To prevent treating subjects with a light dose greater than that which already provides substantial clinical benefit, the Safety Monitoring Committee will review preliminary efficacy data (AUA SI scores and Qmax values) after all subjects in a cohort (for each of the first 4 cohorts) have completed the Day 90 visit. Further enrollment will be curtailed if more than 75% of subjects in a cohort experience both of the following efficacy stopping criteria by Day 90: