What are the causes of high eye pressure, besides glaucoma?

Various. Eye pressure can be falsely elevated (machine error, operator error, corneal scar, etc.), elevated due to thick central corneal thickness, high due to recent eye surgery (i.e. Retained viscoelastic, etc.), etc. However we commonly refer to high eye pressure as having glaucoma, but it's not always true since there are ocular hypertensives with high pressure that never develop glaucoma.
Many. Infection such as by herpes virus or toxoplasmosis can increase eye pressure. Trauma can cause immediate or delayed pressure increase. Cancer of the eye can raise eye pressure. Retinal detachment often lowers eye pressure but there is a rare situation where the outer segments of the photoreceptors can collect in the mesh work and raise the pressure. Steroid can classically inc pressure.
Contradictory quest. The definition of glaucoma is elevated pressure that causes optic nerve damage. So if there is anything that results in increased eye pressure that causes nerve damage then that is by definition glaucoma. Better to ask what causes nerve damage besides glaucoma, there are many causes such as atherosclerosis, high blood pressure, many other systemic conditions.