Why do rats' eyes become red? - briefly
Rats exhibit red eyes because the lack of pigment in the scleral membrane permits underlying blood vessels to be visible, a trait especially pronounced in albino individuals. This coloration is a normal physiological feature, not an indication of pathology.
Why do rats' eyes become red? - in detail
Rats display a reddish appearance of the ocular surface primarily because the iris lacks melanin, allowing the dense network of choroidal and conjunctival blood vessels to be seen through the thin sclera. In albino strains, the absence of pigment accentuates this effect, making the eyes appear bright red even under normal lighting conditions.
Pathological conditions can also produce or intensify ocular redness:
- Conjunctivitis or keratitis: inflammation of the conjunctiva or cornea leads to hyperemia, swelling, and discharge, resulting in a pronounced red hue.
- Uveitis: inflammation of the uveal tract increases vascular permeability, causing visible blood vessel dilation and potential hemorrhage.
- Trauma: scratches or blunt injury disrupt capillary integrity, producing localized bleeding and swelling.
- Vitamin A deficiency: impairs epithelial maintenance, leading to xerosis, ulceration, and secondary infection, all of which generate redness.
- Systemic anemia or hypoxia: reduced oxygen-carrying capacity induces compensatory vasodilation in ocular tissues, making blood vessels more conspicuous.
Environmental factors influence the perception of eye color as well. Bright illumination enhances the contrast between blood vessels and the transparent ocular media, while low light may mask the red appearance. Genetic mutations affecting pigment synthesis, such as those in the tyrosinase gene, directly determine the degree of iris coloration and, consequently, the visibility of underlying vasculature.
Diagnostic evaluation should include:
- Visual inspection for discharge, swelling, or corneal opacity.
- Slit‑lamp examination to assess conjunctival hyperemia, corneal lesions, and intra‑ocular pressure.
- Laboratory analysis of blood parameters to detect systemic anemia or nutritional deficiencies.
- Microbial culture when infectious agents are suspected.
Treatment protocols depend on the underlying cause. Antimicrobial eye drops address bacterial conjunctivitis; anti‑inflammatory agents mitigate uveitis; vitamin A supplementation corrects nutritional deficits; and protective housing reduces exposure to irritants and trauma. Regular health monitoring in laboratory and pet rat populations helps detect early signs of ocular pathology, preventing progression to severe visual impairment.