The effect of colonoscopy on intraocular pressure: an observational prospective study

Colonoscopy is an endoscopic examination of the bowel. It requires insufflation of the large bowel lumen with gas which leads to intraabdominal hypertension (IAH). There is evidence suggesting that IAH positively correlates with intracranial pressure (ICP) and possibly with intraocular pressure (IOP). The aim of this study was to examine the effect of routine screening colonoscopy performed under sedation on the IOP in healthy individuals.

This was a prospective, single site, observational study. Healthy adults undergoing routine colonoscopy performed under sedation including propofol, fentanyl, and midazolam were recruited. Right eye IOP measurements were performed using Tonopen XL® in a left decubitus position at 5 time points during the procedure. Statistical analysis was performed using Student's t-test for paired samples.

Twenty-three Caucasians were recruited. There are 14 males (60%) with a mean age of 60.4 ± 10.4 years (range 36-74). Colonoscopy was conducted under sedation and completed in 22 subjects. Mean baseline IOP was 19.9 ± 4.7 mmHg, 15.8 ± 4.8 mmHg immediately after sedation, 13.5 ± 2.3 mmHg when the colonoscope had reached the cecum, 15.4 ± 5.0 mmHg 5 min after colonoscopy beginning, and 16.5 ± 5.5 mmHg when located in the rectum. The IOP reduction during the procedure was statistically significant (P < 0.01).

Routine colonoscopy performed under sedation using propofol, fentanyl, and midazolam does not increase the IOP in healthy adults.