Dark adaptation

Reference: PVM-AO

When the eye is placed in a dark environment, rods progressively replace cones and their sensitivity increases.
The exam consists in drawing a curve representing the light sensitivity threshold as a function of time.

After 5 minutes of light adaptation, the subject is placed in the dark.

The adaptation curve which is obtained presents two successive phases:

  • During the first phase, the light sensitivity threshold dicreases sharply before stabilizing after a few minutes. This phase represents the adaptation of cones.
  • After about 5 minutes, sensitivity increases again and stabilizes once more.
    This phase represents the adaptation of rods (or scotopic adaptation).

The separation between these two phases defines the "alpha point" reached after about 5 minutes and the second phase ends with the "terminal threshold" reached after about 30 minutes of complete darkness.

The dark adaptation exam presents several clinical applications:

Stimulators from the Vision Monitor range compatible with this program:

Additional information: