You squint your way through the drive home every afternoon. Your sunglasses live in the car door and the lenses are scratched. The pair you wear at the pool was eight dollars from a gas station three summers ago. Sound familiar? Every one of those choices is doing something to the back of your eye that you cannot see, and the costs do not show up for twenty years. Frisco summers deliver enough UV in a single season to make this worth thinking about.
How UV damages the eye
UV radiation comes in two wavelengths that matter for the eye:
- UV-A reaches deeper structures, including the lens and retina.
- UV-B is mostly absorbed by the cornea and the front of the lens.
Long-term, cumulative UV exposure is associated with earlier cataract formation, contributes to macular degeneration risk, and drives the growth of pterygium (a fleshy growth that can creep across the cornea and pull on the surface). Short-term, a single intense exposure (a day on the lake without sunglasses, time on the slopes, prolonged welding) can cause photokeratitis, which is essentially a sunburn of the cornea. It clears in a day or two, but the pain during healing is real.
The polarization myth
One of the most common assumptions we hear: "They are polarized, so they block UV." Not necessarily. Polarization and UV protection are two unrelated features.
- Polarization filters horizontal glare bouncing off flat surfaces (water, asphalt, car hoods). Great for driving and fishing. Has nothing to do with UV.
- UV protection is a coating or material property that blocks wavelengths up to 400 nanometers (UV400 or "100% UV protection" on the label).
A lens can be one without the other. Many premium sunglasses combine both, but the only way to know is to read the label. And the cheap dark-tinted glasses at the gas station are actively worse than wearing nothing, because the dark tint dilates the pupil and lets more UV reach the back of the eye.
Kids carry most of the lifetime UV load
By age 18, a person has typically received roughly half of their lifetime UV exposure. Children's pupils are larger than adults', and the lens of a child's eye filters less UV than an adult's lens, so a higher percentage of incoming UV reaches the retina.
Practical translation for parents:
- Sunglasses on infants and toddlers at the pool are not overcautious. They are correct.
- Wraparound styles outperform aviators because they block side-incident UV.
- A wide-brim hat doubles the protection.
- If your child wears glasses, ask about prescription sunglasses or photochromic lenses for outdoor activity.
How to choose a pair that actually works
The label matters more than the price tag. Look for:
- UV400 or 100% UV protection. Anything less is incomplete.
- Adequate coverage. A frame that lets sun reach the eye from the side is doing only part of the job.
- Good fit. Sunglasses that slide down the nose end up on top of the head. Sunglasses on top of the head do not block UV.
- Polarization for driving and water. Optional but useful.
- Prescription if you need it. Squinting through clip-ons or drugstore lenses worn over contacts strains the eye and reduces clarity.
About your current pair
UV coatings degrade. A pair that was rated UV400 five years ago may not be performing at that level today, especially after living in a hot car summer after summer. Scratches reduce both clarity and UV blocking. If your sunglasses are scratched, faded, or older than three or four years, the protective function is likely compromised even if the frames still look fine.
Prescription options at our office
At our Frisco office we carry HOYA prescription lenses, where the UV blocker is built into the lens material itself rather than applied as a surface coating. That gives a more durable level of protection than a coating alone, and it does not degrade with scratches. We also carry a full range of sunglass frames in fit ranges for adults and children.
If you have not had a recent eye exam, a comprehensive eye exam is the right starting point. The dilated portion of the exam is when we check for early UV damage at the back of the eye and the lens, well before changes affect your vision. Summer is when the exposure is happening, and the protection you put in place this season is what lowers risk decades later.