Summary about Disease
Aniridia is a rare genetic disorder characterized by the complete or partial absence of the iris (the colored part of the eye). The term "aniridia" literally means "absence of iris," but in most cases, a small amount of iris tissue remains. Aniridia is not just an absence of the iris; it often involves other eye structures and can lead to a range of visual problems. The severity can vary greatly from person to person. Aniridia often occurs with other ocular conditions.
Symptoms
Partial or complete absence of the iris: This is the defining characteristic.
Photophobia (light sensitivity): Due to the lack of iris, which normally controls the amount of light entering the eye.
Nystagmus (involuntary eye movements): Jerky, repetitive eye movements.
Reduced visual acuity: Blurry or poor vision.
Glaucoma: Increased pressure inside the eye.
Cataracts: Clouding of the lens of the eye.
Corneal problems (pannus or corneal clouding): Affecting the clear front surface of the eye.
Optic nerve hypoplasia: Underdevelopment of the optic nerve.
Causes
Aniridia is primarily caused by mutations in the PAX6 gene, located on chromosome 11 (11p13). This gene is crucial for eye development. It is usually inherited in an autosomal dominant pattern, meaning that only one copy of the mutated gene is necessary to cause the condition. In some cases, it can occur as a new mutation (de novo) in individuals with no family history of the disorder. Approximately 1/3 of cases are de novo. It can also be associated with other genetic syndromes, such as WAGR syndrome (Wilms tumor, Aniridia, Genitourinary abnormalities, and intellectual disability), which involves a larger deletion on chromosome 11 that includes the *PAX6* gene and neighboring genes.
Medicine Used
There is no cure for aniridia; treatment focuses on managing the symptoms and preventing complications. Common treatments include:
Eyedrops: To manage glaucoma (pressure-lowering drops).
Artificial tears: To lubricate the eyes and alleviate dryness.
Medications for Pain: Pain relievers for any eye discomfort
Contact lenses: Special tinted contact lenses to reduce light sensitivity and improve vision (often used as an alternative to surgery).
Surgery:
Cataract surgery: To remove cataracts.
Glaucoma surgery: To lower intraocular pressure.
Corneal transplant: In severe cases of corneal disease.
Iris Implants: These are sometimes used to create a more normal-appearing pupil and decrease glare. They are not without risk.
PAX6 target therapy: A research being conducted using CRISPR gene editing to target the mutation of PAX6
Is Communicable
No, aniridia is not communicable. It is a genetic disorder, not an infectious disease.
Precautions
Regular eye exams: To monitor for complications like glaucoma and cataracts.
Sun protection: Wear sunglasses and hats to protect the eyes from bright light and UV radiation.
Avoid eye rubbing: Can worsen corneal problems.
Genetic counseling: For individuals with aniridia who are planning to have children.
Early intervention: For visual impairments, including low vision aids and therapies.
How long does an outbreak last?
Aniridia is a chronic condition, not an outbreak. It is a lifelong condition that requires ongoing management. The symptoms are present from birth or early childhood and persist throughout life.
How is it diagnosed?
Clinical examination: An ophthalmologist can diagnose aniridia by examining the eyes and observing the absence or partial absence of the iris.
Genetic testing: To confirm the diagnosis and identify the specific PAX6 mutation. This can be helpful for genetic counseling.
Slit-lamp examination: Allows detailed examination of the eye structures.
Intraocular pressure measurement (tonometry): To check for glaucoma.
Visual acuity testing: To assess the level of vision.
Optical Coherence Tomography (OCT): Assesses the retina and optic nerve.
Timeline of Symptoms
At birth or early infancy: The absence or partial absence of the iris is usually apparent. Nystagmus and photophobia may also be present.
Childhood: Reduced visual acuity becomes more noticeable. Glaucoma and cataracts can develop. Corneal problems may progress.
Adulthood: The risk of glaucoma and cataracts continues. Corneal disease can worsen. Regular monitoring is crucial throughout life to manage complications and preserve vision.
Important Considerations
Aniridia is a complex condition that requires a multidisciplinary approach involving ophthalmologists, geneticists, and other specialists.
Early diagnosis and intervention are crucial to minimize vision loss and improve quality of life.
Individuals with aniridia may benefit from support groups and resources for people with visual impairments.
The severity of aniridia can vary greatly, so treatment plans should be individualized.
Because it can be associated with WAGR syndrome, people with aniridia should also be checked for Wilms tumor and genitourinary abnormalities, especially early in life.