OM t of c.iii - Vision Research Coordinating Center - Washington ...

1/1/2005 Chapter 8 Corneal Curvature and Topography page 8-8
(2) Choose Option 8 from the Utilities Submenu. The label on the back of the
standard housing identifies it as either an A or B Cone standard and gives the power of
the standard in diopters. Enter this power, including the decimal. Press the joystick
button. Hold the ball standard against the front face of the cone so that the standard
housing fits snugly and evenly with the cone edge. Holding the standard in place, check
for damage or contamination of the standard surface by watching the image on the live
video monitor. The image should be sharp and free from defect.
(3) Take one picture and process it as per the standard procedure.
(4) The ring processing screen will appear with a “43.xx diopter” in the patient
name field. The horizontal/vertical alignment error is reported, and the ring
information displays the average value of the standard.
(5) If the TMS is properly calibrated, the message “OK, Value=43.xx” is
displayed. If the message “No Good” flashes, you should:
•Make sure the cone is seated properly.
•Make sure that the cone is properly identified in the set-up routine.
•Check the standard for scratches or dirt.
•Take another picture and confirm that the horizontal/vertical alignment error is
minimal.
8.4.2 TMS-1 Topography Protocol
The TMS-1 (Tomey Technologies) is used to obtain corneal topography data at all
Clinics equipped with a unit. Clinics without a TMS-1 will use whatever
videokeratographic device they have. Two diskettes are needed per patient visit, and
each is labeled with a stick-on diskette label bearing the patient’s CLEK Study
identification number (eg, C1-00099-JS), the date, and the eye (OD or OS).
The Clinician, Technician, or Photographer enters the patient’s complete CLEK
ID number (eg, C1-10459-JS), and the eye on the TMS-1’s history screen.
The measurement procedure is as follows:
(1) Position the patient with his/her chin resting comfortably on the chin rest and
forehead resting against the forehead rest.
(2) Adjust the chin rest up or down so that the patient’s eyes align with the red
mark on the chin rest shaft.
(3) Ask the patient to turn his/her head slightly to the side opposite the eye
being examined to get a clear path with the patient’s nose out of the way.