Although nature ensures that most people see well, in some eyes a mismatch between the “power” and “length” of the eyeball, results in poor vision – this is termed a refractive error. These can be classified as myopia, hyperopia, or astigmatism – depending on whether the power is too high, too low, or different in different axes. Presbyopia is the term used to describe the need for reading glasses. Traditionally, refractive errors have been treated with spectacles, and while these work well in the majority of patients, some simple rules have to be followed when selecting them. These include –
1. Choose the right frame – Since spectacles are usually worn throughout the day, having a comfortable frame is very important. A good fit is as important as a trendy look. The most important aspect of a frame is that the eyes should see through the center of the lens. Hence, please wear he frame and look at yourself in the mirror to ensure this. Since the shape of each face is different, this can sometimes be a challenge. Once this is done, make sure that the length of the side stem is appropriate – the loop of the stem should fit securely around your ear – if it is too long, the frame will tend to slide forwards when the head is tilted. However, if too short or too tight, the pressure exerted by the frame will result in a headache. A shell frame distributes the weight of the spectacles on the bridge of the nose and is less likely to leave unsightly pressure marks on the nose, unlike frames with nose pads. Rimless frames look nice, but are quite delicate and should be chosen only if proper care will be exercised, as they tend to get bent and distorted quite easily.
2. Choose the correct lens – The optician will ensure that the power and centration of the lens are appropriate. However, there are other choices that you can make when choosing your spectacles and it is important to be aware of them. In general, glass lenses are heavier than plastic lenses and this is especially true for higher refractive errors. Plastic lenses are also the best choice when choosing spectacles for children, as they do not break and are hence safer. Similarly, when choosing a delicate frame, be sure to use a plastic lens to lessen the weight of the spectacles. To reduce the thickness of the lens – in higher refractive errors, choose a high index material – both in glass and plastic. Choosing a frame with a smaller eye segment will also help in achieving a better cosmetic appearance in such cases. Tints in the lens help reduce glare, and do not interfere with vision in indoor lighting conditions. For those who spend a lot of time outdoors, a photochromatic lens, which darkens on exposure to sunlight, can be helpful. Antireflective coatings help to reduce glare at night. Scratch resistant coatings will reduce the risk of damage to the lens surface.
3. Reading glasses – For those who do the prolonged reading, a separate pair of glasses in a regular frame will provide greater reading comfort. However, for those who are mostly outdoors, with only occasional reading requirements, using half segment readers are more convenient as they can carry these small frames more easily. For those whose work requires the constant use of both distance and near vision, as in an office environment, the use of bifocals is recommended. These lenses consist of two distinct segments – an upper portion for distance viewing and a lower portion for near viewing. If the person has predominantly distance viewing requirements, a kryptok bifocal, with a smaller reading segment is helpful; while for those with more reading requirements, an executive bifocal, with a larger reading segment is helpful. The presence of two distinct segments with a dividing line can be disturbing in some individuals, due to the image jump when the eye traverses this line. In these individuals, and also in those who use computers a lot, the use of a progressive or transition lens – in which there is no distinct separation of the distance and near segments of the lens, is helpful.
Looking after your spectacles is as important as making the right choice when ordering them. Carry the spectacles in the provided box to ensure that they do not get damaged. Clean the lens with soap and running water, and then shake them dry, before gently cleaning the surface of the lens with the provided cloth. Do not clean them when there is dust and grime on the surface – as this can result in scratches. Be sure to regularly clean the hinges of the frame to ensure that they open and close smoothly. We hope the above information has been helpful in making your use of spectacles a safe, comfortable, and rewarding experience.