Which part first refracts incoming light as it enters the eye?

Which part first refracts incoming light as it enters the eye?

• A. Pupil
• B. Iris
• C. Cornea
• D. Vitreous humor

Answer: (C)

Light first encounters the cornea, the clear, curved front surface of the eye. The air-to-cornea interface causes the light to bend, starting the focusing process. The cornea provides most of the eye’s refractive power, shaping the incoming light toward the retina. The iris and pupil aren’t refractive surfaces—they’re just the colored ring and the opening that regulate how much light enters. The vitreous humor is a gel behind the lens and does not contribute to the initial refraction; it mainly helps keep the eye’s shape and transmit light to the retina. After the cornea, light passes through the aqueous humor and the lens, which add further refraction to fine-tune focusing.

Light first encounters the cornea, the clear, curved front surface of the eye. The air-to-cornea interface causes the light to bend, starting the focusing process. The cornea provides most of the eye’s refractive power, shaping the incoming light toward the retina. The iris and pupil aren’t refractive surfaces—they’re just the colored ring and the opening that regulate how much light enters. The vitreous humor is a gel behind the lens and does not contribute to the initial refraction; it mainly helps keep the eye’s shape and transmit light to the retina. After the cornea, light passes through the aqueous humor and the lens, which add further refraction to fine-tune focusing.