Consider booking your Fuchsʼ dystrophy patients for afternoon appointments, as new evidence suggests their corneal parameters may be compromised in the hours after eye opening. Diurnal variations in corneal thickness and curvature may result in the misclassification of corneal edema and Scheimpflug imaging parameters between patients with and without Fuchsʼ, researchers in Germany noted in a study recently published in the American Journal of Ophthalmology. They found a noticeable degree of morning edema exists in corneas with advanced Fuchsʼ dystrophy, which resolves within the first four hours after eye opening.

The study, which included 44 participants with Fuchs’ dystrophy and 11 controls, recorded corneal thickness and curvature over the course of the day using Scheimpflug imaging. Directly upon awakening, mean corneal thickness was 663μm  in Fuchs’ patients and 557μm in controls. In Fuchs’ dystrophy eyes, corneal thickness decreased after awakening. The researchers note that most patients (95%) can be expected to have a change in corneal thickness over the first four hours after awakening of -58μm to -31μm.

Beyond demonstrating the existence of morning edema, the researchers found it imperative to quantify the extent of diurnal variation to make the clinical evaluation of corneas with Fuchsʼ dystrophy more reliable and reproducible. Doing so could make it possible to image the cornea to assist in determining the optimal point of time for corneal endothelial transplantation.

Fritz M, Grewing V, Maier P, et al. Diurnal variation in corneal edema in Fuchsʼ endothelial corneal dystrophy. Am J Ophthalmol. August 12, 2019. [Epub ahead of print].