What structure primarily protects the eye and helps in maintaining intraocular pressure?

The sclera is the outermost layer of the eye and plays a critical role in protecting the internal structures while also maintaining the shape of the eye. It is a tough, fibrous tissue that provides both structural support and protection to the eye, making it resilient against external trauma. The sclera encases the more delicate components of the eye, such as the retina, ciliary body, and the choroid, and helps to provide an environment that is essential for their functions.

Additionally, the sclera is instrumental in maintaining intraocular pressure. This pressure is crucial for the eye's shape and overall function, and the sclera’s rigidity helps withstand the internal pressures exerted by the aqueous humor produced within the eye. This pressure is necessary for various functions, including proper visual focus and the maintenance of optical alignment.

In contrast, while the cornea is essential for refracting light and contributes to some extent to the eye's protection, its primary function differs from maintaining intraocular pressure. The retina is involved in the processing of visual information, and the limbus serves as the border between the cornea and the sclera but is not primarily responsible for maintaining intraocular pressure. Overall, the sclera's combination of protective and supportive roles makes it