  Subretinal injection methods and other procedures for treating retinal
conditions and diseases (many considered incurable) have been limited in scope
due to limited human motor control. This study demonstrates the next
generation, cooperatively controlled Steady-Hand Eye Robot (SHER 3.0), a
precise and intuitive-to-use robotic platform achieving clinical standards for
targeting accuracy and resolution for subretinal injections. The system design
and basic kinematics are reported and a deflection model for the incorporated
delta stage and validation experiments are presented. This model optimizes the
delta stage parameters, maximizing the global conditioning index and minimizing
torsional compliance. Five tests measuring accuracy, repeatability, and
deflection show the optimized stage design achieves a tip accuracy of <30
$\mu$m, tip repeatability of 9.3 $\mu$m and 0.02{\deg}, and deflections between
20-350 $\mu$m/N. Future work will use updated control models to refine tip
positioning outcomes and will be tested on in vivo animal models.
