Recommended measurements of Fuchs endothelial corneal dystrophy for clinical trials. Before intervention, some parameters help classify the disease state, and some are necessary to compare to post-intervention measures. Not all parameters may be necessary to measure, depending on the type of intervention.
| Before intervention (Classifying the disease state) | After intervention (Outcome measures) | |
| Anatomy (endothelial morphology) | Guttae distribution* Peripheral ECD | Central ECD† or Guttae distribution* Peripheral ECD |
| Physiology (endothelial function) | Central corneal thickness‡ Tomography maps§ Corneal backscatter¶ | Central corneal thickness‡ Tomography maps§ Corneal backscatter¶ |
| Clinical impact | Best-corrected visual acuity Visual disability (PRO)** Other domains of vision†† | Best-corrected visual acuity Visual disability (PRO)** Other domains of vision†† |
*Guttae distribution can include objective grading of the confluency and area of guttae from endothelial images (ideally if retaining host Descemet membrane) or subjective clinical grading (reasonable if host Descemet membrane will be removed). It is unknown if guttae distribution improves with any interventions that will retain host Descemet membrane at this time.
†Central ECD can be measured post-intervention if host endothelium has been removed (whether replaced with donor endothelium or not), but has limited role if guttae are present (pre-intervention or post-intervention).
‡Central corneal thickness does not classify the disease state, but changes after intervention are important for assessing corneal function.
§Pachymetry and posterior float maps derived from Scheimpflug tomography.35
¶Corneal backscatter can be derived from Scheimpflug tomography39 69 and measurements should be standardised.71 The role of backscatter for disease classification is uncertain at present, but changes post-intervention can be indicative of changes in corneal function.
**The Visual Function and Corneal Health Status instrument has been validated for FECD.77
††Consider low-contract visual acuity and disability glare (straylight).
ECD, endothelial cell density; PRO, patient-reported outcome.