Severity of ocular surface disease13
| Grade I | Punctate epithelial erosions (PEEs) involving the inferior third of the cornea |
| Grade II | PEEs involving more than the inferior thrd of the corneal surface |
| Grade III | Macroepithelial defect (MED) |
| Grade IV | Stromal whitening in the presence of epithelial defect (SWED) |
| Grade V | Stromal scar |
| Grade VI | Microbial keratitis |