Frontalis suspension is a commonly used surgery that is indicated in patients with droopy eyelids (blepharoptosis) and poor levator muscle function. The surgery is based on connecting the tarsal plate of the droopy eyelid to the frontalis muscle with various slings made either from fascia lata tissue or synthetic materials. However, one of the main complications of this surgery is the high rate of blepharoptosis recurrence, which has been reported for some slings as high as 100%.

We initiated a collaborative multidisciplinary research to explore the effect of choice of sling material on this common problem. Two different experimental setups for testing the behavior of various sling materials in-vitro have been developed. Using our first experimental setup, we explored possible gradual permanent elongation of sling materials due to cyclic loading caused by eye blinking. In addition, a more sophisticated second experimental setup was developed to investigate fatigue behavior of different implants under physiologically relevant conditions.

We could show that physical changes such as permanent elongation, and holding load drop in the slings could happen under fatigue conditions caused by eye blinking. These changes can contribute to the failure of the frontalis suspension slings and recurrence of blepharoptosis. Our experiments show that different sling materials exhibit significantly different responses. The results of the present study indicate that characterizing the in vitro fatigue behavior of different sling materials can lead to a better understanding of what causes high recurrence rates in frontalis suspension. The characterization methods developed can also be used to improve material selection as well as assist in the development of new materials for this procedure.