Table of Contents
Every time the sun blazes high up in the sky, the first and most important thing you should do is to keep your eyes protected from its harsh brightness without compromising your level of visibility. This is the reason why sunglasses with dioptre get glowing recommendations from many ophthalmologists far and wide.
Even though it’s technically a measurement unit, dioptre refers to lenses with close-up filters that allow easier focus when closer. It means that these are prescription glasses.
Quick Definition of Dioptre
You are probably curious about the meaning behind the numbers on your prescription contact lenses or glasses. You might have even attempted to decipher the numbers on the dioptre chart while shopping for a pair of reading glasses at the local drugstore.
For your information, these numbers refer to the lenses’ focusing strength. A dioptre is the unit used to calculate the focusing strength of a pair of contact lenses or glasses.
This is also the measurement unit for optical prescriptions. You can determine the focal length or distance where the light is focused when you know the lens’s power in dioptres and take the inverse.
Relationship between Meters and Dioptres
A lens with a focusing power of one dioptre focuses light from something extremely far away, such as the sun, at a distance of one meter behind the lens. The focal length of the lens is the distance where light is focused.
If you double the lens’s focusing power to two dioptres, the sun’s light will get focused twice as near behind the lens at half a meter, resulting in half a meter focal length.
Connection between Focal Length and Dioptres
Taking the inverse of a lens’ power in dioptres gives you the focal length. Being familiar with the concept of focal length and dioptre will help you understand why some people need to wear contact lenses or glasses while others don’t.
The human eye has two focusing lenses: the crystalline lens and the cornea. The cornea has approximately 45 dioptres, while the crystalline has around 15 dioptres, resulting in a combined focusing power of 60 dioptres.
For people whose eyeball has a length of exactly 1/60th of a meter, the light is focused exactly on the retina located in the very back part of the eye. Additional lenses that will focus the light are no longer required in this case
Just like the human eye, there are also lenses measured in dioptres. The lenses help set the focus of the camera at a certain distance.
Why People Wear Glasses, and Others Don’t
Many people either have too many or too few dioptres of focusing strength in their eyes.
The cornea and lens of a farsighted person have very minimal power. In this case, The focal length is longer than the eyeball, with the light focused at the back of the retina. It needs correction with the help of lenses that have plus or positive dioptres.
As for too many dioptres in relation to the eye’s length, there is a focal length of less than 1/60th of a meter with the light focused right in front of the retina. It’s the case for nearsighted people.
When there is more nearsightedness, the light is focused farther in front of the retina, with the image becoming more out of focus.
For the light to be focused on the retina again, a part of the additional focusing strength of the lens and cornea should be removed. It is done with minus or negative lenses, neutralizing the eye’s excess focusing power.
Why Wear Sunglasses with Dioptre
There are many benefits associated with wearing or using sunglasses with dioptre. Its most obvious advantage is that it protects and safeguards your eyes from the sun without compromising your visibility or ability to see.
Most sunglasses offer up to 100% protection from the UV rays. On top of that, they also look cool most of the time. You can also choose from a wide variety of sunglasses. Aside from prescription fashion sunglasses, these can also be specifically made for swimming, diving, and other sports. There are also prescriptions available for children.
Features to Consider When Shopping for Sunglasses
You need to consider several features when buying your new pair of sunglasses. For instance, you may want to get polarized or progressive sunglasses. With polarized lenses, you can ensure that the light you want will be the only one to get to your eyes.
Meanwhile, progressive lenses change how dark or clear they are depending on the sunlight present. These will be dark outside, similar to traditional sunglasses. But while inside, these will still be sufficiently light to give you a comfortable enough sight.
Do your eyes have a different prescription? If yes, you must make sure you buy your sunglasses with dioptre from a specialized manufacturer who can cater to this need. Remember that choosing a more reliable manufacturer can assure you that you will get the exact and correct pair of sunglasses you need and want for comfort, vision, and style.
Regardless of your choice, ensure you get lenses with an anti-reflective coating that protects you from the harsh UV rays of the sun.
Choosing the Right Frames and Lenses
Choosing the correct type of frames and lenses to meet your needs is critical. As far as lenses are concerned, you can choose between plastic and glass. Ophthalmologists often suggest polycarbonate.
Polycarbonate lenses are plastic shatterproof, fog-resistant, and scratch-resistant, making them safer for playing sports and driving. You can expect polycarbonate lenses to last for years when made correctly and bought from a trusted manufacturer.
It’s also necessary to choose the right frames. Choose frames that offer a wraparound style, with rubber on the nose bridge and at the temples. This will ensure that your sunglasses with dioptre will stay in place, particularly when playing sports.