Morphofunctional changes of the ocular drainage system and ocular hypertension in thyroid eye disease

Purpose. To perform a clinical and functional evaluation of ocular tone disturbances and their consequences in patients with thyroid eye disease (TED), with an emphasis on determining the role of structural changes in Schlemm’s canal in the development of ocular hypertension. Materials and Methods. Ninety-two patients (150 eyes) were examined and divided into four groups: TED with ocular hypertension, TED without ocular hypertension, primary open-angle glaucoma, and healthy controls. Comprehensive ophthalmological assessment included visual acuity testing, tonometry, tonography, perimetry, optical coherence tomography (OCT) of the anterior segment and optic nerve head, as well as morphometric analysis of Schlemm’s canal. The NOSPECS and CAS scales were used to assess disease activity. Results and Discussion. Patients with TED and ocular hypertension demonstrated significantly more severe disease manifestations according to the NOSPECS scale, a decreased outflow coefficient (0,12±0,02 mm³/min/mm Hg), elevated intraocular pressure and ocular rigidity coefficient, and morphological narrowing of Schlemm’s canal. These parameters correlated with retinal nerve fiber layer (RNFL) thickness and the severity of visual field defects, closely resembling the ocular hydrodynamic profile of primary open-angle glaucoma. Conclusion. Ocular tone disturbances in thyroid eye disease are associated with morphofunctional changes of the ocular drainage system and require early diagnosis using OCT and tonography for timely detection of ocular hypertension and prevention of glaucomatous complications.