An ophthalmic diagnostic system, method and medium for determining the lens crystallin index includes: focused delivery of a coherent source to a measurement volume in the interior of the lens； a second focused delivery of a coherent source is combined with the first source for precise location of the measurement volume； a third coherent optical path collects the backward scattered signal from the random movement of crystallins within the lens； a power splitter obtains two copies of the backward scattered signal； cross/auto correlation of the backward scattered signal is performed and modulated over a time scale； and various time scale signatures are processed obtain the lens crystalline index. The system, method, and medium are self-correcting and account for abnormal counter values.
