There are at least five reasons why tinted lenses are prescribed: comfort, vision enhancement, fashion, concealment, and protection. In the morning, it can be uncomfortable to drive towards the rising sun. A golf ball can easily get lost in the sky. Wearing sunglasses may help tired eyes. Long-term exposure to the sun's UV rays and short wavelength blue light can damage eye structures. For a patient with vision loss tinted lenses can often make a major difference towards improving the contrast of colors and subsequently their day to day vision.
Different diseases can impact our visual abilities differently and therefore certain tints may be more suited for specific conditions. For example someone with glaucoma will perceive light differently than someone with macular degeneration However, with that said, sometimes patients with the same disease can have different preferences of tints. During an eye exam for low vision, a low vision optometrist will demonstrate different tints and assess what if any tint the patient prefers. In particular, the low vision optometrist is looking to see how the tint enhances the patients vision, both for reading and distance vision. While there are general rules about what tints can help different patients, no two patients will always find benefits with the same tint. As a rule however a low vision optometrist wouldn't put someone in a dark gray sunglass if they have trouble discerning light from dark objects - meaning that they cannot distinguish light from dark. This would make it that much harder for them to see. When patients use a brown amber tent, or even a yellow orange tent, the contrast actually increases. This makes it easier to see targets in the distance.
Some patients benefit greatly from it. However, some people try these and don't see any difference. So it's really one of those cases where at the evaluation, it's more about informing and showing patients what is available and how things can change. Again, it is truly an individual process to see what is actually helpful to a patient when an eye doctor evaluates them.
Tinted lenses come in a variety of colors and shades, and can be solid or gradient.
Different color tints are usually found to be beneficial for specific diseases, for example:
Retinitis Pigmentosa
Migraines
Light Sensitivity
Color Blind
The above colors are general guidelines on the colors of tint that are most effective for specific conditions.