Purpose: Use the anterior segment optical coherence tomography (AS-OCT) to evaluate the tear meniscus parameters, total corneal thickness (CT), and epithelial thickness in active and inactive thyroid eye disease (TED) patients and compare them with age-matched controls. Patients and methods: This is a prospective case-control clinical study in which the subjects were divided into three groups, group I of inactive thyroid patients, group II of active thyroid patients, and group III of healthy controls. The AS-OCT was used to measure lower tear meniscus parameters (tear meniscus height (TMH), tear meniscus depth (TMD), and tear meniscus area (TMA)), total CT, and epithelial thickness. Results: All tear meniscus parameters (TMH, TMD, and TMA) were reduced in groups I and II with more reduction in group II with no significant difference between them with a significant difference when comparing groups I and II with group III. The mean total CT was 496.7±19.9 in group I, 497.8±20.6 in group II, and 520.3±23.9 in group III with no significant difference (p-value = 0.757) between groups I and II while there was a significant difference when compared with healthy controls. The mean epithelial thickness was 46.5±2.6 in group I, 47.3±2.7 in group II, and 53.2±4.5 in group III with no significant difference between groups I and II while there was a significant difference when compared with healthy control. Conclusion: TED patients had reduced tear film parameters regardless of the thyroid activity, also the total CT and epithelial thickness was thinner in comparison with healthy controls.