Aim: To investigate the effects of severe preeclampsia on the retinal nerve fiber layer (RNFL), macula thickness and ganglion cell density in pregnancy and postpartum, using High Definition Optical Coherence Tomography (HD-OCT). Material and Method: The study group included 28 stable pregnant patients diagnosed with severe preeclampsia and the control group, 28 age and gestational week-matched healthy pregnant women. HD-OCT measurements were taken by the same researcher using a Cirrus HD-OCT device and were repeated at 8 weeks postpartum. Results: The mean systolic pressure, diastolic pressure, and intraocular perfusion pressure (IPP) values measured in pregnacy were determined to be higher in the preeclampsia group than in the control group (158.4 ± 7.3 vs.113.6 ± 6.8, 97.0 ± 5.7vs.73.8 ± 5.9 and 68.1 ± 3.9 vs.48.8 ± 3.3 mm Hg, respectively) (p < 0.05 for all). The mean RNFL, macula thickness, ganglion cell analysis, and intraocular pressure (IOP) values during pregnancy were determined to be similar in both groups (p > 0.05 for all). No significant difference was determined postpartum between the groups in respect of mean systolic pressure, diastolic pressure, RNFL, macula thickness, ganglion cell analysis, and IOP values (114.3 ± 5.0 vs 114.6 ± 5.9 mm Hg, 74.6 ± 5.1 vs.74.5 ± 5.5 mm Hg, 96.0 ± 7.3 vs. 95.9 ± 6.7 µm, 228.2 ± 18.9 vs.234.5 ± 15.4 µm, 81.8 ± 8.0 vs. 84.2 ± 4.6 µm, 14.1 ± 2.4 vs.13.8 ± 2, respectively) (p < 0.05 for all). Mean IPP during pregnancy was higher than the mean postpartum IPP in the severe pre-eclampsia group (68.1 ± 3.9 vs 49.1 ± 3.1 mm Hg) (p < 0.001). Conclusion: This is the first study to have evaluated ganglion cell density of the retina, macula thickness, and RNFL using HD-OCT in severe pre-eclampsia cases, both during pregnancy and postpartum.