Posterior plane emulsification can minimize capsule damage

The "stepdown"technique reduces trauma to the posterior capsule or zonules during phaco in the posterior plane.

ByShetal M. Raj, DO, MS

ByAbhay R. Vasavada, MS, FRCS

During phacoemulsification, it is desirable to remove nuclear fragments in the posterior plane to reduce the risk of endothelial damage. However, this increases the risk of posterior capsule rupture, so many of us subconsciously bring the phaco probe anterior to the rhexis as the posterior capsule gets progressively exposed.

We propose a technique where, although emulsification is performed at the posterior plane, the possibility of damage to the posterior capsule or the zonules is minimized. We call it the “stepdown” technique.

Surgical technique

Parameters for stepdown technique in a cataract with optimum density, at various stages of phacoemulsification: (A) sculpting; (B) division of nucleus; (C) to (F) fragment removal from beginning to end. Parameters are reduced as appropriate to the stage of fragment removal.

After ensuring rotation of the nucleus, a central space (trench) is sculpted using an Alcon Legacy 20000 series on surgeon control. We proceed with sculpting and, if necessary, we keep reducing the preset energy and aspiration flow rate while thinning the plate.

This is followed by the “step-by-step chop in situ and lateral separation technique” that we have evolved to enable the surgeon to divide the nucleus into multiple small fragments.

The application of the stepdown technique commences from the stage of fragment removal. The parameters that have been preset for dividing the nucleus are modified to remove the first two clock hours of fragment, wherein we reduce all the parameters, ie, energy, vacuum and aspiration flow rate, in a step-by-step manner.

From then on, after removing every two fragments we reduce the vacuum by 50 to 100 mm Hg and also the preset energy and aspiration flow rate.

Figure 1 shows the typical settings of the machine, while operating upon a cataract of optimum density, which is common in our part of the world. The fragments are consumed in the central space, at the posterior plane, without bringing the phaco tip anteriorly. The phaco tip remains in the posterior plane during the entire process of fragment removal and, instead, the parameters are reduced.

In a dense cataract with grade 4 or higher of nuclear sclerosis (in a grading system for cataracts from grades 1 to 5), the progressive reduction of the parameters necessitates more steps than required in emulsification of a cataract, which is less dense.

Discussion

Plane of emulsification. The boxes on the right side in each of these figures represent the parameters in the descending order as: energy, aspiration flow rate and vacuum.

Figures 1-2 courtesy of Abhay R. Vasavada, MS, FRCS and Shetal M. Raj, MS.

Typically, there are two to three steps of parameters for each stage of sculpting, chopping and fragment removal. This is particularly unfavorable for emulsification of dense cataracts. As the procedure progresses, the posterior capsule is exposed, and surgeons tend to bring the phaco probe anteriorly. This energy is dissipated near the endo-thelium and hard fragments could hit it. Therefore, it is preferable to emulsify fragments in the posterior plane safely by stepping down (reducing) all three parameters (Figures 2A, 2B).

Thus, the essence of the technique lies in the safety it provides during the entire stage of fragment removal.

Our technique is a subtle variation of the slow-motion technique of Robert Osher, MD, as we employ the principle of varying all the parameters, rather than continuing with low parameters throughout the procedure. It also promotes adaptation of various parameters to the appropriate stages of surgery.

We have used this technique for over 3 years in more than 5,000 surgeries and find it to be safe and effective. It is valuable, especially for residents in training or surgeons beginning phaco, as it is safe, easy to learn and reproducible.

It can also be beneficial to expert surgeons for emulsification in dense cataracts or while using the bevel-down technique.

Even with the advent of newer-generation phaco machines, equipped with programmable mode options with better fluidic control and advanced tip design, application of the stepdown technique is beneficial, as it promotes posterior plane phacoemulsification.

We believe this is a valuable concept in certain situations. We recommend it for routine use by trainee and expert surgeons.

Source: Vasavada A et al.

For Your Information:

Abhay R. Vasavada, MS, FRCS, and Shetal M. Raj, MS, can be reached at Iladevi Cataract & IOL Research Centre & Raghudeep Eye Clinic, Gurukul Road, Memnagar, Ahmedabad-380 052, India; +91-79-749-2303 or 749-0909; fax: +91-79-741-1200; e-mail: shailad1@sancharnet.in.