Excessive lacrimation (tearing) with the Pascal Tonometer

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Excessive lacrimation (tearing) with the Pascal Tonometer Powered By Docstoc
					                                   Excessive Lacrimation
                                     (too many tears)
Symptoms/Diagnosis
  1. Unusually low-pitch, broken sound instead of the regular oscillating sound that you
     typically hear. This is because when the entire SensorTip is filled with tear film, the tip “floats”
     on the tear film and the pressure sensor is not actually contacting the cornea. The tear acts like a
     sponge to absorb the pressure pulse from inside the eye so the pressure sensor “sees” a low
     pressure. Since the pitch of the sound correlates with the pressure reading, the pitch of the
     sound is unusually low. Also, since the sound only begins at a pressure higher than 5 mmHg, it
     becomes intermittent as the “seen” pressure fluctuates above and below 5 mmHg. If the “seen”
     pressure stays below 5 mmHg, the Pascal will not make any sound at all (The 5 mmHg
     threshold is to keep the Pascal from making sound before it touches the eye and starts to see a
     pressure.) It is not uncommon for a user to report that the Pascal must be broken because of the
     unusually low pitch and intermittent sound, or the absence of sound altogether.

  2. You can’t see the edge of the Contact Zone on the cornea; the entire tip is filled with
     the Contact Zone. It is common for the Contact Zone to be OK at first, but then as the patient
     tears up, the Contact Zone grows to fill the entire tip. This is the point at which the sound starts
     to seem bad as discussed above. It is critical that you can see the entire circumference of the
     Contact Zone. The pressure sensor should be centered in the Contact Zone, and the Contact
     Zone should be centered within the outer edge of the SensorTip. If you can’t see the entire edge
     of the Contact Zone all the way around when you are centered properly, there is too much tear
     film.




                                                 Excessive
                                                  Tearing




  3. If you get a reading, the reading seems unbelievably low , in the range of 3 to 6 mmHg
     when the eye has no reason to have that low a pressure. (Post-op trabeculectomy patients may
     have true pressures that low.)

What to do:
  1. Withdraw the SensorTip away from the patient’s eye.
  2. Dry the patient’s eye with a tissue. (Carefully! The cornea is anesthetized.)
  3. Dry the SensorTip with a tissue (a surgical spear/sponge works well for this as it does not leave
     lint on the SensorTip.)
  4. Put another drop of anesthetic into both eyes to decrease the tearing reflex. Repeat if necessary.
  5. Turn down the intensity of the slit beam illumination of the SensorTip to decrease the patient’s
     apprehension of “something coming at their eye”. (With practice you can actually take readings
     with the illumination turned off, using just the overhead lights in the room. The Contact Zone
     will be dim, but it is still usually visible.)
  6. Pull the lower eyelid down and away from the cornea to facilitate drainage of the tears as you
     take the reading.
  7. Ask the patient to concentrate on listening to the sound the Pascal is making. This distracts
     them from thinking about “something coming at their eye”.
  8. Don’t stay on the cornea with the Pascal any longer than necessary. Get three quick waves and
     get off. Once you get a reading you can repeat the measurement to try to improve your Q score,
     but first at least get a reading.

				
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posted:2/1/2010
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