OPHTHALMIC DISEASE DETECTION APPARATUS

Abstract: An apparatus for detecting ophthalmic diseases such as an inflammation in the camera oculi (11a) of a patient's eye which includes means for focussing a laser beam (1) at a selected spot in the camera oculi of an eye (11), and according to which the light scattered from the eye is photoelectrically detected and converted into an electrical signal which is subsequently used to determine the protein concentration essential to ophthalmic disease detection in the camera oculi of the patient's eye.

Description: This invention relates to apparatus for detecting ophthalmic diseases in the camera oculi of a patient's eye, and more particularly to apparatus for detecting ophthalmic diseases in which laser light is radiated via an optical system towards a spot in the camera oculi of the patient's eye and the laser light scattered therefrom is analysed to measure the protein concentration for ophthalmic disease detection in the camera oculi. The camera oculi is comprised of the camera oculi anterior (anterior chamber) and the camera oculi posterior (posterior chamber). The camera oculi anterior is defined by a space surrounded by the rear surface of the cornea, a part of ciliary body, the iris, and the front surface of the crystalline lens, while the camera oculi posterior is defined by a space surrounded by the rear surface of the iris, inner surface of the ciliary body, and front surface of the crystalline lens. The camera oculi is filled with transparent aqueous humor, which has chemical and physical characteristics different from lymphatic liquid and has a close relation with the metabolism of the cornea and crystalline lens. The aqueous humor contains proteins which, when it becomes inflamed, increase causing the camera oculi to be turbid. In this respect, the measurement of protein concentration in the camera oculi of the patient's eye is of great importance in determining whether the camera oculi is inflamed, that is, whether a blood-aqueous barrier exists or not. To measure the protein concentration in the camera oculi, a slit lamp microscope is very often used to determine the turbidity by grading using the naked eye. This is, however, disadvantageous because the judgment depends upon the person who performs the measurement. A more accurate apparatus is disclosed in US-A-4,350,163, which describes apparatus for measuring contaminants in the aqueous humor without rupturing the examined eye. On the other hand, a photographic measuring method has been developed to make a quantitative measurement of the protein concentration. This method is, however, too complicated to analyse, thus very difficult to apply in a clinical examination. The present invention therefore seeks to provide apparatus for detecting ophthalmic diseases which is capable of easily and precisely measuring the protein concentration in the camera oculi of a patient's eye. According to the present invention, there is provided apparatus for detecting ophthalmic disease in the camera oculi of a patient's eye comprising a laser source for producing a laser beam; focussing means for focussing the laser beam at a selected spot in the camera oculi of the patient's eye; photoelectric converting means for receiving light scattered from the camera oculi and converting it into an electric signal; a counter for determining the intensity of said scattered light by counting pulses of an electrical signal received from the said photoelectric converting means; and evaluating means for evaluating the output signal of said counter to derive therefrom the protein concentration due to the inflammation in the camera oculi of said eye, characterised in that a swingable mirror driven by a mirror driver is provided in the path of the laser beam, and the evaluating means is connected to the mirror driver so as to displace the laser beam transversely with respect to its direction of projection and thereby measure a greater area in the camera oculi of the patient's eye. This arrangement makes it possible to calculate the protein concentration in the camera oculi of the patient's eye quantitatively on the basis of the measurement of the scattered laser beam from the camera oculi, thus providing powerful and effective means for the detection of ophthalmic disease, particularly for the detection of inflammation in the camera oculi of the eye. One embodiment of the present invention will now be more particularly described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a schematic perspective view showing the whole appearance of the apparatus of the present invention; and Figure 2 is a block diagram showing the optical arrangement of the apparatus. Figure 1 and Figure 2 show the general arrangement of an ophthalmic disease detection apparatus according to the present invention. In the drawings, reference numeral 1 indicates a helium-neon or argon type laser light source. The laser light source 1 is mounted on a base 2. The light emitted from the laser light source 1 is passed through a laser filter 3, a prism 4, a swingable mirror 5, a prism 6, a lens 7, a beam splitter 8, a lens 9, and a prism 10, and imaged so as to converge at one spot in a camera oculi 11a of a patient's eye 11. A slit light source 12 is located along the laser light path, and arranged so that the light emitted from this slit light source 12 passes through a slit light shutter 13, a slit 14, and via the beam splitter 8, the lens 9 and the prism 10, to be imaged as a slit image on the camera oculi 11a. Because the light emitted from the above­ mentioned laser light source 1 is imaged as a spot of light, the slit light image is intended to illuminate the periphery of the light spot and thereby make the verification of the location of the spot image easy. Adjustment as well as switching of the length of the slit along the lengthwise dimension of the slit 14 are carried out by means of an adjusting knob 15 and a switching knob 16, respectively. Part of the laser light scattered from the spot being measured in the camera oculi 11a passes through the objective lens 20 of a detector 29, and is then divided by a beam splitter 21, whereupon a portion of the light passes through a lens 22, a prism 23, an optical fibre 24, a lens 25 and a shutter 26, and strikes a photomultiplier 27 which performs the function of a photoelectric converter. Another portion of the scattered light divided by the beam splitter 21 is directed in another direction and passes through a variator lens 30, a prism 31, and a monitoring plate 34. The image may be viewed by an observer 33 through an eyepiece 32. The output signal of the photomultiplier 27, which comprises a series of pulses each generated when the light intensity exceeds a certain threshold, is amplified by an amplifier 28 and then applied to a counter 40 for counting the number of pulses, thus determining the intensity of the scattered light detected by the photomultiplier 27. The counter 40 counts the number of pulses appearing. When the photomultiplier 27 receives scattered light greater in intensity than a predetermined value, the counter 40 produces an output signal, which is then applied to an evaluating device 41 to calculate the protein concentration in the camera oculi 11a. In the present embodiment, an eye fixation lamp 50 comprising a light emitting diode fed by a power supply 51 is disposed in such a position as to enable the patient to fix the gaze of his eye thereto. The colour of the light emitted by the eye fixation lamp 50 is selected so as to differ from the colour of the light emitted by the laser light source 1. As an example, if the light emitted from the laser light source is red, the light emitted by the eye fixation lamp may be green. This eye fixation lamp 50 may be swivelled in the directions indicated by the arrows according to a linkage 52, and hence is adjustable to the optimal position for any given patient. An input device such as, for example, a joy stick 45 equipped with a push-button 46 is provided on the base 2, the manipulating of which effects insertion of the laser filter 3, the slit light shutter 13, and the shutter 26 into the optical system, as well as the extraction of same therefrom. The operation of the apparatus described above will be explained below. Immediately preceding measurement, the light source 12 is turned on, and the slit image of the slit 14 is passed through the beam splitter 8, the prism 10 and the lens 9 and imaged on the camera oculi 11a over an area that covers the spot P to be measured. Next, light from the laser light source 1 is passed through the optical arrangement of same and caused to converge on the spot to be measured. The laser light beam is then scattered from the spot P, whereupon the beam splitter 21 directs a portion of the scattered light in the direction of the observer 33 for observation, and simultaneously directs another portion thereof to the photomultiplier 27 via the optical system comprising the lens 22, the prism 23, and the optical fibre 24. The photomultiplier 27 detects the intensity of the light scattered by the protein particles in the camera oculi 11a of the patient's eye. The counter 40 then counts the intensity of the scattered light, and produces an output signal, which is applied to the evaluating device 41 in which the intensity of scattered light due to the scattering of big scattering members such as cells is subtracted to derive therefrom the protein concentration due to the inflammation in the camera oculi of the patient's eye. It is to be noted that the mirror 5 is constructed to be swingable by a mirror driver 60 connected to the evaluating device 41 so as to be able to scan the laser light and displace the laser spot by displacing the laser beam transversely with respect to its direction of projection. This allows the displacement of the measuring spot to cover a greater area than the stationary spot, thus improving the accuracy in measuring the protein concentration.

Claims: 1. Apparatus for detecting ophthalmic disease in the camera oculi of a patient's eye comprising a laser source (1) for producing a laser beam; focussing means (9, 10) for focussing the laser beam at a selected spot in the camera oculi (11a) of the patient's eye; photoelectric converting means (27) for receiving light scattered from the camera oculi and converting it into an electric signal; a counter (40) for determining the intensity of said scattered light by counting pulses of an electrical signal received from the said photoelectric converting means; and evaluating means (41) for evaluating the output signal of said counter to derive therefrom the protein concentration due to the inflammation in the camera oculi of said eye, characterised in that a swingable mirror (5) driven by a mirror driver (60) is provided in the path of the laser beam, and the evaluating means (41) is connected to the mirror driver (60) so as to displace the laser beam transversely with respect to its direction of projection and thereby measure a greater area in the camera oculi of the patient's eye. 2. Apparatus according to claim 1 characterised in that an eye fixation lamp (50) is provided whose colour is different from that of the laser beam.

Inventors: ICHIHASHI, TADASHI, KAKIZAWA, KOICHIRO
Applicants: KOWA COMPANY, LTD.
Application year: 1986
Main classification: A61B3
IPC codes: A61B3