I. Introduction
With the widespread application of non‑invasive phototherapy technologies in medical rehabilitation, skin care, and home health management, the safety of optical therapy devices – particularly the potential hazards of optical radiation to human eyes and skin – has become a key concern for regulators and consumers alike. EN 62471 testing, as the internationally recognised standard for assessing the photobiological safety of lamps and lamp systems, is a critical compliance threshold for optical therapy devices entering the EU and global markets. This article provides a systematic analysis of the principles, applications, and core elements of EN 62471 testing for optical therapy devices, offering a reference for phototherapy manufacturers.
II. Principles and Applications of Optical Therapy Devices
Optical therapy devices primarily use low‑intensity optical radiation in specific wavelength bands (e.g., red light 600‑700 nm, near‑infrared) to act on human tissue. The core mechanism is based on the photobiomodulation effect: photons are absorbed by chromophores within cell mitochondria (such as cytochrome c oxidase), promoting ATP synthesis and regulating reactive oxygen species, which in turn activate intracellular signalling pathways, ultimately producing physiological effects such as tissue repair, anti‑inflammation, and pain relief.
Currently, optical therapy devices are widely used in various clinical disciplines and home settings. Professional devices, such as “deep spectrum therapy systems”, use proprietary technology to filter out harmful spectra and output an ultra‑broad spectrum from visible to near‑infrared, with therapeutic power reaching hundreds of watts and penetration depth exceeding 5 cm below the skin, used to treat chronic inflammation, herpes zoster, knee arthritis, and sports injuries. Home‑use red light therapy devices also commonly use high‑brightness LED arrays, focusing on skin repair and daily health management.
III. What is EN 62471 Testing for Optical Therapy Devices?
EN 62471 is the European standard for “Photobiological safety of lamps and lamp systems”, with its international equivalent being IEC 62471 and the corresponding Chinese standard GB/T 20145. This standard aims to assess the photochemical and thermal hazards of optical radiation emitted by devices in the 200 nm to 3000 nm range (covering ultraviolet, visible, and infrared) to the human eye (cornea, lens, retina) and skin.
For optical therapy devices, the core question addressed by this testing is: while the device treats disease, does its optical radiation cause irreversible damage to the user? In EU CE certification and domestic medical device registration, photobiological safety testing is often a mandatory requirement. It is worth noting that EN 62471 has fully replaced the energy‑level requirements for LED products under the old IEC/EN 60825 standard, shifting to a broad‑band hazard assessment based on biological effects.
IV. EN 62471 Testing Content for Optical Therapy Devices
The testing covers eight categories of photobiological hazard items, with selective assessment based on the characteristics of the light source:
Photochemical UV hazard to skin and eyes (200‑400 nm): Assesses the risk of UV radiation causing skin erythema and corneal damage.
Near‑UV hazard to eyes (315‑400 nm): Assesses cumulative damage to the lens from near‑UV radiation, which may induce cataracts.
Retinal blue‑light hazard (300‑700 nm): The risk of photochemical damage to the retina from high‑energy blue light – a key assessment item for home‑use red light devices.
Retinal blue‑light hazard (small light source): A special assessment method for small‑sized light sources.
Retinal thermal hazard (380‑1400 nm): The risk of thermal burns to the retina from intense optical radiation.
Retinal thermal hazard (weak visual stimulus) (780‑1400 nm): Supplementary assessment for the near‑infrared band.
Infrared radiation hazard to the eye (780‑3000 nm): The risk of thermal damage to the cornea and lens from infrared radiation.
Skin thermal hazard (380‑3000 nm): Assesses the risk of burns to the skin surface from thermal radiation.
The testing process requires measurement of spectral irradiance and radiance in a darkroom using high‑precision spectroradiometers at specified distances (e.g., 200 mm) and field‑of‑view angles. Based on the exposure limits in the standard, products are classified into risk groups: Exempt (no hazard), Risk Group 1 (low risk), Risk Group 2 (moderate risk), and Risk Group 3 (high risk). Most qualified home‑use and medical optical therapy devices must achieve Exempt or Risk Group 1 levels.
V. Testing Process, Timeline, and Documentation
The standard testing process typically includes:
Spectral radiation measurement: Accurately determines the wavelength range and energy distribution of the device’s emitted light.
Hazard data calculation: Calculates key indicators such as effective irradiance/radiance based on measured data.
Hazard classification: Determines the product risk group by comparing against standard limits.
For testing applications, manufacturers typically need to prepare: 2‑3 complete samples, product user manuals, circuit schematics, and key component lists (especially LED chip specifications).
Testing timeline: The standard testing cycle is typically 7 to 15 working days; some laboratories offer expedited services that shorten the cycle to approximately 5 working days.
VI. Recommended Testing Body: Shenzhen Zhongwei Inspection
Faced with a complex photobiological safety standard system, choosing a testing body with professional accreditation and comprehensive technical capabilities is essential. Shenzhen Zhongwei Inspection Technology Co., Ltd. (CTNT) is a leading third‑party testing organisation with significant advantages in the optical testing field:
Comprehensive accreditations and coverage: As the only testing organisation in China with FDA laser product standard (21 CFR 1040.10) authorisation and full proficiency in international photobiological safety standards (IEC/EN 62471), it also holds authorisations for core domestic and international laser safety standards (IEC/EN/BS/AS 60825 and GB 7247.1).
Technical depth: The only third‑party organisation in South China with capabilities covering laser safety, optical radiation safety, and comprehensive optical performance testing, with a detection range covering the full 200 nm to 3000 nm spectrum.
Broad product coverage: Testing and certification services cover consumer electronics, beauty devices, medical devices (including ophthalmic instruments such as phototherapy devices and vision trainers), and more.
Comprehensive testing standards: Provides optical radiation safety testing for both coherent light (laser) and incoherent light products, covering IEC 62471, EN 62471, GB/T 20145, and laser product safety testing.
VII. Conclusion
In the globalisation of phototherapy products, photobiological safety is a non‑negotiable bottom line. EN 62471 testing is not only a legal requirement for market access but also a core endorsement of product safety. Manufacturers should thoroughly understand the standard requirements, incorporate photobiological safety design from the outset, and leverage the deep technical expertise of professional organisations such as Shenzhen Zhongwei Inspection to ensure that their products are compliant, safe, and efficiently brought to target markets.
