Difficulty in enrolling subjects.

This study is to determine if there is a rise in eye pressure, when patients are placed in a position where the head is lower than the rest of the body during long surgeries.

Eye pressure will be measured at protocol specified intervals.

Inclusion Criteria:

1. Subjects undergoing prolonged procedures (scheduled >3hr) in steep Trendelenburg position (eg. robotic prostatectomy, hysterectomy, cystectomy)
2. Morbidly obese subjects: BMI ≥ 35 kg/m2
3. Thin subjects: BMI ≤ 30 kg/m2
4. Age 18-70
5. ASA (American Society of Anesthesiologists) physical status classification I, II, or III

Exclusion Criteria:

1. Known history of glaucoma
2. Note:if initial IOP is noted to be >21mmHg (millimeters of mercury), patient will be excluded from study and an ophthalmology consultation will be obtained.Surgery will not be postponed.
3. Recent use of IOP lowering topical ophthalmic agents
4. Allergy to latex or proparacaine hydrochloride ophthalmic solution
5. Patients with active corneal epithelial defects or history of recurrent corneal erosion
6. Patients with underlying disorders that can directly increase intraocular pressure (thyroid eye disease, intra orbital tumors, orbital vascular malformation, Sturge-Weber disease, carotid or dural cavernous arteriovenous malformation, cavernous sinus pathology)
7. History of corneal surgery, to include LASIK (laser-assisted in-situ keratomileusis)
8. Any eye surgery within prior 1 month
9. Known pregnancy
10. Cognitive impairment

Adult Subjects undergoing prolonged procedures expected to be in steep Trendelenburg position. Procedure must be scheduled for > 3 hours, eg. robotic prostatectomy, hysterectomy, and cystectomy.