Taiwan has a very high prevalence rate of myopia. We retrospectively studied the influence of myopia on the progression of visual field (VF) loss in primary open-angle glaucoma (POAG) patients. Methods: We studied 515 POAG patients for a minimum follow-up period of 5 years. VF examination was performed with Humphrey perimeter, 30-2 SITA standard program, every 6 months. A point-wise numerical comparison was applied to judge the VF changes. Test points showing more than 1.0 dB of sensitivity loss in mean defect were identified. A location was considered to have progression if it was detected on two consecutive visits. Progression of VF loss was confirmed if three or more test points deteriorated. Multivariate logistic regression was used to evaluate the association between progression of VF loss and various risk factors. Results: There were 262 cases. Progression of VF loss occurred in 57 eyes (21.8%) during the 5-year follow-up period. Logistic regression revealed that the deterioration was associated with older age, higher mean intraocular pressure, larger vertical cup-to-disc ratio, and greater myopic refraction status. The incidence of VF loss progression was 15.1% in the group of eyes with myopia less than −3 D, 10.5% in the group with −3 D to −6 D, 34.4% in the group with −6 D to −9 D, and 38.9% in the group with myopia greater than −9D. Conclusion: POAG patients with myopia greater than −6 D had a greater progression of VF loss.