Question

Your cornea doesn’t have blood vessels, so the living cells of the cornea must get their oxygen from other sources. Cells in the front of the cornea obtain their oxygen from the air. Wearing a contact lens interferes with this oxygen uptake, so contact lenses are designed to permit the diffusion of oxygen. The diffusion coefficient of one brand of soft contact lenses was measured to be 1. 3×10−13 m^2/s We can model the lens as a 14-mm-diameter disk with a thickness of 40 μm. The partial pressure of oxygen at the front of the lens is 20% of atmospheric pressure, and the partial pressure at the rear is 7. 3 kPa.

At 30°C how many oxygen molecules cross the lens in 1 h?

N = ? molecules

Answer 1

Oxygen diffuses through the tear layer on the cornea to reach the veinless cornea of the eye. The average time required for an oxygen molecule to diffuse through a 0.200-mm-thick tear layer can be calculated using Fick's law of diffusion. The time required to diffuse a specific volume of oxygen to the cornea can be calculated using the formula t = V/(D*A).

Step-by-step explanation:

Oxygen reaches the veinless cornea of the eye by diffusing through its tear layer. To find the average time required for an oxygen molecule to diffuse through a 0.200-mm-thick tear layer on the cornea, we can use Fick's law of diffusion. The time required to diffuse 0.500 cm³ of oxygen to the cornea with a surface area of 1.00 cm² can be calculated using the formula t = V/(D*A), where t is the time, V is the volume, D is the diffusion coefficient, and A is the surface area.