The protective effect of the eyelid on ocular injuries in blunt trauma

The instinctive blink reflex makes the eyelid close when a foreign body is approaching the eye. This study aimed to investigate the protective effect of eyelid on ocular injuries in blunt trauma. A finite element model of the eyelid model was created and was incorporated into a validated eye model. The process of a projectile impacting on a naked eye and an eyelid-covered eye were reproduced in dynamic simulation. Dynamic responses on the cornea and retina were performed to evaluate the risk of damage to the tissues. The simulation indicated that the eyelid significantly protected the cornea against damage from blunt impact, especially for a small-size projectile. This is because the eyelid distributes the local stress concentration to the whole ocular surface. However, the eyelid failed to provide the retina with an effective protection against damage in blunt trauma. This is because the retinal damage is a typical contre-coup injury, which is the result of shockwave propagation in the eyeball. In conclusion, the eyelid has different protective effects on ocular injuries caused by different injury mechanisms for eye closure.