The errors in optical communication are of the asymmetric type. Using the Z-channel model, the Bose-Lin asymmetric error detecting codes are analyzed as part of a feedback communication system. The probabilities of detectable and undetectable errors are derived from the code construction using certain properties of the information and check sequences. This is done for two check bits initially, then generalized for any number of check bits. Based on these probabilities, the accepted packet error rate and the throughput can be calculated for pure ARQ protocols. The results obtained show very good performance, in terms of error rate and throughput efficiency, for optical networks.