Light: waves of electromagnetic energy that are between 380 and 760 nanometres in length. Rattlesnakes can see infrared waves which we cannot, and can see warm-blooded prey in complete darkness. Wavelength plays an important role in the perception of colour. Intensity plays an important role in the perception of brightness. Depth of focus: a greater range of depths are simultaneously kept in focus on the retinas. The retina is composed of five layers of different types of neurons: Lateral communication: communication across the major channels of sensory input. Incoming light is distorted by the retinal tissue through which it must pass before reaching the receptors. Blind spot: a gap in the receptor layer in order for the bundle of retinal ganglion cell axons to leave the eye. Fovea: an indentation (0. 33 cm in diameter) at the center of the retina that is specialized for high-acuity vision for seeing fine details.