d-β-Aspartic acid residues, which are biologically uncommon, posses been reported to accumulate in indefinite proteins of the living protest with age. In the immediate study, d-β-aspartic acid-containing proteins were initiate to be localised in pingueculae, which body one of the most prominent age-related ocular changes.

Surgical specimens of conjunctivae with or without pingueculae were obtained from eight patients. Immunohistochemical localisation of d-β-aspartic acid-containing proteins was performed using a polyclonal antibody against d-β-aspartic acid-containing peptides.

Strong immunoreactivity to d-β-aspartic acid-containing peptides was detected in the subepithelial amorphous materials of all surgical specimens with pingueculae. In contrast, no immunoreactivity to d-β-aspartic acid-containing peptides was detected in the specimens without pingueculae.

Pingueculae are deriving to be aggregates of proteins that comprehend d-β-aspartic acid residues. It is established that the conversion of l- to d-aspartyl residues is quick by ultraviolet irradiation. In addition, d-β-aspartic acid-containing proteins, in general, tend to aggregate with everyone other and accumulate in the tissues. These material show that ultraviolet irradiation-induced racemisation of aspartic acid is closely related to the step of pingueculae.