May Be Caused by

 Common

Craniometaphyseal dysplasia

Enucleation

Fibrous dysplasia

Hypercalcemia

Meningioma

Optic nerve atrophy

Osteopetrosis

Osteosarcoma

Paget disease of bone

Radiation therapy

Thalassemia

 Uncommon

Anophthalmos

Antral cyst

Antral neoplasm

Apert syndrome

Cloverleaf skull deformity

Congenital orbital hypoplasia

Coronal suture craniosynostosis

Crouzon syndrome

Enucleation in childhood

Forebrain hypoplasia

Frontal sinus mucocele

Frontal sinus neoplasm

Hallermann-Streiff syndrome

Hurler syndrome

Larsen syndrome

Marshall-Smith syndrome

Microphthalmia

Neurofibromatosis

Oculo-dento-osseous dysplasia

Orbital dysplasia

Osteoporosis-pseudoglioma syndrome

Sphenoid sinusitis

Trisomy 13

Weill-Marchesani syndrome

Zellweger syndrome