This paper presents the preliminary study on monitoring of intraocular pressure (IOP) of human eye by using optical coherence tomography (OCT). Because hypertension IOP can lead to Glaucoma, one of chronic diseases of the optic nerve, the periodic monitoring of IOP through tonometry is essential to prevent the Glaucoma. One of the most common tonometry methods to estimate IOP includes measuring corneal deflection by using either a direct contact or non-contact (e.g. air puff) impact force. However, this approach may be harmful to human eye. Therefore, it is necessary to develop the more reliable and safe monitoring method. In ophthalmology, the differentiation of open-angle glaucoma and normal eyes is used to monitor the IOP by using. Typically, peripapillary vessel density or superficial perifoveal macular vessel density measurements are currently utilized. In this study, optical OCT images of bovine eye was captured with different IOPs of bovine and analyzed to extract the signature where defines the relationship between IOP and optical OCT images.
This paper presents the new G-Fresnel lens-based μ-spectrometer with an image-processing algorithm, such as a color space conversion, in the range of visible light. The proposed μ-spectrometer is developed by using the cost-effective and compact G-Fresnel lens, which diffuses the mixed visible light into the spectrum image, and an image processing algorithm. The RGB color space commonly used in the image signal from CMOS type image sensor is converted into the HSV color space, which is one of the most popular methods to express the color as the numeric value, Hue (H), Saturation (S), and Value (V), using the color space conversion algorithm. Because the HSV color space has the advantages of expressing not only the three primary color of light as the H-value, but also its intensity as the V-value, it was possible to obtain both the wavelength and intensity information of the visible light from its spectrum image. The proposed μ-spectrometer yielded an inverse linear sensitivity (hue vs. the wavelength). We demonstrated the potential of G-Fresnel lens-based μ-spectrometer for the wavelength measurement of visible light such as mechanoluminescence (ML), typically green light across the region of 500 nm.