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J. Bovet |
•2 Paracentesis 20G for injection, phacochops manipulation,Irrigation-aspiration
•1 Incision for Phacoemulsification &
Injection the lens
6.9.4.5 Ultrasound Power Delivery
Any phaco machine with the surgeon’s desired phaco setting can be used with CoMICS.
Fig. 6.80 CoMics incision
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Flow pump cc/min |
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Max Vacuum limit |
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60 cm |
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20 cm
Pressure inside the eye 58.8 mmHg
Flow from the bottle Inside the eye
63.5 cc/min
Fig. 6.81 Real pressure and flow with the CoMics
6.9.4.3 The Phaco Machines (Fig. 6.81)
The level of the irrigation bottle should be between 80 and 100cm. The aspiration flow rate used is 25mL/min. The aspiration pressure is set at 400 mmHg. It is imperative to set the irrigation bottle sufficiently high in order to maintain adequate fluid inflow, thereby avoiding corneal burns which can be produced by the phaco tip.
6.9.4.4 Phaco Pumps
It is easier to use a machine combining peristaltic and venturi pumps.
6.9.4.6 Irrigation-Aspiration
The aspiration instrument should be replaced by a 2.2 mm diameter instrument when using a bimanual irrigation aspiration system to maintain water tightness so that the anterior chamber remains stable.
6.9.4.7 Incision-Assisted IOL Implantation
Most IOLs can be injected through a 2.2 mm incision by applying the injector directly against the incision with adequate pressure and then ejecting with force the plate or monobloc IOL into the tunnel and the anterior chamber (Table 6.6).
6.9.5 Conclusion
The BiMICS and CoMICS techniques are two complementary methods of practical phacoemulsification practiced nowadays by surgeons. As we have seen, each method has its advantages and disadvantages. Here, we have outlined the most important differences that would enable a surgeon to choose one method over the other.
It is easier to transition from the classic phacoemulsification technique to the CoMICS technique as only the parameters of the machine being used need to be changed. The learning curve in the CoMICS technique is less steep than in the BiMICS technique. In addition, improper planning of the incisions for both irrigation and aspiration in BiMICS can lead to anterior chamber instability and consequently lead to complications.
On the other hand, the BiMICS technique has an advantage of allowing a wider room for movement inside the anterior chamber, as both the functions of irrigation and aspiration are separated. Any complications experienced during the operation are easier to manage using the BiMICS technique.
These two technical differences can help the surgeon to choose one surgical technique over the other.
6.9 BiMICS vs. CoMICS: Our Actual Technique (Bimanual Micro Cataract Surgery vs. Coaxial Micro Cataract Surgery) |
155 |
Table 6.6 Advantages/disadvantages of CoMics
Advantages of CoMICS
No learning curve
Increased water tightness of the incision
The setting for the phacomachine is comparable to the 3 mm incision technique
IOLs and injectors are well adapted to a 2.2 mm incision
Disadvantages of CoMICS
The width of the incision is limited to 1.6 mm
Management of posterior capsular rupture is more problematic than with BiMICS
Small pupils are more difficult to deal with than with BiMICS
However, if we consider the visual outcomes of the patient, it is important to note the following aspects. First, the incision length of CoMICS, which at the minimum is 1.6 mm, cannot be reduced due to the limitations of the instrument. This, in addition to implanting the IOL in the same site instead of at the periphery, can lead to induced astigmatism.
In contrast, BiMICS allows reduction of the incision sizes up to 0.7 mm. The incision for the IOL implantation can be performed at another site, different from the first two incisions. This allows the incision to be exactly the size of the implant. It also allows a more precise positioning of the incision in relation to the patient’s preexisting astigmatism. The introduction of toric implants presents an important development and is the only real technique for fine correction of astigmatism. BiMICS will therefore, be the method of the future for allowing neutrality of astigmatism.
Take Home Pearls
ßIf one wants to shift from conventional phacoemulsification to microincision cataract sur-
gery, it is safer and more secure to start with CoMICS.
ßUnderstanding the phacodynamics during MICS is the key element to any successful
surgery.
ßIf one would like to use the newer generation IOLs, namely, the toric, multifocal and aspheric
IOLs, it is best to use BiMICS.
References
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