Introduces a functional nictitating membrane — a translucent third eyelid that sweeps horizontally across the eye from the inner corner. The membrane protects the eye from debris, water, wind, and bright light while allowing continued vision through its semi-transparent surface. Sharks, birds, and reptiles possess this structure naturally; humans lost it millions of years ago. The reinstalled membrane is voluntarily controlled — the user can deploy it instantly as an eye shield. It provides underwater vision without goggles (the membrane acts as a natural goggle lens), protects against flash blindness, and keeps the eyes moist in dry environments. Zheng-Dao Bioelectric's version includes UV-filtering proteins in the membrane, combining eye protection with glare reduction.