Abstract: A method and apparatus for measuring an apparent depth of a section of an animal body are disclosed. Light is focused concurrently to an extended focal region comprising a plurality or continuum of measurement locations. Light reflected by a refractive index interface coincident with one of the plurality of measurement locations is detected. Detected light signals are generated from light reflected from first and second interfaces respectively defining the section under investigation, so that the apparent positions of the interfaces may be derived. A confocal arrangement and an axicon element may be employed. Preferably, the section is the aqueous humor of an eye. From changes in its refractive index corresponding changes in glucose concentration in the aqueous humor and, in turn, in the bloodstream of a patient may be derived, offering a non-invasive monitoring means for diabetic patients. Other compounds and structures of the body may alternatively be investigated.

Abstract: A method and apparatus for measuring an apparent depth (1) of a section of an eye (30) are disclosed. Light is focused to a measurement location (15) proximate or within the eye. The measurement location is scanned through the section and upon passing through first and second refractive index interfaces defining the section, a respective reflected light signal is detected, from which apparent positions of the first and second interfaces may be derived. Preferably, a confocal scanning arrangement is employed. Preferably, the section is the aqueous humor (34) of the eye (30). From changes in its refractive index (n) corresponding changes in glucose concentration in the aqueous humor and, in turn, in the bloodstream of a patient may be derived, offering a non-invasive monitoring means for diabetic patients. The apparatus may be a hand-held device, employing microelectromechanical systems.