Phacoemulsification is a popular method of cataract removal. Among the available techniques, we can identify two types of cataract phacoemulsification surgeries: (1) coaxial, using a sleeved phaco tip to break the cataract into fragments and then aspirate it,1 and (2) biaxial, using the phaco tip to emulsify and aspirate the cataract and a separate irrigating chopper to avoid anterior chamber collapse.2
There are a variety of phaco tip models for each technique, the most common being circular. Circular phaco tips range in diameter from 19 to 21 gauge.3 Theoretically, a circular-shaped tip — introduced through a linear incision — produces the maximum amount of friction at the superior and inferior opposite points of contact between the corneal tissue and the phaco tip.
Almost total contact energy will act on these points, causing easier corneal burning;4 moreover, stretching of the corneal incision will occur. If a flat tip is used, however, friction energy is distributed along a wider contact surface and less incision stretching occurs (Figure 1). Therefore, the quantity of friction energy per surface unit as well as heat production will be less.
RESEMBLES A TRUMPET
Considering these concepts, one of the authors (Dr. Migliorati) designed the Tromb Tip (Optikon 2000 Industrie, Rome), named for its resemblance to a trumpet. *Editor's Note: For ordering information, visit www.optikon.com/en/default.esp. The diameter of this 17-gauge flat phaco tip is 2 mm horizontal and- 0.9 mm vertical. The angulation is 30º (Figure 2).
We have used the new phaco tip in 50 eyes of 50 patients (ie, 27 females and 23 males, mean age 78 years, range 61 years to 86 years) scheduled for cataract extraction with phacoemulsification. All patients underwent complete ophthalmological examination including BCVA determination, tonometry with the Goldmann applanation tonometer (Haag-Streit, Bern, Switzerland), fundus biomicroscopy with the 90-D Volk lens (Volk Optical, Mentor, Ohio), corneal topography, central corneal thickness measurement and corneal endothelial biomicroscopy. All surgery was performed by the tip's designer.
GREAT ASPIRATING POWER
We used biaxial phacoemulsification with the Optikon assistant phaco machine in all eyes. After a clear-corneal incision of 2 mm to 2.1 mm, we performed capsulorhexis with microcoaxial forceps and then hydrodissection. A venturi pump and the Tromb Tip were used for the phaco procedure. Because the 17-gauge phaco-tip has great aspirating power, a large-flux irrigating chopper (ie, 1-mm external diameter and flux rising to 96 mL/min) (Figure 3) was employed. We used phaco chop or stop-and-chop if the cataract had a hardness of 3+ or higher (Figure 4), and if the cataract was soft, we only used the phaco aspiration without the chopper. After phaco and cortical material aspiration, we enlarged the clear-corneal incision to 2.5 mm and introduced the IOL into the capsular bag. No sutures were used in any case. We used a short-chain hyaluronic acid for viscoelastic.5
We examined the total duration of surgery and the time of the phacoemulsification phase, the percentage of ultrasound used and the presence of signs of corneal burning. Patients were examined preoperatively and 1 month after surgery for BCVA, mean corneal topographic astigmatism, mean endothelial cell count, presence of intra- and postoperative complications and signs of corneal burning.
SURGERY, PHACO DURATION
Surgery duration ranged between 3 minutes (ie, for soft cataracts) and 12 minutes (ie, for hard dark cataracts). Phaco duration ranged between 20 seconds and 3 minutes. The mean ultrasound percentage was 25% (range, 10% to 40%). The only intraoperative complication we observed was one posterior capsular rupture; we performed an anterior vitrectomy and introduced a sulcus-fixated soft IOL.
No postoperative complications were present in our case series. Particularly, no signs of corneal burn were noted. All patients had an improvement in visual acuity after surgery (ie, minimum three lines and maximum seven lines), and no clinically significant topographic surgically induced astigmatism was present after surgery in any patient.
The mean endothelial cell count was 1,750 cells/mm2 before surgery and 1,640 cells/mm2 1 month after surgery. Minimum cell loss was 1% and maximum cell loss was 12%. In our opinion, both the new phaco tip and irrigating chopper (Figure 3) appeared easy and safe to manipulate with every type of cataract. The total duration of surgery, including the phacoemulsification phase, was fast in all cases, especially in patients with soft cataracts.
DISCUSSION
Theoretically, introducing a round phacoemulsification tip through a linear incision is a difficult physical concept. Compared with the round tip, a flat tip induces less corneal incision stress and lowers the probability of corneal burning, especially if the phaco tip has no covering sleeve.
Furthermore, in our experience, the biaxial 21-gauge phacoemulsification technique (ie, cold phaco) frequently takes more time than 20-gauge monoaxial phacoemulsification. In cases of hard cataracts, not only is it time consuming, but the stress on corneal tissue is prolonged.
The Tromb Tip, designed to allow a wider contact surface between the corneal tissue and the tip, distributes friction energy along the whole contact surface and, so, reduces the friction energy per contact surface unit.
Moreover, the 17-gauge aspiration diameter permits fast surgery and a low ultrasound percentage. As reported previously, also in presence of hard dark cataracts, the maximum ultrasound level was 40%, and the maximum phaco time was 3 minutes.
PREVENTING CHAMBER COLLAPSE
Obviously, a greater aspiration rate is present using a larger tip; a more abundant infusion flux is necessary to prevent dangerous anterior chamber collapses, which is why we use a large irrigating chopper. A phacoemulsification machine with forced isobaric infusion may also be used.
To summarize, our new phaco tip allows for:
• A 2-mm to 2.1-mm corneal incision with less corneal friction energy per surface unit and less corneal incision stress;
• Shorter surgery duration; and
• Less total ultrasound use.
The surgeon must become accustomed to large irrigating choppers and pay attention to the phaco tip maneuvers (ie, big phaco tip) so that corneal endothelium damage is avoided. To protect the corneal endothelium, it is better to use an adhesive or short-chain cohesive viscoelastic substance.
We believe that the Tromb Tip is a good alternative phaco tip for biaxial phacoemulsification and traditional monoaxial phacoemulsification because it allows a better respect of the corneal incision and a shorter surgery duration.
Giuseppe Migliorati, MD, is from the department of ophthalmology at the S. Maria della Misericordia Hospital, in Udine, Italy. Dr. Migliorati states that he has no financial interest in the products or companies mentioned. He may be reached at Giuseppe.migliorati@libero.it; phone: +39 0432 552047; or fax +39 0432 552741.
Maria Letizia Salvetat, MD, is from the department of ophthalmology at the S. Maria della Misericordia Hospital, in Udine, Italy. Dr. Salvetat states that she has no financial interest in the products or companies mentioned. She may be reached at mlsalvetat@libero.it; phone: +39 0432 552047; or fax +39 0432 552741.
Paolo Brusini, MD, is from the department of ophthalmology at the S. Maria della Misericordia Hospital, in Udine, Italy. Dr. Brusini states that he has no financial interest in the products or companies mentioned. He may be reached at prim.oculistica@aoud.sanita.fvg.it; phone: +39 0432 552047; or fax +39 0432 552741.
Up Front | Sep 2006
The Tromb Tip: A Brand New Phacoemulsification Tip
This flat phaco tip results in a shorter surgery duration and may be a good alternative tip for biaxial and traditional monoaxial procedures.
Giuseppe Migliorati, MD; Maria Letizia Salvetat, MD; and Paolo Brusini, MD
