The iris is a natural light-transmitting diaphragm with an opening at the center called the pupil. The iris comprises a capillary vascular network, connective tissue, and melanocytes framework.
The iris is a sensitive and delicate ocular structure that can be damaged due to blunt, penetrating, or iatrogenic trauma.
Traumatic injury to the iris can manifest with varied symptoms depending on the extent of injury, site of injury, and severity of symptoms. The manifestation can be dilated atonic pupil, sluggishly reactive pupil secondary to sphincter damage.
Iris root can also be damaged, leading to iridodialysis. Full or partial-thickness defects can occur at the stromal level, leading to iris transillumination defects. The traumatic damage can be managed non-surgically as well as surgically.
The non-surgical treatment modalities can be miotics and the use of contact lenses. Surgical repair techniques can be corneal tattooing, laser iridoplasty, iridopexy, closed globe single-armed or double-armed peripheral approach, cross pupil approach, lasso technique, open globe approach, and prosthesis insertion.
In some cases, patients are born with defects in their iris, and other inherited conditions may even involve absence of the iris. In these types of cases, the surgeon may offer a form of iris surgery to the patient.
Symptoms of iris conditions are usually secondary to the amount of light that enters the eye, and patients typically report light sensitivity (photophobia) due to excessive light exposure.
Iris repair often involves the use of sutures inside the eye to reshape the iris to its original shape, re-creating a round pupil. Sometimes the surgeon may cut some of the existing iris to help improve the appearance.
If the iris is so badly damaged that it cannot be repaired, an iris prosthesis can be used. Iris prosthetics involves inserting a custom made artificial iris that is carefully matched to the color of the other eye.
This artificial iris can be sutured to the wall of the eye (sclera) in front of the “bag” that holds the lens, a region called the sulcus. Alternatively, the artificial iris can be placed inside the “bag” in a combined procedure with cataract surgery.
Iris reconstructive surgery is among the most difficult operations performed by the anterior segment surgeon, especially after ocular trauma.
Patients in need of such reconstructive efforts, either in cases of congenital, traumatic or other causes of iris loss, often are significantly debilitated by light and glare sensitivity, as well as other visual disturbances resulting from a compromised iris diaphragm.
The visual dysfunction may vary from mild to severe. Other symptoms include reduced visual acuity and contrast sensitivity loss. In addition, cosmetic issues are often present, especially when a patient has a light-colored iris. Abnormalities of pupil size, shape and location may also be reasons for pupil reconstruction.
In cases of open globe injuries when there is iris prolapse, it is good to make a paracentesis opposite to the area of the prolapse; this is followed by injection of a minimal amount of a viscoelastic and gentle repositioning of the iris using an iris sweep.
Injecting excessive viscoelastic can result in increased pressure and additional iris prolapse. An important point in such cases is to avoid inadvertent incarceration of the iris into the suture as well as to avoid cutting the iris, except in cases in which it is frankly necrotic or epithelialized because the iris tissue can be used for future reconstruction.
Traumatic mydriasis can result from open or closed globe injuries. Given as an example, a case with an iris sphincter tear a superior iridodialysis, which is defined as separation of the iris from its attachment to the ciliary body, and a traumatic cataract.
Diffuse dilation also can occur following trauma. In these cases, if the patient is symptomatic, surgical repair can be performed at the time of the cataract surgery. The repair process is by pupilloplasty with an internal Siepser sliding knot.
When performing a pupilloplasty, a 9-0 or 10-0 Prolene suture on a long CTC needle is first passed through a paracentesis at the limbus. It is important to move the needle side to side in the paracentesis to ensure no cornea tissue has been inadvertently caught.
MaxGrip forceps through a paracentesis can be used to stabilize the iris for passage of the suture. A loop is then externalized through the paracentesis and a Siepser knot is tied. If the iris assumes a keyhole appearance, a second bite may be necessary to eliminate the small second created opening.
In some cases, a iridodialysis may be small, cause no symptoms, and be obscured by the superior eyelid. An iridodialysis that is symptomatic can cause diplopia or polycoria, glare, or photophobia require surgery.
When surgery is required, there are 2 ways to proceed. In the first case, the iridodialysis can be corrected by creating a scleral flap; 9-0 or 10-0 Prolene sutures on double-armed Drews needles are passed through a paracentesis created on the side opposite to the site of the iridodialysis.
The sutures are threaded internally in the eye using a 27-gauge needle to dock and externalize the sutures, which then are tied under the scleral flap. Second approach is to perform the surgery using a Hoffman pocket to avoid creation of a peritomy.
In cases of extensive traumatic aniridia, implantation of an artificial iris (Customflex artificial iris; HumanOptics) may be possible. This device, approved by the United States Food and Drug Administration, is 12.8 mm in diameter with a pupil diameter of about 3.35 mm.
The device is customized to match the color of the patient’s fellow eye. The device can be trephined to ensure a perfect fit in the patient’s eye. Currently, the cost of the device can be prohibitive, which is the main disadvantage, and it is not covered by insurance in all cases.