1 | Thin growth, 1–2 cells thick, non-progressive, difficult to detect, well-delineated white line along advancing edge, no flap change | No | 2 mm within flap edge | No treatment required |
2 | Thicker growth, discrete cells within epithelial nest, no demarcation line along nest, easily detectable on slit lamp, rolled or grey flap edge with no melt | Usually (but slowly) | 2 mm within flap edge | Non-urgent treatment within 2–3 weeks |
3 | Pronounced growth, several cells thick, opaque ingrowth, geographic areas of necrotic cells with no demarcation line, flap rolled with thickened whitish-grey appearance, peripheral confluent haze at flap edge | Yes | >2 mm from flap edge | Urgent treatment |
4 | Aggressive growth, strands of epithelial cells invading towards visual axis, may result in flap melt | Yes | Threatening/affecting visual axis | Urgent treatment |