Age-related changes of iris stromal melanocytes in human eyes.

Age-related changes of the melanocytes in the human iris stroma were studied by electron microscopy. The iris specimens were obtained during cataract surgery of patients aged from 70 to 84 years. The most characteristic age-related changes in the iris stromal melanocytes were formation of melanosome complexes in the cytoplasm. In addition, nuclear bodies were seen within the nucleus. The diameter of the nuclear bodies varied from 0.8 to 2.0 micron and they contained dense osmiophilic granules similar to melanin granules. Lipofuscin granules, which are known as an age-related marker of cardiac muscle cells and neurons, were not observed in the cytoplasm. The clinical significance of these age-related changes in the iris stromal melanocytes remains to be discussed in the future.