Is colonoscopy prep. dangerous if you have glaucoma?
APR 27, 2021
Question:
I read that drinking large amounts of water quickly raises eye pressure. As massive fluid intake is required before a colonoscopy, would this be dangerous for someone with glaucoma and is there an alternative option?
Answer:
This is an interesting question as the water test was an older way to assess glaucoma risk. Glaucoma specialists would measure a patient's eye pressure (intraocular pressure or IOP) before drinking a gallon of water, and then recheck the pressure soon after. The fluid intake served as a stress test on the outflow system in the eye and was predictive of who was likely to develop glaucoma. Now, of course, there are more pleasant ways to test glaucoma risk.
The preparation for a colonoscopy also involves drinking lots of fluid, but the colonoscopy prep is a laxative. Because this fluid is designed to clean you out, it should not have the same effect on your eye pressure as water. The bigger concern is dehydration.