Clinical assessment of corneal hydration control in Fuchs' dystrophy

The diagnosis and monitoring of Fuchs' disease is typically based on information obtained from patient symptoms and a slitlamp examination. Although this clinical information provides a basis for diagnosis, it does not give a quantitative method for charting the progression of the disease systematically or a reliable basis for predicting the cornea's capacity to remain transparent after stress (e.g., cataract extraction). However, it is possible to quantify overall corneal hydration control by inducing corneal swelling and then monitoring the deswelling rate expressed as percent recovery per hour (PRPH). We have tested subjects with Fuchs' dystrophy and found that the PRPH provides a reasonable estimate of corneal hydration control. Unfortunately, the PRPH procedure involves considerable time and technical assistance and therefore is not convenient for clinical practice. In this report, we document the results of an initial effort to explore the relations between PRPH and six clinical measures consisting of five biomicroscopic indices and a subjective synthesis of clinical information called the probability of decompensation (POD) based on these indices. PRPH was significantly related to striae (p less than 0.001), stromal haze (p = 0.025), microcysts (p less than 0.001), and the POD (p less than 0.001) and not significantly related to guttae (p = 0.252) or Descemet's folds (p = 0.185). An empirically weighted predictor of PRPH was constructed from a statistical analysis of five slitlamp assessments and age. This approach for synthesizing clinical information produced a result at least as good as that obtained from the POD summary. These results show an important link between a quantitative laboratory assessment of corneal function and a clinical evaluation of corneal status and suggest that with continued refinement, clinical assessment may provide more quantitative information on Fuch's dystrophy and other diseases that affect corneal status.