Tear film measurement

An apparatus for measuring the thickness of the lipid layer on the surface of an eye after distribution of the lipid layer subsequent to blinking comprising:

• an illuminator that directs light to the lipid layer of a patient's eye, the illuminator being a broad spectrum light source in the visible region and being a lambertian emitter such that the light source is specularly reflected from the lipid layer and undergoes constructive and destructive interference in the lipid layer and wherein the total light emitted from the surface of the illuminator is less that 10 μW/mm2, wherein said illuminator further includes a plurality of spaced apart light emitting diodes adapted to emit light in the visible region;
• an imaging device for observing the specularly reflected light such that the interference patterns on the tear film lipid layer are observable;
• and
• a diffuser for diffusing the light emitted by the respective light emitting diodes positioned between said light emitting diodes and the surface of the eye, wherein the diffuser is arcuate such that the light rays emitted from the lambertian emitter strike the surface of the eye such that Snell's law is satisfied with respect to the acceptance angle of said imaging device so as to produce an observable area of interference on the eye.

An apparatus for measuring the thickness of the lipid layer on the surface of a patient's eye after distribution of the lipid layer subsequent to blinking comprising:

• an illuminator that directs light to the lipid layer of a patient's eye, the illuminator comprising a broad spectrum light source in the visible region and being a uniform illumination lambertian emitter such that the light source is specularly reflected from the lipid layer and undergoes constructive and destructive interference in the lipid layer wherein said illuminator illuminates the patient's face, but wherein only an area below the pupil satisfies Snell's law, wherein said illuminator further includes a plurality of spaced apart light emitting diodes adapted to emit light in the visible region;
• an imaging device for observing the specularly reflected light such that the interference patterns on the tear film lipid layer are observable in the area below the pupil with respect to the acceptance angle of said imaging device so as to produce an observable area of interference on the eye below the pupil;
• and
• a diffuser for diffusing the light emitted by the respective light emitting diodes positioned between said light emitting diodes and the surface of the eye, wherein the diffuser is arcuate such that the light rays emitted from the lambertian emitter strike the surface of the eye such that Snell's law is satisfied with respect to the acceptance angle of said imaging device so as to produce an observable area of interference on the eye.

An apparatus for measuring the thickness of the lipid layer on the surface of an eye after distribution of the lipid layer subsequent to blinking comprising:

• an illuminator that directs light to the lipid layer of a patient's eye, the illuminator being a broad spectrum light source in the visible region and being a uniform illumination lambertian emitter such that the light source is specularly reflected from the lipid layer and undergoes constructive and destructive interference in the lipid layer and wherein the light emitted from the illuminator travels directly to the lipid layer without reflection and strikes the lipid layer, wherein said illuminator further includes a plurality of spaced apart light emitting diodes adapted to emit light in the visible region;
• an imaging device for collecting the specularly reflected light and for focusing the specularly reflected light such that the interference patterns on the tear film lipid layer are observable;
• and
• a diffuser for diffusing the light emitted by the respective light emitting diodes positioned between said light emitting diodes and the surface of the eye, wherein the diffuser is arcuate such that the light rays emitted from the lambertian emitter strike the surface of the eye such that Snell's law is satisfied with respect to the acceptance angle of said imaging device so as to produce an observable area of interference on the eye.