Direct orbital manometry in patients with thyroid-associated orbitopathy

Area of Science:

• Ophthalmology
• Endocrinology
• Surgical Science

Background:

• Thyroid-associated orbitopathy (TAO) is an autoimmune condition affecting the eye socket.
• Understanding orbital dynamics is crucial for managing TAO complications like compressive optic neuropathy.

Purpose of the Study:

• To quantify orbital tissue tension and orbital compartment compliance in patients with and without TAO.
• To investigate the relationship between these parameters and compressive optic neuropathy in TAO.

Main Methods:

• A prospective case series involving 18 orbits with TAO and 35 control orbits.
• Development and use of a novel orbital manometer to measure orbital tissue tension during retrobulbar anesthesia injection.
• Calculation of orbital compartment compliance based on volume and tension changes.

Main Results:

• TAO orbits exhibited significantly higher resting orbital tissue tension (9.7 mmHg vs. 4.4 mmHg) and lower compliance (0.27 ml/mmHg vs. 0.80 ml/mmHg) compared to controls.
• Retrobulbar injection caused a greater tension increase in TAO orbits (36.3 mmHg vs. 12.0 mmHg).
• Higher resting tension was observed in TAO orbits with compressive optic neuropathy (12.4 mmHg vs. 7.8 mmHg).

Conclusions:

• Orbital manometry is a safe and effective method to assess orbital tissue tension and compliance.
• Elevated orbital tissue tension and reduced compliance are characteristic of TAO.
• Orbital compartment syndrome may be a contributing factor to compressive optic neuropathy in TAO patients.