Tuberculum sellae meningiomas frequently produce visual loss by direct compression from tumor, constriction of the [[optic nerve]] (ON) under the [[falciform ligament]], and/or ON ischemia.

Gradual [[loss of vision]] is the most common initial complaint by [[optic nerve]] compression
((Al-Mefty O., Holoubi A., Rifai A., Fox J. L. Microsurgical removal of suprasellar meningiomas. Neurosurgery. 1985;16(3):364–372. doi: 10.1227/00006123-198503000-00014.))
((Andrews B. T., Wilson C. B. Supresellar meningiomas: the effect of tumor location on postoperative visual outcome. Journal of Neurosurgery. 1988;69(4):523–528. doi: 10.3171/jns.1988.69.4.0523.))
((Fahlbusch R., Schoot W. Pterional surgery of meningiomas of the tuberculum sellae and planum sphenoidale: surgical results with special consideration of ophthalmological and endocrinological outcomes. Journal of Neurosurgery. 2002;96(2):235–243. doi: 10.3171/jns.2002.96.2.0235.))
((Margalit N., Kesler A., Ezer H., Freedman S., Ram Z. Tuberculum and diaphragma sella meningioma—surgical technique and visual outcome in a series of 20 cases operated over a 2.5-year period. Acta Neurochirurgica. 2007;149(12):1199–1204. doi: 10.1007/s00701-007-1280-4.))
((Margalit N. S., Lesser J. B., Moche J., et al. Meningiomas involving the optic nerve: technical aspects and outcomes for a series of 50 patients. Neurosurgery. 2003;53(3):523–533. doi: 10.1227/01.neu.0000079506.75164.f4.))
, and it has been reported that vascular elements may play a significant role in the mechanism of compression ((Bejjani G. K., Cockerham K. P., Kennerdell J. S., et al. Visual field deficit caused by vascular compression from a suprasellar meningioma: case report. Neurosurgery. 2002;50(5):1129–1132. doi: 10.1097/00006123-200205000-00033.))
((Levatin P. Eye findings in strangulation of the optic nerve. American Journal of Ophthalmology. 1961;51(6):1308–1312. doi: 10.1016/0002-9394(61)92482-5.))
((Steno J. Compression of structures in the visual pathway by arteries of the circle of Willis in suprasellar tumors. Ceskoslovenska Neurologie a Neurochirurgie. 1989;52(2):143–147.))
Levatin 
((Levatin P. Eye findings in strangulation of the optic nerve. American Journal of Ophthalmology. 1961;51(6):1308–1312. doi: 10.1016/0002-9394(61)92482-5.))
was a pioneer in 1961 when he described strangulation of the [[optic tract]] by the [[anterior cerebral artery]] in a patient harboring a [[suprasellar tumor]].
((Mizrahi CJ, Moscovici S, Dotan S, Spektor S. Optic nerve vascular compression 
in a patient with a tuberculum sellae meningioma. Case Rep Ophthalmol Med.
2015;2015:681632. doi: 10.1155/2015/681632. Epub 2015 Feb 1. PubMed PMID:
25705535; PubMed Central PMCID: PMC4331469.)).

Renewed visual deterioration after some initial recovery is highly indicative of [[tumor recurrence]]
((Park CK, Jung HW, Yang SY, Seol HJ, Paek SH, Kim DG. Surgically treated tuberculum sellae and diaphragm sellae meningiomas: The importance of short-term visual outcome. Neurosurgery. 2006;59:238–43.)).

In case of pressure on the chiasm, bitemporal filed defects may occur, while in prechiasmal involvement, vision in one eye may be more seriously involved than the other.