Materials and Methods: This is a retrospective non randomized comparative interventional study that was performed on 216 eyes of 108 patients with Primary open angle (POAG).and Normal tension glaucoma from the outpatient clinics at Fayoum University hospital and MISR University hospital, from 2009 till 2014 . We calculated the target IOP according to Saif?s table4 of prediction and C/D ratio. Patients were classiefied into two groups: Group 1 : achieved target IOP( 48 female& 24 male) patients. Group 2 : didn?t achieve target IOP (18 female& 18 male) patients.

Results: C/D ratio in group 1 was 0.373 ± 0.179, (ranged 0.3 - 0.8), while group 2: the mean C/D ratio was 0.860 ± 0.103 (ranged 0.6 -0.93) The V.F. difference in group 1: the mean (MD) was -1.90 ±4.92 , (ranged -16.60 to -1.90). and group 2: the mean (MD) was 0.27 ± 1.48 (ranged . -1.90 to 0.03)

Conclusion: After comparing mean deviation (MD) difference between two groups we found that there is statistically significant difference between both groups as regard the group that achieved target IOP there was regressive changes or stabilization of the visual field MD . Optimal target IOP may be different for different individuals depending on the severity of the disease and should be updated periodically as the disease progress Keywords : Target IOP, primary open angle glaucoma, normal tension glaucoma, glaucoma suspect