There are many cases of patients getting a new prescription after a long period of time that involves more dramatic curvature of the lens to correct things like astigmatism or farsightedness.
In some cases it quickly becomes apparent that the new prescription is distorting what you see through the lens. Another case is when you have lenses that have a large amount of curve in them such as wrap around sunglasses.
These wrap around sunglass lenses can cause some distortion making the sunglasses uncomfortable to wear.
In fact in some cases the distortion can cause nausea or even dizziness when wearing them.
Visual acuity is acuteness or clearness of vision, which is dependent on the sharpness of the retinal focus within the eye and the sensitivity of the interpretative faculty of the brain.
Normal visual acuity is commonly referred to as 20/20 vision, the metric equivalent of which is 6/6 vision.
It is possible to have vision superior to 20/20: the limit of acuity in the unaided human eye is around 20/10-20/8 (6/3-6/2.4), although 20/8.9 was the highest score recorded in a study of some US professional athletes.
Some birds of prey, such as hawks, are believed to have an acuity of around 20/2; in this respect, their vision is much better than human eyesight.
When wearing eye wear one of the considerations is the effect the lenses have on your visual acuity. Not all sunglass lenses provide the same degree of visual acuity, and in fact some lenses will introduce distortion in the lenses.
Distortion Free Lenses
There are really only 3 types of lens materials used in glasses and sunglasses:
In most sunglasses manufactured today polycarbonate is really the only material used for non-prescription sunglasses eye wear. Because of the nature of polycarbonate it can be “bent” or “curved” to fit sunglass frames that are designed for fashion look instead of performance.
As a result many sunglasses with polycarbonate lenses are not distortion free lenses at all.
Glass Distortion Free Lenses
On the other hand glass can be precision ground to incredible tolerances making them ideal for producing distortion free lenses. Besides being highly scratch resistant, glass lenses absorb heat keeping eyes cooler and when properly ground actually can improve visual acuity for the wearer.
In other words distortion free glass lenses are easier on the eyes, allow you to see everything in more detail and protect your eyes best from harmful ultraviolet radiation.
Distortion free lenses are particularly important for pilots and drivers because they tend to observe traffic from the corners of our eyes.
Video On Distortion Free Lenses
Randolph Engineering Distortion Free Lenses
Almost all of Randolph Engineering’s sunglasses come with precision ground glass lenses which provide exceptional visual acuity throughout the entire range of your visual focusing making them ideal for pilots and anyone who drives a motorized vehicle.
You can find a great selection of sunglass styles on our Randolph Engineering Sunglasses Review page.
Keep your eyes cool and protected today my friend!
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