A Comparison of Intraocular Pressures (IOP) During Prolonged Trendelenburg Positioning in Morbidly Obese and Thin Patients

Study Overview
=================
Brief Summary
-----------------
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.

Detailed Description
-----------------
Eye pressure will be measured at protocol specified intervals.

Official Title
-----------------
A Comparison of Intraocular Pressures (IOP) During Prolonged Trendelenburg Positioning in Morbidly Obese and Thin Patients

Conditions
-----------------
Intraocular Pressure Disorder

Participation Criteria
=================
Eligibility Criteria
-----------------
Inclusion Criteria: Subjects undergoing prolonged procedures (scheduled >3hr) in steep Trendelenburg position (eg. robotic prostatectomy, hysterectomy, cystectomy) Morbidly obese subjects: BMI ≥ 35 kg/m2 Thin subjects: BMI ≤ 30 kg/m2 Age 18-70 ASA (American Society of Anesthesiologists) physical status classification I, II, or III Exclusion Criteria: Known history of glaucoma 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. Recent use of IOP lowering topical ophthalmic agents Allergy to latex or proparacaine hydrochloride ophthalmic solution Patients with active corneal epithelial defects or history of recurrent corneal erosion 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) History of corneal surgery, to include LASIK (laser-assisted in-situ keratomileusis) Any eye surgery within prior 1 month Known pregnancy Cognitive impairment

Ages Eligible for Study
-----------------
Minimum Age: 18 Years
Maximum Age: 70 Years

Sexes Eligible for Study
-----------------
All

Accepts Healthy Volunteers
-----------------
No

Study Plan
=================
How is the study designed?
-----------------

Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| obese patients<br>BMI (body mass index) more than or equal to 35 kg/m2 (weight in kilograms divided by the square of the height in metres) | |
| Thin patients<br>BMI less than or equal to 30 kg/m2 | |

What is the study measuring?
-----------------
Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| To compare the percent change from baseline IOP reading to the peak IOP reading during steep Trendelenburg positioning in thin subjects vs morbidly obese subjects. |  | Measured from baseline IOP to peak IOP during steep Trendelenburg. The overall time frame for which the outcome measure is assessed is up to 3 years. | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| To determine rate of rise of IOP during steep Trendelenburg positioning |  | The time during the surgery when the patient is in steep Trendelenburg positioning. The overall time frame for which the outcome measure is assessed is up to 3 years. | 
| To compare peak IOP and rise of IOP during steep Trendelenburg positioning in thin vs morbidly obese subjects. |  | The time during the surgery when the patient is in steep Trendelenburg positioning. The overall time frame for which the outcome measure is assessed is up to 3 years. |