In recent years online stores for prescription eyeglasses has become really popular and more and more buyers are looking to buy their glasses online. Buying glasses online not only helps to save money but it is also very convenient as you can order glasses from the comfort of you home and will be delivered at your door step. However if you are planning to buy your first pair of glasses there are few things that you need to keep in mind and understand to avoid any inconvenience. Here are few tips on how to buy your glasses online.
Get your prescription:
It is important that you get eyes tested by an optometrist or an ophthalmologist to get the latest prescription. The difference between optometrist and ophthalmologist is that optometrist has a Doctor of Optometry degree from an optometry school which is usually four years of training in examining the eyes and treating certain types of visual and eye disorders and ophthalmologist is a Medical Doctor who has an M.D. degree. That means he or she has gone through four years of medical school and at least one year of post-graduate general medical and surgical training and is a fully trained physician who has specialize in treatment of eye diseases by doing at least three years of extra training in ophthalmology. An ophthalmologist is, therefore, fully trained in all aspects of medical and surgical diagnosis and treatment of eye diseases and has as well a complete background in general medicine.
Once you get your prescription the values may seem absurd but it is important that you understand the prescription as you will need to enter the prescription online.
Understanding Your Prescription:
SPH CYL AXIS ADD
OD( Right)
OS(Left)
PD(Pupillary Distance)
Above is an example of how to enter your prescription when buying glasses online but not all prescription will look same or it is not necessary that all the fields will have a value mentioned on the prescription.
SPHis an abbreviation for spherical. SPH correction corrects refractive error of the eye with a single convergent or divergent refractive power in all meridians.
CYLis an abbreviation for cylindrical. CYL correction corrects astigmatic refractive error of the eye by adding or subtracting power cylindrically in a meridian specified by the prescribed axis.
The axis indicates the angle in degrees of one of two major meridians the prescribed cylindrical power is in.
ADDis an abbreviation for addition power. This determines the reading correction required for the lenses. In some prescription ADD power will be mention and in some reading prescription will be different.
OD is an abbreviation for oculus dexter, Latin for right eye
OS is an abbreviation for oculus sinister, Latin for left eye
PD is an abbreviation for papillary distance. PD is the distance between the two pupils.
Below is an example of a prescription:
SPH CYL AXIS ADD
OD (Right) -1.00 0.25 150 2.25
OS (Left) +125 Dsph 2.25 2.25
PD 65 OD: 32 OS: 33
If you notice all the values has a + or – sign in front of the value. This symbol is very important while processing the lenses thus it is important that you enter the correct value according to what it appears. Eyeglasses prescription is measured in diopter which is a multiple of 0.25 and is always in 2 decimal points except axis value which is in degrees which doesn’t have a decimal point.
Understanding signs:
Negative power always has a (-) sing in front of it but a positive power may or may not have a (+) sign. Like on the prescription above OD, CYL is mentioned as 0.25 which OS, SPH is mentioned as +125. Both the power is in (+) but the only difference is one has a (+) sign and the other doesn’t.
Understanding decimal points:
As I mentioned earlier prescription value is always in 2 decimal points. If we take the prescription value for: OD, SPH = -1.00 and OS, SPH=+125. If we notice OD SPH is mentioned as -1.00 and OS SPH is +125 which mean OS SPH will be equivalent to +1.25. If there is a value mentioned as 025 then it will be equivalent to +0.25
Selecting Eyeglass Frames:
Once you get your eyes tested and get your prescription you will need to select a frame. Selecting frames can be tricky especially with the variety of frame available in the market. While selecting a frame make sure that it compliments your face structure and your complexion. The best and easiest way is to visit a local store and try different frames and see which shape compliments your face or you may also try virtual try on which many of the online eyeglass stores offer.
Selecting Lenses For Eyeglasses:
There are many different brands and lens material available in the market but plastic CR 39 lenses are the most common lenses used by the opticians in US. It is advisable that you ask for a lens recommendation from the ophthalmologist or optometrist but if you have already received your prescription and didn’t request for a recommendation you can always contact the customer service and request them for appropriate lenses. Depending on your prescription they will be able to recommend the best suited lenses. Here are some definition for some basic lenses available:
Standard Lenses- Standard lenses are made of plastic CR39 and has an index of 1.50. These lenses are most suited for all prescriptions as these plastic lenses are lighter and safer.
Thin and Light Lenses – also known as hi-index lenses. These lenses are thinner and flatter than conventional lenses. These lenses are available in different index of 1.60, 1.67, 1.74. These lenses are recommended for high prescription.
Light Weight Polycarbonate Lenses- are 1.6 index lenses which are thinner and lighter than conventional lenses. These lenses are 12 times more impact resistant than conventional plastic CR39 lenses and 40 times more than conventional glass lenses. Due to its impact resistant properties these lenses are highly recommended for children, sports person and with rimless frames.
Bifocal Lenses – provide clear vision for two different ranges, usually for distance and near vision but can also be made intermediate (computer vision) and reading.
Progressive Lenses- Unlike other lenses, which offers mono vision correction or bi-focal correction (Distance and Reading), progressive glasses are designed to offer three different vision zones. They are categorized as near, intermediate and far vision. Thus these lenses are not restricted to specific zones like other lenses which make the person’s vision smooth. These different vision zones are embedded on the lenses and the design may vary according to the manufacturer.
Transition Lenses- also known as photochromatic lenses are almost clear when indoors and automatically darken when exposed to sunlight.
Polarized – has thin laminated surface attached on the lenses that helps eliminate glare from reflective surfaces such as the surface of a lake or the hood of a car. Polarized glasses are generally used by sailors and fishermen to reduce glare from the water
Add On For Eyeglass Lenses:
Once you select the frames and lenses the next selection will be add on for lenses. Theses are basically Anti Scratch coating and Anti-Reflective coating. Some store offers add on for free but most of the stores may charge additional.
Anti-Scratch Coating: is a coating that can be applied to the surface of the lenses. This coating doesn’t affect how the lenses functions and doesn’t interfere with your vision, but helps protect your lenses from getting scratches easily. No lenses, even glass lenses, are scratch proof but anti scratch coating will definitely prevent lenses from getting scratched easily.
Anti-Reflective Coating: is a coating of several ultra-thin layers applied on the surface of the lenses. Normal eyeglass lenses causes reflection. These reflections create hazy, fuzzy, ghost image, and halos that interfere with your vision. The reflection of the lenses make it harder to see – especially while driving, working on the computer, watching TV or working under florescent lights. Anti-reflective coating eliminates lens reflection so you can have a clearer and crisper vision that is not possible with standard lenses. This coating also makes your lenses more transparent and your spectacles more conspicuous and more attractive.
Optic store online is the fastest growing online optical shop which selling high quality Prescription Eyeglasses Online, Prescription Sunglasses Online and other eye wear in all type range.