eMedicine Specialties > Ophthalmology > Iris & Ciliary Body

Iris Prolapse

Author: Guruswami Arunagiri, MD, FRCS, Consulting Staff, Department of Ophthalmology, Geisinger Medical Center
Contributor Information and Disclosures

Updated: Dec 17, 2008

Introduction

Background

The iris is a thin, colored diaphragm that is situated anterior to the lens. Although the root of the iris is attached to the ciliary body, the rest of the iris is unsupported. In the event of a corneal wound, the iris tends to prolapse out. Iris prolapse occurs when the iris tissue is observed outside of the wound; iris incarceration occurs when the iris tissue reaches the wound without prolapsing outside the eye.

Iris prolapse may also occur as part of a condition called intraoperative floppy iris syndrome (IFIS) during cataract surgery or trabeculectomy. This condition is associated with the use of several systemic alpha 1-adrenergic antagonists, such as tamsulosin (Flomax). Intraoperative floppy iris syndrome is characterized by poor pupillary dilation, progressive pupillary constriction, and intraoperative iris bellowing.

Pathophysiology

Iris prolapse can occur when the cornea is perforated due to any cause.

In 1995, using flow mechanics and the Bernoulli principle, Allan provided a theoretical explanation of iris prolapse.¹ With a corneal perforation, the aqueous humor rapidly escapes, and a relative vacuum is created in front of the iris, thus leading to iris prolapse.

Frequency

United States

The exact incidence of iris prolapse in the United States is unknown, but the overall estimated rate of all eye injuries ranges from 8.2-13 per 1000 population. Eye injury rates are highest among individuals in their 20s, males, and whites.

International

The incidence rate worldwide is unknown.

Mortality/Morbidity

Iris prolapse is a serious condition and, if left untreated, can result in infection and loss of the eye. If the prolapsed iris is exposed (eg, corneal laceration), immediate surgical intervention is needed because infection can spread through the iris and into the eye. If the prolapsed iris is covered by the overlying conjunctiva (eg, surgical wound), immediate surgical intervention is usually not needed.

Race

No racial predilection exists.

Sex

Iris prolapse is probably more common in young men than in young women.

Age

Age is not a significant factor for iris prolapse.

Clinical

History

• The iris is a sensitive tissue in the eye. At the time of an iris prolapse, patients often experience pain. Patients with a perforated corneal ulcer frequently provide a history of severe pain that has since subsided.
• The iris can prolapse after surgery (eg, cataract, corneal transplant), following trauma (eg, corneal laceration, scleral laceration), through a perforated corneal ulcer, or through a corneal melt associated with rheumatoid arthritis.
  • With improvements in microsurgical techniques, iris prolapse after surgery is uncommon.
  • Iris prolapse with a perforated corneal ulcer is rare.
  • In the author's experience, the most common cause of iris prolapse is following trauma; however, the exact incidence is not known.

Physical

In peripheral iris prolapse, the iris appears as a knuckle of colored tissue, resulting in a partial peripheral synechia. When the prolapse is central, the entire pupillary margin may prolapse, resulting in a total anterior synechia. In patients with a perforated cornea, the prolapsed iris is exposed.

Depending on the duration of prolapse, the appearance of the iris may vary. In cases of recent prolapse, the iris appears viable. With time, the iris appears dry and nonviable. In patients who have undergone corneal transplant surgery or cataract surgery with a clear corneal incision, the appearance of the iris is the same as in a perforated cornea. When the iris prolapses through a scleral wound, it appears as a colored mass beneath the overlying conjunctiva. In this case, the iris remains viable for a long time.

• The pupil appears peaked in the region of the iris prolapse. The anterior chamber is formed as the prolapsed iris seals the wound. Minimal or no wound leakage occurs. Wound leak is verified using the Seidel test. A drop of 2% fluorescein sodium is instilled in the conjunctival sac. The wound is examined under the slit lamp with cobalt blue light. The fluorescein appears greenish. Wound leak can be easily identified when the fluorescein is diluted by the aqueous humor. Gentle pressure on the eye may be needed to induce leakage.
• Intraocular pressure is lower than normal, but hypotony is uncommon after iris prolapse.
• In long-standing iris prolapse, chronic iridocyclitis, cystoid macular edema, or glaucoma may be seen. The prolapsed iris may act as a scaffold for infection, epithelial downgrowth, or fibrous ingrowth. Rarely, sympathetic ophthalmia may occur. Carefully examining the fellow eye for cells and flare is important.

Causes

Iris prolapse can occur following trauma, after surgery, through a perforated corneal ulcer, or through a corneal melt.

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