This paper presents the characterization and comparison of physiological tremor for pointing tasks in multiple environments, as a baseline for performance evaluation of microsurgical robotics. Previous studies have examined the characteristics of physiological tremor under laboratory settings as well as different operating conditions. However, different test methods make the comparison of results across trials and conditions difficult. Two vitroretinal microsurgeons were evaluated while performing a pointing task with no entry-point constraint, constrained by an artificial eye model, and constrained by a rabbit eye in vivo. For the three respective conditions the 3D RMS positioning error was 144 μm, 258 μm, and 285 μm, and maximum 3D error was 349 μm, 647 μm, and 696 μm. A spectral analysis was also performed, confirming a distinct peak near in the 6-12 Hz frequency range, characteristic of hand tremor during tasks in all three environments.