Considerate outdoor lighting reduces glare and light trespass and improve the night time visual environment. In 2004, the City adopted Outdoor Lighting Standards that apply to new and replaced light fixtures in the business districts. The goal is to improve nighttime visibility, while maintaining safety and security. This usually involves cut-off luminaires. The term "cut-off" refers to a shield that directs light downward.
The International Dark Sky Association is a great resource.
"The City Dark" a PBS documentary explores the impacts of artificial light. Available at the Homer Public Library.
Youtube two-minute video provides an example of how shielding a light fixture reduces glare and light trespass.
Homer's Lighting Standards scroll down to HCC 21.59.020-030.