We have to level with you — when the Media MICE team saw this topic come up, some of our writers (well, okay just this one) weren’t sure if it was about ophthalmology … or instead flying dinosaurs. Yes, you read that right, this is today’s article — but your writer’s mind was on something akin to pterosaurs, those mighty winged dinosaurs that roamed the skies of Earth over 65 million years ago. Strange as that might seem, you may forgive him as not only was he a total dino-nut as a child (and let’s face it, who wasn’t in the Jurassic Park generation?), but the subject of today’s article is pterygium.
Sadly for our writer — and happily for our intended audience — pterygium is not in fact a new form of interesting pterosaur to geek out over but is rather a condition characterized by conjunctival degeneration. While it is common enough, it is certainly one of the less covered conditions in ophthalmology … which is exciting in itself, as it’s always great to write about something new. So, let’s dive into Pterygium: New Insights*, a study on the condition by a group of researchers from the U.S. and Hong Kong, as it offers some dino-tastic insight.
First, let’s start with answering a simple question in more detail: What exactly is pterygium? The term refers to fibrovascular degeneration of the conjunctiva that advances across the cornea over time, usually located in the interpalpebral zone and more often than not, is nasal rather than temporal.
Pterygium, Not Pterosaur
There are a number of symptoms to look out for, with the most common being redness, irritation, dryness, tearing, and decreased vision, with the latter usually arising from the involvement of the visual axis, induced astigmatism, and tear film disruption. Also, when it comes to risk factors, the most common is exposure to ultraviolet light, increasing age and male gender.*
When it comes to the causes or pathogenesis of pterygium, the ophthalmology community is still somewhat unsure, however, some researchers point to the presence of the P53 and mouse double minute 2 (MDM2) proteins, which are found to be elevated in pterygium. This is interesting, particularly as P53 is a tumor suppressor protein that could induce apoptosis and restrict the growth of cancer. It is postulated that cytoplasmic P53 is not efficient in inducing apoptosis in pterygium and that P21 (that controls cell expression target of P53) was not detectable in pterygium tissues, suggesting the P53 transcriptional activity was not active in pterygium.
Now that’s all very interesting — but in ophthalmology, we’re all about the action. So, how does one treat pterygium? Well, life doesn’t, eh, find a way here, and the most commonly encountered course of action is via surgical excision with conjunctival autograft. But this doesn’t mean that more conservative measures can’t be applied, and before resorting to surgery, it is recommended to apply lubricants and use sunglasses.
Reoccurrence: Just Like Jurassic Park?
An important issue to point out, however, is the high rate of recurrence after surgery as simple excisions leaving bare sclera lead to a high recurrence rate of anywhere between 38% to a staggering 88%. Recurrence after pterygium surgery can occur in the cornea or conjunctiva, and corneal recurrences appear as fibrovascular growths of tissue across the limbus and onto the cornea. With such high rates research is naturally focused on finding a solution.
One strong contender is MMC, which is a natural anti-tumor antibiotic that could generate cross-links on the DNA strands, which is now often applied post-procedure. According to our researchers, MMC causes a significant reduction in cell viability and migration in both conjunctiva and pterygium, with an 8.3–8.6% recurrence rate in patients who received MMC 0.02 or 0.04% MMC for 5 min, but a 22.9–42.9% recurrence in patients who received the same treatment for only 3 min.
Could this be, in the world of the wise Dr. Malcolm, be life (ophthalmology) finding a way? Anything that can help reduce the fearsome recurrence rate should be welcome, so to this, we can only give a gigantic kudos the size of any respectable dinosaur.
*Chu, WK, Choi HL, Bhar AK, Jhanji V. Pterygium: New Insights. Eye (Lond). 2020; 34(6):1047-1050.
