There is a cumulative therapeutic dose in the range of 120mg – 140mg/kg that some doctors adhere to in the bid to reduce the relapse of acne.
Sometimes, doctors may prescribe lower doses (with lower side effects) until the acne has cleared and continue the course for a few more months after.
It really depends on the prescribing doctor as each has his/her own protocol.
If you find that you are still having relapses with lower doses then discuss with your doctor the option of a course to achieve the therapeutic accumulative dose.
With invasive procedures, Acnotin can affect the healing process and sometimes cause scarring. As such, your Lasik doctor is correct in deferring the procedure since you are still currently on Acnotin.
Hope that helps.
All the best!