Lenses

 These are popular because they allow the most visible light through to the eyes and they are the least expensive in both Rx and Non-Rx forms.  Especially good for people who need to see true colors such as artists and chemical analysts and for pople who need maximal night vision such as truck drivers and pilots. 

Lenses that block blue light actually have a yellowish tint that protects vision from harmful radiation, including blue, violet and ultra-violet colors that can harm eyes and vision if excessive.  Very helpful for people who use video displays such as computers, cell phones and even  LASER or X-ray devices.

Also known as Dark Glasses,, these lenses are meant to ONLY be worn in direct sunlight situations.  Unfortunately, some makers of sunglasses do not include UV blockers (Ultra-Violet rays from the sun which can be very harmful to the eyes and the delicate skin around the eyes). Worse yet, any dark lens worn indoors or at night can cause fatal falls or crashes.