OPT8241: What is role of comparator and XOR?

I understood driver and power supply for laser diode. However, I have one question of quad laser circuit.

Your Hex LED circuit which is not used is designed without XOR and Comparator. 

I think that XOR and Comparator is digitally compare actual illumination with reference, but it is not feedback.

Is it essential for laser circuit? What is role of XOR and Comparator?

Thanks.