One-size-fits-all reading glasses not only do not work well for most people who have a different prescription in each eye, and/or astigmatism, or whose lens and frame parameters are not measured correctly, they bypass the opportunity to have their eyes checked for early detection of many manageable diseases or conditions. For those insisting on selecting glasses not measured specifically for there eyes, headaches and eye fatigue are common symptoms.
Bifocals allow the wearer to see clearly both at distance and near despite the reduced focusing ability. Bifocals may also be used to help align the eyes if a person tends to over-cross his or her eyes at near. If you are over 40 or have any difficulty performing tasks at near, ask us whether bifocals or progressive lenses could be right for you.
In any case a visit to your doctor should not be only considered when you feel it is time for new glasses. You should visit your eye doctor at least once every year, unless otherwise instructed by your eyecare provider.
You know how the sun’s UV rays can harm your skin-wrinkles; premature aging and skin cancer are some of the dangers of unprotected sun exposure. The same rays that age and damage your skin can and will hurt your eyes as well. Strong sunlight, and artificial light from sources like welding arcs or tanning lamps can burn the surface of the eye, much like sunburn on the skin.
Reflected sunlight (from the water, for example) is particularly dangerous. There is also evidence that exposure to UV light can contribute to the development of eye diseases that commonly occur as we age, such as cataract and macular degeneration.
Visible light is the part of the sun’s energy that you can see. It is made up of a spectrum of colors: red, orange, yellow, green, blue, and violet. The eye is not equally sensitive to all of these colors. It is most sensitive to yellows and greens which it can see the best. The eye is less sensitive to reds and blues.Different Ultraviolet Rays Ultraviolet rays have shorter wavelengths and more energy than visible light rays. They can have a harmful effect on the eyes immediately or cumulatively from regular exposure over a number of years. The industry has set standards for how much UV may be transmitted (passed) by types of sunglasses. Ultraviolet (UV) rays are strongest at high altitudes, low latitudes, and in open or reflective environments (like sand, snow, or water). They are also strongest at midday. Scientists divide UV rays into three bands according to wavelength: UVA, UVB, and UVC.
UVA rays have been shown to penetrate the under layers of the skin, causing damage and contributing to the skin’s aging and cataracts. Therefore, it is certainly wise to require protection from them in sunglasses.
UVB rays, the sunburn rays, are the ones that cause the most concern. They can cause keratitis, which is similar to sunburn on the eye, and also have been linked to the development of cataracts.
UVC rays are the shortest, the most energetic, and may be the most harmful. Fortunately, they are blocked in the upper atmosphere and never reach the earth. If sunglasses protect against UVB, we can assume they protect against any possible exposure to UVC.
-2.00 -1.00 x 90. The first number (-2.00) tells us the spherical refractive diopter (a unit of measurement) needed to correct (farsightedness or nearsightedness). In this example, a minus sign in front of the number indicates a correction for nearsightedness. A plus sign would indicate a correction for farsightedness. This is generally true when you are talking about the first set of numbers.
The plus and minus signs on the second number, generally indicates what professional examined your eyes. An optometrist usually refracts in what’s referred to as “Minus Cylinder, while an ophthalmologists refracts in “Plus Cylinder”. For example, an optometrists script would be -2.00 -1.00 x 90, while the same prescription written by an ophthalmologists would be; -2.00 +1.00 x 180. Please note that the second number has a plus sign, and the last number (180, the Axis) has been transposed 90 degrees.
The second number (-1.00) is for astigmatism. If there is no astigmatism correction needed then you would not see the third (180) number. Sometimes you might see the following; SPH written for a cylinder correction instead of a number and nothing written for the third number. SPH stands for “Sphere” which indicates that there is no astigmatism correction needed.
The final number (180, the Axis line) is the direction of the astigmatism. Astigmatism can be measured in any direction around the clock. We use the numbers from 001 to 180 to indicate the orientation of the correction needed.
Depending on your need, there may be additional numbers in a eyeglasses prescription as well. If your prescription has a set of numbers, or a single number with a symbol such as a triangle, or the letters ” BI, BO, BU, or BD that would indicate a prism correction. BI = Base In, BO = Base Out, BU = Base Up, and BD = Base Down. It is not uncommon to have different base directions for either eye.
Also, you will see “ADD” numbers for those requiring bifocals or reading glasses. The ADD number is exactly what it indicates…; an ADD, or an additional script to an otherwise already existing prescription. For example, your prescription is -2.00 for the first number. (In this example there is no astigmatism). For the “ADD ” number you have a +3.00.This would indicate that by ‘Adding” the +3.00 to the -2.00, your reading prescription would be +1.00 (adding a greater positive number to a lesser negative number results in a positive answer).
Radiation in the Electromagnetic Spectrum is often categorized by wavelength. Short wavelength radiation is of the highest energy and can be very dangerous – Gamma, X-rays and ultraviolet are examples of short wavelength radiation. Longer wavelength radiation is of lower energy and is usually less harmful – examples include radio, microwaves and infrared. A rainbow shows the optical (visible) part of the Electromagnetic Spectrum and infrared (if you could see it) would be located just beyond the red side of the rainbow.
Ultraviolet light (UV) is an invisible light that is part of the sun’s radiant spectrum. Exposure to ultraviolet light can cause the lenses of the eye to become cloudy, causing cataracts among many other conditions. Ultraviolet light causes the eye to age faster, thus can also cause macular degeneration. You can’t see ultraviolet light. It affects the eye without your awareness to its being there, and the effects are cumulative. Almost everything in nature is affected by UV light, and almost everything deteriorates because of it. Not all sunglass lenses block all of the UV light, but the lens we recommend most is a polarized sunglass lens for sunglasses and polycarbonate lenses for dress wear.
Infrared (IR) is an invisible electromagnetic radiation that has a longer wavelength than visible light and is detected most often by its heating effect. Part of the discomfort you feel in your eyes after being out in the sun for a while is caused by IR light. Not all sunglass lenses block all of the UV light, but the lens we recommend most is a polarized sunglass lens for sunglasses and polycarbonate lenses for dress wear. Although infrared radiation is not visible, humans can sense it – as heat. Put your hand next to a hot oven if you want to experience infrared radiation “first-hand!
The main difference between the two, is that ophthalmologists perform surgery, where an optometrist would not, preferring to specialize in eye examinations, as well as eyeglass and contact lens related services.
Optometrists would be involved in all of the pre- and post-operative care of these patients; collecting accurate data, educating the patient, and insuring proper healing after the procedure. An ophthalmologist is more of a medical related specialist, who would need only to be involved if some kind of surgery were being considered. An optometrist can treat most any eye condition, including the use of topical or oral medications if needed. This might include the treatment of glaucoma, eye infections, allergic eye conditions and others, to name just a few.
A third “O” that often is overlooked, is the optician. An optician is not a doctor, and they cannot examine your eye under their own license. However, a highly trained optician plays an indispensable role in the most successful eye doctors’ offices. An optician most often handles the optical, contact lens, and glasses side of things. Based on their vast knowledge of lenses, lens technology and frames, they manufacture eyeglasses, as well as assist in the selection of eyewear, based on the requirements of each individual patient.