Most users do not know that contact lens prescription and eyeglass prescription are not necessarily the same. Apparently they don’t understand their own recipe. They get an eye exam and buy glasses at the eye exam site. They could buy glasses online for men, women and children and buy anti-reflective glasses from other sources, such as online glasses stores, but that would need the buyer to know the detailed description of their eye power. Also, if you need to buy contact lenses, you have to know how to convert them.
With glasses, it is also essential to keep all the necessary technical factors in place. Measurement of PD (pupillary distance) is important. It is measured as the distance between the two pupils. It can be measured with a simple scale and a mirror in front. It is measured in millimeters. If you notice a figure like 62/59 written on a recipe, that would mean that the distance PD is 62 while the near PD is 59.
Distance PD is measured by looking directly and PD reading is measured when looking closely. Each eye when measured individually is called MPD, which is monocular PD. There is not much variation in adult PD that occurs over time. Correct PD measurement helps ensure precision in eyewear manufacturing. If one intends to buy glasses online, this measure helps.
We can also convert an eyeglass prescription into a contact lens prescription, but not the other way around. This is because there could be a cylindrical power involved in the prescription that can become the contact lens prescription. However, with contact lens prescription, it is difficult to know what the eyeglass prescription may be. Some good online stores have a conversion table for converting the wattage of glasses to wattage of contact lenses.
You should also know how to read a prescription for glasses. Once the user receives a prescription for glasses from their doctor, after having done a complete refraction to find out if there is any refractive error of the eyes, they can think about wearing contact lenses depending on the power of the glasses.
The eyeglass prescription has some abbreviated forms like OD and OS, which stands for Oculus Dexter and Oculus Sinister. In simple words, it is Right and Left. These numbers are positive or negative, indicating hyperopia or myopia. A positive indicates that the person is farsighted, while a negative indicates myopia. Ideally, if you know the spherical, cylindrical, and complete axis of each eye, then you know that you are nearsighted, farsighted, or have astigmatism. However, a full prescription could also include astigmatic features.
Apart from the two measurements given in the prescription, for astigmatism, there must also be the axis. The axis is between zero and one hundred and eighty. The axis gives you the location of the astigmatism. The greater the cylindrical power, the greater the astigmatism.
A prescription can also consist of prism power. This occurs rarely and could indicate diplopia. Whenever there is prismatic power, they have a direction or a base. This feature can be enabled, disabled, enabled, or disabled.
As long as there is a prescription with a power of addition written at the end that would always be a positive number, this would indicate a prescription for bifocal or progressive lenses. The positive power is the amount of extra concentration needed to aid in the reading.
However, with contact lenses, there is more at stake. One should be able to turn the power of glasses or spectacles into the power of contact lenses or seek professional help for the same. Depending on the type of lenses used, prescription and fitting of contact lenses involves much more than fitting lenses for glasses. There are a different variety of lenses available such as hard lenses, semi-soft lenses, and soft lenses.
Soft lenses are available in annual, monthly, and daily lenses.
It makes perfect sense to shop for glasses and contact lenses online. Obtaining an eyeglass prescription from your eye care professional and ordering eyeglasses and contact lenses online saves you money and time.
