A revolutionary step forward in ophthalmic diagnostics has been achieved by a group of Korean scientists, who have successfully integrated an ultra-thin Organic Light-Emitting Diode (OLED) into a contact lens. This pioneering development enables a wireless, wearable platform for electroretinography (ERG), marking a significant departure from the cumbersome, darkroom-based methods historically employed for assessing retinal function. This breakthrough promises to reshape the landscape of eye care, providing a more accessible and comfortable diagnostic experience for patients and practitioners alike.

Electroretinography, or ERG, is a fundamental diagnostic technique in ophthalmology, used to evaluate the normal functioning of the retina and diagnose various hereditary retinal diseases or track the progression of retinal degeneration. The conventional ERG procedure necessitates patients to remain still in a darkened room, often with large, specialized light sources, which can be an uncomfortable and spatially restrictive experience, particularly for vulnerable populations such as children or elderly individuals.

Addressing these challenges, a collaborative research team, spearheaded by Professor Seunghyup Yoo from KAIST's School of Electrical Engineering, alongside Professor Se Joon Woo of Seoul National University Bundang Hospital, Professor Sei Kwang Hahn of POSTECH (who is also the CEO of PHI Biomed Co.), and the Electronics and Telecommunications Research Institute (ETRI), has engineered the world's inaugural wireless contact lens-based wearable retinal diagnostic system. This cutting-edge device simplifies ERG testing, allowing it to be performed with unprecedented ease by merely wearing the contact lens.

The innovative contact lens system integrates a flexible OLED, remarkably thin at approximately 12.5 micrometers—about six to eight times finer than a human hair—directly into the contact lens electrode. This design eliminates the need for external, bulky illumination equipment, enhancing patient comfort and convenience. The device also includes a wireless power reception antenna and a control chip, rendering it a self-sufficient operational unit capable of conducting ERG measurements independently. For robust power delivery, the researchers adopted a 433 MHz resonant frequency wireless power transfer method, which ensures stable communication. Furthermore, the system's practicality was showcased through its integration into a sleep mask with a wireless controller that can interface with a smartphone, indicating its potential for broader consumer applications.

Unlike previous smart contact lens designs that often utilized rigid inorganic LEDs, which could cause excessive heat accumulation and limited light distribution, the OLED technology offers an areal light source. This enables the contact lens to induce retinal responses even at low luminance levels. The study demonstrated that the OLED contact lens successfully generated stable ERG signals at a relatively modest luminance of 126 nits, yielding diagnostic outcomes comparable to those from established commercial light sources. Animal trials further corroborated the safety and efficacy of this new diagnostic tool. Tests conducted on rabbit eyes wearing the OLED contact lens revealed that the surface temperature remained below 27°C, thereby preventing corneal thermal damage. Moreover, the light-emitting capabilities of the lens were sustained even in humid conditions, underscoring its potential for practical use in clinical environments.

This pioneering research underscores a significant leap in smart contact lens technology, extending its utility beyond vision correction to encompass advanced optical diagnostics and phototherapeutic applications. The integration of flexible, diffusively emitting ultrathin OLEDs into a contact lens is a testament to the ingenuity of the research team, promising to usher in a new era of digital healthcare marked by enhanced patient convenience and diagnostic precision.