Overview of Traumatic Iris Reconstruction
The iris is the colored part of the eye that controls the amount of light going into the pupil, the black hole in the center of the eye. It does this by changing the size of the pupil. The iris not only controls the light but it also helps us see clearly. It does this by handling any blurring caused by the lens and cornea, or the outer parts of the eye, by controlling the amount of light that enters the pupil, preventing too much brightness, and helping us see things in depth.
Unfortunately, if the iris gets injured, it could cause discomfort from too much light (glare), sensitivity to light (photophobia), cosmetic problems, and trouble seeing things clearly especially against a bright background (contrast sensitivity).
Way back in 1917, a man by the name of Key was the first to try to fix a damaged iris by suing it to the nearby white part of the eye. Later in 1957, Emmerich proposed the idea of repairing the iris by attaching it to itself. However, due to the lack of the right equipment and microscopes, these methods took a while to become popular.
Traumatic damage to the iris can range from tears in various parts, defects that allow light to pass through, or even a complete loss of the iris. There are many ways to treat a damaged iris, both surgical and non-surgical, which are discussed further in this activity.
Anatomy and Physiology of Traumatic Iris Reconstruction
The human iris, which is the colored part of the eye, consists of two sections: the front or anterior stromal section and the back or posterior pigmented epithelium. There are two muscles inside the iris – the iris dilator muscle and the sphincter pupillae muscle. These muscles are sandwiched between the front and back layers of the iris.
The stromal layer is made up of various cells, such as stromal cells, melanocytes (pigment cells), and fibrocytes (connective tissue cells). Between these cells, there are large gaps filled with collagen fibers, some sort of matrix, and a fluid called aqueous humor. There are also small channels or crypts in the stroma that allow this fluid to pass through. This layer also contains blood vessels and compound known as hyaluronic acid, which helps give it elasticity, particularly during eye surgery.
The posterior layer of the iris is one continuous layer. It’s the part that contacts with the ring of the sphincter muscle, the pigmented epithelium (the layer that gives the iris its color), and the muscle fibers of the dilator pupillae. The thickness of the dilator pupillae muscle is greatest at its origin – called the iris root – and gradually thins out towards the edge of the iris. It is important to note that any cuts or injuries to the iris don’t naturally heal. In a surgical procedure called iridotomy, a hole is made in the iris, but there’s no support for the stromal and pigment cells, or the fibroblasts to migrate and form a bridge to repair the hole. So, no fibrosis (formation of fibrous tissue) or scarring happens at this site.
Research has shown that healing in iris defects can only occur near a suture (a stitch). In this area, scarring occurs with the buildup of fibroblasts, plasma cells, and macrophages (types of immune cells). The long-term strength of the iris defect depends on the presence of this suture. The hole in the iris heals by forming a cyclitic membrane due to a reaction that involves fibrinoid, a protein involved in blood clotting. Blood vessels are also found in the iris, divided into the major and minor arterial arcs. The major arc provides blood to the ciliary body (a muscular part of the eye), and the minor arc supplies the stromal part of the iris. These blood vessels can cause a bloody eye, or hyphema, if the iris is injured.
Why do People Need Traumatic Iris Reconstruction
Your eyes can get injured in many ways such as a foreign object entering the eye, cuts or punctures, or even through certain medical procedures. These injuries are called penetrating injuries and can cause the muscles in your eyes that control your pupil (iris) to stretch or become damaged. Temporary pupil widening can also happen from these injuries. These are conditions medically known as ‘Open globe Injuries’, ‘traumatic mydriasis’ and ‘Iatrogenic surgical trauma’.
Blunt trauma, like a hard blow to your eye, can also cause damage to your iris, leading to conditions known as ‘Iridodialysis’ and ‘traumatic mydriasis’. This means that your iris, the colored part of your eye, detaches or the muscles controlling the size of your pupils are damaged.
Some eye issues can be caused by your genes. Two such conditions are ‘Iridocorneal endothelial syndrome’ and ‘Axenfeld-Reigler syndrome’, which involve changes in your iris that can affect your vision. You can also be born with a hole or defect in your iris, which is called ‘iris coloboma’.
Certain eye surgeries could lead to changes in your iris. This could happen during procedures to treat inflammation in your eyes (uveitis), surgeries to help the liquid in your eyes drain better (trabeculectomy), when removing cataracts, or when replacing the clear front surface of your eye (penetrating keratoplasty). Additionally, placement of a specific type of contact lens inside the eye, known as ‘implantable Collamer lenses’, could also affect the iris.
‘Laser peripheral iridotomy’ is a procedure used to create a small hole in the iris to relieve pressure in the eye. This procedure is commonly used for people suffering from a type of eye disease called ‘glaucoma’, where the pressure inside the eye is too high. Certain types of glaucoma that can be treated this way include ‘primary angle-closure glaucoma’, ‘primary angle-closure’, ‘acute angle-closure glaucoma’ and ‘pupillary block glaucoma’.
Eye conditions can also arise without a clear cause. For instance, in a condition known as ‘idiopathic floppy iris syndrome’, the iris is abnormally flexible and tends to move too much. This can cause the iris to sag, pop out of place, tear, or rub against other parts of the eye.
‘Pseudoexfoliation’ is a situation where flaky, dandruff-like material peels off the lens inside your eye and can cause the iris to detach. A severe inflammatory condition of the eye known as ‘uveitis’ may also lead to ‘Iridodialysis’. Getting hurt in the eye might also lead to problems like sensitivity to light, seeing double out of one eye, and an unusual amount of brightness or light reflection.
In rare cases, some people might get surgery because they’re unhappy with how their eyes look. Changes in the look of the eye might also happen due to an eye surgery performed in the past. These scenarios highlight the variety of situations and conditions that can affect our eyes.
When a Person Should Avoid Traumatic Iris Reconstruction
In some situations, the damage to the iris, which is the colored part of your eye, doesn’t have a major impact on your vision. This could be after an injury to your eye where the layer covering the eye (cornea) is torn, when the iris itself is damaged (iridodialysis), or when the lens of the eye needs to be removed. In these cases, fixing the iris isn’t the most crucial task compared to fixing other parts of the eye.
Moreover, if the patient doesn’t see any difference in their vision and doesn’t want to go through an iris repair surgery, it might not be necessary to do so. Also, during some conditions such as hyphema – a condition where blood fills the front area of the eye, limiting the inner sight of the eye, the surgery may not be possible.
Further, if the iris has been sticking out (prolapsed) and has dead tissue for more than a day, or if there are signs of an eye infection called endophthalmitis, surgery may not be suitable. Finally, if the top part of the iris is damaged (superior iridodialysis), but the eyelid is shielding the eye from light sensitivity (photophobia), iris repair might be unnecessary.
Equipment used for Traumatic Iris Reconstruction
When performing certain medical procedures, doctors use specialized tools to ensure accuracy and care. Some of these tools include:
- Angle suture tying forceps: These are used to securely tie sutures, which are stitches used to close wounds.
- Anterior chamber maintainer (Lewicki): This device helps keep the front part of the eye stable during eye surgeries.
- Kuglen hook and Sinskey hook: These are small hooks used in eye surgeries to manipulate tissues and place lenses.
- Suture holding forceps and Micrograsping forceps (MST or Alcon): These forceps are used for holding and placing stitches with precision.
- Prolene suture 10-0: This is a very fine thread used for stitching, particularly effective for delicate surgeries.
- 13 mm CIF-4 needles with a tapered body and sharp cutting tip, and CTC-6L needle: These are specialized needles designed to puncture and stitch with minimal trauma to the tissue.
- Monofilament polypropylene suture: This type of suture is smooth, resistant to degradation, and retains its shape, making it ideal for long-lasting stitches.
These tools help the doctor to perform surgeries with maximum precision and care for better healing and recovery.
Preparing for Traumatic Iris Reconstruction
Before a specific type of eye exam called “pupillary dilation,” a detailed examination with an instrument called a “slit lamp” is important. Think of this as a microscope for your eyes! It helps doctors analyze different parts of your eye.
Suppose there’s an open wound on the eye, combined with injuries to the cornea (the clear front surface of the eye) and iris (the colored part of the eye). In that case, the tear on the cornea needs to be fixed first. This is to make sure the eye is watertight before any further procedures on the iris. Following the corneal repair, the doctor will further examine the eye to check for any damage to the iris, the lens, and the back of eye where your retina (a layer at the back of the eyeball) and the vitreous (the clear jelly-like substance in the middle of the eye) are.
The doctor will also evaluate the cornea for things like how it responds to touch, any staining, signs of dry eye, and certain marks that could indicate eye disease (such as guttae).
A complete evaluation of the retina (that layer at the back of the eyeball) should be done too, before trying to fix any traumatic iris damage. The doctor will note any signs pointing towards the deterioration of the iris, unusual connection between the iris and the cornea, and whether there is a condition called pseudo-exfoliative material, which are tiny protein fibers clumped together on the eye’s natural lens.
Next, the area where the iris meets the white of the eye will be examined for any changes or tears, and if a cloudy lens (traumatic cataract) is found within the eye, it must be removed. The type of artificial lens to replace it can be decided during the primary procedure or at a later time.
The doctor will also need to thoroughly check your ‘other’ eye (the one not injured). If there’s no natural lens in the eye (aphakia), the capsule that used to hold the lens has to be completely enlarged for further evaluation. In the case of an artificial lens in the eye (pseudophakia), the stability and type of the artificial lens need to be noted.
A gonioscopy, another type of eye exam, is needed to rule out the new growth of blood vessels, a type of glaucoma (eye disease that damages your optic nerve), the extent of damage to the iris, the presence of pigments, and unwanted connections between the iris and cornea.
When the slit lamp examination is not enough or yields unclear results, other imaging techniques like anterior segment optical coherence tomography (ASOCT) or ultrasound biomicroscopy can be used to provide a clearer image of the eye, especially the area called the anterior chamber (the front part of the eye where fluid circulates).
X-rays enjoy a special duty- they discover unseen foreign objects lodged in the skull and orbital area (cavity in the skull where the eye and its appendages are situated). For any distortions of the bone, a CT scan may be called on, while an MRI can provide detailed images of soft tissue injuries. However, in the presence of a metallic foreign object, MRI is not preferred.
Once the pre-surgery checks have been done, it’s time for the surgery preparation . This usually includes administering an eye block to numb the area, using a certain medicine to constrict the pupil and ensure other procedures done for preparing the iris for the repair. If there is vitreous (clear jelly-like substance in the middle of the eye) on the pupil’s surface, it has to be taken care of before any surgical manipulations.
Also, a certain substance is used to protect the cornea’s inside layers and assist a suture (a stitch or row of stitches holding together the edges of a wound or surgical incision). Finally, a needle can pass safely through the anterior chamber (front part of the eye where fluid circulates) when properly done, ensuring no damage to a membrane in the cornea known as the Descemet membrane.
How is Traumatic Iris Reconstruction performed
If you’ve experienced an injury to the iris (the colored part of your eye that controls how much light enters), there are ways to manage it without surgery. Treatment options include eye drops and special contact lenses.
Eye Drops: Medications like pilocarpine and brimonidine can help manage minor iris injuries. Pilocarpine helps the iris constrict (or close) but might not work if the injury is severe. Brimonidine helps to temporarily reduce pupil size, which can be beneficial if you see halos around lights at night.
Contact Lenses: For more noticeable iris damage, such as loss of part of the iris tissue, special contact lenses can help. These lenses have a clear center and a colored edge that matches your eye color, helping to minimize the appearance of the damaged iris and control light sensitivity and glare. These lenses come in various types, and choosing the right one depends on factors like oxygen flow through the lens.
Tattooing: A more permanent non-surgical option is corneal tattooing, where dyes like India ink or metal substances are inserted into the front layers of the cornea (the eye’s outer clear layer). This method can help improve the appearance of the eye and reduce issues like light sensitivity and double vision. However, the effect might fade over time, and the ink particles can accumulate on the eye’s surface.
Laser Iridoplasty: In some cases, a laser can be used to reshape the iris without making any cuts. This method involves using a laser to create small burns at the edge of the pupil, which can alter the iris size and position. It’s a precise method but requires careful handling to avoid damaging nearby eye structures.
Suturing Iris Defects: If there are small tears or holes in the iris, they can sometimes be stitched closed. For larger defects, more complex techniques like the rotational flap or using part of the iris’s root may be needed to properly close the gap without further damaging the iris.
In cases where traditional suturing isn’t enough, more specialized techniques like the McCannel or Shin’s technique are used. These involve passing a fine suture through small needle punctures around the iris to stitch it closed effectively. Another method, the modified Siepser Slipknot technique, uses knots to align and secure the iris tissue precisely.
All these methods aim to restore the eye’s appearance and function after iris damage without needing invasive surgery.
Possible Complications of Traumatic Iris Reconstruction
The following list runs through a number of potential issues you can face after eye surgery, particularly cataract surgery:
* Corneal edema and corneal decompensation: these are conditions relating to the cornea, the clear front surface of the eye. Edema refers to swelling, while decompensation means the cornea is not working properly.
* Descemet membrane detachment: The Descemet membrane is an important layer of the cornea that might become detached or loose.
* Hemorrhage and hyphema: These are conditions where bleeding happens in the eye.
* Secondary glaucoma: Sometimes, surgery can lead to increased eye pressure, known as glaucoma.
* Iridodilaysis and synechiae: These are issues with the iris, the colored part of your eye.
* Post-operative uveitis: This is inflammation of the uvea, the middle layer of your eye, after surgery.
* Endophthalmitis: A severe infection inside the eye.
* Issues with the vitreous: The vitreous is the clear gel that fills the back of your eye. This can sometimes be lost, or move out of place (prolapse), touch the back of your eye leading to irritation (touch syndrome), or get into the surgical wound causing infection (wick syndrome).
* Cystoid macular edema (CME): This occurs when a part of your retina called the macula swells because it’s filled with fluid.
* Issues with the implanted lens (IOL): After cataract surgery, an artificial lens is put into your eye. Sometimes it can tilt, move slightly out of place (decentration), become loose (subluxation), or totally dislocate.
* Retinal detachment: This can occur when the retina, a thin layer at the back of your eye, comes off its normal position.
Remember, it’s essential that you understand all possible risks before any surgery. Not every risk occurs in every person – and some are very rare – but it’s important to have these discussions with your eye surgeon.
What Else Should I Know About Traumatic Iris Reconstruction?
There have been multiple exciting advancements and improvements in the process of traumatic iris reconstruction. The iris is the colored part of your eye, and sometimes it can get damaged due to injury. When this happens, there are options for how to fix it. One of these is a surgery called traumatic iris reconstruction, but there are also non-surgical methods that your eye doctor might consider.
These can include the use of things like miotics, which are medicines that make your pupil smaller, and contact lenses. There have been new and important techniques developed recently to fix damage to the iris. The knowledge and skill of the surgeon in dealing with iridodialysis, which is a fancy term for when the iris separates from its attachment to the eyeball, can have a positive impact on the patient. This skill can help decrease symptoms like seeing double, severe light sensitivity, and glare, while also keeping the patient’s vision sharp.
