Novel System for Measuring Tension Force in Eyeball Movement

Area of Science:

• Ophthalmology
• Biomedical Engineering
• Biomechanics

Background:

• Current methods for assessing extraocular muscle mechanics, like the forced duction test, are subjective and lack precision.
• Objective quantitative measurement of ocular tension and rotation is needed for accurate diagnosis and treatment of ocular motility disorders.

Purpose of the Study:

• To develop and clinically validate a novel biosensing system for objective, simultaneous measurement of passive ocular tension and rotation angle during forced duction.
• To overcome the limitations of subjective tactile assessment and impracticality of previous quantitative devices.

Main Methods:

• A novel biosensing system was developed, integrating custom surgical forceps with dual strain gauges and an infrared video camera.
• The system measures real-time ocular tension and calculates rotation angle via pupil displacement tracking.
• Clinical validation was performed in 10 patients (20 eyes) with intermittent exotropia under general anesthesia.

Main Results:

• Reliable passive tension-angle curves were successfully obtained in all patients without complications.
• Passive tension increased progressively with ocular rotation, following a linear-parabolic trajectory up to 40 degrees.
• The mean duction force of medial and lateral rectus muscles demonstrated comparable symmetry.

Conclusions:

• The developed lightweight, practical, and objective biosensing system reliably quantifies ocular mechanics.
• This system has the potential to enhance diagnostic accuracy for ocular motility disorders.
• It may enable individualized surgical planning and support fundamental research in the field.