Aniridia in the Newborn

Author: Sophie Bakri, MD; Chief Editor: Hampton Roy Sr, MD more...

Updated: Jun 17, 2009

What would you like to print?

Background
Pathophysiology
Epidemiology
Show All

Background

In 1818, Barratta first described aniridia (Greek for absence of the iris). Aniridia is a rare, bilateral, panophthalmic disorder, of which iris hypoplasia is the most striking feature (see image below).

Aniridia. Note the almost complete absence of the iris.

Aniridia also has corneal, lens, optic nerve, and retinal manifestations. Foveal and optic nerve hypoplasia are often present, causing a reduction in visual acuity and congenital sensory nystagmus. Progressive worsening of vision may occur later in life as a result of cataracts, glaucoma, and corneal opacification.

Pathophysiology

Aniridia may be familial or sporadic. It is caused by a mutation in the PAX6 gene on chromosome 11.

Approximately 85% of cases are familial (designated AN1) with autosomal dominant inheritance with complete penetrance but variable expressivity. These familial cases usually have isolated ocular involvement.

The 15% of cases that are sporadic have a deletion or mutation on the short arm of chromosome 11. The same deletion is responsible for the development of Wilms tumor (nephroblastoma).

The exact pathogenesis of aniridia is unknown. After early reports of ocular colobomas in patients with aniridia, some authors proposed that it is a colobomatous disorder. Others attributed it to a failure of mesodermal development with involvement of the rim of the optic cup, causing iris hypoplasia. Still others advocated the neuroectodermal theory, which links the presence of retinal anomalies and iris muscular hypoplasia to a developmental failure of neuroectoderm.

Frequency

United States

Aniridia is a very rare disorder. According to a population-based study in Michigan, it has been estimated to affect approximately 1 per 61,000 newborns.

International

A more recent study from Denmark reported the incidence as 1 per 96,000 live births.

Mortality/Morbidity

Aniridia itself is not a lethal disorder. However, miscarriages and a stillborn child have been the only results of a consanguineous mating between individuals with aniridia. A homozygous mutation of the aniridia gene may possibly be lethal. The morbidity of aniridia is significant because of the decreased vision and nystagmus.

Race

No racial predilection has been described.

Sex

The incidence of aniridia is equal in males and females.

Age

Aniridia is a congenital disorder apparent at birth. It is never acquired.

Proceed to Clinical Presentation

Contributor Information and Disclosures

Author

Sophie Bakri, MD Assistant Professor of Ophthalmology, Vitreoretinal Diseases and Surgery, Mayo Clinic of Rochester

Sophie Bakri, MD is a member of the following medical societies: American Academy of Ophthalmology

Disclosure: Nothing to disclose.

Coauthor(s)

John W Simon, MD Chair, Department of Ophthalmology, Professor, Departments of Ophthalmology and Pediatrics, Albany Medical College

John W Simon, MD is a member of the following medical societies: Alpha Omega Alpha, American Academy of Ophthalmology, and American Association for Pediatric Ophthalmology and Strabismus

Disclosure: Nothing to disclose.

Specialty Editor Board

Gerhard W Cibis, MD Clinical Professor, Director of Pediatric Ophthalmology Service, Department of Ophthalmology, University of Kansas, Kansas City

Gerhard W Cibis, MD is a member of the following medical societies: American Academy of Ophthalmology, American Association for Pediatric Ophthalmology and Strabismus, and American Ophthalmological Society

Disclosure: Nothing to disclose.

Francisco Talavera, PharmD, PhD Senior Pharmacy Editor, eMedicine

Disclosure: eMedicine Salary Employment

J James Rowsey, MD Former Director of Corneal Services, St Luke's Cataract and Laser Institute, Florida

J James Rowsey, MD is a member of the following medical societies: American Academy of Ophthalmology, American Association for the Advancement of Science, American Medical Association, Association for Research in Vision and Ophthalmology, Florida Medical Association, Pan-American Association of Ophthalmology, Sigma Xi, and Southern Medical Association

Disclosure: Nothing to disclose.

Lance L Brown, OD, MD Ophthalmologist, Affiliated With Freeman Hospital and St John's Hospital, Regional Eye Center, Joplin, Missouri

Disclosure: Nothing to disclose.

Chief Editor

Hampton Roy Sr, MD Associate Clinical Professor, Department of Ophthalmology, University of Arkansas for Medical Sciences

Hampton Roy Sr, MD is a member of the following medical societies: American Academy of Ophthalmology, American College of Surgeons, and Pan-American Association of Ophthalmology

Disclosure: Nothing to disclose.

References

Nelson LB, Spaeth GL, Nowinski TS, et al. Aniridia. A review. Surv Ophthalmol. May-Jun 1984;28(6):621-42. [Medline].
Brauner SC, Walton DS, Chen TC. Aniridia. Int Ophthalmol Clin. Spring 2008;48(2):79-85. [Medline].
Callahan A. Aniridia with ectopia lentis and secondary glaucoma. Am J Ophthalmol. 1949;32:28.
Chen TC, Walton DS. Goniosurgery for prevention of aniridic glaucoma. Arch Ophthalmol. Sep 1999;117(9):1144-8. [Medline].
Edén U, Iggman D, Riise R, Tornqvist K. Epidemiology of aniridia in Sweden and Norway. Acta Ophthalmol. May 19 2008;[Medline].
Grant WM, Walton DS. Progressive changes in the angle in congenital aniridia, with development of glaucoma. Am J Ophthalmol. Nov 1974;78(5):842-7. [Medline].
Hamming N, Wilensky J. Persistent pupillary membrane associated with aniridia. Am J Ophthalmol. Jul 1978;86(1):118-20. [Medline].
Hittner HM, Riccardi VM, Ferrell RE, et al. Variable expressivity in autosomal dominant aniridia by clinical, electrophysiologic, and angiographic criteria. Am J Ophthalmol. Apr 1980;89(4):531-9. [Medline].
Jastaneiah S, Al-Rajhi AA. Association of aniridia and dry eyes. Ophthalmology. Sep 2005;112(9):1535-40. [Medline].
Jesberg DO. Aniridia with retinal lipid deposits. Arch Ophthalmol. Sep 1962;68:331-6. [Medline].
Koroma BM, Yang JM, Sundin OH. The Pax-6 homeobox gene is expressed throughout the corneal and conjunctival epithelia. Invest Ophthalmol Vis Sci. Jan 1997;38(1):108-20. [Medline].
Kremer I, Rajpal RK, Rapuano CJ, et al. Results of penetrating keratoplasty in aniridia. Am J Ophthalmol. Mar 15 1993;115(3):317-20. [Medline].
Layman PR, Anderson DR, Flynn JT. Frequent occurrence of hypoplastic optic disks in patients with aniridia. Am J Ophthalmol. Apr 1974;77(4):513-6. [Medline].
Mackman G, Brightbill FS, Optiz JM. Corneal changes in aniridia. Am J Ophthalmol. Apr 1979;87(4):497-502. [Medline].
Margo CE. Congenital aniridia: a histopathologic study of the anterior segment in children. J Pediatr Ophthalmol Strabismus. Sep-Oct 1983;20(5):192-8. [Medline].
Menezo JL, Martinez-Costa R, Cisneros A, et al. Implantation of iris devices in congenital and traumatic aniridias: surgery solutions and complications. Eur J Ophthalmol. Jul-Aug 2005;15(4):451-7. [Medline].
Nishida K, Kinoshita S, Ohashi Y, et al. Ocular surface abnormalities in aniridia. Am J Ophthalmol. Sep 1995;120(3):368-75. [Medline].
Ramaesh K, Ramaesh T, Dutton GN, et al. Evolving concepts on the pathogenic mechanisms of aniridia related keratopathy. Int J Biochem Cell Biol. Mar 2005;37(3):547-57. [Medline].
Warburg M, Mikkelsen M, Andersen SR, et al. Aniridia and interstitial deletion of the short arm of chromosome 11. Metab Pediatr Ophthalmol. 1980;4(2):97-102. [Medline].
Wiggins RE Jr, Tomey KF. The results of glaucoma surgery in aniridia. Arch Ophthalmol. Apr 1992;110(4):503-5. [Medline].