Hello.
Yes definitely a candidate with spectacles can join Indian army but there are some criteria which you need to fulfill that is your eyesights should be in their cutoff which are listed below.
Candidate must be able to read 6/6 in a distant vision chart with each eye with or without glasses myopia should not be more than 3.5D, hypermetropia should not be more than 3.5D including astigmatism, etc.
Best of luck.