An Adjustable Magnetic Levator Prosthesis for Customizable Eyelid Reanimation in Severe Blepharoptosis II: Randomized Evaluation of Angular Translation

Abstract

Purpose Examine the effect of force modulation via angular translation of a static magnetic field for customizable treatment of severe blepharoptosis. Methods Prototype adjustable-force magnetic levator prostheses (aMLP) consisted of a spectacle-mounted magnet in rotatable housing and small eyelid-attached magnets embedded in a biocompatible polymer. Interpalpebral fissure (IPF) of 17 participants with severe blepharoptosis was continuously measured for one minute at five spectacle magnet angles, with order randomized and participant and data analyst masked. The hypothesis that angular position affected opening IPF (o-IPF), minimum blink IPF (m-IPF), and comfort ratings (1–10) was tested. Results The aMLP improved o-IPF from 4.5 mm without the device to 6.2 mm on the lowest force setting ( P < 0.001) and 7.1 mm on the highest setting ( P < 0.001) and allowed for complete volitional blink regardless of setting (average m-IPF 0.4 mm and no change with aMLP; P = 0.76). Spontaneous blink without the device (2.0 mm) was affected on the highest force setting (m-IPF 3.9 mm; P < 0.001) but only marginally so on the lowest setting (3.0 mm; P = 0.06). Comfort (7.6/10) did not vary with the angle ( P > 0.36). Profile analysis found substantial individual responses to angle ( P < 0.001), confirming the value of customization. Conclusions Angular translation provided adjustable force, which had a statistically and clinically meaningful impact on eye opening and the completeness of the spontaneous blink. This quantitative evidence supports continued use of the angular translation mechanism for force adjustment in the customizable magnetic correction of severe blepharoptosis. Translational Relevance Evidence for the benefit of customizable magnetic force via angular translation in a larger sample of participants than reported previously.