Which cataract operation can b done in immature cataract with no complications?

None: There is no surgery on the planet that exists without potential complications. If you want a surgery without complications, then have no surgery at all. Besides, no ethical ophthalmologist would do cataract surgery on a cataract that is immature. If an ophthalmologist guarantees you perfect surgery ; guarantees no complications, i would stick with that one. Just don't be surprised if there is one.

Same surgery: There are always risks of complications with any surgery; this should be fully discussed and understood prior to proceding, especially non-urgent or elective cases. Although there may be some reasons to consider removing a lens not causing visual symptoms (clear lens extraction), i would be very wary of doing so at such a young age, as you will lose the ability to accomodate. Lasik/prk, glasses.

Very safe in general: Depending on other risk factors (length of eye: if very short; history of other eye, h/o trauma, diabetes, on aspirin, flomax, (tamsulosin) general health, etc) cataract surgery is generally very safe and recommended if vision