Magnetic glasses, which use small magnets to hold clip-on accessories or to connect the frame halves, offer convenience and versatility in eyewear. The primary concern centers on the safety of having these magnetic fields in constant proximity to the body and other devices. While the magnets are powerful for their size, their magnetic fields are weak and highly localized compared to large industrial or medical equipment.
Understanding the Magnets Used in Eyewear
Magnetic eyeglasses typically fall into two main categories: those with clip-on sunglass lenses and those that split the frame at the nose bridge for easy removal around the neck. Both designs rely on the attractive force of small, high-strength Neodymium magnets. These magnets are chosen because they provide a strong, secure hold while remaining small and light enough to be discreetly embedded within the frame material. The goal of the magnet placement is purely mechanical, ensuring the components snap into alignment and stay firmly connected during normal daily use. The magnetic field strength of these components is extremely low and drops off rapidly with distance from the frame.
Potential Interference with Implanted Medical Devices
The most significant safety concern involves the potential for magnetic fields to interfere with sensitive medical implants, such as pacemakers and implantable cardioverter-defibrillators (ICDs). These devices contain sensors that can react to external magnets, sometimes causing the implant to switch into a temporary, non-therapeutic mode. The threshold for interference is generally cited by medical device manufacturers as a magnetic field strength above 5 to 10 Gauss at the site of the implant.
Medical experts advise keeping magnets a minimum safe distance away from an implanted cardiac device, often recommending at least 6 inches (about 15 centimeters). Since magnetic glasses are worn on the face, they are generally a safe distance from a device implanted in the chest or shoulder area. However, individuals with pacemakers or ICDs should still consult their physician for personalized guidance, especially if they use the type of magnetic glasses that split the frame and hang around the neck, bringing the magnets closer to the chest.
Impact on External Electronics and Data Storage
Magnetic glasses pose a minimal risk to modern external electronics. Modern smartphones and tablets rely on solid-state flash memory, which is unaffected by the weak static magnetic fields produced by the magnets in eyewear. While a phone’s internal compass may show a temporary fluctuation if the magnetic glasses are held directly against it, the phone’s overall function and data integrity are not compromised.
The main concern for external items involves magnetic stripe cards, such as credit cards, debit cards, and hotel key cards. The data on these stripes is encoded magnetically, making them vulnerable to demagnetization if exposed to a strong enough field. However, the weak, localized magnets in eyewear are generally too distant and too low in strength to affect a card stored in a wallet or pocket. Modern payment cards equipped with EMV chips or contactless technology are significantly more resistant to magnetic interference.
Physical and Ocular Safety Considerations
The static magnetic fields emitted by the magnets in eyeglasses are not known to cause any biological harm to the optic nerve, eye tissue, or brain function. The field strength is far too low to induce any measurable change in the body. Since the magnets are typically encased within the frame material, direct contact with the skin is prevented.
Physical safety concerns relate more to the hardware itself. Small magnets, if they detach from the frame, could present a choking hazard, particularly for small children. Manufacturers design frames to securely encase the magnets to prevent this. Users of magnetic clip-ons should ensure the fit is secure, as a loose attachment could separate and fall off during activity.