This chapter outlines the key anatomical and physiological differences between the normal human adult eye and the normal infant eye. It highlights developmental variations in size, shape, refractive power, and structural maturity. Compared to adults, infant eyes are smaller in axial length, corneal diameter, and anterior chamber depth, with larger lens thickness and relatively higher refractive power. The sclera is thinner and more pliable, and visual acuity and contrast sensitivity are still developing. Tear production, intraocular pressure, and retinal maturity also differ significantly. These distinctions are critical for understanding pediatric ocular development, diagnosing visual disorders early, and guiding age-appropriate clinical care.