A pterygium (plural pterygia) is an abnormal wing-shaped fold of the conjunctiva which invades the corneal surface. It can induce significant astigmatism and, should it encroach on the pupil, visual impairment.
Pterygia are reported to occur more in men than women. It is uncommon for patients to present with pterygia before the age of 20 and patients older than 40 have a significantly higher incidence.
Pterygia can be unilateral or bilateral and can appear on nasal or temporal cornea, although nasal presentation is more common.
My pterygia first started to appear in 1999 and, following a consultation with a local ophthalmologist, it was thought that they would not develop enough to need surgery. I had never done anything to increase my risk of getting pterygia (prolonged exposure to UV radiation or dry, dusty environments) and they didn’t seem to develop further until around five years ago, but were always a great discussion point with pre-reg optometrists.
Around three years ago I noticed that the pterygium in my right eye was starting to encroach further across my cornea (Figure 1). This may have been due to the fact I was spending more time outdoors especially in the summer and taking part in more winter sports. Autorefractor measurements showed an increase in corneal astigmatism (2.00DC) although my preferred spectacle correction remained spherical and unchanged.
[CaptionComponent="79"][CaptionComponent="80"]Finally, in June 2012, I had another ophthalmologist consultation. Autorefractor measurements showed another significant increase in corneal astigmatism (3.50DC) and an Orbscan measurement showed that the affected tissue was now beginning to encroach on my scotopic pupil (Figure 2). Slit-lamp examination showed that the pterygium was active and could possibly continue to grow.
[CaptionComponent="81"]After discussion with my ophthalmologist it was decided that he would operate on my right eye within six months. He suggested I would need to take two weeks off after the operation due to the need to use ointment, making my vision blurred, and also that it would cosmetically appear very red and inflamed. He also recommended waiting until the autumn to do the operation so the weather would not be too hot and dry, meaning the eye would be more comfortable after the operation.
History of pterygium surgery
During surgery the abnormal tissue is removed from the cornea and sclera. Over the years pterygium surgery has evolved significantly and modern surgery techniques have significantly higher success rates than traditional techniques where postoperative recurrence was very common.
In traditional (bare sclera) surgery the abnormal tissue is removed but the sclera is left exposed and in 50 per cent of cases the pterygium can grow back, often at a faster rate than before.
Over the years, surgeons have used a number of techniques to reduce the likelihood of regrowth including radiation treatment and the use of anti-metabolite chemicals. Each of these techniques has risks that could threaten the eye health after surgery, including persistent epithelial defects and corneal melting.
Most ophthalmologists today perform pterygium surgery with conjunctival autograft (transplantation of donor tissue from the same eye). The idea of this form of surgery is that the autograft fills in the area where conjunctival tissue was removed and forms a barrier to the abnormal conjunctival tissue, making a recurrence less likely.
My surgery
The pterygia operation my ophthalmologist now regularly performs, I was pleased to hear, includes conjunctival autograft. The steps of the operation are as follows:
? Retrobulbar anaesthetic – paralysing the extraocular muscles and pupil sphincter and anaesthetising the cornea
? Removal of the conjunctival flap of tissue which had grown across the cornea
? Debridement of cornea to ensure all conjunctival tissue has been removed
? Removal of limbal conjunctival tissue
? Conjunctival autograft tissue removed from inferior bulbar conjunctiva
? Autograft secured in place at the limbus with two stitches
? Site of autograft closed with surgical glue
? Antibiotic and anti-inflammatory drops instilled and eye closed and patched.
Before the retrobulbar injection I was given a mild sedative (Propofol) the action of which meant I had no memory of the injection itself. I then had to wait around 20 minutes while the anaesthetic began to work. During the operation I had no discomfort and my vision was very blurred. I was aware of what the surgeon was doing when his hands passed across my eye and I was also aware of the theatre nurse instilling saline drops at regular intervals to ensure the cornea did not dry out while my lids were held open with a retractor. The surgeon also explained what he was doing at each stage of the procedure so I was fully informed.
The operation took around 20 minutes and, after a short chat with the ophthalmologist, I was allowed home.
The next morning I had my first check-up. The ophthalmologist removed the eye patch and checked the autograft on the slit lamp. Initially I had double, blurred vision and was worried until it was pointed out that the retrobulbar injection still hadn’t fully worn off, meaning my extraocular and intraocular muscles were still not working properly.
I also had significant subconjunctival haemorrhages. I was given a prescription for antibiotic and anti-inflammatory ointment which I had to instil twice a day until my next check-up in 10 days. The double vision, reduced accommodation and dilated pupil wore off by mid-afternoon.
During the next 10 days the subconjunctival haemorrhages started to resolve and I had very little discomfort from the stitches. At the next check-up the stitches were removed under local anaesthetic and a new Orbscan taken (Figure 4). This showed that the corneal astigmatism had reduced significantly (0.50DC) but the cornea was still slightly thinner where it had been debrided. The ophthalmologist gave me a prescription for Bepanthen ointment to aid the healing process which I had to instil every evening before going to bed. A new follow-up appointment was arranged for three months later.
[CaptionComponent="82"]At the follow-up appointment my ophthalmologist was very happy with the results of the surgery. My eye was white, the corneal thickness had increased and the pterygium showed no signs of new growth.
He also reviewed the pterygium in my left eye and decided that as it had shown no signs of further encroachment over the last eight months he could continue to monitor it and that surgery was not yet required (Figure 5). He reiterated the need for good, UV blocking (sun)glasses to be worn at all times but especially in the summer and while taking part in winter sports.
[CaptionComponent="83"]If I should need to have the left eye operated on in the future I would have no hesitation as the operation itself and the outcome were both excellent.?
[GalleryComponent="15"]
Acknowledgements
The author thanks Dr Ken Selde, ophthalmologist, Zurich, for allowing the use of the Orbscan images.
Useful reading
emedicine.medscape.com/article/1192527
? Lisa Crouch is a UK optometrist based in Switzerland