To evaluate the effect of treatment with high-dose glucocorticoids (HDG) on ocular surface parameters and in vivo confocal microscopy (IVCM) findings in patients with active thyroid eye disease (TED). This study included 15 active TED patients treated with a cumulative HDG dose of 4.5g (500 mg and then 250 mg for 6 weeks each). Disease activity was assessed by the clinical activity score (CAS), Graves' Orbitopathy-specific Quality of Life (GO-QoL) questionnaire, ocular surface disease index (OSDI), tear break-up time(T-BUT), ocular surface staining and IVCM. The mean follow-up time was 48.6 months. The treatment resulted in a significant improvement in the T-BUT, ocular surface staining values. In comparison to the baseline, a notable reduction in CAS, OSDI and an increase in GO-QoL were seen after one year. IVCM showed a significant decrease in the number of dendritic cells, activated keratocytes, the degree of tortuosity, there was also a significant increase in the number of basal epithelial cells and total nerves over one-year period. All of those changes remained stable during the follow-up period. HDG treatment results in a sustained decrease in corneal inflammatory cells, an increase in tear film stability, and an improvement in disease symptoms and QoL scores for up to 4 years.