How to convert string to optimization variable?

I'm doing constrained optimization problems using the "problem based optimization workflow". I'm using a set of equations which have been constructed through string concatenation as the optimizaton variables. I now need to convert these strings to optimvars. It's simple to convert these strings to symbolic variables (just use str2sym), but I can't find anything anologous for optimvars. Any ideas on how to do this?

[Ephraim Bryski]

I ended up using "eval" function to solve this issue, but I know "eval" is not recommended.