While civilian medical treatments, the so called doctors of the day were mostly inadequate at best, Roman surgeons were highly advanced and skilled professionals. A detailed knowledge of anatomy and its functions led to many surgical operations in line with success rates enjoyed in the modern era. Most surgeries in the ancient world were likely of the low impact variety such as tumor removal and hernia operations, while more extensive surgeries certainly occurred under military care.
Trepanation was a form of brain surgery designed to relieve pressure and cure headaches. Using a drill, a hole in the skull not only worked to relieve the pressure, but patients had a high survival rate.
Cataract surgery was also known. A thin needle was pushed though the eye to break up the cataract and the remaining pieces suctioned out through a long tube. Evidence suggests this procedure at least had a moderate rate of vision improvement success.
A form of ancient cosmetic surgery was also practiced. Excess skin or tissues could be trimmed from various parts to improve the appearance. Freed slaves also were common customers of branding removal. While an expensive procedure, being able to mask the history of service as a slave was a valuable operation in Roman society.