|MadSci Network: General Biology|
Hey there, The technical name for what your friend has is a pterygium (pronounced ter-IH-gee-um). The plural form is pterygia. The disease is not genetic, as far as I could find out. According to Deborah Pavon- Langston in her "Manual of Ocular Disease" and Jack Kanski in his "Clinical Ophthalmology," pterygia are caused by exposure to sun and the elements, e.g. wind and dry conditions. Most pterygia form on the side closest to the nose, because the nose reflects a lot of sun on the eye. From personal experience, I can tell you that as an optometry student in Indiana, I rarely ever see a true pterygium. But I've made several service trips to Mexico to do exams on farmers down there, and they all have pterygia. They spend morning till night up in the hot desert and thin air of high elevations, and that does it every time. Is your friend (and her parents) from a tropical and/or hot climate? As far as surgery, you can scrape away a pterygium, but they have a tendency to recur. After scraping, some sort of drug such as Mitomycin-C, which inhibits cell growth, is put on the eye to keep a new pterygium from forming. What's actually happening with a pterygium is not that the sclera is growing over the pupil. First, a pterygium is not really sclera, but it does look a lot like it. Pterygia are just generic fibrovascular tissue that extend from the sclera. The other thing I wanted to mention is that pterygia don't grow into the pupil, but they can cover the pupil up. The pupil is that little hole in your iris, the colored part of the eye. Take a good look at your friend's eye and you'll see that the pterygium is on her cornea, the clear front part of her eye. You'll also notice that the pupil is a few millimeters (usually about 3.5 mm) behind her cornea. When a pterygium grows over the cornea far enough to start covering up the pupil, though, that's when it starts to hamper vision, and that's when they're usually scraped off. That's the story. I hope I've helped to answer your question! Tom
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