Comparison of the biochemical properties of normal, unstimulated human tears, and serum51,52
| Tears | Serum | |
|---|---|---|
| EGF, epidermal growth factor; TGF-β, transforming growth factor beta; SIgA, surface immunoglobulin A. | ||
| pH | 7.4 | 7.4 |
| Osmolality (SD) | 298 (10) | 296 |
| EGF (ng/ml) | 0.2–3.0 | 0.5 |
| TGF-β (ng/ml) | 2–10 | 6–33 |
| Vitamin A (mg/ml) | 0.02 | 46 |
| Lysozyme (mg/ml) (SD) | 1.4 (0.2) | 6 |
| SIgA (μg/ml) (SD) | 1190 (904) | 2 |
| Fibronectin (μg/ml) | 21 | 205 |