In its early stages, a cataract is invisible to the naked eye. As it advances, the pupil gradually loses its sharp black appearance and takes on a cloudy, grayish, or whitish hue. In the most advanced cases, the entire pupil can turn milky white. But most cataracts are detected long before they reach that point, during a routine eye exam using specialized equipment.
What You Can See From the Outside
A healthy pupil looks deep black because light passes cleanly through the lens behind it. When a cataract develops, proteins in that lens clump together and create cloudy patches that block or scatter light. Early on, these patches are too small to notice just by looking in a mirror. The lens changes are happening inside the eye, behind the iris, so they only show up under magnification with a slit lamp, the microscope your eye doctor uses during an exam.
As a cataract progresses to moderate or severe stages, the pupil starts to look hazy. You might notice a faint grayish or yellowish tint where the pupil used to be solid black. With a very advanced cataract, the pupil can appear covered in a visible film or look distinctly white. The Mayo Clinic’s clinical images show this clearly: one eye with a normal dark pupil beside another where the pupil looks opaque and pale.
How Different Types Look
Not all cataracts cloud the lens the same way. The three main types each have a distinct pattern that your eye doctor can identify.
Nuclear cataracts form in the center of the lens. They start as a subtle haziness in the middle and gradually turn the lens yellow, then deeper brown over time. This yellowing can actually shift your color perception before it significantly blurs your vision. In early stages, some people even experience a temporary improvement in near vision (sometimes called “second sight”) before the clouding worsens.
Cortical cataracts begin around the outer edges of the lens rather than the center. They develop as whitish, wedge-shaped streaks that radiate inward like the spokes of a wheel. Because they start at the periphery, they initially spare the clear central zone you look through, so vision problems may come on gradually. Over time, the spokes extend inward and, in advanced cases, the entire lens turns white.
Posterior subcapsular cataracts form as a small opaque area on the back surface of the lens, right in the path where light enters the eye. Because of their location, they tend to cause noticeable glare and reading difficulty earlier than other types, even when the cloudy patch is still relatively small. These are more common in younger adults, people who take corticosteroids, and those with diabetes.
What a Cataract Looks Like in Infants
Babies can be born with cataracts, and the visual signs are different from the gradual changes adults experience. In a newborn with a congenital cataract, the center of the pupil looks gray or white instead of black. The whole pupil may appear covered with a film, or you might notice a distinct white spot within it. Parents sometimes first spot this as an unusual white reflection in photos taken with a flash, where one eye gives off a normal red-eye glow and the other reflects white. This white reflex, called leukocoria, is a reason to see a pediatrician promptly.
What a Cataract Looks Like Through Your Own Eyes
Since you can’t easily see the cataract itself in a mirror during the early and moderate stages, most people first notice it through changes in their vision rather than changes in their appearance. The experience varies depending on the type and location of the clouding, but common visual symptoms include:
- General blurriness or haziness, as if you’re looking through a foggy or dirty window
- Increased glare, especially from headlights at night or bright sunlight
- Halos around lights, rings or starbursts that weren’t there before
- Fading or yellowing of colors, so whites look dingy and blues look washed out
- Difficulty seeing in dim light, with a growing need for brighter reading lamps
- Double vision in one eye, which can happen when the clouding scatters light unevenly
These changes usually creep in slowly. The proteins in your lens start breaking down around age 40, but most people don’t notice symptoms until age 60 or later. That long gap is why regular eye exams catch cataracts well before they become visible to anyone looking at your eyes.
Early Stage vs. Advanced Stage
Eye doctors grade cataract severity on a standardized scale, comparing what they see under the slit lamp to a set of reference images. The scale runs from essentially clear (grade 0) through mild, moderate, and severe. At mild grades, the cloudiness is detectable only with clinical equipment. At moderate grades, you’ll likely notice meaningful vision changes, but the cataract still won’t be obvious to someone across the room.
At severe grades, the appearance becomes unmistakable. A nuclear cataract at this stage turns the lens deeply brown, sometimes called a brunescent cataract. A cortical cataract can progress until the entire lens is white. In the most extreme scenario, a hypermature cataract develops: the lens material becomes milky and liquefied, the lens capsule may appear shrunken and wrinkled, and the pupil looks completely opaque. These advanced stages are uncommon in countries with accessible eye care, since surgery is typically performed well before this point.
How Doctors See What You Can’t
The slit lamp is the key tool. It shines a thin, bright beam of light into the eye while the doctor examines the lens through a microscope. Under this light, even a faint nuclear haze or a few tiny cortical spokes become clearly visible. Doctors also use retroillumination, shining light from behind the lens so that any opacities cast shadows and stand out against the glow. This is how small posterior subcapsular cataracts are caught, since they sit on the back of the lens and are nearly impossible to see with a standard penlight.
This is why a cataract can be quietly developing for years before you see any change in the mirror. By the time the pupil looks noticeably cloudy to the outside world, the cataract is usually quite advanced. The visual symptoms, blurred vision, glare, color shifts, are your earlier warning system, and a dilated eye exam is the most reliable way to confirm what’s happening.