retained eye caps are pretty easy to see .... not the usually clear bright eyes you see with a normal shed. aslo a good indication they may still be on ,will be the caps missing from the shed
It isnt a big deal to get them off on a first shed they can be left and monitered until a second shed cycle just be sure and keep the humidity up
In the event there is a problem again with the eye caps on a second shed use some Glycerin and a q-tip and apply it to the eyes about 2 times a day until the caps come off freely Glycerin is a humectant, meaning it attracts moisture to your skin ,so it works very well with removeing stuck caps ,it can be found in most pharmacys
Edit: I just thought i would point out , it is not always as apparent as the pics linked above