What Is Pterygia (or Pterygium)?

So, you’ve recently noticed a little growth over the side of your eye. It’s not sore and no one else seems to have noticed it (at least not that they’ve mentioned it out loud to you). Fast forward after a few years of surfing under the blazing California sun and you notice that the white thing is not so little anymore; it gets red and irritated sometimes, and when you talk to people you can see them squinting at it, wondering what that is. Of course, you then diligently visit your eye doctor who tells you that you have a pterygium, also known as surfer’s eye.

As this pterygium is now starting to bother you, you’re given the option of having it surgically removed. So, you go home to think about it and realize that you really don’t know much about pterygium or, for that matter, the many different types of pterygium removal surgery options. We’ll get to that in a moment.

Pterygium Causes

Pterygium is a benign, wing-shaped growth of fibrovascular tissue that extends from the conjunctiva (the mucous membrane on the whites of the eye, extending under the eyelids) and begins to gradually cover the cornea, which is supposed to be clear and transparent.

In laymen’s terms, pterygium is a non-cancerous growth of the inside lining of the eyelid which covers the white part of your eye. Pterygium is caused by ultraviolet-light exposure (sunlight), low humidity, and dust which is why it is so often referred to as Surfer’s Eye. Pterygium is also referred to as Carnosidad which in Spanish translates to an excess or abundance of flesh or blood.

Many people, both surfers and those who prefer dry land, will continue on quite happily in life, never being bothered by their pterygia. However, for some the cosmetic appearance of the pterygium is unappealing; it frequently becomes inflamed and irritated, or it grows so far across the cornea that it starts to cause vision problems where surgical excision of the offending tissue is the only option. There are a variety of techniques traditionally used during pterygium surgery. Dr Michel’s technique is the Conjunctival Limbal Autograft (CLAU) which has the lowest rates of recurrence.

Pterygium Treatments

Conjunctival Limbal Autograft (CLAU)
Dr. Michel is an ophthalmologist, corneal specialist, Lasik surgeon, and one of the top pterygium removal surgeons in the world. His offices are located in Thousand Oaks (CA), Oxnard (CA), and Los Angeles (CA).

His preferred technique for removal of pterygium is the Conjunctival Limbal Autograft, or CLAU. Whereas the conventional Conjunctival Autograft technique has historically proven to have the lowest rates of pterygium recurrence, Dr. Michel’s use of the Conjunctival Limbal Autograft (CLAU) technique has rates that are even lower – less than a 1% recurrence.

The Conjunctival Limbal Autograft (CLAU) is a variant of the Conjunctival Autograft and has identified pterygium as a localized stem cell deficiency. Those stem cells are replaced by Dr. Michel via specialized grafts that help the eye recover without recurrence.

A tissue glue is used that also doubles as a liquid bandage to cover the eye after surgery, keeping the eye more comfortable.

NCBI Study Results

In a study published by NCBI (National Center for Biotechnology Information), “following the demonstration of limbal location of corneal epithelial stem cells…, it had been recognized that chronic exposure to ultraviolet radiation causes a local acquired deficiency of stem cells which normally act as a barrier between the conjunctival and corneal epithelia. Destruction of this barrier limbal tissue leads to the growth of the conjunctival tissues onto the cornea, forming the basis for inclusion of limbal tissue containing limbal stem cells in the free conjunctival graft in the conjunctival-limbal autograft (CLAU) transplantation procedure.”

Conjunctival Autograft

Conjunctival autografts for pterygium surgery are a much more recent technique, first performed in 1985. Once the pterygium tissue has been removed, a free section of conjunctiva is taken from elsewhere on the whites of the eye and used to cover the defect left by the pterygium removal. This graft is then sutured in place or adhered with biocompatible fibrin glue and the defect left from the graft removal is sutured closed.

The conjunctival autograft technique is also associated with low rates of recurrence, as low as 2% in some studies. MMC use during surgery has also contributed to lower recurrence rates when compared to autografting surgery alone. While the conjunctival flap reconstruction method has the potential to produce some visible folds in the conjunctiva where the flap was slid or rotated to the excision site, the autograft technique results in a smooth, white surface, which some surgeons may feel provides a much better immediate cosmetic outcome. Overall, conjunctival autografting for pterygium surgery is associated with very low risk of complications, none of which are considered sight-threatening.

Amniotic Membrane Transplant

Human placenta tissue has been used in all sorts of off-label ways, some of which are better not imagined. One novel way of employing the healing properties of this tissue is to take from the placenta of a healthy caesarean section birth a piece of amniotic membrane for use in pterygium surgery. In theory, the anti-inflammatory, anti-scarring properties of the amniotic membrane graft reduces the risk of pterygium recurrence when used to cover the excision site, though the reasons behind how exactly this works are not yet fully understood.

Once the pterygium is fully removed, a pre-prepared piece of amniotic membrane is positioned to cover the bare sclera and adhered into place either using sutures or glue. One huge benefit of amniotic membrane transplant is that you don’t leave a hole somewhere else that then needs to be closed, as happens in conjunctival flap reconstruction or autografting. A disadvantage of this technique, however, is the availability of amniotic membranes and possibly also the associated increased cost. Some studies have found amniotic membrane transplants to offer similar rates of recurrence when compared to flap reconstruction or autografting, while other reports demonstrate that flap reconstruction and autografting are associated with slightly better outcomes.

Conjunctival Flap Reconstruction

In an effort to preserve the modesty of a naked sclera, the conjunctival flap reconstruction method uses a flap of conjunctival tissue adjacent to the pterygium to cover the excision site. This flap is rotated over the excision site and then can be secured with sutures or biocompatible glue. If you’re thinking that this just leaves a naked sclera at the site of where the flap was taken, you’re not wrong – this resultant defect is sutured closed.

Recurrence rates of pterygia after initial removal with conjunctival flap reconstruction vary depending on the report. It is thought that the experience and expertise of the surgeon play a big role in the risk of recurrence, no matter the technique used. Nonetheless, conjunctival flap reconstruction is consistently shown to have a lower rate of recurrence compared to the bare sclera method, as low as around 3%. The addition of MMC alongside the surgery has been shown to help keep recurrence rates low.

You’re more likely to find eye surgeons in developed countries who use this technique quite happily. Some ophthalmologists believe the benefit of conjunctival flap reconstruction lies in the fact that the flap still has some attachment to its original position. This means the blood supply remains intact, leading to faster healing times, and there’s no chance of the flap falling off, a potential complication in conjunctival autografting.

Bare Sclera Technique

After the eye is appropriately numbed, using surgical blade and scissors, the eye surgeon separates the wing-tip of the pterygium tissue from where it adheres to the cornea, and then carefully snips away until all the abnormal conjunctival tissue is removed. This leaves an uncovered patch of sclera beneath the excised pterygium area, hence the name of this technique. The conjunctival tissue is then given time to regrow over the bare sclera.

Pterygium excision similar to the bare sclera technique was first described around 500-1000BC. As with many things in medicine and eye surgery, the very first method has been superseded by improved techniques. The bare sclera technique has been found to be consistently associated with the highest rates of pterygium recurrence out of all the techniques, as high as 89% in some reports. Despite this, several countries, particularly those less affluent, still use the bare sclera technique as the procedure of choice. A study conducted among ophthalmologists in Thailand stated that more progressive methods of pterygium removal were not possible to employ because of the lack of access to the resources needed for more modern methods. Moreover, it also stated that the bare sclera technique was simply the fastest procedure.

While the application of a chemical known as mitomycin-C (MMC) either during the operation or as part of the post-operative process has been associated with a decreased rate of recurrence after bare sclera pterygium removal, you will still likely find few eye specialists in developed countries such as the US who elect to use the bare sclera technique for pterygium excision.

Conclusion

The Conjunctival Limbal Autograft (CLAU) has been proven to be a safer and more effective pterygium removal treatment than a conjunctival transplant in preventing recurrence after excision of recurrent pterygia. Dr. Michel’s CLAU is a suture-less and elegant no-stitch technique that removes the pterygium and replaces stem cells where the pterygium used to be in order to help the area regrow with normal tissue.