Ramin Schadlu

BASICS

DESCRIPTION

• Iris atrophy can be caused by a myriad of ocular disorders.

– The etiology can be determined by careful history taking and physical examination.

Pediatric Considerations

Iris atrophy in the pediatric population may indicate syndromes such as ocular albinism or Axenfeld–Rieger syndrome.

Pregnancy Considerations

Iris atrophy with uveitis in a pregnant patient may suggest a diagnosis of herpes simplex, herpes zoster, or Fuchs’ heterochromic iridocyclitis (linked to rubella virus). All of these infectious etiologies should be addressed.

EPIDEMIOLOGY

Incidence

The incidence varies depending upon the etiology and the population in question. Iridocorneal endothelial (ICE) syndrome is quite rare, whereas herpes zoster iritis occurs in ∼43% of patients with herpes zoster ophthalmicus, a fairly common condition (1).

Prevalence

The prevalence varies depending upon the etiology of the iris atrophy. In patients with Fuchs’ heterochromic iridocyclitis, the prevalence of iris atrophy approaches 90% (2).

RISK FACTORS

History of common causes of iris atrophy such as chronic or recurrent uveitis and certain types of glaucoma

Genetics

• Axenfeld–Rieger syndrome is autosomal dominant. The responsible gene has been isolated to chromosome 4q25.

• Ocular albinism follows all of the inheritance patterns, including X-linked recessive pattern.

PATHOPHYSIOLOGY

• In cases of chronic inflammation, iris atrophy manifests as loss of detail and density of the anterior iris as the iris stroma breaks down.

• In Axenfeld–Rieger syndrome, iris atrophy results from abnormal embryologic development of the iris and anterior chamber angle.

• In ocular albinism, the number of melanosomes in the iris pigment epithelium is decreased, resulting in transillumination defects.

ETIOLOGY

• Herpes simplex uveitis

• Herpes zoster uveitis

• Fuchs’ heterochromic iridocyclitis

• Pigment dispersion syndrome and secondary glaucoma

• Pseudophakic pigment dispersion from iris chafing

• Traumatic or iatrogenic

• ICE syndrome

– Essential iris atrophy subtype

– Minimal iris atrophy may also be seen in Chandler’s syndrome and Cogan–Reese syndrome subtypes.

• Axenfeld–Rieger syndrome

• Ocular albinism

• Ischemic iridopathy

– Diabetic

– Ocular ischemic syndrome

– Systemic cryoglobulinemia

COMMONLY ASSOCIATED CONDITIONS

• Chronic uveitis

• Glaucoma

• Cataract

DIAGNOSIS

HISTORY

Patients may be any age. They should be questioned for a history of recurrent red eye, pain, glaucoma, and visual loss.

PHYSICAL EXAM

• The patient’s visual acuity and intraocular pressure should be accurately determined.

– Increased intraocular pressure can be seen in:

Herpes simplex uveitis, herpes zoster uveitis, Fuchs’ heterochromic uveitis, any form of chronic uveitis, ICE syndrome, Axenfeld–Rieger syndrome, and pigment dispersion glaucoma

• Laterality of the iris atrophy is important in making the diagnosis of the underlying disease.

• Fuchs’ heterochromic iridocyclitis and herpetic uveitis are typically unilateral, but can be bilateral. ICE syndrome is unilateral, whereas Axenfeld—Rieger syndrome is bilateral.

• Iris atrophy can be subtle. It is best detected by performing transillumination in the slit-lamp exam.

• Different patterns of iris atrophy may suggest the underlying disorder

– Iris atrophy at the pupillary margin and/or persistent pupillary dilation suggests herpes simplex uveitis (3).

– Sectoral iris atrophy suggests herpes zoster uveitis or herpes simplex uveitis (4).

– Diffuse atrophy suggests Fuchs’ heterochromic iridocyclitis.

– Radial iris atrophy suggests pigment dispersion syndrome (which can cause secondary glaucoma). This pattern results from the lens zonules eroding the iris pigment epithelium.

– Iris corectopia, ectropion uveae, and/or iris hole formation can be seen in ICE and Axenfeld–Rieger syndromes.

• The corneal exam can also aid in diagnosis.

– Corneal edema can be seen in ICE syndrome.

– Keratic precipitates on the corneal endothelium suggest prior or current anterior uveitis. Diffuse keratic precipitates are seen in herpetic uveitis and Fuchs’ heterochromic uveitis.

• Gonioscopy should be performed.

– Peripheral anterior synechiae suggest prior uveitis or ICE syndrome.

– Heavily pigmented trabecular meshwork suggests pigment dispersion syndrome.

• The presence of a cataract can suggest chronic uveitis.

• The posterior segment examination is important in the workup of iris atrophy.

– The optic nerve should be evaluated for glaucomatous cupping.

– The retina should be examined for signs of ocular albinism as well as ischemic processes.

DIAGNOSTIC TESTS & INTERPRETATION

Lab

Initial lab tests

• Laboratory testing is not often indicated, but can be directed by the suspected underlying diagnosis.

– PCR can be performed on aqueous samples to detect herpes simplex, varicella zoster, or rubella virus.

Follow-up & special considerations

Patients with iris atrophy from any etiology should be monitored for glaucoma, cataract formation, and visual loss.

Imaging

• Slit-lamp photographs with and without transillumination may be obtained to document the degree of iris atrophy.

• In cases where iris-chafe from an intraocular lens implant or dislocated crystalline lens is suspected, anterior-segment high-resolution biomicroscopy can be performed to identify the lens location.

DIFFERENTIAL DIAGNOSIS

• Herpes simplex uveitis

• Herpes zoster uveitis

• Fuchs’ heterochromic iridocyclitis

• Pigment dispersion syndrome and secondary glaucoma

• Pseudophakic pigment dispersion

• Iatrogenic

• Trauma

• ICE syndrome

• Axenfeld–Rieger syndrome

• Ocular albinism

• Ischemic iridopathy

– Diabetic

– Ocular ischemic syndrome

– Systemic cryoglobulinemia

TREATMENT

MEDICATION

• The underlying condition should be treated, if indicated, with topical steroids or oral antivirals.

• Glaucoma should be treated with topical drops and surgery if indicated.

ADDITIONAL TREATMENT

Issues for Referral

• Patients in whom the IOP is not controlled with topical drops, or who have progressive visual field loss, should be referred to a glaucoma specialist.

• Patients with suspected Axenfeld–Rieger syndrome or ocular albinism should be evaluated by a pediatrician and a geneticist.

SURGERY/OTHER PROCEDURES

Cataract surgery and glaucoma surgery may be indicated in the management of patients with iris atrophy due to various causes.

ONGOING CARE

FOLLOW-UP RECOMMENDATIONS

Patients need regularly scheduled follow-up visits depending on the presence of glaucoma and cataracts.

PATIENT EDUCATION

• Patients should be educated on the need for regular follow up and the importance of compliance with glaucoma medications.

• Patients with genetic causes of iris atrophy should receive genetic counseling.

PROGNOSIS

Visual prognosis varies depending on the etiology of the iris atrophy.

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