To be precise, not all rabbits have red eyes. The eyes of most rabbits are actually brown, black, or gray, depending on their breed and genetics. However, some rabbits do have red eyes, which is usually caused by a lack of melanin in their eyes. This lack of melanin is called "red eye", and therefore, rabbits with red eyes mainly appear in some rabbits with white or light-colored hair.

The main reason why rabbit eyes are red is due to the lack of melanin. Under normal circumstances, the color of the eyes depends on the melanin content in the iris. Eyes with more melanin will be darker, and vice versa. The eyes of some rabbits appear red due to a genetic inheritance or mutation that causes a lack of melanin in the iris. Specifically, the main reasons why rabbit eyes are red are as follows.

Lack of melanin: Rabbit eyes lack melanin because there is not enough melanin in their eyes to block the blood vessels behind the retina. In a normal eye, melanin absorbs light, making the eye appear black or brown. However, if the eye lacks melanin, light passes through the iris and reflects the color of the blood vessel bed behind the retina, causing the eye to appear red. This phenomenon usually occurs in rabbits with white or light-colored coats because these rabbits do not have enough melanin around their eyes to block the color of the vascular beds.

Genetic factors: Rabbits with red eyes are usually caused by genetic factors. Some genetic mutations affect the production or distribution of melanin, causing eyes to appear red. The genetic mutation may have arisen in the rabbit's genome, affecting the production of melanin in the eyes. In this case, the eyes will appear red even though the rest of the rabbit has normal melanin distribution. This genetic mutation usually does not affect the rabbit's health, but simply makes them look slightly different.

Light-colored fur: Generally, rabbits with light-colored or white fur are more likely to have red eyes because these rabbits have red eyes. There is not enough melanin to obscure the vascular beds. The relationship between coat color and eye color is genetically determined, and some rabbits may have a gene that makes their coat and eyes appear light or white. In this condition, the melanin-deficient areas around the eye cause the eye to reflect the color of the blood vessel bed, giving it a red appearance. This does not affect the rabbit's health, it just makes their eyes look different from other rabbits.

Light reflection: Another reason why rabbit eyes are red may have to do with light reflection. When light hits the eye, a lack of melanin in the eye to absorb the light causes the light to reflect and appear red. This phenomenon is similar to the "red-eye effect" that occurs when people take photos, in which when a camera's flash shines into the eye, if there is insufficient melanin in the eye, it causes the light to reflect and appear red. Therefore, even under normal lighting conditions, rabbit eyes may appear red due to a lack of melanin.

In general, the reason why rabbit eyes are red is mainly due to the lack of melanin, which may be caused by genetic factors or hair color.

The reason why the eyes of these rabbits appear red is because their eyes contain a special reflective layer called the "retinal reflective layer." This reflective layer contains a large number of blood vessels and pigments, mainly a pigment called "opsin". Opsins in rabbits' eyes absorb light, especially short-wavelength blue and ultraviolet light, and then emit a red or orange reflection.

This reflective layer is useful for rabbits in the wild because they are crepuscular or nocturnal animals, helping to improve their visual acuity in the dark. In a dark environment, this reflective layer can increase the absorption of light by the eyes, allowing the rabbit to see surrounding objects and movements more clearly.

In general, the red reflex in rabbit eyes is an adaptive physiological trait that helps them survive and hunt better at dusk or night.