Intraocular pressure in pregnant and non-pregnant Nigerian women.

A number of hormones are known to affect intraocular pressure. Of these, the female sex hormones are the predominant ones to cause variations in intraocular pressure. The aim of this study was to determine if variation in sex hormones in pregnancy affects intraocular pressure. This study was a longitudinal one. 117 pregnant women aged 20 to 35 years in their first trimester of pregnancy were followed longitudinally throughout the course of pregnancy, and six weeks post partum. One hundred non pregnant women with a regular menstrual cycle of 26-29 days were also recruited and examined for changes in intraocular pressure. Intraocular pressure was measured with the handheld Kowa applanation tonometer. Mean Intraocular Pressure (MIOP) was 14.7 +/- 2.2 mmHg, 13.2 +/- 2.0 mmHg and 11.0 +/- 1.3 mmHg in the three trimesters respectively. There was thus a fall in Intraocular Pressure during pregnancy and this was highly statistically significant (P<0.0001). At 6 weeks postpartum MIOP increased to 14.2 +/- 1.8 mmHg. The difference between the mean values of Intraocular Pressure in the third trimester and 6 weeks postpartum was also statistically significant P<0.0001. Intraocular pressure decreased as pregnancy advanced. Postpartum, there was increase in intraocular pressure to near pre pregnant level. The difference in mean IOP between the pregnant and non pregnant women was statistically significant (P<0.05).