Drs Carifi and Zuberbuhler in their letter commend our findings about the relationships among incision sizes, stress, and wound integrity and raise 3 main problems with our study, to which we respond.
First, we express our appreciation to Drs Carifi and Zuberbuhler for their commendation and emphasize our findings. In our study, we found that a 1.8-mm incision did not necessarily have better wound integrity than 2.2-mm and 3.0-mm wounds. Thus, we should consider the tradeoffs in terms of reducing induced astigmatism and maximizing clear corneal incision integrity when selecting an incision size-dependent surgical system. The smallest available incision size systems may not necessarily optimize this tradeoff.
At the same time, concerns were raised regarding the 2 different phacoemulsification machines used in our study because, in their opinion, different machines do not represent the best choice in the study. Actually, the phacoemulsification machine was only 1 component of the incision size-dependent phacoemulsification system in our study. The clinical outcomes of cataract surgery are influenced by many factors, including the blade used to create the incision, the phacoemulsification apparatus, and the intraocular lens used and the mode of insertion, which together constitute a surgical system, the outcomes of which are restricted by the best performance of each component. Our study aim was to compare the outcomes of cataract surgery performed with 3 different incision size-dependent phacoemulsification systems, not just a single component.
Corneal incision size and surgically induced astigmatism were the main clinical outcomes in our study. However, the cumulative dissipated energy (CDE) was obtained as one of the intraoperative outcomes to compare the efficiency of different systems in our study, which also was used in other studies. The mean CDE was calculated as follows: CDE = mean ultrasound power × total phacoemulsification time, the value of which was calculated automatically by the phacoemulsification system and was displayed on the monitor.
The measurement and statistical method of wound enlargement in our study was similar to that of other reports, which now has been accepted by most investigators. In our study, our results suggest that the 1.8-mm wound size may be relatively small for the surgical instruments used in this system. To avoid enlargement of wounds of this size, a phacoemulsification and an irrigation-and-aspiration tip with a smaller diameter and thinner intraocular lenses may be needed, although a smaller tip is likely to decrease surgical efficiency, and a thinner intraocular lens may be less stable in the capsular bag. We also would like to emphasize that technological developments have enabled a reduction in incision size; however, smaller is not always better.