So in my last blog post I received a couple comments asking me to elaborate on some of the things I mentioned.  Hopefully this entry will help lift the fog of befuddlement from your mind.

Glaucoma is a condition of the eye in which the optic nerve is damaged.  This can lead to loss of vision if not properly treated.  In most cases, abnormal intraoccular pressure causes the damage to the nerve. 

A trabeculectomy is a surgery which aleviates the pressure on the eye by permitting increased drainage of the aqueous humor.  This is done by removing a portion of the eye and allowing more liquid to flow out of the eye.

A tube surgery may be done to bypass that area of the eye completely and allow an increased amount of fluid to drain by inserting a tube into the eye.

Both of these surgeries achieve the same thing through different means.

If there is still any confusion then let me know!

Now for some normal blogging.

Since my last blog post I have been doing much of the same thing, going through patient files and entering data into the database I created.  On Friday, however, I worked with Dr. Chris Shen.  He has been working on a research project which Dr. Mansberger assigned to him.  He is attempting to discover a way to measure the pressure on eyes which have a fake lens inserted.  Pressure is usually taken on the cornea, but once patients have received this lens implant it is inaccurate to take pressure from the cornea.  We were working with donor eyeballs and using them to measure the pressure on the cornea, the limbus (where the cornea meets the sclera, the edge of the iris), and a constant point on the sclera.  We hooked up a bottle of fluid to an IV line and ran it through tubing to a machine which measured pressure.  After the tubing went through the machine it was inserted into one of the eyeballs with a needle.  The pressure of the eye was increased and decreased by raising and lowering the IV.  We measured at four different pressures (10, 20, 30, and 40) and used two different instruments.  We used a Tono-Pen, which you use by tapping against the eye.  It takes all of the different readings from the taps and produces an average and a percent error.  We also used a Schiotz tonometer.  The Schiotz physically rests on top of the eye and uses weights to produce a reading for the pressure.  It was more frequently used in the 50s but if it proves accurate it may make a comeback.  After we finished one eye, Dr. Michael Straiko came and replaced the lens with an implant lens.  As we worked on the second eye he worked on the first.  My job was to adjust the IV and write down the pressures as Dr. Shen told them to me.  I was not allowed to tell Dr. Shen the pressures of each test or else he might have biased himself and chose readings which were closer to the actual pressure.  This experience was very interesting, I hope I get to work with Dr. Shen again.