Patent ID: 8596789
Filing Date: 2013-12-03
Classification: A61B

Abstract:
1. A tonometer for measuring intraocular pressure of an examinee's eye in a non-contact manner, the tonometer comprising: an arithmetic part for calculating the intraocular pressure; a fluid blowing unit for blowing a fluid at a cornea of the examinee's eye through a nozzle; a projecting optical system for projecting light onto an anterior segment of the examinee's eye through the nozzle, the system including a visible light source that projects the light, a condensing optical system for condensing the light from the visible light source to the anterior segment, and an aperture placed in a position conjugated with the anterior segment; and an imaging optical system for imaging a cross-sectional image of the anterior segment, the system including an imaging lens and a first imaging element; an infrared light source for observing a front image of the examinee's eye; an optical member that holds the nozzle and transmits at least light from the infrared light source; and a second imaging element placed at a rear of the optical member and configured to form thereon a front image of the anterior segment illustrated by the infrared light source, wherein the imaging optical system is placed so that extended planes of a cross section of the light projected onto the anterior segment by the projecting optical system, a principal plane of the imaging lens, and an imaging plane of the imaging element intersect one another on one axis, the projecting optical system includes a light restriction unit that is placed off the position conjugated with the anterior segment and allows the light from the visible light source to pass through inside of the nozzle but not to pass through outside of the nozzle, and the light restriction unit is a filter placed around the nozzle that transmits the light from the infrared light source and blocks the light from the visible light source, or the light restriction unit is a diaphragm placed between the aperture and the nozzle that allows the light from the visible light source to pass through inside of the nozzle but does not allow the light from the visible light source to pass through outside of the nozzle.