This study examined the mechanism of corneal hydrops in eyes with keratoconus.

Study design

This retrospective study took place across two institutions. Researchers analyzed 16 eyes with comorbid keratoconus and Fuchs endothelial corneal dystrophy undergoing Descemet membrane endothelial keratoplasty (DMEK) surgery and five eyes with keratoconus alone undergoing Bowman layer transplantation that resulted in posterior corneal perforation.

Outcomes

Despite having keratoconus, none of the DMEK patients developed corneal hydrops. However, all five of the patients who received Bowman layer transplantation patients developed instantaneous corneal hydrops. The authors suggest that a break in membrane alone is insufficient to develop corneal hydrops in keratoconus; a posterior stromal disruption is also necessary.

Limitations

The authors note that the Bowman layer transplantation group overall had a more advanced presentation of keratoconus, which may have affected their findings. The study size was small.

Clinical significance

These findings add support to the hypothesis that corneal hydrops in eyes with keratoconus are not dependent upon tears in Descemet membrane alone. Rather, they develop due to a combination of abnormal collagen due to keratoconus, a tear in the Descemet membrane and a tear in the posterior stroma. Future treatment modalities may benefit from this confirmation.