Purpose: To establish a system to transmit laser light transversely into the anterior chamber to avoid the direct entry of light into the retina as a foothold for noninvasively measuring the levels of metabolites in aqueous humor. Additionally, this study aimed to clinically examine the signal detection ability and safety of the system for laser transmission in aqueous humor.
Methods: Using the optical simulator, LightTools (Synopsys), we created an original human eye model while considering the corneal refractive index and aspheric shape and performed ray-tracing simulations. Based on the simulation results, a measurement device was constructed, and transmitted laser light in the anterior chamber was detected in three eyes of three healthy male subjects (average age: 28.3 years). Transmitted light was obtained multiple times at 27 points intermittently for 6 seconds.
Results: Ray tracing simulations run using the original eye model revealed that it is almost impossible to establish a stable optical pathway between the air and cornea, and it is necessary to fill the cornea with saline, which has a similar refractive index similar as aqueous humor. After developing a saline container, an optical transmission mechanism, and a novel device to fix the face of the patients, an intra-aqueous laser light transmission signal (n=2,322) was clinically obtained. The cumulative relative frequency of coefficients of variation less than 0.15 was 67%, and the lowest class of coefficients of variation with mode frequencies ranging from 0 to 0.05 was considered appropriate for the system. No adverse events were observed in the patients.
Conclusions: The developed device could noninvasively detect signals by transmitting laser light in the visible light range transversely into the anterior chamber. In addition, the safety of the device was confirmed in a first-in-human study, and the possibility of clinical application was identified.
Nippon Ganka Gakkai Zasshi (J Jpn Ophthalmol Soc) 127: 672-679,2023.