An eye fundus camera comprising a photographing system for taking a picture of an eye fundus, a fundus illumination system for alternatively providing infrared light and visible light to illuminate the fundus, a viewer connected to the photographing system for the observation of the fundus, an image pick-up part containing therein an image pick-up tube and connected to the photographing system through a stationary wavelength dividing mirror which reflects infrared light and transmits visible light, and a light intercepting screen plate retractably disposed in the optical light path between the wavelength dividing mirror and the image pick-up tube.

Eye fundus camera

An autorefractor utilizes two light emitters and corresponding optics to project images onto the fundus, with the focus of these images bracketing the gross sphere of an emmetrope. A single detector generates a signal corresponding to each emitter. In an alternate embodiment, a single emitter and two detectors having foci bracketing the gross sphere of an emmetrope generate a signal corresponding to each detector. The light reflected from the fundus is detected and the differential intensities of two signals are used to determine departure in refraction from 0 diopter sphere. Multi-segmented or CCD detectors may be used to measure cylinder/axis, determine length and direction of gaze (in combination with a Purkinje image sensor) and to generate and analyze retinal images.

Method for evaluation of length of focus of the eye

An autorefractor utilizes two light emitters (150, 160) and corresponding optics to project images onto the fundus, with the focus of these images bracketing the gross sphere of an emmetrope A single detector (180) generates a signal corresponding to each emitter In an alternate embodiment, a single emitter (406) and two detectors (402, 404) having foci bracketing the gross sphere of an emmetrope generate a signal corresponding to each detector The light reflected from the fundus is detected and the differential intensities of two signals are used to determine departure in refraction from O diopter sphere Multi-segmented or CCD detectors may be used to measure cylinder/axis, determine length and direction of gaze (in combination with a Purkinje image sensor) and to generate and analyze retinal images

Device and method for evaluation of refraction of the eye

An ocular refracting power measuring system includes a projector system (1) for projecting the image of a light source (4) on the eyeground (7) of an eye to be tested and a light receiving system (2) for condensing the light beam from the eyeground onto a light receiving element (9) disposed at a position substantially conjugate with the pupil (6) of the eye to be tested, whereby the ocular refracting power of the eye to be tested can be measured based on the distribution of light amount on the light receiving element and variations of the distribution of light amount due to the changed amount of light in the light source.

Ocular refracting power measuring system

A method and apparatus for measuring refractive properties of a refractive optical system by fitting measurement data points to a derived function are disclosed. In a preferred embodiment relating to an automatic objective optometer, each data point represents a peak signal amplitude extracted from a scan of a plurality of pixels on an area detector array receiving light from the illuminated refractive optical system at a particular optometer position. The derived function describes a relationship between the peak pixel signal and optometer position based on changing focusing conditions of light at the detector array, which correspond to focusing conditions at an image plane of the refractive optical system under a confocal arrangement. A first derived function is applied for fast and slow sphere optometer sweeps through broad and refined ranges and includes a pair of poles at first and second astigmatic focal points to give the magnitude of sphere and cylinder powers of the eye, and a second derived function is applied for a cylinder sweep varying the axis of a non-zero cylinder component introduced to the illuminating light and includes a single pole for giving the cylinder axis.

Automatic optometer evaluation method using data over a wide range of focusing positions

A method of measuring the refractive error of the eye uses a digital computer and directs a variable focus, variable orientation light pattern on the eye, detects the light pattern reflected from the retina to produce an analog signal as a function of the focus of the reflected pattern, and converts the analog signal to a digital signal stream fed to the computer The computer varies the focus of the pattern and the orientation of the pattern and selects and stores results from the digital signal stream It then fits a sine wave to the selected signal results, and calculates the refractive error from the sine wave

Obinson Bruce R

Papers

Apparatus and method of measuring the refractive error of an eye