Extremes of surface brightness in the field of vision are the most important causes of eye discomfort and loss of efficiency in contemporary lighting systems¶

Claim · All claims
Evidence · 1 study (2 entries) · causal r2 · q3
Currency · newest study 1917 · not yet checked against its sources · not reviewed by a person

Subclaims¶

q3 i? Extremes of surface brightness are the most important causes of the eye's discomfort and loss of efficiency in lighting systems as currently installed. → C. E. Ferree and Gertrude Rand 1917 q3 i? From exposed sources, the brightest surface may reach 1,000,000 to 2,500,000 times the brilliance of the darkest surface and 300,000 to 600,000 times that of the reading page. → C. E. Ferree and Gertrude Rand 1917 (2)

Evidence¶

C. E. Ferree and Gertrude Rand 1917¶

C. E. Ferree and Gertrude Rand. (1917). The Power of the Eye to Sustain Clear Seeing Under Different Conditions of Lighting. The Journal of Educational Psychology. https://doi.org/10.1037/h0072369

q3 · i? · causal · r2

Results of the acuity-sustain tests across the tested lighting situations. The authors rank surface-brightness extremes above the angle of incident light as a factor, reporting they are "the most important causes of the eye's discomfort and loss of efficiency."

"Extremes of surface brightness in the field of vision seem to be the most important causes of the eye's discomfort and loss of efficiency in lighting systems as we have them at the present time."

C. E. Ferree and Gertrude Rand 1917 (2)¶

C. E. Ferree and Gertrude Rand. (1917). The Power of the Eye to Sustain Clear Seeing Under Different Conditions of Lighting. The Journal of Educational Psychology. https://doi.org/10.1037/h0072369

q3 · i? · causal · r2

Brightness measurements made with a Sharp-Millar illuminometer, calibrated against a magnesium oxide surface, in the tested installations. The printed ratios describe the brightness extremes the authors' tests show are "very fatiguing to the eye."

"In lighting from exposed sources it is not infrequent to find the brightest surface from 1,000,000 to 2,500,000 times as brilliant as the darkest; and from 300,000 to 600,000 times as brilliant as the reading page."

Discussion¶

Related Claims¶

• Across all conditions tested, a lighting condition's tendency to cause loss of visual efficiency correlates closely with its tendency to produce ocular discomfort — related
• When light is well distributed and diffuse with no extremes of surface brightness, the eye is practically independent of illumination intensity within ordinary lighting ranges — a narrower finding that bears on this claim
• Indirect systems and semi-indirect systems with high-density reflectors produced the best results for sustaining clear seeing among the artificial lighting systems tested — a narrower finding that bears on this claim
• The loss of efficiency sustained by the eye in an unfavorable lighting situation is muscular, not retinal — related
• Too much light is being used in ordinary work for the comfort and welfare of the eye with reflectors that introduce harmful brilliancies — a narrower finding that bears on this claim