absorptive lens
Also called tinted lens, filter lens
An absorptive lens is a spectacle lens tinted or coated to absorb part of the light that passes through it. It is described by its color and by its transmittance, the share of visible light it lets through.1 A neutral gray lens absorbs evenly across the visible spectrum, so colors keep their natural relationships, while a colored filter absorbs some wavelengths more than others.1
The international sunglass standard, ISO 12312-1, sorts these lenses into five categories by transmittance, from category 0 (more than 80 percent) to category 4 (3 to 8 percent). Category 4 is too dark for driving, and a lens that passes less than 75 percent of visible light is unsuitable for driving at twilight or at night.2 In most studies a colored filter did no better than a gray lens of the same darkness, so a gray lens is the fair comparison when trialing one.1,3
More detail
Ordinary sun lenses pass 15 to 30 percent of visible light. A tint built into glass gets darker where the glass is thicker. The same tint therefore looks darker at the center of a strong plus lens and at the edge of a strong minus lens.1
Gray suits people with color vision deficiency, because it adds none of the new color errors a colored tint can cause, and the FAA recommends neutral gray for pilots because it distorts color the least.1,4
Tints cost acuity at night. In a classic study, night acuity fell from 20/32 to 20/40 through an 82 percent pink lens. An antireflection coating reduces headlight reflections better than a tint does.1
Sources (4)
- Brooks and Borish, System for Ophthalmic Dispensing, ch. 22, Absorptive Lenses
- College of Optometrists. Guidance for professional practice A307 to A309: tints and driving (after BS EN ISO 12312-1:2013).
- Barron C, Waiss B. An evaluation of visual acuity with the Corning CPF 527 lens. J Am Optom Assoc. 1987;58(1):50-54.
- Federal Aviation Administration. Sunglasses for pilots. Pilot safety brochure OK-24-1154, 2024.
Reviewed October 2026
Through the lens
This gray lens passes about 15% of visible light, a category 3 sunglass. Curve: Neutral gray, drawn flat at 15% (College A307).
Simulated from the lens’s transmission curve.