| Stage I (membranous deformity) |
Lateralized maxillary fontanelle |
| Stage II (bone deformity) |
Inward bowing of one or more osseous walls (anterior, superior, and/or posterolateral bony walls) of the maxillary antrum |
| Stage III (clinical deformity) |
Enophthalmos, hypoglobus, and/or midfacial deformity |
