| Grade | Prognosis | Clinical findings | Conjunctival involvement | Analogue scale* |
| I | Very good | 0 clock h of limbal involvement | 0% | 0/0% |
| II | Good | ⩽3 clock h of limbal involvement | ⩽30% | 0.1–3/1–29.9% |
| III | Good | >3 to 6 clock h of limbal involvement | >30–50% | 3.1–6/31–50% |
| IV | Good to guarded | >6 to 9 clock h of limbal involvement | >50–75% | 6.1–9/51–75% |
| V | Guarded to poor | >9 to <12 clock h of limbal involvement | >75–<100% | 9.1–11.9/75.1–99.9% |
| VI | Very poor | Total limbus (12 clock h) involved | 100% | 12/100% |
*The analogue scale records the limbal involvement in clock h of affected limbus/percentage of conjunctival involvement. Only involvement of bulbar conjunctiva, up to and including the conjunctival fornices, is considered.