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Ask The Experts

Our medical 
editors answer readers’ questions. Dr Clare Quigley asks which is the superior technique, coaxial phacoemulsification or bimanual phacoemulsification?

Colin Kerr

Posted: Tuesday, June 20, 2017

Dr Clare Quigley
Second-year Resident at Mater Misericordiae University Hospital, Dublin, Ireland
Q. I have trained with surgeons who use coaxial phacoemulsification, and others who use bimanual, and I am similarly proficient at both now. Which is the superior technique, or is there only personal preference in the difference?

Marie-José Tassignon MD, PhD, FEBO
Chief and Head of the Department of Ophthalmology, University Hospital Antwerp, Belgium
A. The choice between coaxial or bimanual is triggered by different parameters:
1. Type of cataract:
In the case of very soft cataract, a bimanual approach is preferred. In children and certainly in babies, this is the best approach in order to maintain the anterior chamber (AC) deep and avoid iris prolapse. When following the technique of micro-incision cataract surgery (MICS), a bimanual approach presents the advantage to better stabilise the eye. The tighter the incision to introduce the instruments, the more the eye will present pressure spikes. This should be kept in mind when operating terminal glaucoma patients. MICS should be avoided in these cases.
2. Type of intraocular lens (IOL):
If the type of IOL needs a 2.2mm or larger incision, then a coaxial gets the preference but with only one incision, so without side-port incision. The idea is to reduce the total incision size. Even if working coaxial, both instruments of right (phaco probe) and left (lens manipulator) hand, are glided through the same single main incision. This allows you to operate with wound sizes of 2.2mm, not augmented by a 1mm side-port.
3. Degree of difficulty:
In the case of loose zonules, a coaxial incision will be used but with the help of one or four additional side-port incisions, depending on the degree of severity of the zonular lysis. If four side-ports are needed for the capsule suspension, no additional side-port will be performed for the phacoemulsification. We will then follow the technique as described in point 2.
4. The preferred position of the surgeon:
In a case of temporal position, a bimanual coaxial single incision is my preferred option (except for babies). In a case of superior incision, a bimanual double incision might be preferable.

Bekir Sıtkı Aslan MD
Head of Eye Department, Ankara Memorial Hospital, Turkey
A. Bimanual and coaxial MICS are not two conflicting surgical techniques. The common goal is to control surgery better and reduce induced astigmatism during cataract surgery.
A balance between irrigation and aspiration is the key element to avoid complications in phacoemulsification in micro-incision. The inflow of the fluid inside the anterior chamber is as important as the outflow.
With bimanual surgery, the amount of infusion is compromised and the leakage is significantly more when compared to coaxial phacoemulsification. It is nearly impossible to obtain an adequate seal when you put a rigid instrument through corneal incisions.
Phaco tip with a sleeve leads to better seal. Incisions around 2.2mm are almost astigmatically neutral. Coaxial phacoemulsification is feasible through this incision and you don’t need to enlarge the wound for any IOL implantation, whereas you need to enlarge one of the bimanual wounds for IOL implantation.
Anterior chamber maintenance, and of zonular stability, can be achieved far more superiorly with coaxial technique due to better fluidics and wound seal, especially in harder cataracts.
Though the literature revealed no significant differences in outcome parameters including topographic corneal and ocular abberrometric variables between each surgical technique, the bimanual technique may work for some moderate uncomplicated cataracts but coaxial is for all circumstances.
So I advocate coaxial phacoemulsification.

Oliver Findl MD
Chief, Department of Ophthalmology, Hanusch Hospital, Vienna, Austria
A. As far as I can see from my colleagues, many tried bimanual phaco when it was first proposed, but stopped using it soon thereafter.
Promoting bimanual phaco is like beating a dead horse – the reason being that the only real advantage of bimanual over coaxial, namely smaller incisions and more delicate (thinner) instruments, has been made obsolete with the introduction of axial tips with silicone sleeves that pass through 1.8mm and smaller incisions.
The sleeve ensures better stability of the AC during surgery and better sealing after surgery due to less strain on the wound. The IOLs need incisions of 1.8mm and larger anyhow, so it does not make much sense to enlarge a paracentesis for IOL implantation at the end of surgery.
Even with small floppy iris pupils, the coaxial phase works sufficiently well.

Small pupils can create difficulty in phacoemulsification