scheme (attached) is supposed to be free from spherical aberrations in output point B. A is input.
I simulated the case, but aberrations was found, is it right ? or I missed something ?
Blue lines is spherical mirrors, Middle blue circle is curvature center both same for lenses.
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Arkadily,  This is an Offner mirror system known as aberration free in terms of spherical aberration, coma and distortion.  But there still remains astigmatism as shown in wavefront analysis of Offner mirror in my attachment.  Regards,  Shigeo
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Many studies, even studies published in impact journals include the two eyes of the same patient. This is not a good practice, since these observations are not independent observations, because both eyes are usually similar. Including the two eyes of the same patient increases the size of the sample, and narrows confidence intervals, making easier the task of achieving statistical significance. However I think that some methods can correct to a certain extent the bias generated by including both eyes. Anyone knows where can I find information about how to address inter-ocular correlation?
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Julio,
About 60 years ago, mixed-effects models were developed (e.g. see Wikipedia).  That approach allows the inclusion of data from both eyes of a subject with the relationship dealt with appropriately when the "clustering" is declared (e.g. error terms, DoF).  Note that there is value in having data from two eyes, in that the high correlation (in healthy eyes) provides a better estimate than data from only one eye.  Such models can also account for other relationships (clusters) such as between siblings and repeated measures over space or time.  Most statistical packages include mixed-effects models (there are a variety of other names for the same thing).
Russell
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Most birds can see ultraviolet light. This capacity is possible because birds have a forth type of cone that is sensitive to this wavelength and because their ocular media allows this light to enter the eye. Apparently the cornea and the lens of the birds is similar to our cornea. Which histological differences can explain such a different behavior?
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For an excellent review see: Douglas, R. H., & Marshall, N. J. A review of vertebrate and invertebrate ocular filters. In Adaptive mechanisms in the ecology of vision (pp. 95-162). Springer Netherlands, 1999
The amount of short wavelength transmission by the ocular media depends on the normal light absorption below 310 nm by nucleic acids and proteins of the cornea and lens as well as other short wavelength pigments found (typically in the lens).  Birds and other vertebrates (some fish and reptiles) with UV receptors usually are lacking some of these lenticular short wavelength filtering pigments, thus transmission in the UVA is solely dependent on the path length of  typical nucleic acid/protein absorption. See e.g.
Muntz, WRA. Inert absorbing and reflecting pigments. In HJ A Dartnall (ed.), Handbook of sensory physiology, VII71 Photochemistry of vision,  530-565. Springer-Verlag, Berlin, 1972
Bowmaker, J  Visual pigments, oil droplets and photoreceptors. In P  Gouras (ed.), The perception of colour,  108-127. CRC Press, Boca Raton, Florida, 1991
Finally, primates have an additional short wavelength filter (the macular pigment)  found near the fovea that further reduces short wavelengths from reaching the retina.  See e.g.  Snodderly, D. M., Brown, P. K., Delori, F. C., & Auran, J. D. (1984). The macular pigment. I. Absorbance spectra, localization, and discrimination from other yellow pigments in primate retinas. Investigative Ophthalmology & Visual Science, 25(6), 660-673, 1984.
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Hi,
I was performing MTT assay in my lab hood. Accidentally, I did not turn off germicidal lamp (UV-C 254 nm) in the hood and I worked for about 25 minutes. I was wearing latex gloves and my hands and arms were completely covered in my labcoat and also my winter coat. My face however was uncovered and I was wearing my glasses. There was hood glass between the lamp and myself and the distance between my face and lamp was as usual as in normal airflow hoods. 
This happened 4 days from writing this post. After overexposure, I did not see any symptoms like burns in my cornea or erythema so far. I am really scared as to what fate awaits me after 6-12 months as they say this can lead to skin cancer. 
I would be really grateful if anyone could suggest on what I should do and what fate awaits me in the next one or two years.
Regards,
Pratik
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Thank you Mr. Martin. I have not got any sunburns or any sorts of issues with my skin. The problem is skin cancer symptoms would not be seen until 6-8 months after exposure. So, I am worried on the same.
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I want to transfer a cornea from a donor to a receiver.So I would like to know which temperature is the best condition to keep a cornea in the box.Is there any factors that affect the cornea.
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Dear Piraya,
Corneal Preservation and Storage
Hypothermic storage at 2–8 °C is perhaps the most widely applied method world-wide; for example, all eye banks in North America use hypothermic storage owing to its perceived simplicity and its effectiveness. On the other hand, the majority of European eye banks use organ culture at 28–37 °C for storing corneas because of the extended storage time compared with hypothermic storage. Non-viable corneal tissue can be stored by freezing, by freeze drying, in glycerol, or in ethanol.
For more on this topic, please read the review article contained in the following link:
Hoping this will be helpful,
Rafik
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I am trying to see the growth of macrophage after corneal injury in whole flat mounts of cornea. I would really appreciate if you could suggest me the best protocol on that. 
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Thank you so much for this article. I am wondering if I can see macrophage growth in 12 hours time points after corneal injury. I will follow this method and see. 
Thank you so much.
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Hi, everyone, I'm culturing human corneal fibroblasts now. I found that their proliferation seems not very well. You could say that they don't proliferate ever. I use Dulbecco's Modified Eagle Medium (high glucose) with 10%FBS ,and 1% antibiotics to culture them. Do I need to add growth factors?  
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Hi Yi-Chia, I have some experience with oral fibroblasts, one of the strategies that we used was including insuline as growth factor in the medium or maybe increase the % of  FBS.  I hope this helps you in some way.
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Does anyone know a CRO that can perform alkaline injury on the eye of rabbits or rats?
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Contract research organisation
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Currently in Singapore Eye Bank, we practice passive warming of corneas at room temperature (19-21'C), and we are having high percentage of cell drop-out or incidences of unable to get decent cells after 2-5 hours of warming. 
Would the idea of active warming (using thermo incubator at 34-35'C) to optimize the endothelial function improve specular evaluation results?
Any study or publishing regarding this issue? 
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What about these papers:
Preservation of the Corneal Epithelium in Different Corneal Storage Media.
Soni NG, Hoover CK, Da Silva H, Jeng BH.
Cornea. 2015 Nov;34(11):1400-3. doi: 10.1097/ICO.0000000000000601.
Endothelial Cell Viability of Donor Corneas Preserved in Eusol-C Corneal Storage Medium.
Yüksel B, Uzunel UD, Küsbeci T.
Exp Clin Transplant. 2015 Oct 14. doi: 10.6002/ect.2014.0295. [Epub ahead of print]
PMID:
Cornea preservation time study: methods and potential impact on the cornea donor pool in the United States.
Lass JH, Szczotka-Flynn LB, Ayala AR, Benetz BA, Gal RL, Aldave AJ, Corrigan MM, Dunn SP, McCall TL, Pramanik S, Rosenwasser GO, Ross KW, Terry MA, Verdier DD; Writing Committee for the Cornea Preservation Time Study Group.
Cornea. 2015 Jun;34(6):601-8. doi: 10.1097/ICO.0000000000000417.
Anterior corneal buttons from DSAEK donor tissue can be stored in optisol GS for later use in tectonic lamellar patch grafting.
Chu HS, Hsieh MC, Chen YM, Hou YC, Hu FR, Chen WL.
Cornea. 2014 Jun;33(6):555-8. doi: 10.1097/ICO.0000000000000102.
Eye preservation tectonic graft using glycerol-preserved donor cornea.
Lin HC, Ong SJ, Chao AN.
Eye (Lond). 2012 Nov;26(11):1446-50. doi: 10.1038/eye.2012.192. Epub 2012 Sep 14.
Comparison of different methods of glycerol preservation for deep anterior lamellar keratoplasty eligible corneas.
Li J, Shi S, Zhang X, Ni S, Wang Y, Curcio CA, Chen W.
Invest Ophthalmol Vis Sci. 2012 Aug 17;53(9):5675-85. doi: 10.1167/iovs.12-9936.
Prospective clinical evaluation of McCarey-Kaufman and organ culture cornea preservation media: 14-year follow-up.
Rijneveld WJ, Remeijer L, van Rij G, Beekhuis H, Pels E.
Cornea. 2008 Oct;27(9):996-1000. doi: 10.1097/ICO.0b013e3181783a35.
Influence of temporary hypothermia on corneal endothelial cell density during organ culture preservation.
Schroeter J, Meltendorf C, Ohrloff C, Rieck P.
Graefes Arch Clin Exp Ophthalmol. 2008 Mar;246(3):369-72. Epub 2007 Nov 16.
First report of evaluation of K-M media: a new corneal preservation medium.
Desai BM, Khamar BM, Ghodadra BK.
Indian J Ophthalmol. 2007 Jan-Feb;55(1):43-7.
Optisol vs Dexsol as storage media for preservation of human corneal epithelium.
Greenbaum A, Hasany SM, Rootman D.
Eye (Lond). 2004 May;18(5):519-24.
Improvement of human corneal endothelium in culture after prolonged hypothermic storage.
Camposampiero D, Tiso R, Zanetti E, Ruzza A, Bruni A, Ponzin D.
Eur J Ophthalmol. 2003 Nov-Dec;13(9-10):745-51.
Use of glycerol as an alternative to freeze-drying for long-term preservation of antigen for the direct agglutination test.
el Harith A, el Mutasim M, Mansour D, Fadil Mustafa E, Arvidson H.
Trop Med Int Health. 2003 Nov;8(11):1025-9.
Fibroblast growth factor-2 protects endothelial cells from damage after corneal storage at 4 degrees C.
Rieck PW, von Stockhausen RM, Metzner S, Hartmann C, Courtois Y.
Graefes Arch Clin Exp Ophthalmol. 2003 Sep;241(9):757-64. Epub 2003 Sep 6.
Influence of temperature on corneas stored in culture medium. A comparative study using functional and morphological methods.
Sandboe FD, Medin W, Frøslie KF.
Acta Ophthalmol Scand. 2003 Feb;81(1):54-9.
[Corneal preservation at 31 degrees C--experimental study].
Zemba M, Bobeico V, Bratulescu M, Ciuca C, Popescu M, Musat A.
Oftalmologia. 2003;59(4):54-9. Romanian. 
Comparison of Chen Medium and Optisol-GS for human corneal preservation at 4 degrees C: results of transplantation.
Bourne WM, Nelson LR, Maguire LJ, Baratz KH, Hodge DO.
Cornea. 2001 Oct;20(7):683-6.
Corneal temperature reversal after storage in Chen medium compared with Optisol GS.
Yap C, Wong AM, Naor J, Rootman DS.
Cornea. 2001 Jul;20(5):501-4.
In vitro comparison of Chen medium and Optisol-GS medium for human corneal storage.
Nelson LR, Hodge DO, Bourne WM.
Cornea. 2000 Nov;19(6):782-7.
Preservation of donor cornea prevents corneal allograft rejection by inhibiting induction of alloimmunity.
Kamiya K, Hori J, Kagaya F, Usui T, Amano S, Oshika T, Mizouchi T, Tsuru T, Yamagami S.
Exp Eye Res. 2000 Jun;70(6):737-43.
A morphometric study of endothelial cells of human corneas stored in MK media and warmed at 37 degrees C.
Rootman DS, Hasany SM, Basu PK.
Br J Ophthalmol. 1988 Jul;72(7):545-9.
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For an upcoming animal trial. Just the name of the reference would be sufficient. 
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Please take a look on the following
Title: The Rabbit in Eye Research,
Author: Compiled and Edited by Jack H. Prince.
Publisher: Springfield, Ill., C.C. Thomas (1964)
You can also look on Kirk N Gelatt's book "Veterinary Ophthalmology" 
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Regarding corneal decellularization, Most of the people  uses chemicals like hypotonic,  hypertonic solutions and enzymes or both.Otherwise some are using physical methods like HHP .  
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Contact Dr. Vickery Trinkaus-Randall at Boston University School of Medicine. She has pioneered this, along with her mentor Dr. Ilene Gipson who has retired..
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I am planning to see the number of neutrophils and macrophages in cornea after chemical burn. Would it better to flat mount the cornea or just making the section for doing immunohistochemistry? I would really appreciate your suggestions.
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I would do both if feasible. If nothing else, it shows the lengths you are prepared to go to find your answer. 
Below is a link to the video for the flat mounting.
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With cryosectioning of tissues radial, tangential and cross section of eye, how is the cut made on human cornea tissue?
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Hello,
İf you want to see all the layers of cornea, that is epithelium, bowman, stroma, descemet and endothelium, than you have to cut perpendicular to corneal surface. In such a section you will have approximately 50 micron of epithelium, 450 micron of stroma, and 20 micron of endothelium.
If you cut parallel to front surface of eye, then you will have epithelium in first sections, then a large stromal surface is obtained, and lastly you may catch endothelium in last sections. This is good if you want to study on corneal stroma, but epithelium and endothelium orientation will be difficult.
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Hi all,
I'm currently doing some experiments to observe corneal stroma of chicks and have some troubles with sectioning methods. I have been trying cryostat sectioning in -20 C, after 4%PFA fix->10,15,30% sucrose for a day. And tissue thickness is 12um. Problems during this method are,
1. Cornea seemed to be too weak and became flipped during cutting, especially central cornea part. I only need central area, so this makes me quite troublesome.
2. After sectioning, i move to normal temperature room just to check through light microscopy, and found that tissue experiences dramatic change during 'melting', specifically stroma.
3. When staining through toluidine blue, tissue experiences huge change. Stroma is highly altered in its shape.
I wonder, will it be better to try another sectioning methods (eg.paraffin embedded) ? But, i found there are some literatures that using cryostat and seems cornea is quite good looking. So if anyone has tried this to observe cornea, can you give any advices?
Thanks,
Jeremy
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Hi Jeremy, 
I teach histological techniques and research the cornea.
It would help to know a bit more about what your research question is, but if looking to study to chick corneal structure, then my advice would be as follows.
1. Fix for 1-2 hours in neutral buffered formalin (e.g. 3.7% formaldehyde in phosphate buffered saline. This may also be referred to as "10% formalin". Just make sure that buffered around neutral pH).
2. Process into paraffin using a short cycle of around 4 hours in total.
3. Cut 3 micron thick sections (using microtome) and mount on charged/coated slides (will help with adhesion). 
4. Bake sections onto slides in 60 degree drying oven for 45-60 minutes.
5. Deparaffinise slides in two changes of fresh xylene, then rehydrate through graded alcohols, followed by water.
6. Stain sections with hematoxylin and eosin (let me know if you need a protocol).
7. Dehydrate slides back through alcohols, clear in xylene, and attach coverslip using plastic mounting medium. 
I regularly use this technique for both human and animal corneas with good results. 
good luck.
Damien
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I am trying to use the electrospun polymer for transplanting stem cells to injured corneal surface of rabbit in LSCD model but the problem is suturability of this sheet. The electrospun polymer is not that much tough so that is could be sutured. So I am looking for the alternative option to stick the cell-polymer sheet over the cornea. That may be bioadhesive or other contact lens if there is available. Please give me the suggestion to resolve the problem of putting the cell-polymer sheet over the rabbit cornea (LSCD rabbits). 
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You should give a look at this book. Perhaps it will help you.
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I want to use a contact lens for rabbit for transplantation of stem cells to the corneal surface with substrate. i want to put a contact lens which can also able to diffuse gas (oxygen and CO2). I want to use this lens just to avoid the problems due to blinking. Please suggest me from where I can get this. Please also suggest me, what other methods would be possible. As I am also not able to suture the cell-substrate sheet. I also would like to get information about other ways to put the cell-substrate patch over the cornea other than chemically defined bioadhesive. Please do help in this. Thanks!!!
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For an adult rabbit, 5 kg or greater, you want a silicone hydrogel lens, such as O2 OPTIX from Alcon.  Most likely need 8.4 - 8.6 mm diameter.  A thicker lens such as a -3.0 OD lens should stay in the eye better.  The nictitating membrane should not be a problem.  Years ago we used to excise the nictitating membrane but risk developing an infection.  Also, the lens should be fairly flat.
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 Apart of that her IOT was 21,9 mmHg right eye and 23,0 mmHg left eye.
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Would completely agree with Drs. Aquavella and Robaei
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Is there any study or experimental data available, showing differences in corneal biomechanical properties between females and males? 
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The findings are mixed:  some studies have reported no gender effects on corneal biomechanics (e.g. Iyamu E, Osuobeni E. Age, gender, corneal diameter, corneal curvature and central corneal thickness in Nigerians with normal intra ocular pressure. Journal of Optometry. 2012;5(2):87-97.
While other have found significant gender differences: e.g. Strobbe E, Cellini M, Barbaresi U, Campos EC. Influence of age and gender on corneal biomechanical properties in a healthy Italian population. Cornea. 2014 ;33(9):968-72 found men demonstrated greater corneal hysteresis and corneal resistance factor than women did
While another study reported the opposite effect with women having greater corneal hysteresis and corneal resistance factor.  Allam RS, Khalil NM. Evaluation of sex differences in corneal hysteresis. Eur J Ophthalmol. 2015 Feb 7:0. doi: 10.5301/ejo.5000572. [Epub ahead of print]
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Hello, I am trying to model the impact of change in temperature on the diffusion of water particles (from a material mostly composed of water) in to air. The relationship between the diffusion coefficient and temperature suggested by the Stokes-Einstein equation is based on the model of motion of a spherical particle of diffusing substance A in a viscous liquid continuum B. Can I use the same relation for the opposite direction (i.e diffusion of water molecule in to air)? Can you suggest if any other relation would suit my problem better (like Wilke and Chang, or other http://www.thermopedia.com/content/696/).
Thanks for your help,
Shwetabh Verma 
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This is not a simple diffusion of water in one phase. This involves a phase transformation as well. Based on the gas flow rate around the cornea you can select different models. This paper (although in a totally different context) gives you an idea to start:
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I am planning to perform some steps to improve the ocular surgery visualisation. A binocular microscope is almost all we have now. Blurred cornea, cataract, intraocular bleeding and many reasons make us to fight for better insight.
Is anyone interested in ?
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Thank you for all suggestions. An OCT image is very useful in transparent cornea/ lens/ vitreous cases. The " hi speed" OCT system in the surgical microscope will be necessary equipment for good result. Micro optical probes seem to be good exploring tool below the opaque barrier. Adaptive optics with subtraction techniques in ocular surgery is verily a challenge. If a (doubled) optical hardware connected with software capable to make corrected images fast enough showing " live video", it could be very interesting solution.
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I'm facing problems regarding extraction of RNA from corneal tissues acquired post DSEK. I have been using Qiagen RNA extraction Kit so far. But the conc. is as low as 2ng/ul with 260/280  2.23 and 260/230 1.86. Does anybody have any better method(s) or kit to extract RNA from such tissues?
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in my opinion the best method to isolate RNA from cornea is the RNeasy Plus Micro kit of Qiagen. The amounts of RNA from cornea are always lower than in others tissues. It is very important introduce the cornea tissue after the DSAEK surgery in RNA protect buffer to protect the RNA and avoid his degradation
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The irregular cornea has irregular topographic changes, that makes the variations values of K readings are random and effect the K flat and K steep values. The question here is how to create a protocol of evaluating the K reading per x-y location upon the corneal surface..
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In previous, I have made work in corneal contour lines by estimating them from high resolution thermogarphical camera, It was very interested to deal with the k reading and biomechanics of cornea at the same time. I received a real signs for either future stability or ectopic change (ectesia). This made the close follow up especially for the KC cases more cleared and sensed w.r.t regular protocols.   
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Please I need some help with possible differential diagnoses and/or management plan. Fundus photo of an active 47year old male African, Right eye. VA=CF,  exotropia approx. 30o. Lens, cornea, vitreous are all normal. Good pupillary reaction with mild RAPD, IOP 14mmHg. History of decreased vision since childhood. No history of trauma, diabetes, HIV, or hypertension. The left eye is normal. 
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You have presented an interesting case of an adult male with a history of poor vision OD since childhood, a sensory exotropia, healthy nerves and vessels, and a unilateral pigmentary retinopathy. Most likely this is due to old infection, but other possibilities include an old foreign body with siderosis, inflammatory causes such as Harada's disease or AZOOR, old retinal vascular occlusive events or perhaps an atypical presentation of a bilateral process such as retinitis pigmentosa or vitamin A deficiency. Likely infectious causes are onchocerciasis, diffuse unilateral subacute neuroretinitis, syphilis, ophthalmomyiasis, toxoplasmosis, or rubella. As he is from Africa, there are probably several more infectious diseases that may cause a pigmentary retinopathy that I am unfamiliar with. Perhaps someone with expertise in tropical medicine could add to my list. I recommend a careful history, consider a plain-film x-ray if there is a chance of a retained foreign body, then a laboratory work-up for the most likely infectious diseases. If that does not lead to a diagnosis then I would consider electrophysiology studies to rule out unilateral retinitis pigmentosa, but this is unlikely. There are many good papers on the differential diagnosis of unilateral pigmentary retinopathy. Here is one:
Silveira C, Belfort R Jr, Nussenblatt R, Farah M, Takahashi W, Imamura P, Burnier M Jr. Unilateral pigmentary retinopathy associated with ocular toxoplasmosis. Am J Ophthalmol. 1989 Jun 15;107(6):682-4.
Thank you again for presenting an interesting case. Please let us know what you find.
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Can anyone suggest a way to rapidly fixate ex vivo corneas soaked in a water soluble dye (riboflavin), such that the dye can not continue to migrate within the tissue? A cryostat would be quick enough, but once sections are cut and the tissue thaws the dye would presumably be able to move again? Thawing tissue to chemically fixate would carry the same problem. Any suggestions gratefully received.
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You can make frozen sections mount them frozen on precoated slides. Keep them frozenadd 3% paraformaldehyde solution on the slides while defreezing them. They should fixe immeadiately.
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We extract the full eye from a mouse, and then fix it in 4% paraformaldehyde immediately after extraction. After punching a hole in the cornea, we fix it with 4% PFA in 20 degrees for 4 hours, and then we put the eye into a sucrose gradient 10% 20% and then 30% sucrose overnight. The tissues are put into OCT medium cryomold and sectioned onto superfrost slides. Will these tissues be acceptable for In Situ Hybridization? Do I need to refix before pretreating the tissues?
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I use a well standardized method for in situ with formalin fixed tissue. There are a lot of protocols in literature. Of course you need to unmask the dna from linked protein and forming bridges with Proteinase k ( from loweest to highest concentrations, depending on different factors), but is works!No doubts! But this is the reason for using superfrost slices, as Virginie sayd.
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I have a problem with this - the image has more cells so that makes a problem when I enhance or segment. 
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Dear Shumoos Taha Hammadi,
If you want to get any serious reply or help with your matter I suggest you attach at least a .jpg or .bmp out of your recent analysis/analyses to this thread.
It makes no sense to discuss anything about not knowing what your problem really is (specimen: ok: we know about EYE (animal-human?) / Cornea epithelium.... but nothing about methods to get sections(?): paraffin-, cryo-, semithin plastic /resin sections, stain(s) used, method of image acquisition etc, etc.).
Sorry to bother you with my request,  but hopefully you'll answer some of my questions.
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I have been using a procedure for mouse eye fixation in paraformaldehyde. We remove the mouse eye after sacrafice. We immediately put it in 4% pfa for 30 minutes. After that we punch a hole in the eye, we do not remove the cornea or lens. After fixing for 4 hours, we put it in 10% sucrose for an hour, 20% sucrose for an hour, then 30% sucrose overnight. We then put the fixed eye into a cryomold filled with OCT mixture without sucrose. We freeze the tissue on dry ice. Sometimes the retina is perfectly sectioned, other times, it is extremely detached and has cells missing or shrunken. Any advice would be helpful. Thanks
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Be very careful when taking the eyes out. Sometimes just a little too much pressure and the retina will detach and no matter what you do after it is too late.
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I've got this image after enhancement and when I segment it I've got problem because it didn't segment in a good way and some weak nerve will disappear and this images content cells that effect on my work.
Do you have any idea? I just need the nerve to appear after the segmentation.
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Thanks Dear
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Fig. 14-4 on page 268 of the current edition of Adams and Victors textbook “Principles of Neurology” states " A lesion at the level of the oculomotor nucleus results in homolateral third-nerve paralysis and homolateral anesthesia of the cornea”.
Is this an error and if not, what structures are located in that area that could cause homolateral corneal anesthesia?
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I have looked again at several cross sectional diagrams of the brainstem at the level of the Oculomotror Nuclear Complex and I don't see how a focal lesion at this level would give ipsilateral corneal anesthesia.  Where are the Neuro-ophthalmologists members of researchgate who should be commenting on this?
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Does anyone have any suggestions for whether there are good markers for identifying the sensory neurons (I am interested in sensory fibers leading to the cornea) in a mouse trigeminal nerve section?
Also, I am wondering if anyone has experience with using ATF3 as a marker for injured sensory nerves, and an antibody recommendation if so?
Thanks!
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Sensory neuron fibres can be identified by staining with the isolectin IB4 (non-peptidergic nociceptive neurons) or CGRP/substance P (peptidergic nocicptors). A non-selective marker for small neurons is peripherin (cornea doesn't contain sympathetic efferents). A very sensitive marker for neurons is beta-3 tubulin. Although beta-3 tubulin labels all neurons, trigeminal afferents are the only fibres that innervate the cornea. In addition to ATF3, a good marker for damaged neurons is damaged-induced neuronal endopeptidase (DINE).
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I am looking at the expression of macrophages in corneas of mice. is there a standard procedure for sample preparation for IHC/  immunofluorescence ?
Thanks
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I would not bother dissecting the cornea at all since the mouse eye is so small.  Just pull out the entire eye.  If you are just looking at macrophages, pull the eye, embed fresh in OCT orienting to give a nice cross section through cornea, make frozen sections (16-20 microns), fix in acetone methanol then stain with a robust macrophage cell surface marker and view on a confocal microscope.  Morphology may not be 100% perfect, but it will be pretty good due to the section thickness, certainly pub quality.... 
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Research
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Contact Simon Kilvington at University of Leicester who uses and stores our large collection email: sk46@le.ac.uk
Best wishes
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Hello,
           In one of the experiments that am doing I need to stain for M1, M2 macrophages in mice tissue (cornea). I would like to know whether or not I can successfully stain M1 and M2 macrophages using antibodies against CD 206, PD-L2 (M2) and CD68+/CD80+ (M1) ?
Is it possible further narrow down the staining to find M2a, M2b and M2c  type mouse macrophages ?
Thank you
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F4/80 is an excellent marker for all macrophages. Mannose receptor CD206 should be increased in M2, and CD68 gives good staining, although not be specific for M1. Consider MHC class II for M1.
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Does someone have a detailed protocol for Proteoglycan extraction from ocular tissue such as cornea or sclera? or have any experience with PG extraction? List of supplies and chemicals are also needed. thank you
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Isolation of proteoglycans is a multistep complex process. I isolated the PG of palmar fascia. If you want, I will send you the materials and methods section of my dissertation. unfortunately it is Polish.
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Corneal Asphericity and Zernike coefficients
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Sure there is:
Michael Mrochen published something on that, but also Antonio Guirao, or Damien Gatinel and independently myself.
You can read from my publications These:
de Ortueta D, Arba Mosquera S. Mathematical properties of asphericity: a method to calculate with asphericities. J Refract Surg; 2008; 24: 119-121
Arbelaez MC, Vidal C, Arba Mosquera S. Clinical outcomes of corneal wavefront customized ablation strategies with SCHWIND CAM in LASIK treatments. Ophthalmic Physiol Opt;. 2009; 29: 487-496
Arba Mosquera S, de Ortueta D. Analysis of optimized profiles for ‘aberration-free’ refractive surgery. Ophthalmic Physiol Opt;. 2009; 29: 535-548
Arba-Mosquera S, Merayo-Lloves J, de Ortueta D.  Asphericity analysis using corneal wavefront and topographic meridional fits.  Journal of biomedical optics 2010;15(2):028003
Arba Mosquera S, de Ortueta D.  Correlation Among Ocular Spherical Aberration, Corneal Spherical Aberration, and Corneal Asphericity Before and After LASIK for Myopic Astigmatism with the SCHWIND Amaris Platform.  J Refract Surg. 2011 Jun;27(6):434-43
anyway the Equations you are asking for are:
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Based on our past years’ experience in training clinicians, we feel that following a proper workflow can really help them improving their dry eye practice. Most frequent questions in workshops are still:
How do I know that this is a dry eye?
Which tests are the appropriate ones, what are they telling me?
What do I need to recommend making the patient feeling better?
An iPad APP answering these questions was developed over the past months based on our research and current literature. We are pleased to report that the new dry eye management APP had passed all evaluation tests and now is going to be tested in clinical practice as beta-version. Such launch of the Dry Eye Tool Box APP will be soon.
What do you think about it? www.dry-eye-tool-box.com
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Thank you. I will take a look.
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We are running a trial and may like to collaborate.
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I am trying to analyze small deflection of bovine cornea under uniformly distributed load. Cornea is modeled as a thin shell in the literature and for small deflections its load-deflection relation is given as linear, however we are measuring a non-linear response even for small deflections. Can someone help me to derive/understand the theoretical formulation of load-deflection of cornea? We believe it is third order polynomial function.
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The answer from the bio-mechanics finite element modeling group will include the following aspects:
1) Material is non-linear - in the direction of Mooney–Rivlin, Neo-Hookean or Ogden Material. The simplest case is non-compressible Mooney-Rivlin which requires only one constant. (many references from Ogden)
2) FE Model should include large strains possibility for the shell finite element model.
3) Known models with 1) and 2) are showing good correlations with biomechanical experiments - for validation of material parameters, however, it is better to use the standard 1D tension test - only a fiber. And then to validate the shell model of the real structure (in your case bovine cornea). The final shape of the deflection curve is without any doubts nonlinear.
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A patient sees 6/9 in each eye and complains of seeing haloes and dry-eye-type symptoms. He has a minor degree of lens opacity and the microcystic corneal dystrophy. How would colleagues manage this patient? Would they proceed to cataract surgery in the first instance?
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You first need to assess the severity of the dry eye since this can get worse after cataract surgery and should therfore be assessed preopertively to secure proper Treatment and prevent decompensation after surgery. If this has been done with lubrication and/or punctum plugs you can proceed to surgery. Be sure that what you have diagnosed is not Fuchs corneal dystrophy since then a triple procedure might be consiedered.
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It does not matter how old or how recent those are, and whether its use was therapeutical or not.
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-> the very first entry may be the one you are looking for.
or
May I know how your interest in this question is motivated?
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Does hyperosmolarity change the surface curvature of the cornea?
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in the case of these patients, A-scan ultrasound biometry should be avoid, the biometry always be done with LASER (double pass technique).
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Is there any extra advantage of prescribing oral anti-fungal agents in addition to topical anti-fungal drops in patients of fungal keratitis? If yes, then what is the indication, what is the best agent for this purpose and the correct dosing and duration?
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In my opinion for Fungal keratitis the patient will receive topically clotrimazole (1%)- crem twice a day , fluconazole (1%) dros 3 times a day, besides Betadine 2.5% also has antifungal activity. The latest study revealed that fluconazol is better that voriconazole , which earlier was presentes as a very active topical antifungal.
Oral: fluconazole 150-mg/day only 7 days. Good luck !
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Patient aged 71, compensated diabetes, worked and got infected in Iraq after a severe pneumonia. Bacteriology revealed Klebsiella, E. coli and S. aureus.
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I agree with Andrea Leonardi ,when fungal infection is suspected and smear and culture are negative for fungus repeat scraping or even biopsy is necessary to identify fungal material .I am not agree for aqueous humor culture because usually hypopyon is steril.
for treatment i use Natamycin 5% or Amphotericin B and Voriconazol when it doesn't respond to traditional treatment .
You must think to necrotizing Herpetic interstitial keratitis too.