UV and your eyes in New Zealand

A sunny day feels harmless until your eyes ache that night

You spent the afternoon on the water at Browns Bay, or watching the kids at athletics, without sunglasses because it was a bit cloudy. That evening your eyes are gritty, watery and sore in the light. Or nothing happens at all, which is the more common story, and the effect only shows up decades later as a growth on the white of the eye or a cataract earlier than expected.

This guide explains what ultraviolet light does to the eye, why the New Zealand sun is a special case, who is most exposed, and what to look for on sunglasses. Our older post on UV protection for the eyes is linked rather than repeated.

Why New Zealand UV is higher than the latitude suggests

NIWA, now part of Earth Sciences New Zealand, states that because of differences in ozone, sun-earth separation and pollution, the peak UV index in New Zealand is approximately 40 percent greater than at comparable latitudes in the Northern Hemisphere. SunSmart's school resource spells out the three reasons: clearer skies with less pollution, the Earth being closer to the sun during the southern summer, and ozone.

Timing matters as much as place. SunSmart advises sun protection from September to the beginning of April, especially between 10am and 4pm, and all year round whenever the UV index is 3 or more, which includes cooler, cloudy days. NIWA notes that in the New Zealand winter the UV index rarely exceeds 3, which is the level at and above which the World Health Organization recommends protection. UV is strongest when your shadow is shortest, and the AAO adds that clouds do not block UV light and that sunlight is stronger when reflected off water, ice, sand or snow.

What UV does to the eye

Some of the damage is quick and some is slow. The quick kind is photokeratitis, which the AAO describes as a sunburn of the cornea and conjunctiva from UV reflected off sand, water, ice and snow, or from welding arcs and sunbeds. Like skin sunburn, it is not noticed until well after the exposure. It brings pain, redness, blurriness, watering, a gritty feeling and light sensitivity, and it usually settles on its own within a day or two.

The slow kind builds over years. The WHO lists cataract and pterygium among the chronic effects of UV on the eye. Healthify NZ describes pterygium as a growth on the white of the eye that usually starts in the inner corner nearest the nose, says it is very common in Aotearoa New Zealand, and that people who spend a lot of time in sun and wind are most at risk; surgery is considered if it affects vision or if drops do not give enough relief. For cataract, Healthify lists increased exposure to sunlight and UV among the risk factors, and the AAO says protecting your eyes from sunlight is a main way to slow cataract development. The AAO also notes that eye cancers can take years to develop and that pterygium can appear as early as the teens or twenties in surfers, skiers, fishers and farmers. SunSmart lists macular degeneration among the conditions associated with overexposure as well.

Who is most exposed

Exposure adds up over a lifetime, so the people most affected are those outdoors most: on roofs, farms, roads and boats, or spending weekends on the water, the slopes or a bike. Reflection adds to the dose, which is why surfers and skiers feature in the AAO's list and why snow blindness is a form of photokeratitis.

Children need the most attention. The WHO states that children and adolescents are particularly vulnerable to the harmful effects of UV because of their skin and eye structure. SunSmart recommends a legionnaire, broad-brimmed or bucket hat whenever children are outside, and sunglasses that meet the AS/NZS 1067:2016 standard if they wear them, especially around reflective surfaces such as snow. The AAO puts it simply: babies and children need to wear hats and sunglasses.

• Outdoor workers: builders, farmers, road crews, lifeguards, anyone on a boat.
• Water and snow sports: surfers, sailors, skiers and snowboarders, because of reflection.
• Cyclists and runners who are out in the middle of the day for long periods.
• Children and teenagers, whose eyes let more UV through and who are outside more.
• Anyone with a pterygium, pinguecula or early cataract already noted at an exam.

What a sunglasses label tells you

Darkness is not protection. SunSmart, the Cancer Society and Standards New Zealand all point to the same thing: sunglasses should conform to AS/NZS 1067:2016, the joint Australian and New Zealand standard for sunglasses and fashion spectacles, and the Cancer Society warns that not all sunglasses protect against UV. Look for the standard number on the arm or swing tag rather than judging by tint. The standard's lens categories are not described here because the standard is a paid document we could not open; ask us or check the label.

Fit matters as much as the lens. SunSmart notes that UV can come around the edges of ordinary spectacle frames, so it recommends close-fitting, wrap-around styles, and the WHO recommends wraparound sunglasses with 99 to 100 percent UV-A and UV-B protection. Polarised lenses cut glare and make a bright day easier on the eyes, but SunSmart is clear that polarisation does not increase UV protection. A wide-brimmed hat adds protection on its own and more again with sunglasses.

If you wear glasses, you have three options: clear prescription lenses with UV protection in the lens material, lenses that darken in sunlight, or a separate pair of prescription sunglasses. Ask us which of our lens options carry UV protection, and see the frames page for frame choices. For riders, our prescription cycling sunglasses page covers wraparound sports frames made to your prescription. Contact lens wearers still need sunglasses: a lens covers only the cornea, not the lids or the white of the eye.

When this practice is the wrong place

Mild sunburned eyes after a day on the water usually settle within a day or two with rest in a dim room, cool compresses and lubricating drops; the AAO advises taking contact lenses out straight away and not rubbing. If the pain is severe, vision is noticeably reduced, or it followed a welding arc without a helmet, go to an urgent care clinic or the hospital emergency department rather than an optometry appointment.

Some symptoms are emergencies whatever caused them. Sudden loss of vision, a shadow or curtain across part of your vision, flashes with a sudden shower of new floaters, a chemical splash, something in or through the eye, an eye injury, or a red and painful eye that cannot tolerate light need 111 or the nearest hospital emergency department. Healthify NZ advises flushing a chemical splash with clean running water for at least 15 minutes first, and says most eye injuries are covered by ACC. A new lump or a spot on an eyelid that bleeds or will not heal needs a GP skin check. If you are unsure, Healthline on 0800 611 116 is free and open around the clock. A pterygium reaching the cornea or a cataract affecting your driving is assessed at an eye exam and, if surgery is needed, referred to a hospital eye clinic or an ophthalmologist; we do not operate.

What to do with this

Wear sunglasses that carry the AS/NZS 1067 mark and fit close to the face, add a brimmed hat, and keep both on your children from September to April and on any day the UV index reaches 3. If you are outside for work or sport, treat eye protection the way you treat sunscreen. At your next eye exam, ask whether there is any early UV change on the surface of your eye or in the lens. The screen time guide covers the other light question people ask about, and the single vision vs progressive guide helps when the sunglasses need a prescription too.