Phosarts

How does vision relate to lighting design? 👁️💡

At intermediate light levels, such as dusk or low-level exterior lighting(mesopic), both rods and cones are active.

This means visibility isn’t determined by lux alone(photopic). Spectrum, luminance, contrast and visual adaptation all influence how bright, clear and comfortable an environment appears.

Good lighting design considers not only how much light we provide, but how the human eye actually perceives it.

What defines vision? 👁️

Vision is not simply the eye detecting light, it is a complex interaction between optics, photoreception and neural processing.

Light entering the eye is focused onto the retina, where photoreceptors convert electromagnetic radiation within the visible spectrum into neural signals. Cones support colour vision and fine spatial detail under brighter conditions, while rods are highly sensitive at low light levels and contribute strongly to peripheral and night vision.

These signals are processed through retinal neural circuits and transmitted via the optic nerve to visual areas of the brain, where information about luminance, contrast, colour, form, depth and movement is integrated into our visual perception.

In lighting design, this matters because we do not experience illuminance alone. Spectral composition, luminance distribution, contrast, adaptation and the surrounding environment all influence what we see and how comfortably we see it.

Light reaches the eye. The visual system turns it into perception.

Circadian Rhythm in Nature

Nature doesn’t experience time through a clock. It responds to light.

Flowers open, birds become active, plants respond to changing day length, and animals time feeding, migration and rest around recurring environmental cycles.

Light and darkness are among nature’s most powerful clock.

Natural rhythms keep life in balance.

Human Circadian Rhythm

Light does more than help us see.

Specialised cells in the retina — melanopsin-containing ipRGCs — detect light and send signals to the brain’s master circadian clock, the suprachiasmatic nucleus (SCN).

This helps synchronise our approximately 24-hour rhythms, influencing when we feel alert or sleepy and helping coordinate processes such as hormone rhythms and body temperature.

What reaches the eye matters.
Light shapes how we see, feel and function.

Daylight is never static.

Its intensity, direction and spectral composition continuously change from morning to afternoon and into sunset — transforming both the atmosphere of a space and the signals our bodies receive from light.

Glare exposure at workplace can cause visual discomfort, eye strain and reduced performance

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