Iris prolapse refers to the protrusion of the iris after an injury to the cornea. The iris is the circular diaphragm forming the colored part of the eye. Even though the root of the iris is attached to the ciliary body, the remaining part of the iris is not supported. That would explain why a wound on the cornea could easily cause an iris prolapse.
Iris prolapse can occur as part of intraoperative floppy iris syndrome (IFIS) during cataract surgery. It is an emergency that should be attended to within 24 hours. If left untreated, iris prolapse can lead to infection and possibly loss of the eye. However, if the prolapsed iris is covered by the conjunctiva, immediate surgery is not necessary.
Causes and Risk Factors
Iris prolapse occurs as a result of a cornea perforation. The aqueous humor quickly escapes creating a vacuum that leads to the prolapse. It can occur:
- Post-surgical as a result of cataract surgery or corneal transplant
- Post-trauma such as in corneal laceration, sclera laceration
- From a punctured corneal ulcer
- With Rheumatoid arthritis-related corneal melt
Improvements in modern medicine means that iris prolapse after surgery is rare. It is also rare with a perforated corneal ulcer. The most common cause is trauma.
Iris prolapse affects young men more than it does women.
Signs & Symptoms
The signs of a prolapsed iris include:
- Appearance of a knuckle-like colored tissue
- An exposed prolapsed iris in a perforated cornea
- When an entire pupillary margin prolapses
- The iris may appear dry and viable
The eye professional will perform a complete eye examination. He/she may do the following:
- A CT scan to check for intraocular foreign bodies
- Gentle dilation to check if the Intraocular lens (IOL) is loose
- Use the seidel test to verify the wound leak
- Examine the wound using a slit lamp
- Ocular coherence tomography (OCT) and fluorescein angiography tests if he/she suspects cystoid macular edema
Treatment of iris prolapse is aimed towards restoring the function of the iris. It is also focuses on healing the cornea and preventing infection.
If the prolapse is small, medical treatment can be indicated. Medical treatment is also recommended if the prolapsed iris rests under the conjunctiva and there is no other complication. Eye observation and antibiotic eye drops are used. Intravenous antibiotics will help prevent infection.
Immediate surgical repair (excision of the prolapsed iris) is necessary in the absence of a conjunctival cover. It is also recommended for iris prolapse that comes with complications. At this point, visual restoration is secondary to the restoration of the anatomical integrity of the eye.
Surgical options will depend on the cause. If a corneal perforation caused the prolapse, the surgeon will reposit the iris. The wound is sealed using a bandage contact lens and glue. Should this procedure fail, the surgeon will perform an emergency corneal transplant.
Different cataract surgical techniques can manage IFIS. They include pupil expander rings and preoperative atropine drops to help dilate the pupil. Ophthalmic viscoelastic devices, iris retractors, and intracameral epinephrine can be used.
Topical antibiotics may be administered before and after surgery. A postoperative NSAID and steroid is good especially for patients with Usher’s syndrome. The drug may help prevent incidents of cystoid macular edema. Patients can also use systemic antibiotics for one week after surgery.
An iris prolapse may present the following complications:
- Intraocular infections like endophthalmitis. Other postoperative risks include epithelial ingrowth, symptomatic glare, glaucoma and others
- An epithelial and fibrous tissue that can grow into the eye and cover the prolapsed iris
- Iris prolapse can occur in the other eye although it rarely happens
- Iritis and cystoid macular edema can arise
- Secondary glaucoma may result from synechiae, epithelial downgrowth and iritis
- Another iris prolapse may occur after surgery
The prognosis depends on the nature of the prolapse. A smaller prolapse has a better prognosis. A traumatic prolapse and one with infection may have a poor prognosis.
The patient needs constant monitoring to prevent infections. He/she may be hospitalized or treated as an outpatient. The patient should also receive a tetanus and diphtheria vaccination if he/she last received it seven years ago. Should corneal sutures get loose, they can be removed in stages after 4-6 weeks. Intraocular pressure and cataract formation should be monitored in the long-term.
Individuals should wear protective eyewear during sports.
If working with mechanical tools and devices, an individual should be advised to wear polycarbonate eyeglasses.