The effect of pregnancy on corneal biomechanical parameters

PURPOSE: To detect the corneal biomechanical alterations in healthy eyes during normal pregnancy and to observe the relationship between these alterations and pregnancy hormones and their progress after the parturition. MATERIALS AND METHODS: Sixty six eyes of thirty three cases which their antenatal follow-ups were done in the Outpatient Clinic of the Department of Gynecology and Obstetrics of Faculty of Medicine of Celal Bayar University with ages ranging from eighteen to forty years old and being within the first twelfth week of the pregnancy were included into the study. Visual acuity and biomicroscopic examination, central corneal thickness (CCT) measurement with ultrasonographic pachymetry (UP), fundus examination and corneal biomechanical characteristic measurements with ORA (Ocular Response Analyser) instrument were performed in all of the cases once every three months until the parturition and in three- to six-month intervals after the parturition. Furthermore, estrogen and progesterone levels were studied in each trimester and after the parturition. RESULTS: For CH among the corneal biomechanical parameters, no statistically significant difference between the pregnant females and the control group. However, CRF expressing rather the stiffness of the cornea was found significantly lower in pregnant females compared to control group (p=0.034). Alterations for CH between the pregnant groups were not found statistically significant along the trimesters. However, it was detected that CRF values reduced in the second trimester significantly and it was observed that this value risen again to the values of the first trimester after the parturition. Intraocular pressure was found lower significantly in pregnant females compared to control group (p=0.00). Mean intraocular pressure tends to decrease during the trimesters of the pregnancy. In central corneal thickness (CCT) measurements, significant increase in the third trimester were detected (p=0.00). When central corneal thickness (CCT) values after the parturition were compared with first trimester period, they were found lower in statistically significant level (p < 0.001). No significant alteration was detected in corneal curvature during the pregnancy. CONCLUSION: Either the increase in hormone levels in pregnancy or the impairment of the balance between hormones leads to alterations in corneal biomechanics. CH demonstrates more resistive alterations to hormonal alterations compared CRF. It will be convenient to make evaluations by considering alterations of central corneal thickness, intraocular pressure and CRF changes in the corneal diseases detected either during pregnancy or in those existing before pregnancy and the monitoring of glaucoma. Keywords: Pregnancy, Cornea, ORA