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Measurement of Energy Metabolism in Explanted Retinal Tissue Using Extracellular Flux Analysis

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ENERGY, QUANTA, AND VISION.

S Hecht¹, S Shlaer, M H Pirenne

¹Laboratory of Biophysics, Columbia University, New York.

The Journal of General Physiology

|October 30, 2009

Summary

This summary is machine-generated.

The minimum light energy for vision requires only 5-14 quanta absorbed by retinal rods. This finding explains visual fluctuations, indicating the light stimulus, not the organism, is variable at vision

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Area of Science:

Vision science
Photobiology
Neuroscience

Background:

Threshold vision is the minimum light intensity detectable by the human eye.
Previous studies estimated the energy required for threshold vision, but corrections for ocular factors were needed.

Purpose of the Study:

To directly measure the minimum energy for threshold vision.
To correct these measurements for physiological factors within the eye.
To determine the number of light quanta absorbed by retinal rods for vision.

Main Methods:

Direct measurement of light energy at the cornea.
Correction for corneal reflection (4%), ocular media absorption (50%), and retinal transmission (80%).
Comparison of visual purple absorption spectrum with dim-vision luminosity function.
Statistical analysis of light flash intensity versus frequency of seeing.

Main Results:

Direct measurements yielded 54-148 quanta at the cornea.
After corrections, 5-14 quanta are absorbed by retinal rods.
This necessitates absorption by 5-14 individual rods per visual event.
Statistical studies independently estimated 5-8 critical events at vision threshold.

Conclusions:

Vision threshold is determined by a small number of absorbed quanta (5-14).
This explains response fluctuations, attributing them to stimulus variability, not organism variability.
The findings reconcile direct physical measurements with statistical observations of vision.