Result from:
Dysthyroid eye disease (the most common)
Hemorrhage, edema, inflammation behind the eye
Extraocular muscle relaxation
Space-occurpying intraorbital lesions
Metastatis tumors
Medical cause:
Cavernous sinus thrombosis
Dacryoadenitis
Foreign body in the eye
Hemangioma
Hopgkin's disease
Lacrimal gland tumor
Leiomyosarcoma
Leukemia
Lymphangioma
Neubroblastoma
Ocular tuberculosis
Optic nerve meningioma
Orbital cellulitis
Orbital choristoma
Orbital emphysema
Orbital pseudotumor
Parasite infestation
Scleritis
Thyrotoxicosis