Concord, California (PressExposure) July 10, 2009 -- Almost everybody uses eyeglasses. Some people use reading glasses, and some are using sunglasses, or prescription eyeglasses. Huge demand for eyeglasses has encouraged several eyeglass manufacturers and dealers to launch online eyeglass stores as well. Basic purpose of all sorts of eyeglasses is to provide eye protection. Quality of lenses and different layers on the glass determine the intensity of eye care, provided by eyeglasses. Amid nail-biting competition, it is quite reliving to hear that some leading online eyeglasses stores strive to provide high-end quality and style even in their budget and Discounted eyeglasses segment.
Experts suggest that aspheric lens is counted amongst the lightest lenses. In the eyeglass store, you can get such lenses in single vision as well as bifocal prescription eyeglasses segments. Another lightest lens is the resin plastic lens. But, the biggest setback with this lens is its inability in protection against ultra violet rays. High-index plastic lens seems immaculate here. It offers the best protection against ultra violet rays. So, it is bit expensive too.
Other protective elements in eyeglasses are photo chromic coating, polarizing lens coating, mirror coating and so on. Photo chromic coating is available in brown or gray tint for both formats 'glass and plastic lenses'. It adjusts the intensity of light. Polarizing coating has been assumed excellent blocking layer. It is highly recommended for skiers, boaters and for those who spend maximum time on drive. Mirror coating is like looking through the two-way mirror. Scratch resistant coating is applied front as well as back of the lenses. It protects eyeglasses from accidental scratch and makes it more durable.
Have you ever tried to read your eyeglass prescription? By convention, first line of the prescription speaks about the right eye. Usually, it is denoted by O.D. Similarly, O.S is used for left eye. First column number in your eyeglass prescription speaks about spherical power of your eyes. Diopter is the unit for eye power. Measurements in prescription are mentioned into diopters only. Minus (-) power refers to nearsightedness problem and plus (+) power is used for farsightedness problem. Now, moving towards the second column in prescription, you will get cylinder power of your eyes. The last column is about axis and it represents location or direction of the cylinder power.