yläsilmäluomen

Yläsilmäluomen, also known as the upper eyelid, is the movable fold of skin and muscle that covers the front of the eyeball from above. It plays a crucial role in protecting the eye from foreign objects and excessive light, and in spreading tears across the ocular surface to keep it moist and clean.

The upper eyelid is composed of several layers, including skin, subcutaneous tissue, orbicularis oculi muscle (responsible for closing the eyelid), levator palpebrae superioris muscle (responsible for opening the eyelid), tarsal plates (fibrous connective tissues that give the eyelid its shape), and conjunctiva (a thin, transparent membrane that lines the inner surface of the eyelid and covers the white part of the eye). Meibomian glands within the tarsal plates produce an oily substance that forms the outer layer of the tear film, preventing rapid evaporation.

Movement of the upper eyelid is essential for blinking, which is an involuntary reflex that helps to redistribute the tear film, clear debris, and protect the eye. Voluntary control allows for deliberate opening and closing of the eye. The appearance of the upper eyelid can vary significantly among individuals due to genetic factors, aging, and ethnicity. Conditions affecting the upper eyelid can range from minor cosmetic concerns like drooping (ptosis) to more serious medical issues impacting vision or eye health.