Why do albino rats have red eyes? - briefly
Albino rats lack melanin in the iris, so the underlying blood vessels are visible, giving the eyes a reddish hue. The absence of pigment is caused by a genetic mutation that prevents normal pigment synthesis.
Why do albino rats have red eyes? - in detail
Albino rats lack functional melanin pigment due to mutations in the tyrosinase gene. Melanin normally absorbs light and gives color to the iris, retina, and surrounding tissues. In its absence, the thin layers of the eye become translucent, allowing blood vessels in the choroid and retinal capillaries to be seen through the sclera. The visible blood imparts a reddish hue to the ocular region.
Key factors contributing to the reddish appearance:
- Genetic mutation – loss‑of‑function variants in the enzyme required for melanin synthesis.
- Pigment deficiency – complete absence of eumelanin and pheomelanin in the iris and retinal pigment epithelium.
- Increased light transmission – reduced light‑absorbing capacity lets incident light reach underlying vasculature.
- Blood vessel visibility – choroidal and retinal vessels reflect light, producing the characteristic red coloration.
The same mechanism explains the pinkish skin and fur of albino rodents, where underlying capillaries become visible through unpigmented tissue. Consequently, the red eyes are a direct optical consequence of melanin deficiency combined with the anatomical arrangement of ocular blood vessels.