Purpose: To investigate whether the advanced glycation end-products (AGEs) pentosidine, N( epsilon )-(carboxymethyl)lysine (CML), and imidazolone are present in the aqueous of cataract patients and how AGE levels correlate to cataract type or the diabetic condition of the patient.
Setting: Departments of Ophthalmology and Internal Medicine, University of Jena, Jena, Germany.
Methods: Aqueous and serum samples from 77 cataractous patients (33 nondiabetics, 44 diabetics; 14 with dense posterior, 63 with nuclear cataracts) were investigated. The mean age of the patients was 69 years +/- 14 (SD). The aqueous protein concentration was examined using a laser flare-cell meter. In the samples, pentosidine was measured by high-performance liquid chromatography and CML using a competitive enzyme-linked immunosorbent assay. Western blot analysis was used to detect imidazolone, pentosidine, and CML in the aqueous.
Results: The aqueous samples contained CML, pentosidine, or imidazolone. These AGEs occurred mainly bound to albumin. Significant correlations existed between serum pentosidine and aqueous CML and flare levels as well as between serum and aqueous CML. Patients with nuclear cataract had insignificantly higher pentosidine and CML levels than patients with posterior cataract, whereas the flare was significantly higher. No significant differences were found between the aqueous AGE levels in nondiabetic and diabetic patients.
Conclusions: The aqueous of cataractous eyes contained the AGEs CML, pentosidine, and imidazolone. All 3 AGEs occurred mainly albumin-bound, providing evidence they may originate from the blood. Further investigation is needed to determine the relevance of aqueous AGEs in cataractogenesis.