Figure 4.

H&E staining of representative retinal tissue sections from control rats (A) and from rats exposed to white LED for 28 days (B) or to blue LED (C), white LED (D), white CFL (E), or yellow CFL (F) for 9 days. (G) ONL thickness (mean ± SD) measured in retinas (n = 3 controls, n = 8 for each light-exposure group at either time point). Abbreviations: GCL, ganglion cell layer; INL, inner nuclear layer; IS, inner segment; ONL, outer nuclear layer; OS, outer segment; RPE, retinal pigment epithelium (usually next to the OS layer but is detached and cannot be found within this scope). (A) Control tissue shows normal retinal layers. (B) After exposure to white LED for 28 days, retinal injury included pyknotic photo­receptor nuclei (arrow), swelling of the inner segment (arrow head), a dis­organized outer segment with no visable RPE [asterisk (*)], and INL degeneration. Photoreceptors were not present in retinals from rats exposed to blue LED (C) or white LED (D) light; the white CFL group (E) exhibited distortion of the OS and ONL, and the yellow CFL group (F) exhibited less movement in each layer. In (A–F), bar = 50 μm. (G) ONL thickness was significantly decreased in the LED groups at days 9 and 28, whereas the ONL thickness in white and yellow CFL groups was not significantly altered at day 9. **p < 0.01, compared with the control group by ANOVA and the Tukey post hoc test.