JPS621723B2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention provides an objective automatic refractometer that includes:
The present invention relates to a device that allows the subject's eye to view an astigmatism axis confirmation chart after the measurement is completed, thereby allowing the patient to confirm the astigmatism axis by his or her own consciousness.

Conventionally, in this type of device, infrared rays are irradiated from the pupil of the eye to be examined, and spherical refractive power, cylindrical refractive power, and axial angle are objectively and automatically measured using the light energy reflected from the fundus. However, there are various problems with measurement accuracy. In order to ensure measurement accuracy with this type of device, it is desirable that the pupil diameter of the eye to be examined be approximately φ3 mm or more at the time of measurement; if it is less than this value, a measurement error will occur. However, since measurements are usually performed in a bright room, the way the pupil of the eye to be examined opens differs depending on the surrounding brightness or depending on the subject. Furthermore, it was often not possible to guarantee a pupil diameter of 3 mm due to the condition of the eyelids and eyelashes of the eye being examined. In particular, the astigmatic axis angle is easily affected by this.

This invention aims to eliminate the above-mentioned drawbacks, and after the refractive power measurement is completed, the astigmatism axis confirmation chart is moved to a position corresponding to the refractive power value of the eye to be examined, and the examinee is asked to view the chart. This allows the user to consciously check the astigmatic axis angle.

The details of this invention will be explained below with reference to the drawings.

FIG. 1 is a diagram showing the arrangement of the measurement optical system of the refractometer according to the present invention. Reference numeral 1 denotes a measurement light source having a wavelength in the infrared region, which is arranged approximately at the focal point of the condenser lens 2. As shown in FIG. Reference numeral 3 designates a spot diaphragm that is movable so as to be placed at a position conjugate with the fundus of the eye to be examined, 4 an objective lens, 5 a prism, and 6 the eye to be examined. 7 is an objective lens, 8 is a prism, 9 is a first relay lens, 10 is a corneal reflection removal mask placed at a position conjugate with the cornea of the eye 6 to be examined, 11 is a second relay lens, and 12 is the spot diaphragm 3. 13 is an imaging lens.

Reference numeral 14 denotes a measuring light-receiving element that rotates about the optical axis in synchronization with the measuring light source 1 and the corneal removal mask 10. 15 is a visible light source, 16
17 is a condensing lens, 17 is a green filter, and 18 is an optotype plate projected onto the fundus of the eye 6 to be examined, which is movable to provide a fog to the eye to be examined. 19 and 20 are third and fourth relay lenses, and 21 is a reflecting mirror.

FIG. 2 is a plan view of the optotype plate 18, the target of which is an astigmatic axis confirmation chart as shown. The numbers around the target indicate the axis angle.

With the above configuration, infrared light emitted from the light source 1 passes through the condenser lens 2, spot diaphragm 3, objective lens 4, and prism 5, and is focused on the cornea of the eye 6 to be examined, and is then directed to the fundus of the eye. reach. On the other hand, visible light source 1
The light from 5 passes through a condensing lens 16 and a green filter 17, projects a chart for self-awareness confirmation on an optotype plate 18 onto the fundus of the eye 6 to be examined, and causes the eye 6 to fixate. The light reflected from the fundus of the subject's eye 6 is reflected by the prism 5.
and 8 , passes through a corneal reflection removal mask 10 , and forms an image on a light receiving element 14 by an imaging lens 13 . When the measurement button (not shown) is pressed after the alignment for the eye 6 to be examined is completed, the spot diaphragm 3 and the moving lens 12 are moved to a position where the position of the spot diaphragm 3 is conjugate with the fundus of the eye 6 to be examined. At the same time, the optotype plate 18 moves to a position corresponding to the refractive power of the eye 6 to be examined, and then moves to the + side by an appropriate diopter to provide a fog to the eye 6 to be examined. after that,
The measurement light source 1, the corneal reflection removal mask 10, and the measurement light receiving element 14 rotate 180 degrees around the optical axis to measure the spherical refractive power, cylindrical refractive power, and axial angle of the eye 6 to be examined.

During this measurement, if the pupil of the eye to be examined 6 has shrunk to below a predetermined diameter due to the influence of external light, or if the eyelids or eyelashes are below this diameter, the corneal reflection removal mask 10 will remove them. Therefore, reflected light from the cornea, eyelids, and eyelashes enters the light receiving element 14, resulting in a measurement error. In particular, the astigmatic axis angle is easily affected by this. After the measurement is completed, the optotype plate 18 returns to the position corresponding to the refractive power of the eye 6 to be examined. Here, the subject is asked to read the angle corresponding to the most clearly visible radial line and compare it with the value displayed on the device.

As is clear from the above description, according to the present invention, in an objective automatic refractometer, the astigmatic axis angle, which is easily affected by factors that cause measurement errors, can be immediately confirmed by the user, increasing the reliability of the measurement results. can be increased.

[Brief explanation of the drawing]

FIG. 1 is a layout diagram of a measurement optical system of a refractometer according to the present invention, and FIG. 2 is a drawing showing an astigmatism axis confirmation chart. DESCRIPTION OF SYMBOLS 1... Light source for measurement, 3... Spot aperture, 6... Eye to be examined, 10... Corneal reflection removal mask, 14... Light receiving element for measurement, 15... Visible light source, 18... Optotype plate.

Claims (1)

[Claims] 1. In an objective automatic refractometer that irradiates light energy onto the eye to be examined and measures refractive power using the light energy reflected from the fundus, the target pattern on the optotype plate is used as an astigmatism axis confirmation chart, and An objective automatic refractometer capable of consciously confirming the axis of astigmatism, characterized in that it is provided with a means of moving the optotype plate back to a position corresponding to the refractive power value of the eye to be examined after measuring the objective refractive power. .