Aniridia is a condition where the iris (colored part around pupil) is missing partially or fully. Some people develop it later from trauma or surgery. But others are born with it, called congenital aniridia, affecting both eyes. Most congenital cases are inherited in an autosomal dominant pattern. But some irregular congenital aniridia cases occur sporadically, like with WAGR syndrome. This rare disorder involves Wilms tumor, aniridia, genital abnormalities, and intellectual disability. Gillespie syndrome is another rare, recessively inherited form with aniridia, ataxia, and intellectual disability. Scientists linked congenital aniridia to mutations in the PAX6 gene on chromosome 11p13. Acquired aniridia occurs following surgery or trauma to the eyes.

Approximately 1,800 babies out of every 100 million newborns experience aniridia. Gender plays no significant role as it affects men and women in a similar way.

The cause of congenital aniridia has been connected to several genes. Aniridia 1 or AN1 (OMIM # 106210) results from a mutation in the PAX6 gene on chromosome 11p13. It is inherited in an autosomal dominant pattern. Other features may include congenital cataracts, late onset corneal dystrophy, absence of the pineal gland, underdeveloped corpus callosum or anterior commissure, reduced sense of smell, and Peters anomaly. A different mutation, in a regulatory region near the ELP4 gene’s intron on 11p13, leads to Aniridia 2 (AN2) (OMIM # 617141. TRIM44 gene mutations on 11p13 cause Aniridia 3 (AN3) (OMIM # 617142), an autosomal dominant disorder as aniridia 2. The ITPR1 gene on 3p26.1, when mutated, results in Gillespie syndrome (OMIM # 206700). Some studies suggest that autosomal dominant aniridia may connect to the acid phosphatase 1 (ACP1) gene on chromosome 2p.

The most important reason for congenital aniridia is the paired box gene or PAX6 found on chromosome 11p13. This uncommon genetic disorder affects the development of key body parts during the embryo stage. Theories suggest that it may relate to abnormalities in the mesoderm, neuroectoderm, or iris coloboma. Congenital aniridia can be categorized as sporadic, autosomal recessive, or autosomal dominant condition. Autosomal dominant is most common in up to 85% of cases. Sporadic congenital aniridia results from a new gene mutation, sometimes linked to nephroblastoma and WAGR syndrome. The rarest form, autosomal recessive aniridia, is associated with mental delays and impaired coordination of cerebellum. Still, the precise cause behind aniridia remains unclear.

Aniridia causes vision problems from birth. Common signs include decreased eyesight, involuntary eye movements, sensitivity to light, crossed eyes, and missing iris. Reviewing family medical records for developmental delays, hearing issues, belly button positioning, digestive problems, and eye abnormalities is crucial. A thorough, multisystem evaluation is essential for proper diagnosis.

Slit lamp flash images show fine details like the depth of the anterior eye chamber, zonular fibers connecting the crystalline lens to the ciliary body, cloudy spots on the lens (lenticular opacities), cloudy spots on the cornea (corneal opacities), and the edge of a dislocated but transparent lens. Especially in children, these images help to track tissue changes over time. Besides aniridia associated keratopathy, the patient may show symptoms like abnormally small cornea (microcornea), premature arcus clouding around the cornea’s periphery (arcus juvenilis), involuntary eye movements (nystagmus), misaligned eyes (strabismus), light sensitivity (photophobia), corneal surface inflammation with blood vessel growth (pannus), and sores on the cornea’s outermost layer (epithelial ulcers). Depending on the position of the crystalline lens, the arrangement inside the anterior chamber varies. Sometimes, there is no iris at all, other times, it appears underdeveloped with irregular pupil margins. The iris root, or stump, may hide part or all of the drainage angle of the anterior chamber, when viewed through a specialized lens (gonioscopy).

Aniridia can be complicated due to

1. Glaucoma
2. Painless or painful blind eye
3. Systemic associations such as Wilms tumor
4. Aniridic fibrosis syndrome

Correction of refractive errors: Aniridia patients frequently experience refractive errors. Their eyes commonly have conditions like nearsightedness, farsightedness, or astigmatism. However, prescribed glasses or contact lens can correct these vision issues, enhancing visual clarity.

Management of photophobia: Light sensitivity, also known as photophobia, is a frequent issue for people with aniridia. They often find bright spaces uncomfortable. To make things easier, wearing tinted or polarized lenses can help reduce glare. In addition, having a wide brimmed hat or sunglasses with extra coverage provides more light protection and relief from bright conditions.

Treatment of nystagmus: Nystagmus is an involuntary, rhythmic eye movement. It impacts vision clarity a lot. There is no cure for nystagmus yet. However, some medicines may help reduce eye movements for some people. Anti-seizure drugs like gabapentin or muscle relaxants such as baclofen could help. Vision therapy exercises may also improve eye stability and control.

Surgical interventions: Aniridia patients may require surgeries for complications. Possibilities include:

Cataract surgery removes cloudy lenses, restoring vision. Aniridia raises cataract risk at younger ages due to abnormal eye development.

Keratoplasty transplants corneas for thinning (keratopathy) or scarring, improving transparency and vision. Corneal issues can occur with aniridia.

Glaucoma management treats increased eye pressure damaging optic nerves and increasing risk of vision loss. Glaucoma is more common with aniridia. Treatment options may include medications, laser therapy, surgeries like trabeculectomy or drainage implants.

Ophthalmology

Protective eye wear:

For people with aniridia, specialized eyewear provides relief from challenges. Tinted or polarized lenses reduce glare, helping eyes to feel comfortable in bright places. Glasses or contact lens fix vision problems. Wearing hats or wraparound sunglasses offers protection from the sun. These block harsh rays, minimizing discomfort. As a result, outdoor activities become more convenient.

Vision therapy: For improving vision stability, coordination, and perce­ption in aniridia patients, vision therapy methods might ge­t used. A skilled vision therapist dire­cts these exe­rcises. They work to boost visual abilities. The­y help ease symptoms like­ nystagmus and depth insight problems.

Assistive devices: Individuals living with aniridia have access to support devices. Simple tools like magnifiers help improve reduced vision. Also, audio technology assists with reading digital content and navigation. Other low-vision aids compensate for vision challenges in everyday tasks.

Modification of the environment: People with aniridia face visual challenges. Simple changes at home and work can make things easier for them. Brighter lights help them see better. Reducing harsh glare from windows or lamps is important too. Moving furniture or objects out of the way prevents bumping into things. These basic accommodations aid navigation and performing tasks more safely.

Ophthalmology

• Treatment options for aniridia-related limb stem cell deficiency include the following:
  Use of lubricating drops
  b. Administration of pulses of topical steroids
  c. Treating with ointments containing vitamin A
  d. use of drops of autologous serum
  e. Bevacizumab drops for topical use have been shown in one study.
  f. Transplantation of limb stem cells
• Controlling intraocular pressure is the goal of medical treatment for aniridia, and topical application of the following medications is part of that treatment:
  Employemnt of miotics
  b. Use of beta-blockers
  c. Use of sympathomimetics
  d. Administration of inhibitors of carbonic anhydrase IV
  e. Use of analogs of prostaglandins

Ophthalmology

• Corneal opacification manage­ment for patients having aniridia-relate­d keratopathy involves:

1. Transplantation of limbal stem cell
2. Keratoplasty
3. Simultaneous lamellar keratoplasty and limbal graft
4. Keratoprosthesis

• In patients of aniridia, cataract can be treated by

1. Implantation of in-the- bag lens where dislocation of lens in not seen.
2. Placement of in-the-bag IOL with intracapsular rings in case of slight displacement of lens.
3. To form an artificial pupil, opaque intracapsular ring should be used.
4. If the lens is almost dislocated, extraction of lens followed by correction of contact lens should be done.
5. Extraction of lens after scleral fixation of posterior chamber lens.

• For managing glaucoma in patients with aniridia following procedures may be employed:

1. Goniotomy
2. Trabeculotomy
3. Laser therapy for correcting angle abnormality
4. Cyclocryotherapy
5. Filterating procedures
6. Glaucoma valve procedure

Ophthalmology

• Diagnosis: The right diagnosis of aniridia is very important. It needs doctors to look at medical history of patient and perform a thorough examination. Opthalmologists employ special tests like slit-lamp test, vision checks, and imaging to see how much of the iris is missing and identify any issues present. Doctors may recommend genetic testing also. This can confirm the diagnosis of aniridia and find the specific gene changes that caused it. Knowing the gene changes can guide in treatment choices and provide helpful information for genetic counselling.
• Symptomatic management: Many people with aniridia need correction for refractive errors. These include near sightedness, farsightedness, and astigmatism problems that frequently occur alongside aniridia. For better vision, eyeglasses or contact lenses may help. Photophobia is another issue, where bright light feels uncomfortable. To reduce light sensitivity, wear sunglasses, hats with wide brims, or use tinted lenses. Dim indoor lighting helps too. Nystagmus, or involuntary eye movements, is tricky. There is no cure, but sometimes devices, vision therapy, or medicine can steady the eyes.
• Medical and surgical intervention: Cataracts are clouded eye lenses that diminish sight. Since aniridia raises cataract risk, surgery may remove clouded lenses and improve vision. Glaucoma can also arise from aniridia. Checking eye pressure constantly and treating it helps prevent vision loss. Eye drops, laser therapy, or procedures like trabeculectomy may control glaucoma. If corneas grow thin, scarred, or unclear, a corneal transplant is needed. This surgery called keratoplasty boosts corneal transparency and visual clarity.
• Rehabilitation phase: Vision rehabilitation programs aim to increase eye function and promote independence in everyday tasks. Examples include low-vision aids, technology assistance, and training for navigation. Educational resources, assistive tech, and job training programs support those with aniridia. They help achieve academic and career goals that visual impairment may impact.