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16 The Surgeon at the Operating Table |
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•Adjust the power of the illumination. The brightness level should be the lowest that still allows you to work on the eye surface.19 You will need to turn on/off the microscope light several times during the operation, even after you have already reached partial or full adaptation. It is unwise to get blinded by the reflection of too bright a light from the sclera or the contact lens.
16.5The BIOM
For practical reasons, most of the information about using this indispensable tool is presented here (see also Sect. 12.3).
16.5.1 BIOM: The Advantages
See Table 16.1.
Table 16.1 The advantages of the BIOM*
No |
Corneal damage since there is no physical contact |
|
Contamination by blood from the operative fielda |
|
Assistant required to hold the lens/system in place |
Easy |
Mounting of the adapter plate |
|
Removal of the reduction lens |
|
Focusing with a wheel that is in a permanent position |
|
Exchanging of the front lenses |
Large selection of |
Front lenses for different viewing options |
Superior |
Observation angle/surgical field (wide, magnified, combined) |
|
Resolution |
|
Depth of focus |
Unhindered |
Mobility of eyeball during surgery |
|
Access to eyeball around the swung-in front lens |
No/little interference fromb |
Hazy media (cornea, AC, lens, vitreous) |
|
Small pupil |
Microscope mounting and |
Permanent and easy |
operation |
Available for most types of microscopes |
|
No interference with the use of microscope-mounted other |
|
devices (video camera, laser filter) |
|
Automatic SDI activation |
*Fifth generation.
aUnless the BIOM front lens is extremely close to the epithelium. Conversely, the lens may be dirtied if the cornea is squirted with too much force and the fluid droplets splash back. bObviously, there is a limit to the BIOM’s capability to compensate for the interference.
19 This is also true for the room light.
16.5 The BIOM |
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16.5.2 BIOM Use: Practical Information
See Table 16.2.
16.5.3 BIOM: Setting Up for Daily Use
Follow these steps to optimize the use of the BIOM (see Table 16.3).
16.5.4 BIOM: Checklist
There are numerous practical tricks to maintain excellent visualization throughout the operation (see Table 16.4).
Table 16.2 Useful hints for BIOM users
Working with (switching to) |
Do not give up after the initial frustration during the first few |
the BIOM requires some |
casesb |
getting used toa |
The benefits soon become obvious if you are persistent, and |
|
soon you could not imagine operating without itc |
Microscope’s focus pedal |
This is one of the most important adjustments the surgeon must |
|
make. Once the BIOM is swung in place, the microscope’s |
|
focus pedal does not control the focus anymore, it now |
|
changes the field of view: going down makes the field largerd |
|
The focus is adjusted using the BIOM’s focusing wheel |
The ideal working distance |
The front lens should be at ~2 mm from the cornea. This avoids |
from the cornea |
dipping into the visco yet provides the largest possible field |
|
If the cornea has to be recoated with visco, it is best to lift the |
|
front lens first, but it is not necessary to swing it out |
Scleral indentation |
Even when using the widest-angle front lens, scleral indentation |
|
is recommended to view the vitreous base |
Working in close proximity |
Unless there is substantial cataract to clearly show the border |
to the posterior capsule in |
between lens and vitreous, swing out the BIOM to avoid |
phakic eyes |
biting into the lens (see Sect. 27.5.3) |
Fine work on the posterior |
Use a contact lens instead of the BIOM, unless you are a very |
polee |
experienced surgeon (see Sect. 13.1) |
Do not turn the microscope |
The light reflex is blinding. Condition your brain to follow these |
light on while the BIOM |
sequences: |
is swung in |
(1) Microscope light off; (2) BIOM in |
|
(1) BIOM out; (2) microscope light on (see also Sect. 16.4) |
aNot an issue if the fellow starts his career using the BIOM.
bJust as you often fell off the bicycle when you started to learn cycling or had difficulty wearing a new prescription glass.
cThe best comparison between performing vitreous surgery using a contact lens vs the BIOM is when you compare cataloguing the inside of a room from the outside. You can do it with the door shut, through the keyhole (contact lens) vs with the door wide open and your head in the doorway (BIOM). dI.e., the more peripheral part of the fundus/vitreous to be viewed, the closer the BIOM front lens should be to the cornea.
eE.g., ILM peeling.
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16 The Surgeon at the Operating Table |
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Table 16.3 Basic setting up of the BIOM |
|
Variable |
Make sure that: |
View through the |
The view is sharp for the surgeon’s either eye, even at high magnificationa |
microscope |
|
BIOM adapter plate |
It is securely fixed to the microscope and the screw is tightened |
BIOM reduction |
The lens is not too hot and it properly clicked in place |
lens |
|
BIOM |
It is securely fixed to the adapter plate |
BIOM front lens |
The desired type of lens has been selected |
|
It is pushed all the way into its slot |
|
The focusing wheel is at the lowest positionb |
Imaging |
With the light pipe inside the vitreous cavity, the image is |
|
sharpened at the highest magnification of the microscope. The |
|
position of the front lens is then appr. 20% higher than the |
|
lowest possible point |
Corneal surface |
After squirting, it is coated with visco (see Table 16.4) |
The microscope |
It is lowered to be close to the eye so that the BIOM front lens is ~2 mm |
|
from the surface of the visco; this process is checked by the surgeon |
|
viewing it from the outside, not by looking through the microscope |
|
(see Fig. 16.4) |
aAnd the video camera also captures a highly focused image.
bi.e., the front lens will be in its closest possible position to the cornea. This prevents accidentally dipping into the visco where the focusing wheel turned in the wrong direction.
Fig. 16.4 The BIOM front lens. When in position, the lens should be about 2 mm from the top of the visco on the cornea. Note that the distance is measured not from the rim of the lens but from the apex of its inferior dome, which is much closer to the cornea
16.5.5 BIOM: Troubleshooting
The BIOM is a highly reliable tool, but the image quality may still be suboptimal. The causes and their fixes are listed in Table 16.5.