Evaluation of Corneal Endothelial Pump Function by an Ice Test

Abstract

Abstract: : Purpose: The barrier and pump functions of the corneal endothelium are responsible for preventing stromal swelling, thereby maintaining corneal transparency. This study was undertaken to estimate corneal endothelial pump function by a cold–stress test. Methods: The subjects were 17 healthy volunteers (21 eyes), 12 patients with penetrating keratoplasty (PK) (15 eyes), 9 patients with decreased corneal sensitivity (DCS) (9 eyes), and 7 patients with corneal endothelial disorders (CED) (10 eyes). Prior informed consent was obtained from all subjects before entering them into this study. After measuring corneal temperature by infrared radiation thermometry and corneal thickness by ultrasound pachometry, an ice pack was pressed on the closed eye for 10 minutes. Immediately after cooling, corneal temperature and the thickness were measured as indicated above and the swelling rate was calculated. Results: The average corneal temperature was decreased from 34.6 C to 25.8 C after cooling. The corneal swelling rates for the control, PK, DCS, and CED groups were 1.27 ± 0.87%, 3.21 ± 2.45%, 4.36% ± 2.62%, and 3.40 ± 1.92%, respectively. The swelling rates in the 3 patient groups were significantly higher compared to the control (p<0.05). There was a significant negative correlation between corneal swelling rate and the corneal sensitivity (r= –0.55), but not endothelial cell density. Conclusions: Ours is the first study that provides statistical evidence for the correlation between corneal sensitivity and corneal swelling induce by cold. We posit that in the presence of cold stress there is a link between reduced endothelial pump function and the trigeminal nerve stimulation.

Keywords: cornea: clinical science • cornea: endothelium • NaK ATPase