AIM: To evaluate changes in pulsatile ocular blood flow in normal tension glaucoma(NTG)patients.

METHODS: In this prospective case control study color Doppler imaging(CDI)was used to determine ocular blood flow parameters - peak systolic velocity(V_max), end diastolic velocity(V_d), time average mean of maximum velocity(TA_max), pulsatility index(PI), resistive index(RI)and systolic/diastolic ratio(S/D)in ophthalmic artery(OA), central retinal artery(CRA)and short posterior ciliary artery(SPCA)in NTG patients and a comparision was made with the normal subjects. Unpaired Student's t-test was used to compare the two groups and P≤0.05 was considered significant.

RESULTS: V_max in OA, CRA and SPCA in the NTG group was decreased when compared to normals with P values 0.605, 0.254 and 0.348 respectively. V_d in the NTG group was also decreased in all the three vessels when compared to the normal subjects with P values 0.000, 0.014 and 0.138 in OA, CRA, and SPCA respectively. The PI and RI were increased in all the vessels in the NTG group with P values 0.000 and 0.045 for the OA, 0.000 and 0.006 for the CRA and 0.002 and 0.024 for the SPCA. S/D ratio was increased in the NTG group as compared to normals with P values 0.047, 0.041 and 0.189 in OA, CRA and SPCA respectively.

CONCLUSION: This study concludes that CDI may provide an effective way of measuring part of the vascular component of glaucoma. We found decreased blood flow velocity and increased resistive indices in the ocular vasculature in the NTG group as compared to normal subjects.