There are a few potential reasons why someone’s eye color may appear to suddenly change from another color to green:
An injury or infection
One possibility is some type of trauma or infection in the eye. If bleeding occurs within the eye (hyphema) or the eye becomes inflamed due to injury or infection, the release of pigment within the eye can sometimes cause a short-term color change.
This occurs because inflammation and bleeding disrupt the normal anatomy and cell layers in the iris, resulting in changes in the way light is reflected and absorbed by the iris. Usually once the injury/inflammation/infection resolves, the eye color reverts back to its original shade.
Medications
Certain medications are associated with changes in eye color as a side effect. Drugs within the family of antimalarial medications, such as chloroquine and hydroxychloroquine, can lead to a darkening of the iris that may appear brown, black, or greenish over time.
Eye drops containing prostaglandin analog medications like latanoprost and bimatoprost, which are used to treat glaucoma, are also associated with increased brown pigment in the iris and a resulting color change. The higher melanin content may cause eyes to shift to a greenish hue.
Inflammation due to autoimmune disease
In some cases, inflammation in the eye related to autoimmune diseases can temporarily change the eye color. Inflammation of the middle layer of the eye, called the uvea, can occur in autoimmune disorders like sarcoidosis, Vogt-Koyanagi-Harada syndrome, and sympathetic ophthalmia.
The dispersed pigment and inflammatory cells can change the color of the iris by altering how light scatters and reflects. Once the inflammation subsides, usually the original eye color returns.
Pigment dispersion syndrome
Pigment dispersion syndrome occurs when the pigmented cells in the back of the iris (called the iris pigment epithelium) begin to break down and release their pigment particles into other areas of the eye. This excess pigment can then be deposited onto the clear surface of the eye and the front of the iris, causing the iris to change to a darker color.
In pigment dispersion syndrome, the iris can go from a lighter color to a deeper brown, gray, or olive green shade. Usually both eyes are affected. Much of the time, the color change is permanent.
Fuchs heterochromic iridocyclitis
Fuchs heterochromic iridocyclitis is a rare type of eye inflammation that typically only affects one eye. It often causes the iris of the affected eye to lighten in color permanently.
With this condition, the iris can change from a brown or darker shade to a lighter green, gray, or blue color. The cause is not fully understood but may be related to localized inflammation and a decrease in pigment cells.
Birthmarks on the iris (nevi)
Iris nevi are benign freckle-like collections of pigment cells on the surface of the iris. These birthmarks can grow or change in color over time, particularly in the first few years of life. This could cause someone’s eye to appear darker or multicolored. Large nevi may produce areas that look darker brown or green compared to the rest of the iris.
Heterochromia
Sometimes one eye is a different color than the other. This is called heterochromia iridium. In some cases, part of one iris can be a different color from the rest.
Heterochromia is typically benign and present from birth. But in some cases, a later onset type of heterochromia related to disease or injury can occur and cause one eye to change to a lighter or darker shade.
Aging
With increasing age, the melanin pigment in the iris can start to break down and deplete over time. This can cause the eyes to appear to change to a lighter shade than in childhood. Aging can also lead to changes in the fibrous tissue composition of the iris, further impacting the eye color.
Tumors
Rarely, tumors in the eye (like intraocular melanoma or sarcoma) could alter the vascular nature and pigmentation of the iris enough to cause a color change. This would likely only affect one eye. Any suspected tumors or growths in the eye need evaluation by an ophthalmologist.
Conclusion
In summary, a sudden apparent change in eye color from another shade to green most often results from:
| Injury or infection |
| Medication side effects |
| Inflammation from autoimmune disease |
| Pigment dispersion syndrome |
| Fuchs heterochromic iridocyclitis |
| Iris nevi or other benign growths |
| Aging changes in pigment |
More rarely, heterochromia iridium, tumors, and other systemic diseases affecting the pigment of the iris could be associated with an eye color change.
In most cases, if the underlying cause is treated, the eye color will stabilize and often revert back towards the original shade. Since some color changes can indicate a more serious eye condition, it is recommended to see an ophthalmologist for a full exam of the eyes and surrounding structures. Especially if the color change occurs suddenly, appears different between the two eyes, or is accompanied by any other symptoms like pain or vision changes.
With a thorough diagnosis, an underlying cause can be identified. If the color change is expected to be temporary, follow-up exams can help monitor when and if the original eye color returns. Permanent color changes may be monitored for any worsening or associated eye health issues.
While it can be alarming to notice a sudden change in eye color, the cause is usually identifiable. With appropriate follow-up and treatment as needed, prognosis can be good. Increased awareness of the various reasons eyes may change color can help reduce worry if this occurs.
In most cases, a detailed eye exam and discussion of medical history makes it possible to diagnose the specific reason the eyes have changed color. Identifying and addressing any underlying condition will allow for appropriate treatment to protect eye health or restore the usual eye color, if possible. With doctor and patient working together, good visual outcomes can be achieved even when changes in eye color are noted.
Some key points to remember include:
– Sudden color changes need prompt evaluation to identify the cause
– Many factors like injuries, drugs, inflammation, and eye diseases can contribute
– Most causes are benign and treatable, with the color change often reversing
– A minority of cases may be linked to serious conditions like tumors
– Ophthalmologist exams are crucial to detect any worrisome conditions
– Follow-up is recommended to monitor color changes and eye health
– Education, diagnosis, and timely treatment provide reassurance and good visual results
In the majority of instances, a change to green eye color ends up being temporary and harmless. While some causes like melanoma would be concerning, they are quite rare. Being evaluated promptly means underlying reasons can be caught early and managed appropriately. With the right knowledge and care, good vision and healthy eyes can be preserved when unexpected color changes occur.
