Evaluation of choroid and retinal blood flow and choroid thickness changes according to pregnancy periods with optical coherence tomography and optical coherence tomography angiography

Purpose: Evaluation of choroidal and retinal blood flow and choroidal thickness changes between trimesters during pregnancy with OCT and OCTA and comparison with a healthy non-pregnant female control group. Material and Method: A total of 172 eyes, 82 eyes of 41 pregnant women and 90 eyes of 45 healthy women, were included in the study. 3 measurements were made in the second and third trimesters in 41 pregnant women who were followed up in the first trimester, and 1 measurement was made in 45 healthy female controls. Intraocular Pressure (IOP), Visual Acuity, Spherical equivalent (SE) values and Ocular Perfusion Pressures (OPP) of the patients were measured. Retinal thickness, retinal nerve fiber layer (RNFL) thickness, ganglion cell layer (GCL) thickness, choroid thickness (CT), superficial capillary plexus (SCP) and deep capillary plexus (DCP) foveal avascular zone (FAZ) area and vascular density (VD) measurements, choriocapillary VD measurements were made by evaluating the OCT and OCTA images of the patients taken with Topcon Swept Source OCT- Angiography, DRI OCT Triton (Topcon Co, Japan) device. All values were compared statistically and a p value less than 0.05 was considered significant. Results: Pregnant women were measured at an average of 9,5 ± 2,7 (5-13) weeks in the first trimester, 20,1 ± 2,4 (17-27) weeks in the second trimester, and 31 ± 2 (29-36) weeks in the third trimester. The mean age in the pregnant group was 30,8 ± 5,9 (20-40), while the mean age in the control group was 29,7 ± 5,9 (20-40), and the difference was not statistically significant (p = 0,227). In pregnant women group IOP in the 2nd and 3rd trimesters was found to be significantly lower than the control. As the gestational week progressed, a significant decrease was detected in IOP. No significant difference was detected in visual acuity. A significant shift to myopia was observed in the third trimester in SE values (p= 0,01). An increase was observed in OPP as the gestational week progressed, but the difference was not significant (p=0.06). No significant difference was observed in retinal thickness at central and all parafoveal quadrants, between trimesters and the control group. RNFL thickness was found to be significantly lower than the control in the 1st and 2nd trimesters, and higher than the control in the 3rd trimester, but the difference was not significant. Parafoveal temporal, superior and mean RNFL thicknesses increased significantly as the gestational week progressed. There was no significant change in GCL thickness between trimesters in both eyes and when compared with the control group. CT measurements in all SFCT and parafoveal quadrants were found to be higher than the control group in the whole trimester. In the 1st and 3rd trimesters, except for the parafoveal nasal quadrant, this height was significant in other quadrants compared to the control. There was no significant difference in CT measurements between trimesters. An increase was detected in the FAZ area of SCP as the gestational week progressed in both eyes. The increase in the 3rd trimester was statistically significant when compared to the 1st trimester (p= 0,01). If we compare with the control group, the FAZ area of the 1st trimester was significantly lower than the control group. SCP FAZ area in the 3rd trimester was higher than the control, but the difference was not significant. In the 2nd and 3rd trimesters, SCP VD values were found to be significantly higher than the control. A significant decrease was detected in SCP central VD in both eyes in the 3rd trimester compared to the 1st and 2nd trimesters. As the gestational week progressed, a significant increase was detected in the DCP FAZ area in both eyes. The DCP FAZ area was found to be significantly lower in the 1st trimester compared to the control group and significantly higher in the 3rd trimester compared to the control group. VD measurement in all quadrants of DCP was found to be higher than the control in all trimesters. There is a significant decrease in DCP central VD measurement in the 3rd trimester compared to the 1st trimester. A significant increase was observed in the parafoveal superior and inferior quadrants compared to the first trimester. Choriocapillary VD was found to be significantly lower in all quadrants in both eyes in the 1st and 2nd trimesters compared to the control, and significantly higher in the 3rd trimester compared to the control. As the gestational week progressed, a significant increase was detected in choriocapillary VD. This increase was observed to be the highest especially in the third trimester. Conclusion: Physiological changes during pregnancy cause changes in the retina and choroid. It has been observed that significant vascular changes occur between trimesters of pregnancy and when compared with healthy women. Keywords: Pregnancy, optical coherence tomography angiography, foveal avascular zone, vascular density, choroidal thickness