By Dr. Callie Sincennes · · 3 min read
Everyone here knows about skin and sunscreen. Almost nobody applies the same thinking to their eyes, despite living in one of the highest-UV environments in the country.
The eye has no equivalent of sunscreen and no repair mechanism for accumulated UV damage. What it has is whatever you put in front of it.
What UV does to the eye
- Cataract
- Ultraviolet exposure is an established risk factor, and cataracts form measurably earlier in high-UV regions. We see this directly: cataract surgery conversations here happen at younger ages than the national average would predict.
- Pterygium
- A growth of tissue that creeps across the cornea, strongly associated with sun, wind and dust exposure. Common enough in this climate that we see it regularly in people who have never been near a beach.
- Macular degeneration
- Cumulative UV is among the contributing risk factors alongside genetics, smoking and blood pressure.
- Photokeratitis
- Essentially sunburn of the cornea, painful and possible after a single intense exposure. Reflected light off pale rock and water is a common cause here.
- Eyelid skin cancer
- The eyelids are thin-skinned, high-exposure and almost universally missed by sunscreen. A frame that covers them helps.
Dark lenses are not UV protection
This is the most important practical misconception, and getting it backwards is actively harmful.
Tint darkness and UV protection are unrelated. A completely clear lens can have full UV protection, and a very dark lens can have none.
A dark lens without UV protection is worse than no sunglasses at all, because the darkness causes your pupil to dilate, letting more unfiltered ultraviolet reach the retina. Always confirm full UV protection rather than assuming darkness implies it.
Polarisation, separately
Polarisation is a different feature again. It blocks horizontally oriented light, which is what reflected glare off a road surface, a windscreen, water or pale rock consists of.
In the desert this is not marginal. Road glare, reflection off caliche and light stone, and windscreen reflection are constant, and removing them produces an immediately obvious improvement in contrast and comfort.
It is a comfort and performance feature rather than a protective one, and in this environment it is worth having.
Children need this more than you do
A substantial proportion of a person's lifetime UV exposure occurs before age eighteen. A child's crystalline lens is also clearer than an adult's, so it filters less UV and allows more to reach the retina.
Children here spend far more time outdoors than adults. Protective sunglasses for a child are genuinely preventive medicine, and they cost very little relative to the exposure they remove. This is one of the highest-value things a parent can do for their child's long-term eye health, and almost nobody does it.
The dust problem
Monsoon season produces a reliable wave of corneal abrasions and foreign bodies in our appointment book. Fine grit driven at speed gets under an eyelid, and then the natural response, rubbing, drags it across the cornea.
If you get something in your eye, do not rub. Blink repeatedly and flush with clean water or saline. If it does not clear, call us rather than persisting, because a slit lamp finds and removes what fingers cannot.
Dust also drives chronic ocular surface inflammation, which worsens dry eye and, in a loop, makes the eye more sensitive to the next dust event.
What to actually do
- Wear sunglasses with confirmed full UV protection whenever you are outdoors, including in winter and on overcast days
- Choose wraparound or larger frames, since a substantial amount of light reaches the eye around a small frame
- Get children into protective sunglasses early and consistently
- Add polarisation if you drive, golf, hike or spend time near water
- Wear eye protection for yard work, power tools and anything that generates particulate
- Never leave glasses in a parked car. A Phoenix dashboard in summer exceeds the temperature at which lens coatings craze
- Rinse dusty lenses before wiping them, since dry-wiping drags grit across the coating
The short version
- Ultraviolet damage to the eye is cumulative and permanent, and Phoenix residents accumulate more of it than almost anyone.
- Tint darkness and UV protection are unrelated. A dark lens without UV protection is worse than no sunglasses, because your pupil dilates behind it.
- Polarisation is a separate feature that removes reflected glare off roads and pale rock. In the desert it is genuinely worth having.
- A large share of lifetime UV exposure happens in childhood, and a child's lens filters less of it than an adult's.
- Monsoon dust drives a reliable wave of corneal abrasions. Do not rub. Flush, and call us if it does not clear.
- Never leave glasses in a parked car, and rinse dusty lenses before wiping them.
Want the full detail?
Read about prescription sunglassesThis article is general educational information, not medical advice or a diagnosis, and it is not a substitute for an examination. If you are experiencing sudden vision loss, eye pain or an eye injury, contact us immediately or go to an emergency room.