Aniridia Clinical Presentation
- Author: Daljit Singh, MBBS, MS, DSc; Chief Editor: Hampton Roy, Sr, MD more...
The history is straightforward. The condition is discovered early in life, especially in whites. In blacks, the condition might remain undiscovered for a long time until an ophthalmologist examines the eyes for visual problems. The patient presents with the following problems:
- Absence of iris
- Reduced vision
Thorough family history includes the following:
- Specific inquiry about any ocular abnormality and/or low vision
- Dental anomaly
- Protruding umbilicus
- Genitourinary abnormalities (Wilms tumor)
- Mental retardation
Perform a thorough systemic examination of the patient.
A detailed ocular examination is sometimes difficult because of photophobia and nystagmus. If slit lamp flash pictures are taken, they can provide detailed information on corneal opacities and blood vessels, the depth of the anterior chamber, the edge of a transparent dislocated lens, the presence or absence of zonular fibers, and the presence of lenticular opacities. Photographs are useful to observe changes in the tissues with the passage of time. A picture session is especially important in children.
The patient might show the following findings:
- Anterior chamber
- Best judged with a slit lamp microscope
- Configuration dependent upon the position of the crystalline lens
- Complete absence of iris on oblique illumination
- Hypoplasia with irregular pupillary margins (atypical coloboma of pupil)
- Root of the iris visible on gonioscopy
- Angle of the anterior chamber - Trabecular meshwork may be partially or completely covered by the iris stump.
- Vitreous - Usually normal
- Optic nerve hypoplasia
- Macular reflex dull
- Glaucomatous cupping
- Intraocular pressure
- Vision - Usually about 20/200 or less
Aniridia is caused by the following:
- An identifiable chromosome deletion of the short arm of chromosome 11, including band p13.
- Patients with aniridia who have a positive family history: Two genetic loci for aniridia have been identified, one (AN1) on chromosome arm 2p and one (AN2) on chromosome 11.
- As an isolated ocular malformation, aniridia is an autosomal dominant disorder, which is caused by a mutation in the PAX6 (paired box gene family) gene.
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