VisionFirst CEBT Practice Test

Understanding the eye's internal compartments shows that the center of the eye is filled by the vitreous humor, a clear, gel-like substance. It sits in the vitreous chamber behind the lens, helping to keep the eyeball's shape and maintain its volume. The aqueous humor, by contrast, fills the anterior and posterior chambers in front of the lens and is much smaller in volume. The optic nerve is a neural pathway, not a filling material, and the retinal pigment epithelium is a layer of cells in the retina. Since the center is occupied by the gelatinous vitreous that preserves shape and accounts for most of the eye’s volume, it is the correct structure.