Apparatus for use in the measurement of macular pigment optical density and/or lens optical density of an eye
Inventors
Assignees
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Publication Number
US-10456028-B2
Publication Date
2019-10-29
Expiration Date
Abstract
An apparatus for use in the measurement of the optical density of macular pigment in the human eye, and an apparatus for the use in measuring the lens optical density of a human eye. The apparatus is particularly applicable to flicker photometers, which are used to measure the macular pigment in the human eye.
Core Innovation
The invention provides an apparatus for use in the measurement of macular pigment optical density in an eye under examination. The apparatus uses illumination means in which a blue light source and a green light source alternately illuminate an area constituted by a light diffusing surface, and the light diffusing surface comprises an integrating sphere for illuminating an area with light. The apparatus includes a photodetector for measuring the intensity of light in the sphere.
The apparatus further includes intensity adjustment means that adjust the intensity of one color relative to the other until any flicker in the stimulus perceived by the eye is minimized or removed. Measurement means determine the intensity of the one color at which the minimizing or removal of flicker occurs, so that the blue and green intensities are related to the perceived flicker condition.
Size selection means enable selection of a small stimulus size in which all or most of the stimulus falls on the macula, or a large stimulus size in which the stimulus extends to a portion of the retina having substantially no macular pigment. Calibration means comprise adjusting the intensity using a calibrated photodiode prior to measurement of macular pigment optical density.
Claims Coverage
The independent claim covers an apparatus that measures macular pigment optical density by alternating blue and green illumination through a light diffusing integrating sphere, controlling relative color intensities to minimize or remove perceived flicker, selecting small versus large stimulus sizes tied to macula coverage versus non-macular retinal coverage, and calibrating using a calibrated photodiode prior to measurement. Four inventive features are identified.
Alternating blue and green illumination through an integrating sphere
The illumination means comprises a blue light source and a green light source which alternately illuminate an area constituted by a light diffusing surface wherein the light diffusing surface comprises an integrating sphere for illuminating an area with light, to provide a stimulus for said eye, wherein the apparatus includes a photodetector for measuring the intensity of light in the sphere.
Flicker minimization via relative intensity adjustment of the two colors
Intensity adjustment means for adjusting the intensity of light of one of the colors relative to light of another of the colors, until any flicker in the stimulus perceived by the eye is minimized or removed; measurement means for determining the intensity of light of said one of the colors at which said minimizing or removal of flicker occurs.
Small versus large stimulus size selection based on macular coverage
Size selection means for enabling the size of the stimulus to be selected from either a small size, in which all or most of the stimulus falls on the macula of the eye, or a large size, in which the stimulus extends to a portion of the retina of the eye at which there is substantially no macular pigment.
Calibrated photodiode intensity adjustment prior to MPOD measurement
Calibration means wherein the calibration means comprises adjusting the intensity using a calibrated photodiode prior to measurement of macular pigment optical density.
Overall claim coverage centers on a flicker-controlled, alternating blue/green integrating-sphere apparatus with small and large stimulus selection distinguishing macular from substantially non-macular retinal regions, combined with photodiode-based calibration prior to measuring macular pigment optical density.
Stated Advantages
Minimizing or removing flicker in the stimulus perceived by the eye during measurement.
Documented Applications
Measurement of macular pigment optical density in an eye under examination using a flicker-photometer apparatus.
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