Mishima Hk

Dynamic sensing of human eye using a high speed camera

The eye pressure is an important index for judging whether an eye suffers from glaucoma or not. Conventional eye pressure measurements provide us with meaningful data only under the assumption that all the subjects have the same eye stiffness. Our former work, however, says that the assumption is not valid. This work is an extended version. By combining both a high speed camera with 5000[fps] and an air puff supply system, the eye surface can be precisely tracked with respect to time. We introduce a new parameter, which is the displacement at a predetermined applied force. We found that the parameter can strongly emphasize the characteristic of the individual eye stiffness and keeps a high correlation with the measured external eye pressure, so called IOP (intraocular pressure).

Elevated Intraocular Pressure, Optic Nerve Atrophy, and Impaired Retinal Development in ODAG Transgenic Mice

PURPOSEnIn an earlier study, a cDNA was cloned that showed abundant expression in the eye at postnatal day (P)2 but was downregulated at P10; it was named ODAG (ocular development-associated gene). Its biological function was examined by generating and analyzing transgenic mice overexpressing ODAG (ODAG Tg) in the eye and by identifying ODAG-binding proteins.nnnMETHODSnTransgenic mice were generated by using the mouse Crx promoter. EGFP was designed to be coexpressed with transgenic ODAG, to identify transgene-expressing cells. Overexpression of ODAG was confirmed by Northern and Western blot analysis. IOP was measured with a microneedle technique. The eyes were macroscopically examined and histologically analyzed. EGFP expression was detected by confocal microscope. Proteins associated with ODAG were isolated by pull-down assay in conjugation with mass spectrometry.nnnRESULTSnMacroscopically, ODAG Tg exhibited gradual protrusion of the eyeballs. The mean IOP of ODAG Tg was significantly higher than that of wild-type (WT) littermates. Histologic analysis exhibited optic nerve atrophy and impaired retinal development in the ODAG Tg eye. EGFP was expressed highly in the presumptive outer nuclear layer and weakly in the presumptive inner nuclear layer in the ODAG Tg retina. Rab6-GTPase-activating protein (Rab6-GAP) and its substrate, Rab6, were identified as ODAG-binding proteins.nnnCONCLUSIONSnDeregulated expression of ODAG in the eye induces elevated intraocular pressure and optic nerve atrophy and impairs retinal development, possibly by interfering with the Rab6/Rab6-GAP-mediated signaling pathway. These results provide new insights into the mechanisms regulating ocular development, and ODAG Tg would be a novel animal model for human diseases caused by ocular hypertension.

Contact Probe Based Stiffness Sensing of Human Eye by Considering Contact Area

The contact tonometer is commonly used for measuring the internal eye pressure to diagnose glaucoma. However, the conventional eye pressure measurement is valid only under the assumption that all subjects have the same structural eye stiffness. This paper challenges to measure the contact area between the probe and the cornea in addition to the corneal deformation for considering the individual differences in the structural eye stiffness. Prior to the experiment, a spherical model of an eye is developed and the analytical eye stiffness is introduced. The experiment is conducted based on the contact method where a contact probe is pressed on an anesthetized cornea. The deformation of the cornea and the contact area are captured by cameras during the experiment. The experimental results show that the measured stiffness nicely matches the analytical solution based on the constructed model. However, some subjects have different relationships between the displacement and the contact area even with similar estimated eye pressures. This suggests that the structural eye stiffness should be considered for more precise diagnoses of glaucoma.