Aniridia Eyes of a Scandinavian male wherein the iris is not present due to aniridia. Notice the lack of common eye color as the eye appears to be one large pupil. ICD-10 | Q13.1 ICD-9 | 743.45 OMIM | 106200 106210 DiseasesDB | 723 MeSH | D015783 WikiDoc Resources for Aniridia Articles Most recent articles on Aniridia Most cited articles on Aniridia Review articles on Aniridia Articles on Aniridia in N Eng J Med, Lancet, BMJ Media Powerpoint slides on Aniridia Images of Aniridia Photos of Aniridia Podcasts & MP3s on Aniridia Videos on Aniridia Evidence Based Medicine Cochrane Collaboration on Aniridia Bandolier on Aniridia TRIP on Aniridia Clinical Trials Ongoing Trials on Aniridia at Clinical Trials.gov Trial results on Aniridia Clinical Trials on Aniridia at Google Guidelines / Policies / Govt US National Guidelines Clearinghouse on Aniridia NICE Guidance on Aniridia NHS PRODIGY Guidance FDA on Aniridia CDC on Aniridia Books Books on Aniridia News Aniridia in the news Be alerted to news on Aniridia News trends on Aniridia Commentary Blogs on Aniridia Definitions Definitions of Aniridia Patient Resources / Community Patient resources on Aniridia Discussion groups on Aniridia Patient Handouts on Aniridia Directions to Hospitals Treating Aniridia Risk calculators and risk factors for Aniridia Healthcare Provider Resources Symptoms of Aniridia Causes & Risk Factors for Aniridia Diagnostic studies for Aniridia Treatment of Aniridia Continuing Medical Education (CME) CME Programs on Aniridia International Aniridia en Espanol Aniridia en Francais Business Aniridia in the Marketplace Patents on Aniridia Experimental / Informatics List of terms related to Aniridia Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] Synonyms and keywords: Absent iris ## Overview[edit | edit source] Aniridia is a rare congenital condition characterized by the underdevelopment of the eye's iris. This usually occurs in both eyes. It is associated with poor development of the retina at the back of the eye preventing normal vision development. ## Classification[edit | edit source] Aniridia may be broadly divided into hereditary and sporadic forms. Hereditary aniridia is usually transmitted in an autosomal dominant manner (each offspring has a 50% chance of being affected), although rarer autosomal recessive forms (such as Gillespie syndrome) have also been reported. Sporadic aniridia mutations may affect the WT1 region adjacent to the AN2 aniridia region, causing a kidney cancer called nephroblastoma (Wilms tumor). These patients often also have genitourinary abnormalities and mental retardation (WAGR syndrome). The AN2 region of the short arm of chromosome 11 (11p13) includes the PAX6 gene (named for its PAired boX status), whose gene product helps regulate a cascade of other genetic processes involved in the development of the eye (as well as other nonocular structures). This PAX6 gene is around 95% similar to the pax gene found in zebrafish, a creature which diverged from the human ancestry around 400 million years ago. Thus, the PAX6 gene constitutes an important evolutionary link to mankind's distant ancestors. Defects in the PAX6 gene cause aniridia-like ocular defects in mice (as well as Drosophilia = fruit flies). Aniridia is a heterozygotic disease, meaning that only one of the two chromosome 11 copies is affected. When both copies are altered (homozygous condition), the result is a uniformly fatal condition with near complete failure of entire eye formation. In 2001, two cases of homozygous Aniridia patients were reported; the foetuses died prior to birth and had severe brain damage. In mice, homozygous Small eye defect (mouse Pax-6) led to loss of eyes, nose and the foetuses suffered severe brain damage.[1] Several different mutations may affect the PAX6 gene. Some mutations appear to inhibit gene function more than others, with subsequent variability in the severity of the disease. Thus, some aniridic individuals are only missing a relatively small amount of iris, do not have foveal hypoplasia, and retain relatively normal vision. Presumably, the genetic defect in these individuals causes less "heterozygous insufficiency," meaning they retain enough gene function to yield a milder phenotype. * Online Mendelian Inheritance in Man (OMIM) 106200 AN1 * Online Mendelian Inheritance in Man (OMIM) 106210 AN2 * Online Mendelian Inheritance in Man (OMIM) 106220 Aniridia and absent patella * Online Mendelian Inheritance in Man (OMIM) 106230 Aniridia, microcornea, and spontaneously reabsorbed cataract * Online Mendelian Inheritance in Man (OMIM) 206700 Aniridia, cerebellar ataxia, and mental deficiency (Gillespie syndrome) ## Clinical Presentation[edit | edit source] ### Ocular[edit | edit source] * Stumps of iris usually apparent * Some patients have partial aniridia with relatively preserved vision * Corneal findings; Limbal stem cell deficiency = aniridic keratopathy * Corneal pannus usually presents in early childhood with radial vessels at 6 and 12 o’clock, developing circumferential grayish haze which advances centrally * Corneal epithelium may harbor ectopic conjunctival goblet cells, and inflammatory cells are usually present * Microcornea is very common in aniridia * Initial fine lens opacities in infants * Visually significant cataract often acquired by 2nd-3rd decade * Multiple cataract types described: anterior polar, pyramidal, nuclear, lamellar, and cortical * Lens subluxation / ectopia lentis * Nystagmus * Sensory strabismus * Glaucoma onset usually by 2nd decade * Gradually increasing angle obstruction, though open angle also possible * Possible glaucoma mechanism: Contractile membrane covering angle, with increase in iridocorneal processes; iris stump may become totally adherent to posterior corneal surface * Foveal hypoplasia, which may be complete or very subtle; Fluorescein angiography may be needed to demonstrate lack of foveal avascular zone * Optic nerve hypoplasia to some degree is present in up to 75% of aniridia patients ### Non-ocular[edit | edit source] * Dysosmia / dysnomia = abnormal sense of smell due to hypoplastic olfactory bulbs * Glucose intolerance / diabetes mellitus * Reduced size of corpus callosum and anterior commissure * Absent pineal gland: abnormal sleep due to melatonin abnormalities * Unilateral polymicrogyria * WAGR syndrome (Wilms tumor, aniridia, genitourinary abnormality, mental retardation) * Wilms tumor occurs in 30–50% of cases * External genital anomalies occur only in males, often delaying recognition of WAGR in females * Late onset nephropathy is a well-recognized feature of this syndrome ## Treatment[edit | edit source] Due to the high risk of glaucoma and cataract formation, aniridia patients should be under the care of an ophthalmologist familiar with the condition. The risk of progressive glaucoma persists from childhood into adulthood, necessitating long-term follow-up. Optometrists and low vision specialists are often valuable in maximizing visual and social functioning, prescribing glasses, and amelioriating light sensitivity (photophobia). The iris functions to restrict the amount of light entering the eye, so if it is absent, most individuals with aniridia are sensitive to bright outdoor light and their eyes may need protecting. This can be done with tinted glasses, or with a contact lens which has an artificial iris painted onto it. Aniridia is often associated with other health and developmental problems, as well as complicating eye conditions such as: foveal hypoplasia, nystagmus, glaucoma, corneal disease, cataract, lens subluxation and optic nerve disease. ## References[edit | edit source] 1. ↑ W. J. Gehring (2001): The genetic control of eye development and its implications for the evolution of various eye-types, Zoology 104:171-181 ## Related Chapters[edit | edit source] * WAGR syndrome Template:Congenital malformations and deformations of eye, ear, face and neck * v * t * e * Diseases of the human eye (H00–H59 * 360–379) Adnexa | Eyelid| | Inflammation| * Stye * Chalazion * Blepharitis | * Entropion * Ectropion * Lagophthalmos * Blepharochalasis * Ptosis * Blepharophimosis * Xanthelasma Eyelash| * Trichiasis * Madarosis Lacrimal apparatus| * Dacryoadenitis * Epiphora * Dacryocystitis * Xerophthalmia Orbit| * Exophthalmos * Enophthalmos * Orbital cellulitis * Orbital lymphoma * Periorbital cellulitis Conjunctiva| * Conjunctivitis * allergic * Pterygium * Pinguecula * Subconjunctival hemorrhage Globe | Fibrous tunic| | Sclera| * Scleritis * Episcleritis | Cornea| * Keratitis * herpetic * acanthamoebic * fungal * Corneal ulcer * Photokeratitis * Thygeson's superficial punctate keratopathy * Corneal dystrophy * Fuchs' * Meesmann * Corneal ectasia * Keratoconus * Pellucid marginal degeneration * Keratoglobus * Terrien's marginal degeneration * Post-LASIK ectasia * Keratoconjunctivitis * sicca * Corneal neovascularization * Kayser–Fleischer ring * Haab's striae * Arcus senilis * Band keratopathy Vascular tunic| * Iris * Ciliary body * Uveitis * Intermediate uveitis * Hyphema * Rubeosis iridis * Persistent pupillary membrane * Iridodialysis * Synechia | Choroid| * Choroideremia * Choroiditis * Chorioretinitis Lens| * Cataract * Congenital cataract * Childhood cataract * Aphakia * Ectopia lentis Retina| * Retinitis * Chorioretinitis * Cytomegalovirus retinitis * Retinal detachment * Retinoschisis * Ocular ischemic syndrome / Central retinal vein occlusion * Central retinal artery occlusion * Branch retinal artery occlusion * Retinopathy * diabetic * hypertensive * Purtscher's * of prematurity * Bietti's crystalline dystrophy * Coats' disease * Macular degeneration * Retinitis pigmentosa * Retinal haemorrhage * Central serous retinopathy * Macular edema * Epiretinal membrane (Macular pucker) * Vitelliform macular dystrophy * Leber's congenital amaurosis * Birdshot chorioretinopathy Other| * Glaucoma / Ocular hypertension / Primary juvenile glaucoma * Floater * Leber's hereditary optic neuropathy * Red eye * Globe rupture * Keratomycosis * Phthisis bulbi * Persistent fetal vasculature / Persistent hyperplastic primary vitreous * Persistent tunica vasculosa lentis * Familial exudative vitreoretinopathy Pathways | Optic nerve Optic disc| * Optic neuritis * optic papillitis * Papilledema * Foster Kennedy syndrome * Optic atrophy * Optic disc drusen Optic neuropathy| * Ischemic * anterior (AION) * posterior (PION) * Kjer's * Leber's hereditary * Toxic and nutritional Strabismus Extraocular muscles Binocular vision Accommodation| | Paralytic strabismus| * Ophthalmoparesis * Chronic progressive external ophthalmoplegia * Kearns–Sayre syndrome palsies| * Oculomotor (III) * Fourth-nerve (IV) * Sixth-nerve (VI) Other strabismus| * Esotropia / Exotropia * Hypertropia * Heterophoria * Esophoria * Exophoria * Cyclotropia * Brown's syndrome * Duane syndrome Other binocular| * Conjugate gaze palsy * Convergence insufficiency * Internuclear ophthalmoplegia * One and a half syndrome Refraction| * Refractive error * Hyperopia * Myopia * Astigmatism * Anisometropia / Aniseikonia * Presbyopia Vision disorders Blindness| * Amblyopia * Leber's congenital amaurosis * Diplopia * Scotoma * Color blindness * Achromatopsia * Dichromacy * Monochromacy * Nyctalopia * Oguchi disease * Blindness / Vision loss / Visual impairment Anopsia| * Hemianopsia * binasal * bitemporal * homonymous * Quadrantanopia subjective| * Asthenopia * Hemeralopia * Photophobia * Scintillating scotoma Pupil| * Anisocoria * Argyll Robertson pupil * Marcus Gunn pupil * Adie syndrome * Miosis * Mydriasis * Cycloplegia * Parinaud's syndrome Other| * Nystagmus * Childhood blindness Infections * Trachoma * Onchocerciasis Template:WS *[v]: View this template *[t]: Discuss this template *[e]: Edit this template