16.6 The Patient |
147 |
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Table 16.4 The BIOM checklist per operation |
|
Make sure that youa: |
Comment |
Have properly secured all |
Pushed all the way in, with screws tightenedb |
attachments |
|
Selected the front lens you want to |
Choose from the following lenses: 60° (macula), 70°, 90°, |
use |
120°, 60–125° (wide field, high definition). In general, |
|
the wider the field, the worse the resolution |
Cleaned both the reduction and |
The lenses must be carefully wiped before, occasionally |
front lenses, and they have |
during, the operation; the reduction lens usually only |
cooled off |
before, the front lens sometimes during the operationc |
Firmly pressed the draping onto the |
To prevent endophthalmitis from contamination on the |
patient’s skin, 360° around |
skin (or discharge from the nose, see Fig. 15.1) and |
|
avoid breath-related fogging |
Gently squirted the corneal |
You must avoid splash back from the corneal surface or |
epithelium with BSS and then |
coating the front lens itself (see Sect. 25.1.4) |
coated the cornea with visco |
|
before swinging the BIOM into |
|
position |
|
Lowered the microscope to reach |
See Table 16.3 |
the proper working distance |
|
Set the focus |
With the BIOM in position, use the lowest zoom of the |
|
microscope and focus the retinal image with the |
|
BIOM wheeld. Zoom then to the highest magnification |
|
and reset the BIOM focus. This should allow you to |
|
work throughout the entire operatione without having |
|
to adjust the wheel – until F-A-X is needed |
Do not use the BIOM for fine |
Although doable with the high-resolution/wide-field lens, |
macular work |
it is best done with a contact lens because of the |
|
higher resolution. You will be able to see very fine |
|
details that were hidden before |
Do not use the BIOM anterior to |
Working here is viewed through the microscope without |
the posterior lens capsulef |
the BIOM swung in |
aOr the nurse, as appropriate.
bAvoid overtightening it: this not only makes the eventual unscrewing more difficult but wears out the mechanism earlier.
cBecause of fogging, touching the visco, or splashed-back BSS droplets.
dIf the vitreous is not clear, perform vitrectomy until you have a clear view of the retina and do the setup then.
eAlthough occasionally, for example, when working high in the vitreous cavity on a detached retina, the focus may have to be readjusted (focus down in this case).
fLens proper, iris, AC etc.
16.6The Patient
If the operation is performed under local anesthesia, it is crucial that the patient:
•Has a comfortable position20 lying on the operating table.
•Is able to maintain this position for extended periods.21
20 Something as simple as a soft pad under the knees is of great value.
21 The risk of moving during surgery must be discussed with the patient in great detail (see Chaps. 5 and 15).
148 |
16 The Surgeon at the Operating Table |
|
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Table 16.5 Troubleshooting: poor visualization through the BIOM |
|
Problem |
Solution |
No image |
The BIOM is not swung in place all the way |
|
The SDI knob is not turned all the waya |
Visual field |
Microscope head not vertical (image no coaxial): cataract surgeon may |
incomplete |
have used the microscope last |
superiorly |
|
(inferiorly) |
|
Image blurry and |
Cornea/AC/lens/capsule too hazy |
cannot be fixed |
The pupil is too small |
(see below) |
|
Image gradually |
Fogging on the front lens, usually because of condensation from the air in |
getting lost |
the OR or from the patient’s breathing on the lensb |
during surgery |
Fogging on the reduction lens: if the BIOM was fixed to the microscope |
|
while it was still rather hot from the sterilizationc, the condensation |
|
will slowly darken the image. The BIOM must be swung out and the |
|
lens cleaned/dried with a sterile cloth |
Image imperfect on |
The microscope’s position was not adjusted to the eye’s movement |
one side of the |
The X-Y joystick must be operated in harmony with the surgeons’ hands |
visual field |
as he rotates the eyeball. This lack of movement coordination is most |
|
conspicuous when the surgeon uses high magnificationd |
Image suddenly |
Front lens dipped into viscoe |
getting blurry |
Elevate the microscope, clean the lens, recoat the cornea |
during surgery |
|
Image getting |
Shift in focus; in the phakic/pseudophakic eye, adjust the BIOM wheel |
blurry during |
upward, in the aphakic eye downward |
F-A-X |
|
Image not central |
Adaptor plate/dovetail not pushed all the way |
|
One of the screws fixating the adaptor plate/dovetail is loose |
|
The screw’s threads are worn out |
|
The front lens is not pushed all the way into its slot on the lens holderf |
Blinding light reflex |
See Table 16.2 |
Difficulty swinging |
The mechanism is stuck |
the BIOM in or |
Needs lubrication (silicone oil is an excellent fix; apply it over the |
out |
swinging mechanism) |
Difficulty going up |
The mechanism is stuck |
with the |
Needs lubrication (silicone oil is an excellent fix; apply it over the |
focusing wheelg |
focusing mechanism). If sterile silicone oil is unavailable, the nurse |
|
should, gently and slightly, pull on the shaft of the BIOM lens holderh |
aNot an issue if it is an automated function.
bCheck whether the drape has not peeled off from the patient’s skin around the nose. If yes, reseal it, drape over it, or “stuff” gauze underneath the drape opening.
cSteam autoclave.
dThis is why the surgeon is advised to (1) work under the lowest magnification possible and (2) have the (dominant) foot on the X-Y joystick throughout the entire operation. The foot is only temporarily taken off the joystick when other functions of the microscope pedal are to be activated.
eThe most common error in clinical practice.
fThis is also dangerous: the lens can drop out of the holder when it is swung out. gDownward it almost never happens.
hThe direction is backward (opposite of [away from] the location of the front lens).
16.6 The Patient |
149 |
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|
•Can breathe without difficulty.22
•Will not become claustrophobic under the draping.
•Will not get cold due to the cool air temperature in the OR (see below,
Sect. 16.10).23
One arm of the patient must remain easily accessible throughout the surgery, ideally so that the surgeon must not stop his activities as the anesthesiologist works on the arm.
Pearl
The patient’s face must be parallel with the floor. It is common to see patients on the operating table with their forehead higher than their chin (this is why the head part of the operating table needs to be adjustable; see Sect. 16.2.1. and Fig. 16.5). The parallel position may be uncomfortable to some people, but it allows surgeon access to the entire vitreous cavity and keeps the macula in the image center. If a patient finds this head position intolerable, he and the surgeon must work out a mutually acceptable compromise.
A uniquely important issue is that the correct eye of the patient gets prepared for surgery.
•The nurse who prepares the patient outside the OR must mark the eye with a sticker or ink on the forehead.
a |
b |
Fig. 16.5 The position of the patient’s head. (a) Ideally, it is parallel to the floor (i.e., horizontal). This allows working on the macula and in most retinal areas without having to rotate the eyeball. The only area that may present accessibility issues is the superior periphery (hence the caveat against using heavy silicone oil (see Sect. 13.3)). (b) The most common error is for the patient’s chin to be lower than his forehead: in this position, even the macular area is inaccessible unless the surgeon rotates the eye and maintains this artificial position even during ILM peeling. The superior quadrants are impossible to reach
22Oxygen is supplied.
23Heated blankets are available.