To determine potential factors associated with the long-term visual prognoses in patients with choroidal osteoma undergoing anti-vascular endothelial growth factor (VEGF) treatment. Retrospective case series. Patients diagnosed at tertiary high-volume hospitals between January 2000 and December 2020 were evaluated. The primary outcome measure was visual acuity at 5-year follow-up. The secondary outcome measures included factors associated with favorable vision, defined as loss of <1 line and >20/200 vision. Of 38 eyes from 36 patients (22 female, 61%; mean age 38 years) with choroidal osteoma, 23 eyes (61%) received anti-VEGF treatment (bevacizumab 1.25mg/0.05 cc, monthly or treat-and-extend) and 65% completed the 5 years of follow-up. All treated eyes had associated chorioretinal comorbidities (subretinal fluid 91%; choroidal neovascularization 74%; subretinal hemorrhage 30%). Although there was significant vision loss by 5 years (P=.002), 12 eyes (44%) had favorable outcomes. Only tumor thickness was significantly associated with unfavorable visual outcomes (OR 917.1, 95% CI 1.0-5687.7; P=.049). The optimal cut-off point predictive of visual outcomes was 1.4 mm, and tumor thickness ≥ 1.4 mm was associated with unfavorable vision (OR 27.0, 95% CI 2.0-368.4; P= .013). Among patients with choroidal osteoma undergoing anti-VEGF therapy, a particular patient subset presented with divergent outcomes with very poor vision. Tumor thickness appeared to be the differentiating factor and is thus a potential prognostic indicator for long-term visual prognoses.