Red Light Therapy (RLT) and Near-Infrared (NIR) light utilize specific wavelengths to promote cellular function, a process often called photobiomodulation. This therapeutic technique commonly targets skin rejuvenation, muscle recovery, and pain relief through non-invasive light exposure. RLT typically uses visible red light (630 to 700 nanometer (nm) range), while NIR employs light from about 700 nm up to 1200 nm, which is invisible to the human eye. The growing use of powerful at-home and clinical devices has brought the issue of eye safety to the forefront. Whether eye protection is necessary depends entirely on the specific device and how it is used.
The Ocular Structures Vulnerable to Light Exposure
The eyes are uniquely susceptible to light energy. The retina, a delicate layer of tissue at the back of the eye, is most vulnerable to both phototoxicity and thermal injury from intense light exposure. Since red and near-infrared light penetrate deeply into the ocular tissue, the retina is exposed to the energy, potentially damaging the photoreceptors.
Phototoxic damage occurs when light energy causes chemical changes, generating free radicals that harm the retinal tissue. This injury is associated with longer exposure durations, even at lower light intensities. Thermal damage is caused by a rapid temperature increase, which can denature proteins and lead to burns on the retina. Near-infrared light carries a greater risk of thermal damage because its energy is readily absorbed by tissue components, increasing the retinal temperature.
The lens, located behind the iris, is also at risk from the heat generated by NIR light. Prolonged exposure to heat, especially from longer NIR wavelengths (over 850 nm), can cause proteins in the lens to clump together. This leads to the formation of opacities, known as cataracts.
Factors Determining the Need for Eye Protection
The necessity of using eye protection is dictated by three factors that determine the total energy dose received by the eye.
Irradiance (Power Density)
The device’s irradiance, or power density, is the first factor. High-powered professional panels deliver a much more intense light dose than low-powered handheld units. Devices with high irradiance levels, such as full-body panels, significantly increase the risk of overexposure and require protective eyewear.
Wavelength
The specific wavelength emitted plays a role in risk assessment. Visible red light (630–670 nm) is primarily absorbed at the surface and poses less thermal risk to deep ocular structures. NIR light (700–1200 nm) penetrates deeper, making it a greater concern for thermal damage to the lens and retina. Devices that emit strong NIR wavelengths, especially those over 850 nm, warrant careful attention to eye protection.
Distance and Duration
The third factor involves the distance between the device and the eyes, combined with the duration of the treatment session. A user positioned very close to a high-irradiance panel receives a much higher energy dose than someone farther away. As distance decreases and time increases, the use of specialized goggles becomes necessary to prevent cumulative damage.
Specific Safety Protocols and Protective Measures
The most effective way to ensure eye safety is to adhere to the manufacturer’s guidelines. For devices that pose a higher risk, such as full-body panels or high-intensity facial units, the manufacturer will include and require the use of specialized eye protection. This protective eyewear must be designed to completely block or filter the specific red and near-infrared wavelengths used in the therapy.
Closing the eyes can minimize light entry, but this action alone may not provide adequate protection. The thin eyelid tissue is not an opaque barrier and can still allow a significant amount of NIR energy to pass through to the deeper structures. Therefore, for high-intensity treatments, certified opaque goggles that fit snugly around the eye socket are the most secure option.
Regular sunglasses or simple sleep masks are insufficient for RLT because they are not rated to block the specific wavelengths and intensity of therapeutic light. For safety, choose protective gear that either completely blocks the light or uses specialized filtering lenses. Use light-blocking goggles when treating areas near the face with any powerful red or near-infrared light device.