Femtosecond Laser-Assisted 'Pauci-Phaco' Cataract Emulsification

William W. Culbertson, MD


March 15, 2013

Effect of Femtosecond Laser Fragmentation of the Nucleus With Different Softening Grid Sizes on Effective Phaco Time in Cataract Surgery

Conrad-Hengerer I, Hengerer FH, Schultz T, Dick HB
J Cataract Refract Surg. 2012;38:1888-1894

Phaco Energy and Time

Phacoemulsification ("phaco") enables removal of the cataractous nucleus through a small incision, with the expected benefit of rapid visual recovery and minimal adverse refractive changes in the cornea. However, added surgical manipulations, ultrasonic energy, and infusion fluid flow in the anterior chamber during the procedure creates the potential for various documented complications, including incision burn, iris damage, torn lens capsule, and damage to the corneal endothelium. In the past 3 years, the femtosecond laser has been repurposed to presoften and presegment the cataract ab externo prior to opening the eye with the goal of minimizing the potential deleterious manipulations and energy required to fragment and emulsify the lens in modern non-laser-assisted phacoemulsification. Recently, surgeons using different cataract lasers have demonstrated that laser presegmentation and softening reduces the phacoemulsification energy and manipulations required to remove the cataract nucleus. Still unknown is the optimal segmentation-softening pattern and whether the added laser energy and lasing time required to produce a tighter pattern truly results in correspondingly reduced phaco energy and time.

Study Summary

Conrad-Hengerer and coinvestigators examined whether using a tighter nuclear softening pattern (350 μ) results in lower phacoemulsification energy and time than when a wider pattern (500 μ) is used. The study eyes were randomly divided into 2 groups of 80 eyes each. The Lens Opacities Classification System III (LOCS III) cataract nucleus scoring system was used to grade each cataract, and statistical equivalence of preoperative nuclear grade (3.7 for the 350 μ group vs 3.5 for the 500 μ group) was achieved between the groups. As outcome measures, the mean absolute phaco time (APT), the mean effective phaco time (EPT), and the mean phaco power (MPP) were recorded for each surgical eye. All surgeries were performed by a single surgeon (Burkhard Dick) using the Catalys femtosecond cataract laser (Optimedica; Santa Clara, California) and a standardized "stop and chop" phaco technique with the Stellaris (Bausch + Lomb; Rochester, New York) phaco machine in venturi fluidics mode.

Results showed that both groups had remarkably reduced phaco energy ("pauci-phaco"), with an average combined EPT of 0.12 seconds compared with an EPT of 2.32 seconds obtained in an unpublished study using standard-technique phaco surgery performed by the same surgeon. By reducing the laser-cut vertical planes from a separation distance of 500 μ to 350 μ, all of the measured parameters of the phaco energy used intracamerally were substantially reduced. The APT decreased from 5.85 seconds to 2.05 seconds. The EPT declined from 0.21 seconds to 0.03 seconds, and the MPP was reduced from 2.5% to 1.6%. No complications occurred in either group.


Ironically, the emphasis of modern phacoemulsification cataract surgery has been to minimize the phaco energy dissipated in the anterior chamber. Through the use of chopping techniques and high vacuum fluidics, EPTs have progressively declined over the past 20 years. However, these techniques have replaced phaco energy with extra manipulations and chamber maintenance challenges that have their own potential complication sets. "No touch" ab externo laser segmentation and softening of the cataract nucleus internally has the theoretical advantage of placing the chopping/disassembly manipulations and cavitation energy deep within the nucleus, avoiding exposing the iris, lens capsule, and endothelium to the effects of the standard phacoemulsification process. This study has demonstrated that, with the help of the laser, we are coming closer to the objective of removing the cataract nucleus with minimal or no requirement for phacoemulsification energy. The handwriting is clearly on the wall: With further innovation and optimization of technique and instruments, including laser dynamics and softening patterns, femtosecond laser-assisted cataract surgery will become phacoless ("aphaco") for most cataracts, whereas dense cataracts may still require the "pauci-phaco" technique.