Bad Vision in Pregnancy

The human cornea must be mechanically stable as a structure. One speaks of the biomechanics of the cornea. In recent years there is increasing evidence that hormones, especially during pregnancy, can negatively affect corneal biomechanics. Our group is one of the international pioneers of this branch of research.

Harmless changes in vision during pregnancy

During pregnancy, many alterations take place in the human body. It has been known for decades that a so-called “myopic shift” takes place in late pregnancy, so the human eye becomes more short-sighted. The causes of this are not yet fully understood, but it is believed that the cornea in late pregnancy stores water and thereby changes their refractive index. These hermetic changes usually return in the first months after pregnancy


It has been known for a number of years now that oestrogen can directly affect the cornea. Increased oestrogen levels during pregnancy can have a direct impact on the biomechanical stability of the cornea. In other words, the cornea becomes “softer” at the end of the pregnancy. This can have a number of consequences.

  • Keratoconus: pregnancy can worsen existing keratoconus. Our group has already published on this topic years ago.
  • Post-LASIK ectasia: our research group was one of the first to report cases of patients who underwent LASIK, who showed excellent results and good vision for years after LASIK… until they became pregnant. During pregnancy, these women then developed post-LASIK ectasia. This is very similar to keratoconus, and is the most threatening complication after LASIK / PRK. These cases demonstrate the importance of the surgeon’s experience in assessing patient’s suitability for undergoing LASIK. Also, the surgeon must be very familiar with the topic of biomechanics of the cornea.

Bad vision and pregnancy


There is increasing evidence that the under-production of thyroid stimulating hormone, TSH, has a direct impact on the biomechanics of the cornea and therefore, good vision. Our research group has been a trailblazer here; read more about our work here.

Our research on this topic

What effect does corneal cross-linking have after 10 years? This August, ELZA doctor and researcher, Emilio Torres-Netto MD was interviewed by TouchOphthalmology on a recent congress presentation he gave on 10-year cross-linking follow-up data collated from two treatment centers in Zurich, and was asked about what the research group found.
This month, Brazil’s top Ophthalmology magazine, Oftalmologica Em Foco, features ELZA’s Prof. Hafezi and Dr. Torres-Netto exploring the story of how CXL at the slit lamp is becoming a reality.

The ELZA Institute