operating microscope basics

It is very important to learn how to operate the microscope before your first day in the OR.

Basics of the Microscope pedal.  While there are some subtle variations among models and manufacturers the basics of the microscope footpedal and operation of the micropscope are similar.  The microscope has a starting XY position which is centered at the start of the case and then small variations in this initial position are made using the foot pedal which makes small XY adjustments of the microscope.  The scope also has a starting focal point (i suppose this is the Z position) which is set up at the start of the cases and small variations from this are made during the case using the foot pedal which moves the focal point of the scope up and down.  Often the intensity of the light can be also be controlled with the foot pedal.

All of your extremities will be busy:  one foot for the microscope pedal, one foot for phaco pedal, one hand for the phaco handpiece, and the other hand for the chopper.  Most surgeons use non dominant foot to control the microscope pedal.  unless you are a soccer player your left foot is probably not that coordinated.  as such you should practice using the pedal way before your first case.  most people take off their shoes so that they can feel the microscope pedal better.

Foot pedal switches.  The typical positions of the microscopes foot switch controls are shown below.  The foot pedal is designed so that the foot can sit on a rasied foot rest.  A rocker swith in front of the foot rest is most important and moves the scope up and down to make small changes in focus.    a rocker switch behind the foot rest controls the zoom or magnification.  the magnification is typically low during wound construction and is increased during steps such as capsulorhexis which require more magnification.  Several inches in front of the foot rest is the joy stick which controls the XY position of the scope.  both the XY position and the focus shuold be centered prior to the case (usually a switch on the scope) and manually put into optimal initial position to allow maximal excursion of these functions during the case.


When you arrive in the OR ask yourself: “where will I be sitting?   Are you operating from a superior approach -- Superior approach is preferred when you may have a large incision with lots of sutures (eg. ICCE, ECCE, tough phaco when you may convert) and/or when you may have iris trauma (tolerated better under the lid) and when you are doing a trabeculectomy and want the bleb under the lid. Typical phaco is from a temporal approach to avoid the brow. i usually do rights eyes a bit inferior and temporal (eg 8 oclock) and left eyes superior andtemporal (eg 2 oclock); however. some surgeons like Dr Tim Johnson are always true temporal whether operating on the right or left eye. 

  

Proper Sequence to adjust Equipment to your body

1.     Place retrobulbar block first (give it time to work while setting up scope)

2.     Put assistant’s eyepiece and camera on proper side of microscope

3.     Push center focus and center XY position buttons on microscope (may be same button)

4.     Adjust ocular inter-pupillary distance and zero both objectives

5.     Lower surgeons chair

6.     Raise bed height to just allow both feet under bed onto both pedals

a.     Dominant foot – phaco pedal

b.     Non dominant foot microscope footswitch

c.     Take off shoes (wear white Nike crew length socks)

7.     Manually move entire microscope (not footswitch) so that you are in focus

8.     Raise surgeon chair height enough to allow surgeon to see comfortably into oculars

9.     Prep and Drape