Green foliage looks like a visual spa, yet your eyes pay the same price after a long stare. The comfort myth starts with physics. The human eye focuses green wavelengths near its optical sweet spot, so cones tuned to medium wavelengths fire efficiently and the image feels stable, almost quiet. That pleasant first impression tempts people to believe color alone can relax a sensory system that runs on muscular work and continuous neural firing.
The real strain is mechanical and metabolic, not chromatic. Ciliary muscle accommodation, the process that bends the lens to keep leaves sharp, must hold a near-constant contraction when you fixate on any object, green or not. Extraocular muscles lock the eyeballs in place. Photoreceptors and retinal ganglion cells keep up a high rate of action potentials. Hold that state for a long session and you load the same circuitry, whether the pixels are emerald, gray, or neon pink.
So the soothing effect of plants is mostly psychological and behavioral. A pot of ivy often sits at a comfortable distance and breaks your gaze into short glances, which cuts down on sustained accommodation and reduces dry-eye from low blink rate. Turn those leaves into a static, close-up target and the advantage disappears. Your ocular hardware does not care about the hue; it only counts how long it must hold focus.