The aim of this study was to monitor the choroidal thickness of pregnant women in the third trimester with enhanced depth imaging optical coherence tomography (EDI-OCT).

30 age-matched healthy women (30 eyes) in their third trimester and 30 healthy pregnant women (30 eyes) were selected according to the random number table who were checked in the Yinzhou Hospital Affiliated to Medical School of Ningbo University from August 2018 to January 2019. In pregnant women group, they were 22 to 30 years-old with the average age of (28.0±2.5) years-old; in non-pregnant women group, they were 25 to 30 years-old with the average age of (27.2±1.5) years-old. Age, intraocular pressure, axial length, diopter, systolic blood pressure and diastolic blood pressure were measured. Choroid thickness was measured at 5 points (3000 μm with a radius of fovea, fovea, up and down to the fovea, nasal, temporal) by EDI-OCT. And the pregnant women group was measured in the 36^th week during gestation and 3 months after delivery, respectively. Data was expressed by mean±standard deviation(±s). The choroidal thickness between pregnant women group and non-pregnant women group was compared by independent sample t test, and that of pregnant women before and after delivery was compared by paired sample t test.

The basic feature between two groups including age, intraocular pressure, axial length, diopter, systolic blood pressure, diastolic blood pressure was showed no statistical difference (t=1.52, 0.22, 0.18, -1.29, 1.29, 1.16; P>0.05). The choroidal thicknesses of the healthy women at 5 points were (210.23±43.37)μm, (231.97±35.00)μm, (222.77±44.32)μm, (154.90±57.46)μm, (220.07±50.78)μm, respectively. The choroidal thicknesses of the pregnant group at 5 points were (243.80±76.20)μm, (259.33±58.56)μm, (254.03±71.08)μm, (160.50±60.62)μm and (249.50±61.86)μm. The choroidal thicknesses of the healthy women were less than the pregnant group at 5 points. Among of them, fovea, up, down and temporal were statistically significant (t=2.10, 2.20, 2.04, 2.01; P<0.05); nasal was non-statistically significant (t=0.37, P>0.05). The choroid of the pregnant women were thicker in the 36^th week during gestation than 3 months after delivery, and 5 points were statistically significant (t=3.68, 2.49, 5.21, 3.34, 2.51; P<0.05).

The choroidal thicknesses of the healthy women were less than the pregnant group at 5 points. Choroidal thickness had thickened during pregnancy, which could be recovered after delivery for 3 months.