Study investigates effects of child delivery on IOP

No significant changes were found at any stage of labor in healthy women.

Issue: November/December 2013

COPENHAGEN — Vaginal child delivery may not be contraindicated in women with glaucoma, as it does not cause IOP increase, according to a study.

“Many ophthalmologists and obstetricians recommend an assisted delivery or a Cesarean section in cases of pre-existing eye diseases, based on the assumption that the IOP increases during the pushing stage of labor; however, these recommendations are not evidence-based,” Noa Geffen, MD, said at the meeting of the European Society of Ophthalmology.

Geffen’s interest in this topic was raised by the question of a 35-year-old woman with severe congenital glaucoma who presented at her office during the third trimester of the patient’s first pregnancy. The patient had multiple filtration surgeries, and her IOP had been stable — around 10 mm Hg — without medication during the previous 10 years. She was concerned regarding what would happen to her pressure during her forthcoming delivery.

“I was not sure what to say. The literary review did not help, as I did not find relevant publications on the topic looking back at the last 35 years. The AGS net didn’t help, either, as I had conflicting answers,” Geffen said. “Eventually, we decided to set up a study in our hospital to evaluate the effects of child delivery on IOP in healthy women.”

Potential IOP-raising factors

Of the three stages of delivery, the first two entail factors that could potentially induce a significant increase in IOP, Geffen said. During the first stage, which is usually the longest, epidural anesthesia is given, and the patient is placed in the supine position.

“We know that the highest IOP and the lowest ocular perfusion pressure are measured in supine position in pregnant women, especially in the third trimester,” she said.

During the second stage, the patient pushes and often utilizes the Valsalva maneuver, forcefully exhaling against a closed airway. The patient may also be doing static exercise, which induces supraphysiological arterial pressure.

“The venous pressure is also elevated, and we know that each 1 mm Hg increase in venous pressure induces at least an equal rise in IOP,” Geffen said.

After performing testing, however, Geffen and colleagues found that not only is IOP not affected, but patients’ heart rate and blood pressure also remain within the normal physiological variation range.

Changes near to zero

“We recruited healthy pregnant women who were candidates for vaginal delivery at the acceptance to the delivery room. At baseline, we collected all the demographic data, performed biomicroscopy with a portable slit lamp and measured heart rate, blood pressure and IOP. Measurements were repeated during the three stages of the delivery,” Geffen said.

At the second stage of delivery, one drop of lidocaine was instilled before a contraction, as measured by a patient monitor, and IOP measurement was performed immediately after pushing was stopped. Further measurements were taken at 24 and 48 hours post-delivery.

A total of 30 women were included, four of whom dropped out due to unexpected Cesarean sections. Average age was 31 years. Epidural anesthesia was performed in all cases. Patients were put into the supine position in 27 cases and in the left decubitus position in three cases. Nineteen women had induction of delivery using oxytocin, and one had vacuum-assisted delivery.

“Heart rate remained quite stable during the delivery process and so, to my surprise, did blood pressure, systolic and diastolic. I was convinced I was going to find significant changes. IOP was also very stable. On average, it remained around 12 mm Hg,” Geffen said.

Repeated measures statistical analysis was performed to obtain more information on within-subjects effects. Individual changes in each patient during the delivery were near to zero.

A limitation of this study is that it included only healthy women and no glaucoma patients, as they would be objectively difficult to recruit in a suitable number within a reasonably short length of time, according to Geffen. However, this was the first study to investigate the impact of modern labor on IOP and led to the important conclusion that the IOP changes during vaginal delivery with an epidural anesthesia are probably insignificant in healthy women.

“We have no evidence to say that the same conclusions apply to glaucomatous patients. However, IOP should probably not serve as an indication for changes in the planned management of labor,” Geffen said.

In a near future, the project might be extended to monitoring during labor for individual glaucoma patients who undergo vaginal delivery. – by Michela Cimberle

Reference:
Noa Geffen, MD, can be reached at Department of Ophthalmology, Meir Medical Center, 59 Tchernichovsky Street, 44281 Kfar Saba, Israel; email: noatal1122@gmail.com.

Disclosure: Geffen has no relevant financial disclosures.