Corneal Optics and Eye Refraction

What is the typical range of corneal refractive power in an emmetropic eye?

• 20-30

• 30-40

• 39-48

• 45-55

Which ocular media has the highest refractive index?

• A. Cornea

• Aqueous humor

• Crystalline lens

• Vitreous humor

Answer explanation

Why does maximum refraction occur at the anterior corneal surface?

• Due to the thickness of the cornea

• Because of its posterior curvature

• Due to high curvature and large index difference with air

• Because it is vascular

What is the average horizontal diameter of the cornea?

• 10.5 mm

• 11.7 mm

• 12.6 mm

• 13.4 mm

Which zone of the cornea is primarily responsible for high-definition vision?

• Peripheral zone

• Paracentral zone

• Limbal zone

• Axial zone

What kind of astigmatism is most common in early childhood?

• Oblique

• Against the rule

• Mixed

• With the rule

How much does a 1 mm change in corneal curvature affect refractive power?

• 2 D

• 4 D

• 6 D

• 8 D

What is the approximate thickness of the central cornea?

• 0.42 mm

• 0.52 mm

• 0.60

• 0.70 mm

Which of the following does NOT contribute to corneal transparency?

• Crystalline lattice of collagen

• Corneal vascularity

• Na/K pump of the endothelium

• Avascular nature of cornea

Exposure to UV light at what wavelength is most

damaging to the cornea?

• 620

• 470

• 370

• 270