Deuteranomaly & Green-Cone Deficiency: Multi-Band Notch Interference Lens Science

The gold standard instrument for diagnosing red-green color vision defects is the Nagel Anomaloscope, which tests the Rayleigh match equation:

$$x\lambda_{589\ \text{nm}} = a\lambda_{546\ \text{nm}} + b\lambda_{670\ \text{nm}}$$

A test subject must mix monochromatic green (546 nm) and red (670 nm) light to match a standard monochromatic yellow (589 nm). A normal trichromat sets the red-green mixture dial around 40 to 45.

In deuteranomaly, because the M-cone is anomalous ($M'$ peak shifted from 530 nm out to ~555 nm), green light stimulates the cone far less effectively. To perceive yellow, the subject requires an abnormally large quantity of green light, shifting their match quotient ($AQ$) dramatically upward. In true deuteranopia (complete absence of M-cones), any mixture of red and green can be matched to yellow simply by adjusting yellow brightness!

Because deuteranomalous individuals have two functioning cone types whose spectral sensitivities are spaced too closely together ($L$ at 560 nm, $M'$ at 550 nm), standard broadband tinted lenses merely darken the entire scene without improving color discrimination.

The engineering breakthrough relies on dielectric multi-cavity thin-film interference filters:

By applying up to 40 alternating nano-layers of high-index zirconium dioxide ($\text{ZrO}_2$, $n = 2.10$) and low-index silica ($\text{SiO}_2$, $n = 1.46$), optical physicists engineer a sharp optical band-stop filter. The filter provides high transmittance (>85%) at 530 nm (green) and 630 nm (red), but sharply drops to <5% transmittance between 570 and 590 nm. By selectively suppressing the ambiguous overlapping wavelength band, the visual cortex receives cleanly separated chromatic signals, enhancing color saturation.

When advising individuals with deuteranomaly:

• Daylight Performance: Multi-band notch lenses require ample light to stimulate suppressed cone pathways. Outdoor sports, landscape appreciation, photography, and art benefit tremendously.
• Office Work and VDU Displays: Standard sRGB computer monitors emit narrow spectral peaks (Red ~610 nm, Green ~525 nm, Blue ~460 nm) that do not always align with outdoor sunlight spectra; testing notch lenses under calibrated display illumination is essential.
• Durability and Super-Hydrophobic Finishes: Dielectric interference coatings are protected beneath a high-density quartz hard-coat and a fluoropolymer super-hydrophobic layer (such as ELLASUV Magenta HMC) to prevent scratching and grease build-up.