Edema of the corneal stroma induced by cold in trigeminal neuropathy

A patient with a left sensorimotor trigeminal neuropathy was found to have edema of the corneal stroma induced by cold. Examination at room temperature demonstrated an anesthetic left cornea with minimal injection of the left eye and multiple punctate epithelial erosions. Corneal thickness, mean endothelial cell size, coefficient of variation of cell size, endothelial permeability to fluorescein, and aqueous humor flow rate, measured at room temperature were similar in the two eyes. After 47 minutes in a cold room at 4 C, the corneal thickness in the left eye increased from 0.55 to 0.65 mm, whereas that of the right eye remained at 0.55 mm. During the period of maximum swelling, the left cornea had clinical stromal edema with folds in Descemet's membrane but no epithelial edema. After return to room temperature there was a gradual return to normal corneal thickness over three hours. Fluorophotometry showed no evidence of increased endothelial permeability during corneal swelling in the left eye. Specular microscopy after 15 minutes of cold exposure demonstrated many swollen and irregular endothelial cells with darkened areas between cells in the left eye. Sensory nerve deficiency in the human cornea can produce an abnormal sensitivity to cold, resulting in defective control of corneal hydration. This study suggests that this effect may be on the endothelium.