Optical lens and light emitting device designs achieve uniform light distribution without producing a light “hot spot”, with a benefit of reducing the number of light sources needed and overall cost for direct-lit backlight device. The optical lens includes coating portions or structures on the bottom surface thereof, and a backlight device, or other light emitting device, incorporating said lens, to produce a uniform distribution of light at a target surface. The disclosed lens and light emitting device are particularly useful when an extremely wide transfer function of backlight is needed.