Perimeter

1. A perimeter for examining a state of a visual field of a patient's eye, the perimeter comprising:

a target presenting unit that presents a stimulation target for examination to the eye, a presentation position and a presentation brightness of the target being variable;

a response unit that provides a response indicating that the patient recognizes the target presented by the target presenting unit;

a first arithmetic unit that obtains a threshold of sensitivity at each examination point on a retina of the eye corresponding to each presentation position based on the response provided by the response unit and the presentation brightness at each examination point;

an input unit that inputs function information at each examination point, the function information at each examination point being objectively obtained by processing a first fundus image of the eye taken before irradiation of visible stimulation light onto a fundus of the eye and a second fundus image of the eye taken after the irradiation of the visible stimulation light; and

a determining unit that determines an initial reference value of the presentation brightness at each presentation position based on the input function information at each examination point.

2. The perimeter according to claim 1 , wherein the input unit inputs a change of an absorbance at each examination point as the function information at each examination point.

3. The perimeter according to claim 2 , wherein the input unit inputs, as the change of the absorbance at each examination point, a value obtained by dividing a brightness of the second fundus image at each examination point by a brightness of the first fundus image at each examination point, or a value obtained by subtracting the brightness of the first fundus image at each examination point from the brightness of the second fundus image at each examination point.

4. The perimeter according to claim 1 further comprising:

a first irradiation optical system that irradiates the visible stimulation light onto the fundus;

a second irradiation optical system that irradiates illumination light different from the visible stimulation light onto the fundus;

an imaging optical system that includes an objective lens and an imaging element and images, as the first and second fundus images, a fundus image by the illumination light reflected from the fundus; and

a second arithmetic unit that obtains the function information at each examination point by processing the first and second images imaged by the imaging element,

wherein the input unit inputs the function information at each examination point obtained by the second arithmetic unit.

5. The perimeter according to claim 4 , wherein

the first irradiation optical system is an optical system that irradiates visible illumination light for a fundus visible photographing onto the fundus, and

the second irradiation optical system is an optical system that irradiates infrared illumination light for a fundus infrared observation onto the fundus.

6. The perimeter according to claim 4 , wherein the target presenting unit comprises a target presenting optical system that presents the target to the eye through the objective lens.