Photochromic safety glasses: how transition lenses work, what the Z87.1 V mark means, and where they fit
A photochromic lens darkens when ultraviolet light hits it and clears again when the UV goes away; “Transitions” is one manufacturer’s trade name for the technology, and on safety eyewear the lens is marked V (variable tint) under ANSI/ISEA Z87.1 beside the Z87+ impact mark and the U scale number. The lens is clear or lightly tinted indoors and darkens outdoors over tens of seconds, so one pair serves a crew that moves in and out; it does not darken behind glass or a windshield, which filter the UV that drives it, and it is not a welding filter. UVEX offers the Hypershock frame with a photochromic lens in PIP’s data; the same frame is sold with fixed clear, gray and mirror lenses, and the indoor/outdoor lens is the fixed-tint alternative for the same work.
UVEX Hypershock S2945 Safety Glasses, ANSI Z87.1+, 10 Lens OptionsUVEX Hypershock with the photochromic lens the manufacturer lists (PIP data)How the lens works. Photochromic molecules in or on the lens change shape when they absorb ultraviolet light and absorb visible light in that state, so the lens darkens in proportion to the UV reaching it; when the UV stops, the molecules relax and the lens clears. That is why the lens darkens in sunlight, less on an overcast day, and hardly at all behind automotive glass or a window, both of which absorb UV. Temperature matters too: the molecules relax faster when warm, so the lens is lighter on a hot day and darker on a cold one. On a safety lens the base is still impact-rated polycarbonate with the Z87+ mark and the U scale number; the photochromic layer is the variable part, and Z87.1 marks it V.
What to know before issuing them
From the Z87.1 marking rules and the manufacturer’s data.
Photochromic vs indoor/outdoor vs two pairs
The alternatives in the same frames:
- Photochromic: one pair, variable tint driven by UV, V mark; the price of the lens is the trade-off, and it stays light in a cab.
- Indoor/outdoor (I/O): one pair, fixed light mirror or light gray that passes most visible light; no change, so the same tint at the door and in the sun.
- Two pairs (clear and gray): the common jobsite answer; each lens carries its own marks and the gray can carry an L glare-filter rating.
- Polarized gray: cuts reflected glare from water and flat surfaces; a different technology from photochromic and listed separately in the manufacturer’s tint options.
The indoor/outdoor lens as Radians rates it
Radians publishes a lens color page with the visible light transmission it assigns each tint: clear at maximum, light smoke and indoor/outdoor at about 50 percent, smoke at about 16 percent, amber at about 84 percent, vermilion 33 percent, orange and light blue 50 percent, copper about 20 percent, and the IRUV filter lenses in 2.0, 3.0 and 5.0 for work near brazing, soldering, gas welding and oxygen cutting. Its mirror lenses are dark tints with a reflective coating for very bright sun. The Lens Tint field on every Radians, Crossfire and DEWALT eyewear page on this site lists which of these the style comes in.
Radians Product Technologies page (radians.com/resources/product-technologies, radians.com, fetched Nov 8 2026)Questions people ask
What are transition lenses?
Photochromic lenses: they darken under ultraviolet light and clear when it goes away. “Transitions” is a trade name of one lens manufacturer; on safety eyewear the mark is V.
What are photochromic safety glasses?
Photochromic molecules absorb UV, change shape and absorb visible light in that state, darkening the lens; without UV they relax and the lens clears. Heat speeds the clearing.
Do photochromic lenses darken in a car?
Very little; vehicle glass absorbs most of the UV the lens needs. The same applies behind a window.
Are photochromic safety glasses Z87 rated?
When the frame carries the Z87 or Z87+ mark; the UVEX Hypershock photochromic lists ANSI Z87.1+ in the manufacturer’s data, and the V mark shows the variable tint.
Can photochromic glasses be used for welding?
No. They carry no W shade number; torch work needs a shade 3 or 5 lens and arc welding a helmet filter, per the shade chart.
Photochromic vs indoor/outdoor: what is the difference?
Photochromic changes with UV; indoor/outdoor is a fixed light tint or mirror that passes most visible light and never changes. Both are one-pair answers for crews that move in and out.
Do safety glasses really work?
To the mark on them: a Z87+ lens and frame stopped a quarter-inch steel ball at 150 feet per second and a 500 gram pointed weight dropped from 50 inches without the lens leaving the frame or touching the eye, in the ANSI/ISEA Z87.1 tests. A photochromic lens carries the same impact mark beside its V mark; what no safety glass does is seal out splash or dust, which is the goggle’s job.
Are polycarbonate lenses safety rated?
Only when the finished protector is tested and marked to Z87.1. Polycarbonate is the lens material in nearly all safety eyewear because it passes the impact tests and blocks ultraviolet (MCR Safety states 99.9 percent UV absorption on its lenses), but a polycarbonate dress lens without the mark is not safety eyewear under 1910.133.
Can safety glasses have transition lenses?
Yes. The photochromic lens is marked V (variable tint) under Z87.1 beside the Z87+ impact mark and the U scale number; the UVEX Hypershock photochromic in the band is one, and MCR Safety’s indoor/outdoor lens (36 percent visible light transmitted) is the fixed-tint alternative for crews that move in and out.
How do transition lenses work?
The lens contains photochromic molecules that change shape when ultraviolet light strikes them, absorbing visible light and darkening the lens; when the UV goes away they relax and the lens clears, over tens of seconds in each direction. Glass and windshields filter the UV, so the lens stays light in a cab. Transitions is one company's trade name; on a safety lens the mark is V.
The ratings, test results and standards shown here are the manufacturers' published values, reproduced as published. Nothing on this page is a recommendation by Bayshore Safety that any product is suitable for a particular task, hazard or workplace. Selecting safety products and protective equipment is the responsibility of the end user and the employer, based on their own hazard assessment and the regulations that apply to their work. Confirm every value on the manufacturer's own documentation before use.