“Cherry eye” is a term commonly heard among pet owners, referring to a condition affecting the eyes of dogs and sometimes cats. This article clarifies what cherry eye is, why it occurs in animals, and whether humans can develop this condition. Understanding the distinctions between animal and human eye anatomy is essential to addressing this question.
Understanding Cherry Eye in Animals
Cherry eye, medically known as a prolapsed gland of the third eyelid, is an eye condition observed in animals. Many animals, including dogs, possess a “third eyelid” (nictitating membrane) in the inner corner of their eye. This membrane protects the eye from debris and distributes tear film for lubrication. It contains a gland crucial for tear production.
When the fibrous attachment holding this gland weakens, it can protrude, appearing as a red, swollen mass in the corner of the eye. This protrusion resembles a small cherry, giving the condition its name. While the exact cause is not fully understood, it is believed to have a genetic component, affecting certain breeds more frequently.
Can Humans Develop Cherry Eye?
Humans cannot develop cherry eye because their eye anatomy fundamentally differs from susceptible animals, primarily due to the absence of a functional third eyelid (nictitating membrane). While many animals possess a well-developed, functional third eyelid for protection and lubrication, humans do not.
Humans possess a small, vestigial remnant called the plica semilunaris in the inner corner of the eye. This structure is homologous to the nictitating membrane in other vertebrates, but it is non-functional and lacks a prolapsing gland. Therefore, humans are biologically unable to develop cherry eye.
Common Human Eye Conditions
While humans do not get cherry eye, they can experience various eye conditions with similar symptoms. One common condition is conjunctivitis, or “pink eye,” an inflammation of the conjunctiva, the transparent membrane lining the eyelid and eyeball. Conjunctivitis can be caused by viral or bacterial infections, or allergies, leading to redness, itchiness, discharge, and a gritty sensation.
Another frequent condition is a stye, a painful red lump on the eyelid caused by a blocked and infected oil gland. Styes resemble pimples, causing localized swelling, tenderness, and sometimes light sensitivity. Dry eye syndrome occurs when eyes don’t produce enough tears or tears evaporate too quickly, resulting in burning, itching, redness, and a gritty feeling. Allergic reactions can also cause eye redness, itching, and swelling, often affecting both eyes.
When to Seek Medical Attention
Any persistent or concerning eye symptoms warrant evaluation by a healthcare professional. Seek prompt medical attention for sudden vision changes, severe eye pain, extreme light sensitivity, or a feeling that something is stuck in your eye. Eye redness with pus or blood, or swelling spreading beyond the eyelid, also requires professional assessment. Consulting an eye doctor ensures proper diagnosis and treatment, preserving eye health.