Method and device for synchronous mapping of the total refraction non-homogeneity of the eye and its refractive components

An instrument for measuring aberration refraction of an eye having a visual axis, the instrument comprising:

• a lens system defining an instrument optical axis;
• an alignment device for aligning the visual axis of the eye with the instrument optical axis;
• a light source producing a probing beam projected through the lens system parallel to the instrument optical axis and selectably positionable partially off-set from the instrument optical axis so that said probing beam imates upon the eye parallel to the instrument optical axis at a plurality of impingement locations on the cornea of the eye;
• a first photodetector for measuring the position of probing beam light scattered back from the retina of the eye to measure aberration refraction of the eye at plurality of locations corresponding to each of said plurality of impingement locations;
• a second photodetector for measuring the position of probing light beam reflected from the cornea at said plurality of impingement locations, and a computer for receiving input from said first and second photodetectors to calculate said total refraction aberration and said component thereof due to said cornea.

An aberration refractometer comprising:

• a) an optical beam input channel which generates parallel light rays along an optical axis at spatially defined points onto an eye of a patient, either simultaneously or sequentially, including at least one light source and at least one lens;
• b) an eye alignment verification channel for confirming alignment of the visual axis of the eye as the patient maintains fixation with the optical axis of the input channel;
• c) a fixation target channel including at least one visual target which can be adjusted manually or in an automatic fashion to simulate different focal distances and which is in optical communication with the eye;
• d) a retinal spot position-detecting channel in optical communication with the eye including at least one first photodetector for recording at least one characteristic of a first portion of input channel light from at least one of said spatially defined points and scattered back from the retina of the eye;
• and
• e) a cornea reflection position detecting channel in optical communication with the eye including at least one second photodetector for recording at least one characteristic of a second portion of input channel light from said at least one of said spatially defined points and reflected back from said cornea.

A method for synchronous mapping of the total refraction non-homogeneity of the eye and selected refractive components of the total refraction non-homogeneity, said method comprising steps of:

• a) directing a measuring beam of light into said eye, the cross-section of beam being narrower than the entrance aperture of said eye, said beam being centered and its axis coinciding with the visual axis of said eye, said beam having a first portion thereof passing through an anterior surface of said eye to impinge upon the cornea of said eye, as well as having a second portion thereof reflecting from the corneal surface;
• b) changing the position of a measuring point of beam entrance into said eye keeping said beam parallel to said visual axis;
• c) measuring an offset between the location on the retina at which said beam impinges on the retina at the central position of said beam and the changed position of said measuring point;
• d) determining the total refractive characteristic of said eye from the measured offset in step 22(c);
• e) determining the angle of reflection of said second portion of said measurable beam reflected from said cornea;
• f) determining the partial refractive characteristic, caused by said cornea, from the determined angle of reflection in step 22(e);
• g) comparing, in each measuring point, the total refractive characteristic determined in step 22(d) with the partial refractive characteristic determined in step 22(c)by means of subtraction of said partial characteristic from said total refractive characteristic;
• h) storing refractive characteristics determined in steps 22(d), 22(f) and 22(g) for each measuring point;
• i) transforming the discrete sets of said refractive characteristics into continuous surfaces by means of approximation;
• and
• j) presenting said surfaces as color coded charts on the screen of a display or in any other way of presentation of the three-dimensional information.

A device for synchronous mapping of the total refraction non-homogeneity of the eye and its refractive components comprising:

• a) means for providing a narrow beam of light to be directed into said eye;
• b) means for shifting said beam over the entrance aperture of said eye in parallel to itself and positioning said beam in a measuring point;
• c) means for detecting the light back-scattered from the retina of said eye;
• d) means for measuring an offset between the location on the retina at which said beam impinges on said retina for the first position when the beam's axis coincides with the visual axis of said eye and for the second position when the beam is displaced to said measuring point;
• e) means for calculating the total refractive characteristic of said eye in said measuring point from the measured offset by means of 26(d);
• f) a semitransparent light-scattering screen inserted in outer zone of said entrance aperture;
• g) means for detecting the light reflected from the cornea of said eye and projected on said semitransparent light-scattering screen;
• h) means for measuring the coordinates of the location of said beam reflected from said cornea in said measuring point and projected on said screen;
• i) means for calculating the partial refraction characteristic of said eye in said measuring point, caused by said cornea, from the coordinates measured by means of 26(h);
• j) means for calculating the difference between the values of said total refractive characteristic calculated by means of 26(d) and the value of said partial refractive characteristic caused by said cornea and calculated by means of 26(i);
• k) means for storing refractive characteristics calculated by means of 26(d), 26(i), and 26(j) for each measuring point;
• l) means for transforming the discrete sets of said refractive characteristics into continues three-dimensional distributions of said refractive characteristics;
• and
• m) means for displaying said three-dimensional distributions of said refractive characteristics.

A device for measuring aberration refraction of both of a patient's eyes, comprising:

• a polarized light source producing a probing beam along paths of a patient's eyes;
• a telescopic system of lenses having an entrance pupil and an exit pupil;
• a two-coordinate deflector consisting of two single-coordinate deflectors separated by a zone;
• a deflection control unit;
• an aperture stop;
• a field stop;
• a collimating lens;
• a first position-sensitive photodetector with an objective lens operatively positioned for receiving non-polarized light reflected from the retina of both eyes, one eye at a time, a second position-sensitive photodetector for simultaneously and selectively receiving polarized light reflected from the cornea of both eyes, one eye at a time, coordinated to receive polarized light from the cornea of the same eye as the non-polarized light is received from the retina;
• and a data processing and display unit including a computer coupled to said first and second photodetectors for calculating total eye refraction aberration and the component caused by cornea aberration separately and substantially simultaneously for both of the patient's eyes.