Contacts and Glasses By: Bianka Tirado

The Cornea The cornea is the transparent front part of the eye that covers the iris, pupil, and anterior chamber, providing most of an eye's optical power. [1] Together with the lens, the cornea refracts light, and as a result helps the eye to focus, accounting for approximately 80% of its production to 20% of the lens focusing power. [2] The cornea contributes more to the total refraction than the lens does, but, whereas the curvature of the lens can be adjusted to "tune" the focus depending upon the object's distance, the curvature of the cornea is fixed.eyeirispupil anterior chamberoptical power [1] lensrefractsfocus [2]curvature

The Cornea pt. 2 Contact lenses are small plastic discs shaped to correct an eyesight problem. They are placed directly on the eye, where they float on a film of tears in front of the cornea. A Cornea is the clear front window of the eye that transmits and focuses light into the eye. Although the cornea is clear and seems to lack substance, it is a highly organized group of cells and proteins. Unlike most tissues in the body, the cornea contains no blood vessels to nourish or protect it against infection. Instead, the cornea receives its nourishment from the tears and aqueous humor that fills the chamber behind it. To see well, all five basic layers, each having an important function, must be free of any cloudy or opaque areas In the United States, 29 million people wear contact lenses not knowing many facts about them; including the dangers they hold inside of them.

Astigmatism The word "astigmatism" comes from the Greek "a-" (without) + "stigma" (point) = "without a point" referring to there being no point of convergence for the light rays on the retina and was not recognized until the 19th century. Although astigmatism occurs in nearly everybody to some degree, it is characterized by an irregular curvature of the cornea. This type of disorder is also known as a refractive error. For significant curvature, treatment is required. A person's eye is naturally a spherical shape and when light enters the eye it is suppose to refract the light evenly, creating a clear view of the object. However, a person with astigmatisms eye is shaped more like a football or even the back of a spoon. When light enters their eyes it is refracted more in one direction than the other, allowing only part of the object to be in focus at one time. Objects at any distance can appear blurry and wavy. People with undetected astigmatism often experience headaches, fatigue, eyestrain and blurred vision at all distances. These symptoms may not necessarily be the result of astigmatism though.

What a person with astigmatism sees…..

… … … The best way to prevent from infections and expense is by choosing to wear eyeglasses. They are the complete opposite of contact lenses. Eyeglass lenses are a tool you use to focus light appropriately on your retina. Any one can get prescribed for them, they correct all vision problems and are not to expensive depending on the style you choose "Eyeglasses area a device to compensate for defective vision or to protect the eyes from light, dust, and the like, consisting usually of two glass or plastic lenses set in a frame that includes a nosepiece for resting on the bridge of the nose and two sidepieces extending over or around the ears". In the past, eyeglass lenses were made exclusively of glass. Today, most eyeglasses are made of high-tech plastics. These new lenses are lighter, do not break as easily as glass lenses, and can be treated with a filter to shield your eyes from damaging ultraviolet light.

… … … Soft contact lenses are thin, gel-like lenses made to the shape of your eye. They are more flexible than gas-permeable contact lenses, so they're more comfortable and easier to get used to. Like hard contact lenses there are several types of soft contact lenses. Daily-wear contact lenses are typically inserted every morning and removed every night. They should not be worn during sleep. One pair of daily-wear lenses may last up to one year. Disposable contact lenses are lenses designed for short-term use during waking hours. Depending on their composition, disposable lenses may laser at longer intervals for up to three months if not every day. Most brands on average are good to wear for two weeks. Extended-wear contact lenses are designed to provide adequate oxygen to your cornea even while you sleep. You can wear these lenses continuously.For seven days with standard extended-wear contact lenses, and up to 30 days with lenses made with super permeable silicone hydrogel. The 30-day lenses maybe stiffer and less comfortable than the seven-day lenses and may get scratched more easily. They also have less clarity than lenses removed every seven days.

… … … The newest types of contact lenses are the Hybrid contact lenses. Hybrid contact lenses, which feature a gas-permeable center surrounded by a soft outer ring, were just made in These lenses offer the combined benefits of better visual acuity associated with gas-permeable contact lenses and greater comfort associated soft contact lenses. Hybrid contact lenses may be an option for people needing major vision correction. Many if not all contact lenses increase your risk of corneal infection. Some of the risks are even unavoidable. All types of contact lenses reduce the amount of oxygen that reaches your cornea Less oxygen promotes infection. Other effects in the cornea are swelling and hazy vision, corneal scratches and scrapes, changes in the cornea's shape. You can also get irritation, pain, blurred vision, redness, light sensitivity, dry eyes, or allergic reactions to contact lens solution. Your eye may also experience eye inflammation or eyelid inflammation. This is an inflammatory bump that forms under the eyelid, making it uncomfortable to wear contacts. When eye inflammation occurs it is usually best to refrain from also using eye makeup until cleared. Fortunately self-treatment can be easily done to help. Just apply something warm and compressed to your eyes for up to minutes 4 times a day to cleanse them and to reduce discomfort. Avoid rubbing or scratching your eyes, and use a cotton swab to carefully clean the lid margins with a baby shampoo or a baby body wash solution in the morning and at bedtime. Also artificial tears are helpful.

The End…….. Like contact lenses problems with eyeglasses may arise. Problems such as reflections, scratches,contrast, distortion, and normal damage such as breakage may occur. Luckily, unlike contact lenses, one does not have to replace their glasses, or take drastic measures to fix these problems. If glare becomes a problem with your eyeglass lenses, one should consider an anti-reflective coating. Anti- reflective coating will reduce reflections, decrease halos around light, and create a nicer cosmetic appearance. If one is scared of scratches they need not fear. For most eyeglass lenses today have built-in scratch resistant coatings and ultraviolet protection. Lastly visit your eye doctor annually to check your eyeglass prescription. While eyeglasses can correct some common vision problems, it is important to have routine eye examinations regularly to keep the eyes healthy!