Sight uses chemical receptors to detect stimuli. These could probably be changed or expanded. Currently the human eye uses three slightly different types of rhodopsin for color vision. Other varieties are known among other animals, and could perhaps conceivably be added to expand the human perceptive range (in order to do this, the synthesis pathways must be added and placed near the other genes coding for rhodopsin synthesis and somehow linked to the cone-cell differentiation signals. Not exactly easy, but hardly impossible). This could expand the range of colors from the near ultraviolet (based on insect rhodopsin) to the near infrared. This would unfortunately work best on the embryonic level, since then the brain will naturally integrate the new type of cone to the visual system. Changes in adults would be much more unpredictable.…
