Family Eye Health & Contact Lens Center

All About Vision – Seeing More Clearly

Adverse Effects of Heat on Eyewear

Here in the height of summer, with the warm temperatures and a plethora of sunny days, I have noticed an increase of people coming in to see me with eyewear and sunwear issues caused by prolonged exposure to the sun and heat especially when left in cars.

Most of us will keep a pair of back up glasses and more commonly our sunglasses in our cars.  With the warmer than normal temperatures that the entire country has been experiencing this year, it has caused eyeglass lenses to craze, crackle or delaminate and plastic frames to melt to the point of being ruined.   It can make the best anti-glare look like crackle coating in a matter of hours with exposure to extreme heat.  The reason is that the excessive heat will cause the lens material to expand much more than is normal and when it begins to cool any coating or lens treatments on the lens will contract down to normal size and crackle making your viewing experience less than perfect.

On an 85 degree day, your car can achieve internal temperatures as high as 150 degrees in less than a couple of hours!  It’s no wonder that plastic eyewear frames will become melted, then become brittle and break after prolonged exposure in these kinds of temperatures.  Keeping your eyewear in a case or compartment will not protect them from super heating either, over time they will show signs of heat damage.  The best rule of thumb for the hottest days of summer is to bring your prescription eyewear inside with you, especially if it has anti-glare on the lenses or if the frame is plastic.

Melted glasses; aside from being costly to replace, it’s annoying to look through crackled lenses, not to mention being uncomfortable wearing a warped frame. Be kind to your eyewear and keep them inside during those dog days of summer!

 

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Study: Buyer beware -online spectacle orders may not meet compliance

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The Journal of American Optometric Association and the Vision Council recently conducted a study to evaluate 10 of the most popular online eyeglass vendors sites, to see how they performed within the industry standards. The study involved 10 participants who ordered two pairs of prescription glasses, including pairs for both adults and children. These orders were then evaluated in terms of sphere power, cyl power, axis, add power, horizontal prism imbalance and impact resistance testing. Of the 154 pairs evaluated 28.6% had at least one lens fail tolerance standards for at least one optical parameter, 22.7% had at least one lens fail impact testing based on center thickness. Overall, 44.8% of the spectacles failed at least 1 parameter of the optical or impact testing according to the study. Patients do not receive the benefit of ensuring an accurate prescription or proper frame fit. It was noted that patients who purchase eyewear without the assistance of a trained professional may not receive a product of equal performance, value or safety. Even though online retailers may effectively market the cost savings associated with the online purchase of eyewear, consumers should beware, as this study points out. The lack of oversight and quality control can lead to inferior products that could be potentially harmful. These important quality checks are performed on eyewear products when dispensed by licensed professionals to assure the safety and accuracy of the prescription.

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