Eyesight, it’s the essential ingredient for full visual enjoyment of all aspects of life and this world. Yet, few people enjoy 20/20 vision right through their lives and require a little help along the way… usually in the form of prescription eyeglasses.
But what are the main problems that necessitate the use of eyeglasses?
Let’s go through them one by one:
Farsightedness (hyperopia): this is when the eyeball is too shallow and the image actually focuses beyond the eye. For people with this problem, they can see things far away very clearly but anything close is a blur. In order to correct such a problem you need to make the light rays converge or come together on the retina. This is usually done using convex corrective lenses.
Nearsightedness (myopia): this occurs when the image is focused in front of the retina and only objects nearby can be seen clearly. What does it mean? Far away objects cannot be seen or are seen in a blur, while close-up objects are much clearer (if not perfectly clear). Concave lenses are used to bend the light rays and allow light from far away objects to focus directly on the retina.
Presbyopia: When the lens of the eye loses it elasticity, it can no longer change shape. Usually, this occurs from around the age 40 and continues through the aging process, making people somewhat farsighted. Sometimes bifocal glasses help to improve this condition. These glasses have a second lens placed on the main lens so that people can see both near and far distances almost simultaneously and without having to change their eyeglasses. There is a new, more sophisticated type of lens for this condition known as progressive glasses or multifocal glasses. In this case, the lens is ground specifically to allow viewing near objects through the lower portion and distant objects through the upper portion; in between, there in a progressive range of lens powers for normal range viewing. The frames for these lenses need to be a specific size so be careful when choosing frames as you must be sure that they will fit the lenses properly.
Astigmatism: This is a very common eye disorder and occurs when there is an irregular curvature of the cornea (the transparent covering of the eye) which causes blurred vision. The irregular curvature makes it impossible for light rays to focus on a single point. To correct this, the position of the irregularity is located, and a corresponding area on the eyeglass lens is ground to bring light rays passing through that area into proper focus. You need this in order to have crisp sight without any blurs.
When these problems of myopia, hypo-myopia, astigmatism or amblyopia develop, in layman’s terms, it means that light isn’t reaching the back of the eye properly. What this means in practice is that when looking at things with the naked eye everything looks blurred and somewhat distorted. Prescription eyeglasses – like single vision or multifocal glasses – as well as sunglasses are designed to bend the light to a certain degree so that it reaches the back of the eye as it should and helps the wearer to see everything around him, clearly.
Whenever one is in the market to buy glasses, one should always remember that the incorrect lenses will severely affect ones general health, as well as the health of one’s eyes. Eye problems can cause anything from headaches to nausea and worse, so don’t buy cheap eyeglasses because you’re on a strict budget. Rather ensure to always have a full eye examination and then to take your updated eyeglasses prescription and look at the option of buying high quality discount glasses online.
Hillary Glaser is the Director of Marketing and Special Projects for GlassesUSA.com – the easiest way to buy glasses online. She over sees day-to-day operations for all marketing and promotions of eyeglasses for the company.