1. A method for immunologically determining a keratan sulfate level, comprising the steps of:(a): contacting a biological sample, simultaneously or sequentially, with a solid phase on which an anti-keratan sulfate monoclonal antibody is immobilized, and with a labeled anti-keratan sulfate monoclonal antibody, to thereby form, on the solid phase, an immune complex of the anti-keratan sulfate antibodies and the keratan sulfate contained in the biological sample;
(b): detecting a signal produced by the labeled antibody in said immune complex; and
(c): determining the level of keratan sulfate in said biological sample based on the intensity of said detected signal,
wherein said immobilized antibody is BCD-4 and wherein said labeled antibody is labeled MK-172,
wherein the biological sample is derived from a rabbit, guinea pig, rat, mouse or human.