Abstract: An ophthalmological diagnosis method is provided in which a laser beam is projected at a region of the eye fundus to produce a laser speckle pattern formed by light scattered from tissues of the eye fundus. Movement of the speckle pattern is detected to produce a speckle signal which is photon-counted as photoelectric pulses per unit sampling time. The counted data are stored in a computer memory as time series data over one measurement time. The stored data are then processed to provide a correlation function using different delay times and are also divided per unit time. For the divided data, the correlation function or variance is calculated for each unit time. Such an arrangement makes it possible to accomplish accurate evaluation even when there is movement of the eye fundus and thus ensures that measurement data are fully utilized to provide accurate ophthalmological diagnosis.

Abstract: An ophthalmological diagnosis method and an apparatus for carrying out the method is disclosed. According to the invention, one of a plurality of laser beams is selected depending upon the tissue layers in the eye fundus to be diagnosed, and is projected thereon. Light is scattered by blood cells within a tissue layer of the eye fundus that depends upon the wavelength of the selected laser beam. The scattered light is received and photoelectrically converted into an electrical signal, which is then evaluated to measure the blood flow state within the tissue layer of the eye fundus.

Abstract: An ophthalmological diagnosis apparatus is provided in which a laser beam is projected at a region of the eye fundus to produce a laser speckle pattern formed by light scattered from tissues of the eye fundus. Movement of the speckle pattern is detected to produce a speckle signal which is photon-counted as photoelectric pulses per unit sampling time. A rate of fluctation of correlation function data is evaluated, on the basis of which the radius of the detecting aperture is determined. This makes it possible to sample accurate data with good reproducibility.

Abstract: Disclosed is an ophthalomological diagnosis method and apparatus in which a blood vessel in the eye fundus is illuminated with a laser beam of a predetermined beam spot whose diameter is substantially equal to or smaller than that of the blood vessel in order to produce diffraction-plane speckles which are formed at a Fourier-transform plane by light scattered from the eye fundus. Boiling motion of the diffraction-plane speckle pattern thus produced is then detected through a multiple detection aperture pattern which is disposed at the Fourier-transform plane and comprised of a plurality of small apertures to obtain a speckle signal which is evaluated to measure velocity of the blood flowing through the blood vessel concerned. This arrangement makes it possible to detect the speckle signal without any effect of averaging the signal with an increase in intensity detected, thus enabling advantageous and successful measurement of the blood flow state in the eye fundus.

Abstract: Disclosed is an ophthalomological diagnosis method and apparatus in which a blood vessel in the eye fundus is illuminated with a laser beam of a predetermined beam spot whose diameter is substantially equal to or smaller than that of the blood vessel in order to produce a speckle pattern which is produced by light scattered from the eye fundus. Boiling motion of the speckle pattern thus produced is then detected through a multiple detection aperture pattern comprised of a plurality of small apertures as fluctuation in a total amount of light passing through the small apertures to obtain a speckle signal which is evaluated to measure velocity of the blood flowing through the blood vessel concerned. This arrangement makes it possible to detect the speckle signal without any averaging process with an increase in intensity detected, thus enabling advantageous and successful measurement of the blood flow state in the eye fundus.

Abstract: An ophthalmic diagnostic method and apparatus measures the distance between the corneal surface and the fundus of an eye being examined by projecting a beam of coherent light at the eye and varying the wavelength of the coherent light while observing differences between the optical paths of two light waves reflected by the cornea and the eye fundus. The differences are based on the length of the optical axis of the eye and observed as a phase difference between the two light waves. The length of the optical axis of the eye being examined can be measured from the amount of change in the measured phase difference corresponding to the variation in wavelength, enabling the length of the optical axis of the eye to be measured without mechanical control.

Abstract: An ophthalmological diagnosis apparatus is disclosed that has an optical spatial frequency filter, a double diffraction optical system whereby an eye fundus image formed at a first image plane that is conjugate with the eye fundus is again formed at a second image plane, a magnifying optical system for expanding the eye fundus image formed on the second image plane, and a detecting aperture for detecting movement of laser speckles formed at the image plane of magnifying optical system as fluctuations in the intensity of the speckle light. Advantages of the apparatus include the ease with which a single, specific blood vessel can be selected; unnecessary light components can be filtered out, improving the S/N ratio of the speckle light detection; the optical system does not need to be high-precision; good operability; and measurement results that are much more reliable and reproducible.

Abstract: An ophthalmological diagnosis method and an apparatus for carrying out the method are disclosed. According to the method a region of the eye, e.g. the fundus, is illuminated with a laser beam of prescribed diameter to produce a laser speckle pattern formed by light scattered by blood cells within the tissue of the eye, movement of the laser speckle pattern is detected as fluctuation in the light intensity of the speckles at an observation point and a speckle signal corresponding to the detected movement is produced, the power spectrum distribution of the speckle signal is obtained, the power spectrum distribution configuration is evaluated from the results of a calculation of the mean frequency thereof and the blood flow state in the tissue is determined from the results of the evaluation.