Scheimpflug-Based Tomographic Risk Factors for the Development of Acute Corneal Hydrops in Keratoconus

Purpose: The purpose of this study was to assess the risk factors that predispose patients with keratoconus to develop acute corneal hydrops (ACH), including both clinical and tomographic risk factors. We additionally describe tomographic changes of the cornea over time after ACH. Methods: We retrospectively reviewed patients with keratoconus who were followed at our institution from January 2015 to May 2023. Control eyes, defined as eyes with advanced keratoconus (stage IV Amsler-Krumeich classification on initial examination) were compared with eyes that developed ACH. Demographic, clinical, and tomographic factors were investigated. Visual acuity, keratometry, and corneal thickness were assessed at each follow-up visit to monitor progression over time. Results: Twenty-three eyes of 19 patients developed ACH over the follow-up period. The incidence of known clinical associations including seasonal allergies, eye rubbing, snoring, asthma, and eczema was similar between the hydrops and control groups. There was a higher incidence of Down syndrome in the hydrops group ( P = 0.04). Eyes that developed hydrops had similar best corrected visual acuity on initial examination, but had steeper keratometry ( P = 0.003) and thinner corneas ( P < 0.001) than controls at baseline. After hydrops, progressive corneal flattening and reduced maximum keratometry occurred over time. However, final best corrected visual acuity was worse compared with initial examination before hydrops ( P = 0.03), as well as compared with control eyes ( P < 0.001). Conclusions: Risk factors of developing ACH include steep keratometry and thin corneas as well as Down syndrome. Although corneal flattening will occur after resolution of acute corneal edema, visual acuity worsened after ACH.