Eye cancer can look like a dark spot on the iris, a white glow in the pupil, a fleshy bump on the eyelid, or a raised patch on the white of the eye. In many cases, though, it produces no visible change at all and is found only during a routine eye exam. What you can see depends entirely on where the cancer is growing, whether on the surface of the eye, inside it, on the eyelid, or in the eye socket behind the eyeball.
About 3,200 new cases of primary eye cancer are diagnosed in the United States each year. The risk increases with age for most types, though one form, retinoblastoma, occurs almost exclusively in young children.
Dark Spots on the Colored Part of the Eye
The most recognizable sign of eye cancer is a new or growing spot on the iris, the colored ring around your pupil. Many people have harmless freckles on their iris that never change. A melanoma, by contrast, tends to be larger, thicker, and may have visible blood vessels running through it. At diagnosis, an iris melanoma averages about 5.5 millimeters across and 2 millimeters thick, roughly the size of a small lentil sitting on the surface of the iris.
These tumors can take different shapes. Some form a dome-shaped nodule, while others spread flat across the iris in a diffuse pattern. A diffuse melanoma can gradually change the entire color of one iris to brown by dusting pigment across it. If one of your eyes slowly becomes a different color than the other, that’s a significant warning sign. Another clue is a change in pupil shape: as the tumor grows, it can pull the dark inner border of the iris outward, distorting the normally round pupil.
A White Glow in a Child’s Pupil
Retinoblastoma, the most common eye cancer in children, often reveals itself through a distinctive white, silvery, or yellowish reflection in the pupil called leukocoria. Normally, when light enters the eye, it bounces off the retina and produces a faint red glow (the “red eye” effect in flash photography). When a tumor sits behind the pupil, light reflects off the tumor instead, producing that abnormal white reflex.
Parents often first notice leukocoria in a flash photograph where one eye glows red and the other glows white. A surface reflection on the eye can sometimes mimic this effect, so taking additional photos from different angles helps distinguish the two. A true leukocoria fills most or all of the pupil and appears consistently across multiple photos. A harmless surface glare is smaller and shifts position from shot to shot. If you see a persistent white pupil in photos of your child, have it evaluated promptly.
Spots on the White of the Eye
Conjunctival melanoma grows on the conjunctiva, the clear membrane covering the white of the eye. It can appear as a pigmented spot, ranging from light brown to very dark, or it can be completely colorless (amelanotic), looking like a pinkish or flesh-toned raised area. The spot may be flat or nodular and occurs in only one eye.
A benign mole on the conjunctiva, called a nevus, is common and usually harmless. The concern arises when a nevus starts to grow, change color, or develop new blood vessels. Not every conjunctival nevus becomes cancer, but the transformation is possible, which is why eye doctors photograph and measure these spots over time to track any changes.
Eyelid Lumps That Don’t Heal
Cancer on the eyelid often mimics a stye or chalazion at first. Sebaceous carcinoma, one of the more serious eyelid cancers, typically starts as a small, painless lump on the upper eyelid. It can look pink, reddish-brown, or yellow. Over time, the skin of the eyelid thickens and becomes swollen or irritated. Unlike a stye, which resolves within a couple of weeks, these lumps persist and gradually get worse. Eyelash loss in the area of the lump is another red flag, since the tumor can destroy hair follicles as it grows.
Basal cell carcinoma, the most common skin cancer, also frequently appears on the eyelid as a pearly or waxy bump, sometimes with a small crater or non-healing sore at its center. Any eyelid sore that doesn’t heal after several weeks deserves attention.
An Eye That Bulges or Won’t Move Normally
Tumors growing in the orbit, the bony socket behind the eyeball, produce a different set of signs. Because the tumor takes up space in a confined area, it pushes the eyeball forward, creating a visible bulge called proptosis. One eye may simply look more prominent than the other. You might also notice difficulty moving the eye in certain directions, since the tumor can press against or infiltrate the muscles that control eye movement. Orbital lymphoma is one of the more common tumors in this location in adults.
Vision Changes You Might Notice
Many internal eye cancers, particularly melanomas of the choroid (the layer beneath the retina), cause no visible external change. Instead, they announce themselves through shifts in vision. Flashes of light, new floaters that look like specks of dust drifting across your field of view, blurry or poor vision in one eye, and loss of side (peripheral) vision are all potential symptoms.
These symptoms overlap with plenty of non-cancerous conditions like retinal detachment, vitreous changes from aging, or migraines. What makes them worth investigating is when they’re persistent, affect only one eye, and are new. A melanoma inside the eye can also leak fluid beneath the retina, causing a shadow or dark curtain across part of your vision.
The tricky reality is that ocular melanoma frequently causes no symptoms at all in its early stages. The tumor may sit quietly in the back of the eye, visible only through a dilated eye exam. This is the single most important reason routine eye exams matter for catching eye cancer early.
How Eye Cancer Is Found
When a doctor suspects an eye tumor, the primary tool is a thorough dilated exam with specialized imaging. Ultrasound is especially valuable for measuring a tumor’s size, shape, and thickness, and for determining whether it has extended through the wall of the eye. High-resolution ultrasound can evaluate tumors as small as a few millimeters and assess whether nearby structures are involved. Specialized photography of the blood vessels inside the eye can also help characterize suspicious lesions. In most cases, a biopsy is not the first step because imaging can provide enough detail to distinguish a melanoma from a benign growth based on its thickness, reflectivity, and shape.
What to Watch For
Eye cancer doesn’t have a single look. The signs vary by type:
- A growing dark spot on the iris, especially one that distorts the pupil or changes your eye color
- A white or yellowish pupil glow in a child, particularly in flash photos
- A pigmented or flesh-colored bump on the white of the eye that changes over time
- A persistent eyelid lump that looks like a stye but doesn’t resolve
- One eye bulging forward or not moving the way it used to
- New floaters, flashes, blurred vision, or peripheral vision loss in one eye
Any of these changes appearing in one eye and not the other is a pattern worth taking seriously. Many of these signs have harmless explanations, but they overlap enough with cancer that only an eye exam can tell the difference.