Acquisition of high-sensitivity human aqueous humor Raman spectra

Abstract Aqueous humor metabolites could serve as novel biomarkers for real-time diagnosis of pathological conditions if analyzed using minimally invasive in vivo methods. This study aimed to develop a low-energy, sensitive detection system by obtaining Raman spectra from aqueous humor with reduced laser irradiation. Aqueous humor was collected during cataract surgery from five consenting patients and analyzed using a specialized Raman spectrometer. Raman spectra were obtained through irradiation with a 420 mJ laser light, approximately one-fourth of the energy used in previous Raman spectroscopy studies. The spectra were interpolated using the Savitzky-Golay method, and second-order differentiation was performed to verify the Raman signals. Specific vibrations were observed in the in vivo Raman spectra of aqueous humor, including CH2 symmetric, C-N stretching, and CH2 antisymmetric stretching vibrations attributed to “glucose”, “urea”, and “glucose and lactate” at 2890, 1006, and 2950 cm⁻¹, respectively. These signals were consistent with those previously reported, despite the use of significantly lower excitation energy. Aqueous humor Raman spectra can be obtained at much lower energy levels than previously reported, indicating the potential for a highly sensitive, minimally invasive metabolite detection system.