JP2003106940A - Method for measuring refracting power of contact lens - Google Patents

Abstract

PROBLEM TO BE SOLVED: To measure refracting power distribution on the whole face of a contact lens using a cornea shape measuring device. SOLUTION: An auxiliary device is added to the cornea shape measuring device for measuring cornea of a human eye to measure refracting power distribution of the contact lens. This auxiliary device has a holding part for the contact lens and a light projection system for projecting a multiple ring pattern on the contact lens. This light projection system is composed of an irradiation light source, a condenser lens for turning irradiation light into parallel luminous fluxes, and a multiple ring slit for repeating penetration/shading alternately. When this auxiliary device is added to the cornea shape measuring device, a multiple slit face is formed in such a way that it is equal to a position of cornea when measuring a cornea shape.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for measuring the refractive power of a contact lens in a corneal shape measuring apparatus for measuring the corneal shape of the human eye in the field of ophthalmology / spectacles.

[0002]

Projecting a plurality of ring patterns on the cornea,
There is provided a device (corneal topographer) that calculates a corneal shape from the reflection image and expresses the corneal shape with a color-coded map. This is to calculate the shape at each position of the cornea from the pattern analysis by taking out the reflected light group from the cornea from the small opening of the device to the flat light receiving element using the light emitting ring generator installed in front of the eye. . This is useful for prescribing contact lenses, finding corneal lesions, and is now an indispensable device in refractive surgery.

FIG. 2 shows a typical cornea shape measuring apparatus using the assisting tool of the present invention. On the optical axis 10 of the apparatus, the eye 1 to be inspected, the ring slit group 4, and the light source 3 for illuminating the ring.
A ring generator 2 (hereinafter referred to as a cone) having a built-in
The objective lens 5 guides the reflected light from the cornea of the ring to the flat light receiving element 6, the processing analysis system 7 for processing the signal from the light receiving element, and the monitor 8 for displaying the result.

FIG. 3 shows a state in which the ring light group is imaged on the cornea and a state in which it is imaged on the light receiving element. After this pattern is calculated by the processing system, the shape distribution is displayed in different colors on the monitor and used for inspection and diagnosis.

[0005]

One of the purposes of the corneal shape measuring device is to prescribe a contact lens (hereinafter referred to as CL), and the corneal shape information / refractive power information calculated by the device is used. The role below is to select the optimum CL. However, the corneal shape measuring device is only intended to measure the refractive power distribution of the human eye, and at the same time cannot measure the refractive power distribution of the contact lens or the like. An object of the present invention is to measure the refractive power distribution of CL using a cornea shape measuring device.

[0006]

As means for solving the problems, there is provided a CL refractive power measurement auxiliary tool added to a corneal shape measuring apparatus. This auxiliary tool has a CL holding part on the end face, and internally has a multiple ring slit for selecting a light beam for repeating alternately transmitting / blocking light for measurement, and a light source part for illuminating the multiple ring slit. . This auxiliary tool is made such that the multiple ring slit is arranged at a position corresponding to the cornea setting of the cornea measuring device, that is, at a position conjugate with the light receiving element of the corneal shape measuring device.

[0007]

The multi-point slit in the auxiliary tool is illuminated by the illumination light source and enters the CL to be inspected. This light beam is refracted by CL and forms an image on the flat light receiving element of the corneal shape measuring device through the device objective lens. By analyzing the change of the multiple ring pattern obtained at this time, the refractive power distribution of CL is calculated and displayed.

[0008]

The details of the present invention will be described with reference to the drawings of the embodiments. FIG. 1 is a cross-sectional view of an auxiliary tool of the present invention.
Reference numeral 11 denotes an auxiliary tool, in which an edge 12 that can be inserted into the inner surface of the cone 12, a recess 13 for CL installation, and a parallel light beam passage 1 are provided.
4, the multiple ring slit plate 15, the condenser lens 16, the light source 17, and the CL 18 to be inspected are arranged on the optical axis 10.
FIG. 4 is a plan view of the multiple ring slit plate 15, and the radius of each transparent ring is Rij. The condensing lens 16 has the purpose of increasing energy efficiency and is described as being present in this embodiment, but the basic function is not impaired without it.

FIG. 4 is a principle diagram for explaining how the auxiliary tool 11 is inserted into the inner surface of the cone 2 of the corneal shape measuring apparatus and the refractive power distribution of CL is measured. The focal length of the objective lens is f, the imaging magnification of the corneal shape device is m, and the test C
The installation position of L is a from the front of the multiplex ring slit, and the image radius when the multiple ring radius Rij is imaged on the light receiving element is rij. Here, i indicates the ring number, and j indicates the measurement dividing point on the ring. Now, if the refractive power distribution of the inspected contact lens is Dij,
Dij is connected by rij and Rij by the following relational expression. rij = Rij / m (1 + Dija) Alternatively, it is expressed as Dij = (mrij / Rij-1) / a.

That is, when there is no CL to be inspected (Dij = 0), rij = Rij / m. It occurs. Rij is a set value, and the amount of change Δrij can be associated with the refractive power distribution Dij by analyzing the data of rij obtained from the light receiving element for each position of the multiplex ring by the processing system.

A power supply is required for the auxiliary tool because it has a light source emitting function, but it may have a built-in dry battery, may be supplied with power from the main body of the apparatus, or may be a separate power supply. Further, although it is limited to the multiple ring slit, a multi-point type slit is not limited to the ring shape as long as its distribution shape can be known in advance.

[0012]

As described above, by adding the auxiliary tool of the present invention, the cornea shape measuring device which has been impossible in the past,
It is possible to measure the refractive power distribution of contact lenses,
It can be a powerful support in the prescription of contact lenses for corneal shape measuring devices. Further, the object is not limited to the contact lens, and by applying this method, it can be used for shape measurement of a spectacle lens or other optical parts.

[Brief description of drawings]

FIG. 1 Example of an auxiliary tool of the present invention

[Fig. 2] Principle diagram of a conventional typical corneal shape measuring apparatus

[Fig. 3] Corneal image and monitor image by a cornea shape measuring device

FIG. 4 is an explanatory view of the principle when an auxiliary tool is attached. 1 Eye to be examined 2 cones 3 Ring illumination light source 4 ring slit 5 Objective lens 6 Planar light receiving element 7 Processing analysis system 8 monitors 10 Device optical axis 11 Auxiliary tool body 12 Insert edge 13 CL installation hollow 14 Luminous flux path 15 Multiple ring slit plate 16 Condensing lens 17 Light source 18 CL to be inspected

Claims (3)

[Claims] 1. A measuring auxiliary tool which is added to a corneal shape measuring apparatus to measure a refractive power distribution of a contact lens. 2. The measuring auxiliary tool according to claim 1, further comprising a contact lens holding portion, an illuminating light source, and a multiple ring slit that alternately transmits light. 3. The measuring aid according to claim 1, wherein the multiple ring slit of the measuring aid is placed at a position corresponding to the cornea of the corneal shape measuring device.