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Model and actress Paris Jackson is believed to have Waardenburg syndrome, hence her unique-looking blue eyes.
Missy Elliot is a famous example of someone who suffers from Graves’ ophthalmopathy.
A free-floating iris cyst is essentially an iris cyst that moves around in the anterior chamber. These manifest as a ball of color moving in the eye.
Graves’ ophthalmopathy symptoms include bulging eyes, light sensitivity, gritty eyes, and puffy eyelids.
Graves' disease is an immune system condition where the body overproduces thyroid hormones. This leads to a number of symptoms, including an ocular condition known as Graves' ophthalmopathy.
CPEO is caused by DNA mutations, which occur later in life, and can affect one or both eyes, as well as other areas of the body (e.g. muscle weakness, heart problems, etc.).
While free-floating iris cysts are mostly harmless, they can cause pain and lead to secondary glaucoma.
Sources: (American Academy of Ophthalmology) (Health Digest) (WebMD) (National Organization for Rare Disorders)
See also: What do your eyes say? Celebrities with different-colored eyes
Unlike other eye features on this list, chronic progressive external ophthalmoplegia (CPEO) develops later in life. A common symptom is a drooping eyelid.
Waardenburg syndrome is a group of genetic conditions. Among other things, it can affect pigmentation, and therefore the coloring of the eyes.
British actress Anna Cannings is one example of a person with microphthalmia. In Cannings’ particular case, she was born blind, with bilateral microphthalmia (both eyes were affected from birth).
A famous example is late musician David Bowie. Following a fistfight as a teen, Bowie’s left pupil was left permanently dilated.
People with microphthalmia have smaller eyes than average. Unfortunately, this comes with some serious side effects, including partial vision loss or even blindness. The condition can affect one or both eyes.
Anisocoria is when people have different sized pupils. Uneven pupils can be hereditary or be caused by trauma (injury) or conditions (e.g. stroke).
Different names are given for the condition, depending on which part is missing. For instance, a person may have eyelid coloboma, lens coloboma, or uveal coloboma (a partly-missing iris).
Uveal coloboma in particular may cause a number of issues, including light sensitivity and blurry vision.
Those with microphthalmia have small eye sockets, so the eyeballs become misshapen as they develop. The root cause of the condition is not known, but genetics and environmental factors are often pointed to as causes.
This feature, which is sometimes mistaken for heterochromia or CES, develops when the embryo is in the womb. It can result in a number of missing eye parts, and it can affect one or both eyes.
Because it’s a chromosomal disorder, CES patients experience other issues in addition to the eyes, including potential problems with the lips, heart, ears, kidneys, and bones.
While some people with polycoria don't experience a lot of symptoms, others may struggle with blurred vision and poor night vision.
Cat eye syndrome (CES) is a rare chromosomal disorder. People who suffer from it are born with elongated pupils, similar to those of cats.
Polycoria is when a person has more than one pupil in the eye. This can manifest in one or both eyes.
Ocular albinism occurs when there is an absence of pigmentation in the iris. Unlike some other features on this list, the absence of color in the eyes may cause some vision issues.
Some people, however, have partial heterochromia. This is when both eyes are mostly the same color, except one of them has another color mixed in. Actor Henry Cavill, for instance, has blue eyes, but also has a shade of brown in his left eye.
People who have more than one pupil that works independently have true polycoria, whereas those who have an extra pupil that's functional have pseudopolycoria. Pseudopolycoria is essentially a hole in the iris, and often occurs as a result of trauma or a condition.
There are a few famous people who have different colors in their left and right irises. Actress Jane Seymour is one example: she has one green and one brown eye.
This is a popular one, among the rare eye features, of course. Heterochromia is essentially when a person’s two eyes are not the same color. People are usually born like this, but it can also appear later in life, as a result of a disorder or an injury.
Ocular albinism is the result of a genetic mutation. People who suffer from it tend to have light blue irises, and the lack of pigmentation in the retina can cause the eyes to have a violet or red hue.
Because ocular albinism causes sensitivity to light, people who have it need to protect their eyes by wearing dark lenses.
People with distichiasis have a second set of eyelashes that grow from the inner mucosal layer of the eye. This is caused by epithelial germ cells failing to differentiate between certain glands.
If you think about it, humans come in all sorts of varieties. Well, our eyes are no different. Sure, we have different colored eyes and different eye shapes, but some of us also have some exceptionally unique features. We're talking about the rare eye characteristics some people are born with or develop later in life.
In this gallery, we look at some of the most fascinating eye features humans have. Click on to get to know them.
Rare eye features you didn't know about
Some celebrities actually have them!
HEALTH Eyes
If you think about it, humans come in all sorts of varieties. Well, our eyes are no different. Sure, we have different colored eyes and different eye shapes, but some of us also have some exceptionally unique features. We're talking about the rare eye characteristics some people are born with or develop later in life.
In this gallery, we look at some of the most fascinating eye features humans have. Click on to get to know them.