Background The changing scope of optometric practice has had a large impact on the profession.

Optometry has gone from a drugless profession to a profession that can use diagnostic pharmaceutical agents (DPAs) in every state and therapeutic pharmaceutical agents (TPAs) in 46 states.

The intent of this study was to determine the influence that these legal variables exert on the scope of practice for optometrists in different states.

Methods Optometrists in three states with varying statutes regulating the scope of practice were surveyed to determine if there were practice differences related to these state laws.

Results In states with TPA usage, more optometrists accepted Medicare assignment and had hospital and nursing home privileges.

Optometrists with TPA certification had, as a group, graduated more recently.

Travel times for patients with conditions requiring treatment with therapeutic drugs were shorter in the states with TPA legislation.

Conclusions Access to care is enhanced for citizens of a state with optometric usage of therapeutic pharmaceutical agents.