s.o.s., si op. sit means si opus sit - if there is a need in Prescription
Similar to s.o.s., si op. sit
noct. - nocte - at night non rep. - non repetatur - no repeats NS - normal saline 0.9% o.p.d. - once per day o.s. - oculus sinister - left eye o.u. - oculus uterque - both eyes od - oculus dexter - right eye