Intraocular pressure is significantly increase during robot-assisted laparoscopic radical prostatectomy which is performed in a steep trendelenburg position at prolonged timeds of pneumoperitoneum. Threrefore we decided to evaluate the effect of dexmedetomidine in intraocular pressure during roboti-assisted laparoscopic radical prostatectomy.

Inclusion Criteria:

1. ASA class I-II
2. obtaining written informed consent from the parents
3. aged 20-70 years who were undergoing robot- assited laparoscopic prostatectomy

Exclusion Criteria:

1. eye surgery prevoiusly
2. unstable angina or congestive heart failure
3. concomittant eye disease (glaucoma, diabetic retinophaty, cataract, retinal detachment)
4. high intraocular pressure over 30mmHg after screening test.
5. uncontrolled hypertension (diastolic bp>110mmHg)
6. bradycardia under 60bpm
7. Ventricular conduction abnormality
8. hepatic failure
9. renal failure
10. drug hyperactivity
11. neurological or psychiatric illnesses
12. mental retardation
13. patients who can't read the consent form due to illiterate or foreigner