Which testing demonstrates mechanical restriction via a positive forced duction test?

Which testing demonstrates mechanical restriction via a positive forced duction test?

• A. A test where gentle passive restriction is felt, indicating a mechanical limitation.
• B. A test of visual acuity
• C. A test of accommodation
• D. A test of pupil reaction to light

Answer: (A)

Forced duction testing is used to distinguish mechanical restriction from neurogenic weakness in eye movements. When the eye is moved passively in the direction of gaze after topical anesthesia, a positive result is felt as a gentle but definite resistance, indicating a mechanical barrier to movement such as scarring, fibrosis, or entrapment around a muscle. If the eye moves freely with no resistance, the limitation is likely due to innervation or muscle weakness rather than a physical restriction. Therefore, the description of gentle passive restriction reflecting a mechanical limitation accurately describes the positive forced duction test. The other tests—visual acuity, accommodation, and pupil light reflex—assess sensory or reflex functions and do not address mechanical restriction of ocular motility.

Forced duction testing is used to distinguish mechanical restriction from neurogenic weakness in eye movements. When the eye is moved passively in the direction of gaze after topical anesthesia, a positive result is felt as a gentle but definite resistance, indicating a mechanical barrier to movement such as scarring, fibrosis, or entrapment around a muscle. If the eye moves freely with no resistance, the limitation is likely due to innervation or muscle weakness rather than a physical restriction. Therefore, the description of gentle passive restriction reflecting a mechanical limitation accurately describes the positive forced duction test. The other tests—visual acuity, accommodation, and pupil light reflex—assess sensory or reflex functions and do not address mechanical restriction of ocular motility.