The iris is a circular, pigmented membrane that provides the eye its color and the opening in the center is the pupil of the eye.
The iris is made up of muscular fibers that control the amount of light entering the pupil so that you can see clearly. The iris accomplishes this task by making the pupil smaller in bright light and larger in dim light.
In some people, the iris can become inflamed. This is termed iritis.
Maybe you're like most people over 40 -- the aging of your eyes
is beginning to change your life in a way you don't like. It was happening to
me. I'd reached the point where I couldn't see the dirt on the kitchen counter
until I put on my reading glasses, and the numbers on my car speedometer were a
So let me flash back to how I ended up, three days after this
past Christmas, wearing plastic bubbles taped over my eyes at the laser surgery
center of Zale Lipshy Hospital at the University of Texas Southwestern Medical
Center in Dallas (UTSW). It may help you decide if this procedure is for
For several years, the idea of LASIK had lurked in the back of
my mind. But until about a year and a half ago, the procedure was FDA-approved
only for nearsightedness, or myopia. This is when the corneal curve is too
steep, causing distant images to blur. When the operation was approved for
farsightedness (the corneal curve is too shallow, causing close objects to
blur), the possibility of having it done myself moved one step closer.
Then last summer, the FDA approved two laser machines for
correcting farsightedness with astigmatism (where the cornea is irregularly
shaped -- more like a football as opposed to a basketball). I did a story about
it, using as my main source H. Dwight Cavanagh, MD, PhD, vice chairman of UTSW
ophthalmology department. I listened carefully to what he had to say about the
procedure; after all, he had been one of the doctors who had conducted LASIK
clinical trials and also one of the researchers on a study comparing this
method with another type of laser surgery called PRK. I also talked with a man
in his late 60s who'd participated in the clinical trial of LASIK at the
medical center, who gave a glowing review.
This was sounding more and more like a real possibility for me,
but the thought of surgery made me squeamish. The surgeons use a tiny
instrument called a microkeratome to cut a flap of corneal tissue, then use a
laser to remove a hair-thin piece of tissue, effectively changing the shape of
the eye. Cavanagh said the surgery for farsightedness was easier and safer
because the laser didn't focus on the field of vision, as in the
nearsightedness procedure. Rather, it removes a donut-shaped piece of tissue
around the corneal edge.