There is an emerging wide use of nanotechnology in the medical fields. The information regarding distribution and clearance of gold nanoparticles (AuNPs) in the ocular tissue is insufficient. We investigated the cumulative effect of AuNPs on rat lens structure and their effect on the redox state and aquaporin-0 (AQP0) expression. Thirty-six male rats were distributed as follow: control, AuNPs-200 (200 μg/kg/rat for 4-weeks) and AuNPs-500 (500 μg/kg/rat for 4-weeks) groups. Rats were euthanized after 4-weeks, and the eye lenses were investigated for histological studies, transmission and scanning electron microscopic studies, immunohistochemistry for AQP0 and morphometric measures. Lens homogenates were investigated for tumour necrosis factor-alpha (TNF-α) and total reactive oxygen species levels by ELISA and for p-c-SRC by western-blot. AuNPs administration induced morphological and ultrastructural changes in rat lens. Degenerative changes in the lens epithelium, cytoplasmic vacuoles, distorted separated cortical lens fibers and loss of ball-and-socket junctions were observed. A significant reduction of AQP0-immune-staining with a significant elevation of TNF-α, total ROS and p-c-SRC content in rat lens homogenates were detected as compared to the control group. Repetitive spherical 20 nm-sized AuNPs administration, especially at 500 μg/kg/rat, induced structural changes in lens fibers of rats and increased oxidative stress level in the lens tissue.