Swapping instruments improves ergonomics in temporal phaco

The surgeon remains in the superior position and the hands switch from dominant to non-dominant roles.

The temporal approach is increasingly the preferred incision location for phacoemulsification, according to the 1999 survey of members of the American Society of Cataract and Refractive Surgery.

For right-handed surgeons operating on right eyes, this incision location demands no special position adjustments, as the right hand naturally holds the phaco probe while the left hand holds the auxiliary instruments and the surgeon maintains the traditional and comfortable superior position for cataract surgery. However, the same right-handed surgeon when confronted with a left eye has to make significant adjustments in his position to perform a temporal incision.

Superior surgeon location provides the most ergonomic adaptation for temporal phacoemulsification by right-handed surgeons in the patient’s right eye.	Opposite eye temporal phaco surgery performed from the lateral aspect can require a non-ergonomic surgeon posture.

These adjustments mainly consist in locating to the side of the patient. This causes problems such as the surgeon’s legs colliding with the operating table supports and the special effort needed to maintain adequate distance from the surgeon’s eye to the oculars of the operating microscope. The surgeon has to twist his spine and extend his neck in a very non-ergonomic adaptation that can lead to fatigue, muscle strain and potential professional illness after repeated procedures. Also, hand and foot position become unbalanced, increasing the torsion effect, a situation usually assumed to be a cost of performing this state-of-the-art technique.

The alternative of operating on the left eye via a nasal approach to avoid abandoning the superior position results in higher surgically induced astigmatism that has proved to be statistically significant.

Both hands highly skilled

It is commonly thought that the hand holding the phaco probe is the only one that must perform fine and precise movements, but close observation of a bimanual phacoemulsification procedure shows that both hands perform precise and skillful maneuvers at different times during surgery. The opposite hand performs very skillful actions such as nucleus rotation, nucleus cracking, chopper manipulation, IOL insertion, guiding and positioning, among others. All these maneuvers can require even a higher degree of skill and precision than those required to operate the phaco probe with the dominant hand.

In fact, the hand holding the phaco probe usually needs to provide only limited mobility of the tip of the instrument inside the eye. A recent report showed that the learning curve in phacoemulsification for residents that were instructed from the beginning always to hold the phaco probe with their non-dominant hand was followed by at least similar or improved results when compared to the conventional dominant-hand approach.

Training the hands

Unaware of these reports, and determined to improve the ergonomic adaptation of the surgeon when performing phacoemulsification in the eye opposite the dominant hand, we focused on training both hands to perform the surgical actions usually done by the opposite hands during phaco surgery. The idea was to enhance the surgeon’s skills to become able to operate right and left eyes through a temporal incision without having to adapt to a different position with respect to the patient for surgery in opposite eyes. In this way, the surgeon could remain in a superior position that is comfortable, balanced and ergonomically correct.

Depending on the side of the eye to be operated, instruments were swapped and the surgery was performed in a mirror-like fashion, holding the phaco probe with the right hand for temporal phaco of right eyes and with the left hand for temporal phaco of left eyes.

We tested the hypothesis that after a training period the tasks performed by each hand during phaco surgery could be performed with comfort and proper skill by the opposite hand, providing enough reliability to allow the surgeon to remain in a superior position. We conducted a single-surgeon study in which 75 right eyes and 75 left eyes were operated always holding the phaco probe with the hand ipsilateral to the eye being operated.

Right and left eyes entered the study randomly in the presenting order. The surgical results were compared between subgroups of the first, second and third 25 eyes for each side. Specially challenging cases such as very hard nuclei and non-dilating pupils were allowed only after the second group had been completed and analyzed.

Hand rest vital

In vitro observation of opposite hand ability to accomplish fine tasks was noted to be highly dependent on an adequate arm and hand rest. Providing an adjustable-height hand rest was considered a fundamental aspect of the in-vivo study. This hand rest was incorporated into the operating table and was adjusted individually for every patient to provide an optimal position of the hand located to the temporal side to match the intended main incision position.

The hand rest relieved the arm and forearm of coarse positioning forces and converted wrist and hand movements into finer finger movements. The absence or misalignment of the hand rest increased fatigue and significantly compromised the ability of the non-dominant hand to comfortably accomplish the surgical maneuvers. With time, we found the hand rest equally useful for performance with both hands.

Measuring the difference

Surgical time, complications, surgeon confidence and surgeon comfort were recorded for each case and later analyzed for each group. Surgical time was divided into capsulotomy time (performed with capsular forceps), phaco time and total procedure time. Time data were extracted by reviewing the videotapes of all cases, to reduce the influence of a time factor in surgeon performance. Subjective parameters such as surgeon comfort and surgeon confidence were recorded as a comparative percentage, using dominant hand phaco procedures as a reference.

We found overall procedure time differences between right and left eye surgeries in the first 25 patient groups. These differences became smaller in the second groups and disappeared in the third groups. Complication rate was similar for right and left eyes. Surgeon comfort and confidence were initially asymmetric but became equivalent in the third group.

Similar skill levels

At the end of this single surgeon study we were able to operate with a similar level of skill in both right and left eyes through a temporal approach with improved ergonomic adaptation. Duration and outcomes of these procedures had become comparable. Several hundred following procedures have been performed through this superior approach regardless of the eye being operated. Currently no special consideration is made by the surgeon for right or left eyes except for draping the corresponding eye. The scrub nurse is always located to the right of the surgeon and should be aware of handing the corresponding instruments to the proper hand according to the eye being operated.

We must emphasize the role played by the adjustable height hand rest for being comfortable during surgery. We consider that this approach to temporal phaco surgery is only advisable to be tested by surgeons that are already confident with the phaco procedure and that have bilateral hand skills. Those still on the slope of their learning curve or markedly asymmetrical in their surgical skills will probably feel more confident performing phacoemulsification in the traditional manner.

Being able to perform phacoemulsification in this bimanual form with swapped instruments is encouraging and exciting and provides the surgeon with an increased level of skill and versatility that may become useful even for performing other procedures in a comfortable manner.

Hand posture and spine curvature become unnatural in the lateral approach.
A temporal incision in one eye (left) and a nasal incision in the opposite eye (right) leads to significant differences in induced astigmatism.
Nuclear cracking and phaco chop under the capsular rim require high skill in the left hand.	The hand that holds the phaco probe is supported by the adjustable hand rest.
The hand rest is helpful for both dominant (left) and non-dominant hand (right) temporal phaco performed from a superior approach.

For Your Information:

• Jaime Zacharias, MD, is in private multispecialty practice and is an assistant professor at the University of Chile. He can be reached at Fundacion Oftalmologica Los Andes, Las Hualtatas 5951, Santiago, Chile; (56) 2-370-4621; fax: (56) 2-371-8934; e-mail: jzacha@entelchile.net. Dr. Zacharias has no direct financial interest in any of the products mentioned in this article nor is he a paid consultant for any companies mentioned.

References:

• Leaming DV. Practice styles and preferences of ASCRS members: 1999 survey. J Cat Ref Surg. 2000;26:913-921.
• Kohnen S, Neuber R. Comparison of the surgically induced corneal astigmatism of a temporal and a nasal clear corneal incision. ASCRS Symposium on Cataract, IOL and Refractive Surgery, May 20-24, 2000. Abstract 751, page 189.
• Householder JA. Left handed phacoemulsification. ASCRS Symposium on Cataract, IOL and Refractive Surgery, May 20-24, 2000. Abstract 126, page 32.