The is the region of the eye where photoreceptors are most highly concentrated.

Fovea. 

The fovea region is where most photoreceptors are located. This is because most of the rods and cons are located in this area of the eye. Moreover, this is also where transduction happens. The part where the ambiguous stimuli which is light is interpreted to be a meeaningful information. 

Animals will lose energy because it is converted to heat