From the 90s to 2025: How the emission of toxic light on your screens has soared

AN INVISIBLE EVOLUTION

You probably remember those big, heavy, beige monitors that took up half your desk in the late 90s. We spent hours in front of them, but the eye strain or insomnia we felt then is not comparable to the "digital hangover" we experience today after a few hours of mobile use. The tech industry has sold us screens with higher resolution, more brightness, and more vivid colors. But no one warned us about the biological price of that improvement. Is it just that we use screens more, or have screens physically changed? To answer this question, the Reticare scientific team took three generations of devices to the lab. We weren't looking to measure image quality, but to analyze the "chemistry" of the light entering your eyes.

METHODOLOGY

For this comparative study, we used a high-precision spectroradiometer, an instrument capable of breaking down light into its exact wavelengths and measuring the energy of each color separately. We analyzed the Spectral Power Distribution (SPD) of:

1. A CRT Monitor (Cathode Ray Tube): The standard technology of 1998.

2. A High-End Smartphone (2024): OLED technology.

3. A High-End Smartphone (2025): Latest generation high-brightness LED panel. All devices were calibrated to emit a white image with comparable luminance, to ensure a fair comparison.

EMPIRICAL EVIDENCE: SPECTRORADIOMETRIC ANALYSIS

The graph below shows the raw results obtained in our laboratory. It illustrates the Spectral Power Distribution (SPD), superimposing the emission curves of the three technologies evaluated under equivalent luminance conditions. This visualization allows us to identify not only the amount of light emitted, but also its exact qualitative and energetic composition.

Analyzing the spectral data, three differentiated physical phenomena are observed that explain the increased risk to the eyes:

1. Wave Morphology: Continuous vs. Discrete Spectrum

The first critical distinction lies in the form of emission:

CRT Technology (Gray Trace):

The bottom line corresponds to the tube monitor. It presents a broad and smooth distribution curve, known as a "continuous spectrum." This is due to the nature of the excited phosphors, which emitted light diffusely and with low saturation.

LED/OLED Technology (Color Traces):

The lines corresponding to smartphones show the opposite behavior. The emission is no longer continuous but is concentrated in narrow monochromatic peaks. This is characteristic of light-emitting diodes, which inject energy in very specific bands to achieve greater efficiency and color purity.

2. Spectral Localization: High-Energy Visible (HEV) Peaks

The analysis of the horizontal axis (wavelength) shows us that the emission of modern screens is not continuous, but rather grouped into three very defined spectral intervals, corresponding to the Red, Green, and Blue subpixels. However, their interaction with the eye is radically different:

The Blue Spectrum (440 - 460 nm):

This is the first large peak to the left of the graph. Modern devices concentrate their maximum power here. This short-wavelength interval is the highest energy (HEV) and the most dangerous, as it easily penetrates to the back of the eye, promoting cellular oxidation.

The Green Spectrum (520 - 540 nm):

This is the second elevated peak we observe. Historically ignored, our data confirm that the emission in this band is as intense and aggressive as in the blue. Being a high-energy interval, it significantly contributes to fatigue and retinal stress if not adequately filtered.

The Red Spectrum (610 - 640 nm):

This is the third peak to the right. Unlike the previous two, this range does not pose a risk to visual health. Being longer waves with lower photonic energy, red light does not have the capacity to damage retinal tissue. Its presence is necessary for color reproduction, but biologically it is harmless compared to the toxicity of the blue and green intervals.

3. Magnitude of Irradiance: A 20x Increase The most significant finding is on the vertical axis (Intensity). Comparing the amplitude of the waves quantifies a drastic power difference.

While the irradiance of the CRT monitor remains at basal levels, the emission peaks of current smartphones reach intensity values up to 20 times higher. This indicates that, at the specific wavelengths of 450 nm and 530 nm, the energy load received by ocular tissue per unit of time is significantly greater in current technology than in its predecessors.