Lens Coatings & The Human Eye

Is "varichromatic" the right term?

No — it's not correct and can be misleading.

"Varichromatic" (or "vari-chromatic") is not a standard term in optics for the effects addressed by lens coatings. The closest real concepts are:

• Chromatic aberration — color fringing caused by different wavelengths focusing at different points
• Achromatic — corrected for two wavelengths
• Apochromatic — corrected for three wavelengths

Lens coatings do not primarily correct chromatic aberration — that is mostly achieved by combining lens elements made of different glass types (achromatic doublets, ED glass, fluorite, APO designs).

What lens coatings actually do

Modern multi-layer anti-reflective (AR) coatings mainly:

• Reduce unwanted reflections at each air-glass surface
• Minimize flare, ghosting, and veiling glare
• Increase light transmission (from ~92% uncoated → 98–99.5% coated per surface)
• Improve contrast and color fidelity

Short, accurate ways to describe their purpose:

• "Reduce flare and reflections"
• "Minimize ghosting and increase contrast"
• "Cut internal reflections for sharper, clearer images"
• "Suppress flare while boosting light transmission"

Human eye equivalents

Yes — the eye experiences very close analogs to flare and ghosting.

Flare → Veiling glare / Disability glare / Light scatter

Bright light scatters inside the eye (cornea, lens, vitreous), creating a diffuse haze that reduces contrast.

• Night driving (headlights)
• Bright screen in dark room
• Snow blindness / glare on water

Ghosting → Monocular diplopia / Ghost images / Secondary images

Faint offset duplicate of bright objects — usually in one eye only.

• streetlampstreetlamp or headlight at night → pale ghost nearby
• Bright text → shadowed duplicate
• Moon or stars → faint halo/duplicate

Common causes: early cataracts, corneal irregularities, vitreous changes, higher-order aberrations.

Quick comparison