Correlation between Intraocular Pressure and Thickness of Extraocular Muscles, the Severity and Activity of Thyroid-associated Orbitopathy

Abstract

Aim: To establish the correlation between intraocular pressure (IOP) and thickness of extraocular muscles (EOM), the severity and activity of thyroid-associated orbitopathy (TAO). Materials and methods: 50 patients with TAO were included in the study. They all underwent a thorough ophthalmic examination, Goldmann tonometry (mm Hg) and computer tomography of the orbits, the muscle thickness sum (MTS) of each eye being measured in millimeters. According to the activity of TAO, the patients were divided into two groups – with and without activity, and according to the severity of the disease – into 6 groups: Group 1 (‘O’) had only subjective symptoms, group 2 (‘S’) had soft tissue symptoms, group 3 (‘P’) – proptosis, group 4 (‘E’) – ocular motility disorders, group 5 (‘C’) – corneal damage, and group 6 (‘Si’) – visual impairment; Results: TAO activity was registered in 21 patients (42 eyes, 42%) with MTS 23.39±3.81 and IOP 18.43±4.16. Twenty-nine patients (58 eyes, 58%) with MTS 19±3.21 and IOP 15.98±4.59 showed no TAO activity. The IOP within the groups, in terms of severity, was as follows: group 1 – 19.92+4.05; group 2 – 14.5±2.55; group 3 – 18.04±4.51; group 4 – 18.2±5.05; group 5 – 20.5±4.5; group 6 – 21.5±4.95. A correlation between the IOP and MTS was found. Conclusions: The IOP in patients with TAO depends on the thickness of the EOM, as well as on the activity and severity of the disease.

Prognostic value of extraocular muscles for intraocular pressure in thyroid-associated ophthalmopathy patients

“…The underlying mechanism and key factors of increased IOP in TAO eyes remain unclear. A recent study found the EOMs to be significantly enlarged in patients with high IOP compared to those with normal IOP, while another study reported that compared to normal participants, patients with TAO who presented IR muscle thickening had a significantly larger increase in IOP, indicating there to be a correlation between EOM and IOP ( 17 , 18 ). Our study found greater EOM enlargement in patients with high IOP patients than in individuals with normal IOP, while the changes in OF and orbit volume, obtained through MRI measurements, were not significantly associated with increased IOP.…”

Disrupted Gray Matter Structural Networks between Active and Inactive Phases of Thyroid-Associated Ophthalmopathy

“…It was found that the left lingual gyrus nodal BC was negatively correlated with bilateral IOP in active TAO group. TAO patients have higher IOP than healthy controls, which depends on the thickness of the extraocular muscle (EOM), varying as a function of disease activity and severity (Stoyanova, Konareva-Kostianeva, Mitkova-Hristova, & Angelova, 2019) . Our study also found that IOP was reduced in TAO patients, which might be attributed to the compressive mechanisms and in ammatory processes inherent to TAO.…”

Correlation Analysis between Intraocular Pressure and Extraocular Muscles Based on Orbital Magnetic Resonance T2 Mapping in Thyroid-Associated Ophthalmopathy Patients

“…A study by Stoyanova et al showed that a group of TAO patients with a larger thickness sum in the EOMs, as shown by orbital computed tomography, had higher IOP [ 9 ]. Studies have also found a negative correlation between IOP and the flow velocity of the supraocular vein in TAO patients [ 7 ].…”

“…The increase in IOP in TAO may be caused by inflammation that causes swelling of the EOMs, which restricts and compresses the eyeball [6]; a decrease in orbital venous drainage leads to an increase in episcleral venous pressure [7], or an increase in mucopolysaccharide deposition in the trabecular meshwork, which thereby reduces the outflow of aqueous humor [8]. A study by Stoyanova et al showed that a group of TAO patients with a larger thickness sum in the EOMs, as shown by orbital computed tomography, had higher IOP [9]. Studies have also found a negative correlation between IOP and the flow velocity of the supraocular vein in TAO patients [7].…”