Phaco chop technique for cataract surgery in the dog

Abstract

Phaco chop is a bimanual phacoemulsification technique to remove cataracts. The technique was first presented at the 1993 3rd American-International Congress on Cataract, IOL, and Refractive Surgery in Seattle by Dr Kunihiro Nagahara. He compared the lens with a block of wood and by applying chopping forces parallel to the natural planes of the lens lamellae, as one does in splitting wood, a nucleus can be cleaved with surprisingly little force and time. Dr Nagahara used the phaco tip to impale and high vacuum to hold the nucleus while a second instrument, or chopper, hooked the equator and was pulled centrally, splitting the nucleus along its natural cleavage planes. This was a breakthrough for surgeons who had been utilizing several minutes of phaco energy sculpting grooves and bowls in a lens. Studies have shown that compared with four-quadrant 'divide and conquer', the phaco chop technique uses less phaco time and energy, significantly reducing endothelial cell damage. Other advantages of phaco chop include reduction of zonular and capsular stress because forces are directed toward an opposing instrument and the phaco tip is kept in a central 'safe zone' in the middle of the pupil. This technique has also been successfully adapted to the canine phacoemulsification procedure. The larger canine lens requires some modifications, and lenses with hard nuclear and cortical material may not be amenable to this procedure.

V-Prechop nucleodissection technique feasibility in the phacoemulsification in dogs with cataracts. Clinical aspects and specular microscopy

“…The primary reason that motivated us to study this technique, was based on the fact that it demonstrates, in principle, respect for the anatomical details of the lens, allowing preparation of a fragment in a "V", whose fragmentation and aspiration is facilitated. Furthermore, cataracts in dogs present cataractous nuclei with variable degrees of hardness (Slatter, 2005;Munger, 2009), which are not always removable using the "Divide and conquer" technique, faced with trans-surgical complications, such as difficulty with nucleus rotation to perform the second fracture (Akahoshi, 1998;Slatter, 2005;Warren, 2004). Furthermore, due to the technical impossibility, irregular fragments can be created which are free in the anterior chamber, increasing the difficulty in performing emulsification and aspiration and thus the degree of endothelial injury and intraocular inflammation (Munger, 2009;Padua et al, 2017).…”

“…There is no doubt that residues of these substances provide mechanical resistance to the aqueous humor flow in the trabecular meshwork (Munger, 2009). The efficient realization of irrigation and aspiration maneuvers (I/A) at the end of phacoemulsification, reduces the intensity of complications (Wilkie & Colitz, 2007;Nasisse et al, 1991;Warren, 2004;Pigatto et al, 2006). In this sense, it can be assumed that the maneuver was conducted efficiently in all animals, since the IOP remained reduced in the immediate postoperative period in all patients included in the study.…”

“…Nagahara cited by Can, Takmaz, Çakici, Özgül and Meltem (2004) introduced a technical variant that performs a "lens chop" (fracture) with the aid of a second instrument, for a service incision, called the "phaco-chop" technique. It considers a cleavage plane situated between the outer layer and "inner core" for the anatomical division of the nucleus, denominated nucleodissection (Warren, 2004).…”

“…One of the recent advances refers to the technique of "prechop", which uses a "prechopper" to perform two perpendicular fractures, one on the other, dividing the lens into quadrants (Akahoshi, 1998;Warren, 2004). However, the procedure cannot be applied in all cases.…”

A modifiedab externoapproach for suture fixation of an intraocular lens implant in the dog

“…Intraocular lens implantation has become the standard of care for most canine cataract patients. Surgeons utilize the techniques of one‐handed and two‐handed phacoemulsification and the various manipulations involved in the techniques of lens sculpting, divide and conquer, phaco chop, chip and flip and other techniques designed to remove the lens in an efficient and atraumatic manner 1–3 . Canine IOLs are constructed from polymethylmethacrylate (PMMA) and acrylic materials, the latter allowing implantation through a small incision using a shooter or folding forceps 3 .…”