How is the lens affected in astigmatism?
113826
Here is a really good link. http://www.allaboutvision.com/conditions/astigmatism.htm\n\nAstigmatism happens when either the cornea or the lens is irregularly shaped
473234
Cataract is an opaque (you can't see through) area on the lens.  Its just caused by trauma and 90% of people have a little bit of a cataract by age 65.  They can fix this by replacing the lens.  \nGlaucoma is a group of eye diseases which affects the nerves and may lead to blindness.  This is caused by fluid accumulation increasing pressure inside the eyeball.  \nVERY different diseases.
831529
Through the cornea and then through the lens.\nMost of the refraction is due to the cornea
1020381
I'd suggest getting the right prescription for your eyes regardless of cost..  If you don't, you won't be able to see clearly, and will also lead to headaches...\n\nTake it from someone who has bad astigmatism. ;)
324551
A cataract is a natural aging condition of the lens.  The lens is the part of your eye that changes shape to allow you to focus to see things when you hold them close to you.  The lens is basically a sack with a bunch of cells in the center.  Over time, these cells grow and divide causing the sack to be more and more stuffed full off cells.  As the number of cells in the lens increases, the body can no longer get enough nutrients into all the cells and their metabolism slows.  These cells all pump water out of the lens to keep it dehydrated and clear.  So as their metabolism slows, water accumulated in between the cells of the lens causing it to become cloudy.  In fact, the word "cataract" in latin means "waterfall" because that is what the Romans and early doctors described the vision as becoming.\n\nTo treat a cataract, the best current solution is cataract surgery.  They don't take out the whole lens, just the cells and water in the center (leaving the sack there to hold the implant lens in place).  It is most commonly currently done with only a 3 mm incision.  Most surgeons will finish the procedure in about 10 minutes and there is no pain.  These are done in the US with about a 99+% success rate.  The implant lens they put in will be focused for your eye, so usually little or no eyeglass prescription needed after the procedure (except for reading glasses).  \n\nI know surgery is scary, but as surgeries go this is one of the easiest to go through.  Also, this approach is too quick, easy and successful to want to play around trying anything else.
516880
no. your eye gets damaged from continued exposure to the contact lens.
687970
There aren't many side effects of wearing contact lenses - you're more likely to have problems if you get laser eye surgery.\n\nWith contact lenses, your eyes can get tired. This is often caused by less oxygen getting to your eyes than normal, but as long as you give your eyes a rest for a day every couple of weeks, you're fine.\n\nContact lenses can change the shape of your eye - sometimes they can correct an astigmatism just by being on your eye - as the eyeball is 'sucked' towards the contact lens. However, this is a reversible change, as your eyes just 'get used' to the contact lenses, and if you stopped wearing them, your eyes would be fine again.\n\nWith disposible contact lenses, you won't suffer any of the effects of dirty lenses (assuming you dispose of them every day) - if you have longer term ones, then you have to be careful to clean them properly, otherwise you can get eye infections.\n\nWearing contact lenses generally means that you will touch your eye more, and you have to make sure your hands are clean when you touch them, else you are risking minor eye infections.\n\nAnd of course, when you get a bit of dust in your eye, the lens can push it against your eye, meaning it hurts more, so you have to be careful not to rub it and scratch the eyeball.\n\n**However** having said all of that, I've worn lenses (rigid gas permeable, supposedly the hardest to wear), for 11 years now, and having worn glasses from the age of 6 till 17 when I got my lenses, I can say they make a big difference - you don't have to wear glasses, and don't get that whole misting up of glasses, and you can wear sunglasses, and don't get the glasses marks on your nose, etc. Altogether much preferred!
757629
It focuses an image on the retina so that you can see it.  The shape of the lens in the eye is controlled by muscles, so that the focal length can be adjusted to get sharp focus of both near and distant objects.  Errors in the shape of the lens can be corrected with eyeglasses.
1126598
Good question.  It all has to do with changing corneal dimensions.  At some point the whole system reverses and as your cornea and lens stiffen as you age you have trouble seeing things close (farsightedness).  Thank god for glasses or we would all be crashing into each other on the highway!
634759
No that will not cause astigmatism. lol    It is common for blood vessels to break with intense straining as in vomiting, constipation, etc.  No teatment makes it look or get better except time. It takes 2-3 weeks for the redness to resolve completely.
325479
It's higher than average, but I don't think I'd call it severe.  Average is about 1.00D of astigmatism (the second number), but I wouldn't call it severe until it gets over 6.00D.  You were probably born with that much astigmatism, so I wouldn't expect it to get worse, although your overall nearsigtedness (the first number) may increase.
514083
See an eye doctor.\n\nIt might be something on the lens, or it might be something on the retina. Or it might be some completely different thing.
470037
It depends on the drug. Two of them that I know that damage the eyes are asparin and antibiotics
873065
The lens in your eye may be too strong and thus focus the image of the outside world in front of your retina, or it may be to weak and focus the image behind the retina.  By placing a lens (glasses) in front of the eye, we can compensate for this by ensuring the image falls exactly on the retina, which allows for good vision.
256089
Basically, light passes through the front of the eye, the pupil, and the crystalline lens.  It hits the retina (the back of the eye), which has special cells that transform the light energy into a signal that the brain can understand.  The brain then interprets the image.  Of course, there are many other things that come into play, like how the eyes work together and how strong the eyes are.
701496
I do hope this helps with your studys.\nIn optics, chromatic aberration is caused by a lens having a different refractive index for different wavelengths of light (the dispersion of the lens). The term "purple fringing" is commonly used in photography, although not all purple fringing can be attributed to chromatic aberration.\n\nLongitudinal and lateral chromatic aberration of a lens is seen as "fringes" of color around the image, because each color in the optical spectrum cannot be focused at a single common point on the optical axis.\n\nSince the focal length f of a lens is dependent on the refractive index n, different wavelengths of light will be focused on different positions. Chromatic aberration can be both longitudinal, in that different wavelengths are focused at a different distance from the lens; and transverse or lateral, in that different wavelengths are focused at different positions in the focal plane (because the magnification of the lens also varies with wavelength).\n\n Minimizing chromatic aberration.\nThere exists a point called the circle of least confusion, where chromatic aberration can be minimized. It can be further minimized by using an achromatic doublet or achromat in which two materials with differing dispersion (usually crown and flint glass) are bonded together to form a single lens. This reduces the amount of chromatic aberration over a certain range of wavelengths, though it does not produce perfect correction. By combining more than two lenses of different chemical composition, the degree of correction can be further increased, as seen in an apochromatic lens or apochromat.\n\nMany types of glass have been developed to reduce chromatic aberration, most notably, glasses containing fluorite. These hybridized glasses have a very low level of optical dispersion; only two compiled lenses made of these substances can yield a high level of correction.\n\n Chromatic aberration of a single lens causes different wavelengths of light to have differing focal lengths. For an achromatic doublet, visible wavelengths have approximately the same focal length. Diffractive optical element with complimentary dispersion properties to that of glass can be used to correct for color aberration. An achromatic doublet brings two wavelengths to a common focus, leaving ultraviolet and infrared uncorrected and out of focus.The use of achromats was an important step in the development of the optical microscope.\n\nAn alternative to achromatic doublets is the use of diffractive optical elements. Diffractive optical elements have complimentary dispersion characteristics to that of optical glasses and plastics. In the visible part of the spectrum, diffractives have an Abbe number of -3.5. Diffractive optical elements can be fabricated using diamond turning techniques.\n\nRead more about it at the following web site below.\n\nAs for the type writer question here is the answer to that.\nA typewriter is a mechanical, electromechanical, or electronic device with a set of "keys" that, when pressed, cause characters to be printed on a document, usually paper.\n\nIn the late 19th and the start of the 20th century a person who operated such a device was sometimes also called a typewriter but it then became more common to call the person a typist.\n\nFor much of the 20th Century, typewriters were indispensable tools in business offices and for many (if not most) professional writers. By the 1980s, however, word processor applications on personal computers largely overtook the tasks previously done with typewriters. However, typewriters are still popular in the developing world, and among some niche markets.\n\nAs of 2006, the following companies manufacture typewriters and accessories: Smith-Corona, Olivetti, Adler-Royal, Olympia, Brother, and Nakajima. Olivetti is the only western company to currently manufacture manual typewriters. All other current models are electronic.
293067
You also may want to ask the optometrist - I have astigmatism and when I went in for new contacts 6 months after my last eye exam, I found out my eye had changed shape quite a bit, changing my prescription for the toric lense (my weights wouldn't hold in the right place).  The blurriness has to be the weight swinging wrongly.  \n\nYou know, it could also be that the company screwed up on your order - maybe give them a call.