What is Aniridia?

Before writing this post, I looked up approximately 20 different websites trying to find a standard definition of Aniridia.  In the process, I discovered that the “definition” of Aniridia varies greatly from website to website!  As such, I am going to attempt to summarize the various different definitions here to the best of my ability, in an attempt to create a “definition”.

I’ll start with the definitions my kids give when asked, show you words that people with Aniridia associate with the term, give a definition in medical terminology, and then describe what that actually means for the rest of us.

Aniridia – According to My Children

For fun, I asked my children to each give me a definition of Aniridia.  (I admit, this was mostly an excuse to show you a picture of them!)  Here were their answers:

My daughter, E, age 10:  “Aniridia is a really rare eye condition that I have.  It means that I don’t have any irises in my eyes and I’m visually impaired.  It is just one ingredient of who I am, but it doesn’t define me.”

My son, R, age 6: “Aniridia means you have black eyes – like my sister!”

Aniridia – According to the Aniridia Community

Recently, an international Aniridia Day was established to bring attention to this rare condition.  As part of the celebration of Aniridia Day, people in the Aniridia community were asked what words they associated with Aniridia.  The following word art was the compilation of those answers:

Aniridia – Medical Terms

Aniridia is a rare congenital genetic medical condition.  It’s primary manifestation is as a bilateral panocular disorder, which is characterized by extreme iris hypoplasia.  It typically includes foveal or optic nerve hypoplasia, cataracts, glaucoma, aniridic keratopathy, nystagmus, strabismus, dry eye, amblyopia, ptosis, photophobia, and aniridic fibrosis syndrome.  The conditions listed here typically result in a reduction of visual acuity.

In addition to the ocular abnormalities mentioned above, systemic non-ocular involvement can occur with Aniridia.  It has historically been believed that Aniridia had three different manifestations:  1) Isolated Aniridia without systemic involvement, 2) as a part of WAGR Syndrome, or 3) as a part of Gillespie Syndrome.  However, recent medical research has made it clear that even “isolated” Aniridia can and often does have systemic involvement.

Aniridia – Medical Terms Explained

Was that enough “Medical-ese” for you?  Ok, here’s the explanation of those terms in (hopefully) plain English.

The word “aniridia” has Greek origins and literally means “without iris”.

Aniridia is…

• Rare:  In order to be classified as a rare disease in the United States, it must affect less than 200,000 Americans at any one time.  Statistics for Aniridia worldwide indicate that it occurs in 1 of 40,000-60,000 people.  For the United States, then, there are likely somewhere between 5000 and 8000 individuals with aniridia.  Rare diseases are often also called orphan diseases.
• Congenital: Means “present at birth”.
• Genetic: Means “related to genes or heredity”.  Aniridia is caused by a mutation or deletion in a person’s gene, causing the gene to function incorrectly.  The vast majority of cases of aniridia are caused by either a mutation or a deletion in the PAX6 gene.
• Medical Condition: Most definitions of Aniridia list it as an “eye condition” or “eye disorder”.   However, since recent research indicates that there are significant non-ocular conditions associated with aniridia, it makes more sense to call it a medical condition, instead of just an eye condition.
• Bilateral: Aniridia affects both eyes.
  

  Example of an eye with Aniridia. Due to the lack of visible iris, the eye looks entirely black.

• Panocular: The prefix “pan” means “all” or “everything”.  The word “ocular” refers to eyes and/or vision.  Therefore, the word “panocular” means that Aniridia involves the entire anatomy of the eye.
• Characterized by extreme iris hypoplasia: The iris is the colored part of the eye. “Hypoplasia” means the underdevelopment of a tissue or organ.  Therefore, “iris hypoplasia” simply means an underdeveloped iris. This is typically the first indication that a person has Aniridia, as they are born without a fully developed iris.  In most cases, the iris seems absent unless viewed with special instruments used by an ophthalmologist.

Anatomy of a Typical Eye

Aniridia often includes the following eye conditions:

• Foveal hypoplasia:  The fovea is a small depression in the center of the eye that is responsible for our central (most detailed) vision.  In Aniridia, the fovea is typically underdeveloped or even absent.
• Optic nerve hypoplasia: The optic nerve is responsible for sending information from the retina to the brain.  In approximately 10% of aniridic patients, the optic nerve is underdeveloped.
• Cataracts:  Cataracts are a clouding of the lens in the eye and occur in 50-85% of aniridic patients.  Cataracts are quite common in the general population as well.  However, in the general population, then tend to occur in people older than 50.  In aniridic patients, they tend to occur frequently in childhood.
• Glaucoma: Glaucoma is increased pressure within the eyeball, which, if not treated, can permanently damage the optic nerve and cause vision loss.  Again, juvenile onset glaucoma is frequent in aniridia patients, whereas it tends to occur in older people in the general population.
• Aniridic Keratopathy:  A number of corneal abnormalities are seen in up to 90 percent of patients with Aniridia.  These abnormalities, which include an overgrowth of blood vessels and conjunctival cells onto the cornea, are collectively called keratopathy.  Over time, keratopathy can progress and eventually lead to vision loss as the cornea becomes cloudy.  Typically, children with Aniridia have clear corneas; the changes to the cornea usually begin sometime in the teen years, and then progress sometime between the ages of 20 and 40.
• Nystagmus: Nystagmus is the term for involuntary eye movements.  Sometimes referred to as “wobbly eyes”, it is believed that nystagmus is the result of foveal hypoplasia.
• Strabismus: Strabismus is a misalignment of the eyes, where an eye “wanders” when looking straight at an object.  Some people will mistakenly call this “lazy eye”, when in fact, it is a “wandering eye”.
• Dry Eye: Due to the underdevelopment of the eye, many structures of the eye do not function in a typical manner.  This can include the tear film and other glands, which can cause dry eyes.  Dry eyes can, in turn, aggravate the corneal problems observed in Aniridia.
• Amblyopia:  Amblyopia, also called “lazy eye”, occurs when the brain does not fully acknowledge the vision being sent to it by one eye.  Anything that interferes with clear vision in the eye during the first 6 years of life can create an amblyopic eye, including strabismus or cataract.
• Ptosis: Ptosis is an abnormal drooping of the upper eyelid.
• Photophobia: Photophobia is extreme light sensitivity to the point of feeling extreme discomfort or even pain due to light.  The iris is responsible for controlling the size of the pupil and therefore the amount of light let into the eye.  Since the iris is functionally missing in Aniridia, the pupil does not have that protection from the sun.
• Aniridic Fibrosis Syndrome: Aniridic Fibrosis Syndrome (AFS) is a potential complication resulting from surgery in an aniridic eye.  Fibrous tissue forms in the anterior chamber of the eye, causing vision loss.  Surgical intervention is often required when AFS is present.

The eye conditions that are a part of Aniridia typically result in a reduction of visual acuity.

Visual acuity refers to how clearly a person can see.  Typically, in the United States, this is expressed based on how well you can see compared to normal vision at 20 feet, as follows:

• 20/20 vision:  This is considered “normal” vision and it means that a person can clearly see at 20 feet what should normally be seen at that distance.
• 20/70 vision:  This means that a person must be as close as 20 feet to see clearly what should normally be seen at 70 feet.  If a person’s best eye (when corrected with glasses) has 20/70 vision or worse, they are legally visually impaired and typically entitled to services through the schools in the United States.
• 20/200 vision:  This means that a person must be as close as 20 feet to see clearly what should normally be seen clearly at 200 feet.  If a person’s best eye (when corrected with glasses) has 20/200 or worse vision, they they are considered legally blind in the United States.

Children with Aniridia who have not had significant complications often have vision somewhere between 20/80 and 20/200 once their vision matures.  It has been observed, however, that it can take some time for an aniridic infant’s eyes to “wake up” and fully begin to use their vision.  As such, a true sense for how well a child will see may not be fully determined until they are preschool age or even early elementary.  So if you are a parent of an infant, and you are concerned that your child may not be able to see much, please know that this may improve for the first few years of your child’s life!

Adults with Aniridia have varying degrees of visual impairment, depending on how many complications they’ve had, how successful their surgeries have been, and many other variables.

Systemic non-ocular involvement can occur with Aniridia.

This simply means that there can be conditions that are not related to the eyes that can occur with aniridia.  Historically, it was believed that Aniridia could be “isolated” to the eyes, OR it was a part of one of two syndromes:  WAGR or Gillespie.  However, much research is being conducted regarding Aniridia, and as a result, it has been determined that even “isolated” Aniridia (i.e., Aniridia not associated with WAGR Syndrome or Gillespie Syndrome) can have complications unrelated to the eyes.

Given the amount of non-ocular complications that can occur, some within the Aniridia community are recommending that Aniridia be referred to as “Aniridia Syndrome”.  While I think there is great validity to calling Aniridia a “syndrome”, I will continue to refer to it as simply “Aniridia” here, because the preponderance of medical literature has not yet made that change.

Aniridia often includes the following non-ocular conditions, as shown through recent medical research:

• Subtle abnormalities in the structure of the brain
• Sleep disturbances
• Central Auditory Processing Disorder
• Glucose Intolerance
• Decreased or absent sense of smell
• Sensory Processing Disorder

I plan to describe these conditions and their link to Aniridia in future posts.

Anecdotally, Aniridia seems to also include the non-ocular conditions listed below at a rate that is significantly higher than that of the general population:

• Feeding challenges
• Metabolism differences
• Insulin resistance
• Anxiety and/or OCD

Research is ongoing into many of these conditions and their relationship with Aniridia.  Truthfully, I fully believe that these issues are linked to Aniridia, based on numerous discussions with others in the Aniridia “family” – the occurrence of these issues in the aniridic population is too high to be a complete coincidence.  However, I hesitate to definitively state without equivocation that they are indeed related until I see research that is published confirming such a link.

I plan to describe these conditions more fully in future posts, as well.

Aniridia can occur as part of WAGR/11p deletion syndrome.

WAGR/11p deletion syndrome is a constellation of medical conditions that include everything listed above for Aniridia, as well as additional medical complications.  This includes the items listed above as anecdotally related to Aniridia, which have also been proven by scientific research to be linked to WAGR/11p deletion syndrome.

The medical complications that occur with WAGR/11p deletions syndrome are beyond the scope of this website.  However, if you are interested in more information and/or support for WAGR/11p deletion syndrome, PLEASE visit the International WAGR Syndrome Association (IWSA) webpage at www.wagr.org.  The website contains a host of wonderful information, and the individuals that run the IWSA are amazing people who have been traveling that journey for some time!

Aniridia can also occur as part of Gillespie Syndrome.

Gillespie Syndrome is an exceedingly rare syndrome that includes Aniridia, cerebellar ataxia, and mild to moderate intellectual disability.  There have only been approximately 20-30 cases described in medical literature.  Given the rarity of this condition, and my limited knowledge of it, Gillespie Syndromes medical conditions are beyond the scope of this website.

Aniridia – My Thoughts

Although Aniridia includes everything I’ve written above, those things are not what I think of when I think of Aniridia.  Instead, I think of the many amazing people I’ve met (both online and in person) that are a part of the Aniridia community.

The adults have worked hard to meet the challenges that Aniridia presents, and they’ve done so with a grace and persistence I’d do well to emulate.  So many have created invaluable support networks, foundations, and other organizations that are at the forefront of funding research into Aniridia.  Throughout all of those efforts, they’ve accomplished many of the same things that their normally sighted peers would do – graduating from college, maintaining careers of all kinds, raising a family, etc.  Their insights and advice to those of us who are parents is absolutely invaluable.

I also think of the many children that I’ve met in the Aniridia community, who are regularly and persistently living amazing lives, conquering challenges, and showing us all that Aniridia is just one of their many characteristics.

I think of the many parents I have met who, like me, are learning on the go, trying our best to navigate this world that we knew nothing about, and finding out that this journey is filled with both blessings and challenges.

Of course, when I think of Aniridia, I mostly think of my sweet girl.  I think of her accomplishing things that I wasn’t sure she’d be able to do when we first received her diagnosis – like hiking mountains…or reading Harry Potter books in normal print…or climbing difficult obstacles – yet here she is, rocking all of those things!

      

It’s not always easy for her (or for us) as we confront the challenges that come along with Aniridia, but it is ALWAYS worth it.