We designed a simple and quantitative method for the clinical evaluation of corneal epithelial barrier function using a slit-lamp fluorophotometer and applied it to healthy volunteers and dry-eye patients. The fluorophotometric method used was as follows: Three microliter of 0.5% fluorescein solution was applied to the cornea in the untouched fashion. Ten minutes after instillation, the ocular surface was washed. Twenty minutes afterward, corneal fluorescence intensity was measured and converted into fluorescein concentration. Corneal condition was classified into four grades: no superficial punctate keratopathy (SPK) anywhere on the cornea (grade 0); no SPK at the central cornea (grade 1), mild SPK at the central cornea (grade 2), and severe SPK at the central cornea (grade 3). In the volunteers, corneal condition was classified as grade 0 and fluorescein uptake (ng/ml) was 22.4 +/- 16.9 (mean +/- SD, n = 86). In dry eye, fluorescein uptakes showed significant increase in accordance with SPK severity: grade 1: 96.4 +/- 51.2 (n = 13); grade 2: 318.6 +/- 146.0 (n = 11); and grade 3: 1479.1 +/- 671.9 (n = 10) (each p < 0.0005). This simple method with the slit-lamp fluorophotometer can be used for the clinical grading of SPK in dry eye or other ocular surface diseases.