What are Eyeglasses/Spectacles?

Pieces of shaped glass or plastic called lenses have now been used for years to help correct the vision of people who have some degree of impairment in their vision. Many people, particular as they get older, find that their vision is diminished in some way, and while the extent of this varies hugely from person to person, the solution does not. If you find yourself questioning your vision, or even just wanting to be reassured that all is well, head over to your local optician’s, where a qualified professional will assess your vision and make the appropriate suggestions.

How do I know if I need glasses?

While it is recommended that you go for regular eye check-ups, you may notice yourself squinting more or having trouble reading sign posts that were, in previous days, clear as day. Either way, any eye testing involves a visit to the optician’s. Here an optician (more correctly an optometrist if they are testing your eyes) examines your eyes and test the limits of your vision, typically using an eye chart with letters that become smaller as you read on. If your optician finds that you need corrective lenses, they will prescribe you a pair and discuss your options. Of these, eyeglasses, also known as glasses, spectacles, and specs, are a popular choice.

What are glasses?

Eyeglasses are essentially a corrective lens mounted on a frame. The frame is generally a cosmetic choice, although some aspects, like weight and field of vision, are important considerations you should take into account for day to day living. Heavier glasses, if worn all the time, can be quite a strain and lead to headaches for example.

A corrective lens is a piece of glass or, more commonly these days, plastic, shaped according to your eye size and your visual problem. For example if you have trouble focusing on objects closer to you (called farsightedness or hyperopia), your lens will curve outwards in what is known as a convex shape. Conversely, a lens curving inwards (concave) is used to correct nearsightedness (also called myopia), a condition in which your eyes’ ability to focus on objects closer to you is reduced. Another common but less well known condition is called astigmatism, which is simply a defect in the shape of either the lens or cornea of the eye. Both of these structures are involved in focusing an image so you can see it clearly, and so if there is an abnormality in the shape of either objects appear blurry. Like near and farsightedness, this condition is easily treated by means of eyeglasses.

The final class of common eye problems is presbyopia, which is a fancy word referring to a loss of focusing ability due to aging. Typically this condition affects people above 40, and presents with blurred vision, headaches, and squinting causing a straining of the eye.

What are the different types of glasses?

There are different types of glasses that may be more suited to your needs than others, below is a list of different names you may have heard in and around your optician’s.

  • Reading glasses are simply glasses used when reading, watching TV, driving, or going to the cinema. They are used to correct a minor visual problem which doesn’t justify wearing glasses all the time. The caveat of course is remembering to carry them around and put them on when you need to!
  • Bifocals are lenses which are basically split into two separate parts. Typically, the upper half or section of the lens is used to focus distant objects (to correct shortsightedness), while the lower half is used to focus on objects closer by (to correct farsightedness). These are used to treat presbyopia.
  • Trifocals are basically bifocals with an extra section used to help focus on objects at a middle distance, usually about one metre away, or more roughly, within arm’s reach.
  • Progressive lenses are slightly more complex in that unlike bi- and trifocals there are no separate sections with set properties. Instead, the focus is on a gradient, meaning that each point of the lens has a different focus. As your eye moves down the lens it focuses on objects progressively closer, hence the name.
  • Polycarbonate lenses are an improvement on traditional plastic and glass lenses in that they are far more scratch and impact resistant, and hence a great choice for children and adults who regularly participate in a sporting activity.
  • Photochromic lenses, also referred to as transient lenses, change colour in response to sunlight. These are extremely convenient in sunny conditions as you don’t need to carry around a pair of sunglasses, but still don’t have to squint painfully in bright light! They also save you the cost of purchasing a pair of separate prescription glasses.
  • High index lenses are lighter and thinner lenses used for people who need high prescription lenses that would otherwise be uncomfortably thick and hard to fit into most standard frames.
  • Aspheric lenses are, as the name suggests, spherical lenses which, because of this shape, are thinner and flatter than others.

If you find yourself confused by these options, don’t worry, your optician will walk you through what it is you might need and, once you understand your choices, leave it up to you to pick what’s best. Your optician will also give you advice on how to care for your glasses.

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