Richard Packard, MD, explains how he created a phaco tip family to fill a need for a coaxial phaco tip that was efficient in small incisions.
By Richard Packard, MD, FRCS, FRCOphth, Special to Ophthalmology Times
London-Microincision cataract surgery (MICS) has become a standard procedure for cataract removal. The widely practiced biaxial and coaxial procedures allow for minimally invasive, sutureless surgery with fast wound healing and almost instant visual recovery.1,2
However, because microincisions provide a limited amount of room to insert and maneuver a phaco tip during lens removal, there has been an increasing demand for narrower phaco tips. These should allow for easier manipulation within the phaco wound, even with incisions of 1.8 mm.
MICS & MIGS: Combined surgery with microstent devices
In response to this demand, I developed a phaco tip (Packard 0.7 Phaco Tip, MicroSurgical Technology), that was intended particularly for coaxial MICS (CMICS). The instrument is part of a family tips with an outer diameter of 700 μm. These tips offer a narrower design than those generally used for MICS, which usually have an outer diameter of between 800 μm and 1 mm.
The Packard family of phaco tips is available in a wide assortment, bent at either 12° or 20° and offered in Dewey Radius, traditional, and reverse bevel versions. Although these phaco tips were designed initially for CMICS and bimanual MICS (BMICS), they also work very effectively with appropriate sleeves for incisions of up to 2.8 mm.
One of the most significant advantages of a narrow phaco tip is that it offers improved visibility of intraocular structures during surgery when compared with larger phaco tips.
Particularly important with microincisions, a 700-μm phaco tip provides more room within the tunnel incision/sleeve for the surgeon to maneuver freely but also less restriction of irrigation fluid entering the eye.
This should assist in maintaining the anterior chamber when high vacuum and aspiration flow rates are in use. The curved tip reduces the overall need to tilt it downward during surgery, which gives a more comfortable hand position-especially when operating temporally. This results in a reduced amount of wound stress and unintentional enlargement of the incision.
Despite the narrow outer diameter of the tip, due to its thin wall the internal diameter of the Packard phaco tips is 570 μm, which is comparable to other MICS phaco tips that have a wider outer diameter. This means that with appropriate fluidics settings, the 700-μm phaco tip is not hindered by reduced performance during phacoemulsification. Also, the narrow profile and thin wall cuts through denser cataracts more effectively than tips with a larger profile.
In addition to offering efficiency through a narrow and angulated design, it is also important that a phaco tip is widely compatible with the various standard phacoemulsification platforms. The phaco tips fit to certain platforms (Alcon’s Infiniti and Centurion platforms using torsional phaco), but also work well with other systems (Stellaris, Bausch + Lomb; Whitestate Signature, Abbott Medical Optics), although a slightly shorter version will need to be ordered.
Although using a curved phaco tip is mandatory for effective torsional phaco, as on the Infiniti and Centurion, I have found that a tip of this design enhances the behaviour of Ellips FX on the Signature over a straight needle.
The narrower profile and ergonomics of a 700-μm phaco tip mean that there are slight differences in the way that the tip is handled, compared with wider-diameter tips. In my experience, however, I have found that this does not entail a significant learning curve. In our practice, most trainees start off with a divide-and-conquer nucleofractis technique. The 700-μm phaco tip allows for the easy creation of a very precise trench. The narrow profile of the tip means that it and the sideport instrument can then be placed right down in the bottom of the trench, making it easier to crack the nucleus.
For medium cataracts, I use a “soft chop” technique. After creating a small opening in the nucleus, the tip can then be buried deeply within it. I would recommend performing such a technique with a low vacuum setting of about 70-75 mm Hg and proceeding with a vertical chop. If the vacuum is too high, the piece of nucleus that is embedded in the phaco tip tends to get pulled through and there is little further purchase of nucleus tissue.
For a denser cataract, you may find that the nucleus rotates after the tip is buried and you begin the chopping procedure. In this case, it useful to pull with the hand wielding the chopper and simultaneously pushing with the hand holding the phaco tip to produce the hard chop of the nucleus. I normally use a vacuum of 400 mm Hg.
With most cataracts when using torsional phaco, burst mode is recommended. When faced with an extremely dense cataract, I would add 50% pulsed longitudinal phaco on top, for optimal efficiency. Although this means temporarily using higher power levels, less cumulative power is used overall because the narrow and angulated tip works more efficiently than a wider one. In a case study in 2009, the phaco tip (at 700 μm) offered the least cumulative dissipated energy, compared with four other tips during CMICS for dense cataracts.
Today, femtosecond lasers offer an effective tool to chop the nucleus safely in dense cataracts. However, even if the nucleus of a dense cataract is pre-chopped with a laser, there is often still the need to use a significant amount of phaco power afterward to remove the fragments from the eye. Using a 700-μm phaco tip to chop the nucleus into eight pieces in a similar manner to the laser uses a similar amount of energy for removal of the nucleus.
As described above, this narrow-profile, angulated phaco tip provides surgeons with a means for safe and effective surgery, whether performing CMICS, BMICS, or surgery utilizing incisions that range from 1.8 to 2.8 mm.
By offering more room for maneuvering, there should be less wound stress. Despite the narrow tip, with appropriate fluidics and ultrasound settings there should be no loss of functionality. It is particularly useful to have a tip that can be used with a wide range of different machines, techniques, skills, and clinical settings.
1. Alió JL, Rodriguez-Prats JL, Galal A. Micro-incision cataract surgery. Highlights of Ophthalmology International, Miami, USA (2004).
2. Elkady B, Piñero D, Alió JL. Corneal incision quality: microincision cataract surgery versus microcoaxial phacoemulsification. J Cataract Refract Surg. 2009;35:466–474.