We investigated the ocular surface (OS) system modifications after completely successful glaucoma surgery in thirty-eight patients undergoing trabeculectomy (surgical group), using laser scanning confocal microscopy (LSCM) and impression cytology (IC). Twenty-six medically controlled glaucomatous patients served as controls (medical group). LSCM, IC, and the ocular surface disease index (OSDI) and National Eye Institute Visual Function Questionnaire-25 (NEI VFQ-25) questionnaires, were performed at baseline and after six months. The main outcomes were: goblet cell density (GCD), limbal dendritic cell density (LDCD), subbasal corneal nerve inhomogeneity (SCNI), Meibomian gland density and inhomogeneity (MGD, MGI), and HLA-DR positivity. There were no significant baseline differences between groups. At the sixth month, the surgical group showed a GCD increase (p < 0.001), and a LDCD, SCNI, MGI, HLA-DR (p < 0.001), OSDI and NEI VFQ-25 scores decrease (p < 0.05). The medical group did not show significant OS modifications, showing LSCM and IC parameters significantly worse compared to the surgical group (p < 0.001). The OSDI score correlated with GCD, MGI, SCNI, LDCD, and HLA-DR (p < 0.001; p < 0.05; p < 0.01). The present study found that the whole OS system objectively improved after completely successful glaucoma filtration surgery. These changes positively affected the OSDI score, but not the NEI VFQ-25 score.