Investigation of Age-Related Changes on Eye by Using Histochemical and Ultrastructural Methods

Objective: The purpose of this study is to evaluate structural changes in the cornea and retina of rats during the critical periods of development in parallel with aging from birth onwards through the histochemical methods and to make comparative examination at the ultrastructural level. Methods: In our study the changes in the cornea and retina in parallel with aging were examined through PAS-Alsian blue staining method by taking the eyes of rats on the 1st and 22nd day, and in the 10th week and 22nd month. Measurements made were evaluated statistically. Also the ultrastructure of the cornea was illustrated at electron microscopy level. Results: In the histochemical stainings, an increase was determined in the descement membrane, stroma, epithelial thickness and general cornea thickness in parallel with aging. An opening in the cornea stroma and fluctuant extention in the collagen fibres in parallel with aging were distinguished. In the examinations made in the retina, evidence of nerve fibre layers as from the 22nd-day group was striking. An intracytoplasmic edema was observed in some areas in the 10-week group. In the 22-month group it was clear that ganglion cells became flat and nerve fibre layer thickened. When the cornea was examined at ultrastructural level, it was determined that the cornea epithelium, descement membrane and stroma gained the structure of the 10-week adult, there were degenerative changes in all layers in the 22-month group. According the statistical analysis, increased thickness in Descement membrane, stroma and epithelial layer were observed in the cornea. Conclusion: In the examinations made at histochemical and ultrastructural level, especially during the critical development periods, it was determined that the stuctures related to the eye developed but there were degenerative changes in these structures in parallel with aging. The most distinct degeneration was determined in the cornea.