The primary optic for an LED only gives directional light 180 degrees. Because it is too broad of a light for most applications, the LED light begins to lack intensity over distance. To alter the radius and get a more focused intensity, it is necessary to add a secondary lens and/or reflectors.
LED lenses are designed for use with single or multiple LEDs. The lens sit over the LED to create the desired lighting effect.
They can offer a nice aesthetic appearance by masking the LED components within.
Shapes of LED Lenses
Clear or diffused Lens?
Clear lenses provide a crisp-edged beam of light.
Diffused lens has a softer edge. Diffusion can also offer a more uniform light output when multiple LEDs are used.