NBEO Ocular Physiology Practice Exam 2025 – The Complete All-in-One Guide to Exam Success!

The critical partial pressure of oxygen (O2) for the cornea is about 10-20 mmHg. This range is important because the cornea is avascular, meaning it does not have its own blood supply and relies on diffusion from the tear film and the aqueous humor behind it for oxygen. If the partial pressure of oxygen falls below this critical range, the metabolic processes of the corneal cells can be adversely affected, leading to cellular dysfunction and possible corneal edema or other complications.

In addition, maintaining an adequate partial pressure of oxygen at this level ensures that the corneal epithelium can sustain its normal metabolic activities, including the maintenance of barrier function and wound healing. This is particularly relevant in the context of contact lens wear and other ocular conditions, as low oxygen levels can compromise corneal health. Understanding this critical range helps in clinical practice when considering lens materials and designs that optimize oxygen transmissibility to support corneal integrity.