Materials and Methods: Sixty-two patients who applied to the Department of Ophthalmology were recruited for the study on the basis of voluntary. Of 62 subjects, 22 constituted the cyclopentolate group and 40 constituted the phenylephrine group. Randomly selected one eye of each subject received either cyclopentolate or phenylephrine and the fellow eye received serum physiologic. At baseline, the peak systolic velocity, end-diastolic velocity, resistivity index and pulsatilite index of the ophthalmic artery, posterior ciliary artery, and central retinal artery were measured in each eye, using color Doppler imaging. The parameters measured at baseline were compared with those measured after the dosing.

Results: After the dosing, we did not determined any significant difference in systemic parameters and intraocular pressure in both groups (p>0.05). In the cyclopentolate group, there was no difference in retrobulbar blood flow velocities after the application of cyclopentolate (p>0.05). In the phenylephrine group, administration of phenylephrine caused a significant decrease in end-diastolic blood flow velocity of posterior ciliary artery (p=0.034). There were insignificant decreases in blood flow velocities and insignificant elevations in resistivity and pulsatilite indices in all retrobulbar vessels in both groups.

Conclusion: This study suggests that both cyclopentolate and phenylephrine do not result in significant changes in intraocular pressure, systemic pressures, and retrobulbar hemodynamics. However, future studies will clarify the effect of both medications on the retrobulbar hemodynamics in patients with impaired orbital hemodynamics. Keywords : Color Doppler imaging, cyclopentolate, phenylephrine, retrobulbar hemodynamics