Predicting Edema Resolution After DMEK for Fuchs
JAMA Ophthalmology, April 2021
Which patients with Fuchs dystrophy are most likely to benefit from Descemet membrane endothelial keratoplasty (DMEK)? Using Scheimpflug imaging, Zander et al. developed and validated a predictive model for edema resolution following DMEK. They identified five pre-op Scheimpflug parameters that may help clinicians identify ideal candidates for the procedure.
For this study, the researchers conducted a post hoc analysis of two prospective studies of patients with advanced Fuchs dystrophy. All told, 88 patients with a minimum stable follow-up of at least two months after DMEK and high-quality Scheimpflug imaging before and after surgery were identified. Development of a predictive model, using linear least absolute shrinkage and selection operator regression, was conducted in a derivation cohort of 100 eyes. This was subsequently validated in a smaller cohort of 32 eyes. The main outcome measure was decrease in central corneal thickness (CCT).
A median of 13 months after DMEK, median corneal thickness was 77 µm lower in the derivation cohort and 75 µm lower in the validation cohort. For each 10 µm of edema resolution, eyes gained 0.66 ETDRS letters in best-corrected visual acuity.
To predict edema resolution, five variables were selected by the statistical learning algorithm: two tomographic features (presence of parallel isopachs and amount of focal posterior depression) and three indicators of corneal profile and structure (anterior backscatter, posterior backscatter, and CCT). With regard to the tomographic features, eyes without any tomographic features before DMEK had more edema after surgery than those eyes with such features (mean difference, 29 µm less resolution of edema). With regard to corneal structure, the authors noted that although single measurements of CCT are not useful to detect corneal edema, CCT added to the predictive model when combined with anterior and posterior corneal backscatter.
Future studies of the model will have to show whether it improves clinical decision-making and leads to better long-term outcomes, the authors said. (Also see related commentary by Viridian Kocaba, MD, PhD, Silke Oellerich, PhD, and Gerrit R.J. Melles, MD, PhD, in the same issue.)
The original article can be found here.