Q: Can i use an eye detecting opencv code on microcontroller?
A: Yes, you can
Q: Is it possible to port an open cv code on a microcontroller
A: OpenCV is already in the Unix and Android platform. The easiest approach therefore will be to get hold of some embedded device with ARM. There are a lot of help available for the 'OpenCV-ARM' combination.
Beagleboard and RasberryPi are the cheapest embedded ARM devices available for less than $150. Sometimes they come preloaded with Unix boot system and opencv2.0. Thus it would be so easy to run the executable that you created in the computer system.
Be aware of the speed of the processor. If your algorithm is computationally intensive then you wont be quiet satisfied with the output being obtained in the low-end embedded devices.