Viscosplit and crack in mini-coaxial small-incision cataract surgery

Take-home: Cataract surgery assisted by viscosplit and crack gives good results compared with standard phacoemulsification. 

Introduction

Introducing femtolasers into cataract surgical procedures has advantages, but also disadvantages such as a range of additional complications.¹ This raises the question of whether this expensive technology adds sufficient benefit to previous techniques. Therefore, scientific comparison of different surgical methods with respect to safety, benefits for the patients and cost is necessary. The aim of this paper, which is based on a presentation at the ESCRS 2010 meeting,² is to compare different phaco techniques in order to evaluate their advantages and disadvantages and to derive implications for future directions in cataract surgical methodology.

In order to investigate and disentangle the costs and benefits of different cataract surgical methods, this study compared cataract surgery assisted by viscosplit and crack (VSC) with that performed using standard phacoemulsification. These are well-known variations of mechanical fragmentation of the nucleus phacofracture divide-and-conquer and bimanual chop techniques,^3–5 all performed at our eye surgery centre in Augsburg, Germany.

Patients and methods

Patients and methods

The study included 200 patients aged between 50 and 75 years. Inclusion criteria related to the hardness of the lens nucleus only.^4,5. Patients with previous eye surgery, retinal disorders, glaucoma, cataract lenses that were softer or harder as well as rock-hard lens nuclei were excluded.

All patients had a comprehensive baseline preoperative assessment. Biometry was performed 8–4 weeks prior to surgery. All surgery was performed by the author.

Our collected data included all biometric measurements as well as pre- and postoperative endothelial cell counts.

During surgery, the following data were collected:

1. Quantity of balanced salt solution (BSS, mL) consumed during phacoemulsification and overall.

2. Ultrasound energy; ultrasound time.

Best corrected visual acuity (BCVA) data were obtained on the first day, as well as 4 weeks and 3 months after surgery; endothelial cell counts were taken 6 weeks postoperatively. These data were compared retrospectively with data from our database of previous conventional one-handed and bimanual phacofracture procedures. Statistical analyses were performed using the sampled t-test. Differences were accepted as significant when the p value was less than 0.05.

Surgical Technique

Surgical technique

After peribulbar anaesthesia, surgery was begun with postlimbal incisions, which were neutral to astigmatism. The main incision size was <2.2 mm, using a temporal limbal approach with two side-port incisions. The continuous curvilinear capsulorhexis (CCC) diameter was 5.5–5.8 mm. After CCC, hydrodissection was performed with a 27 gauge cannula; hydrodelineation was achieved using a sharp, slightly bent cannula to perform a smooth infusion of BSS within the sometimes rigid lens material.

FIGURE 1

(FIGURE 1) The hydrodissection cannula (Klaas/Geuder).

After protection of the endothelium with Viscoat® (Alcon, Fort Worth, USA), viscoelastics were injected at the edge of the most visible golden ring between cortex, epinucleus and lens nucleus. Repeated delineation with viscoelastics was performed (‘viscodelineation’).

Injection behind the lens nucleus from the surgeon’s point of view allowed one pole of the nucleus to shift forward. We also installed a retronuclear pad of viscoelastics to the posterior pole of the core, which made it more easy to lift without zonular affection and created a protection shield for the posterior capsule.

FIGURE 2(FIGURE 2) Split bevel up and split bevel down (Klaas/Catena Inc).

With two specifically designed lens-splitting instruments (Klaas/Catena USA Inc), the lens nucleus can be cut into small pieces: as many as you like. The cross-sections of these instruments are triangular and they have a rounded tip (to protect the lens capsule) and one sharp edge on top (bevel-up and bevel-down) in order to cut the nucleus easily.

FIGURE 3A

FIGURE 3CF

FIGURE 3DIGURE 3B

(FIGURE 3A–D) Viscosplit technique: segmentation of the lens nucleus.

The surgical cataract procedure was performed using the Ocusystem II Advantage Art-System (Surgical Design Corporation, NY, USA). Maximal ultrasound power was 30%, initial flow 12 mL/min, maximum flow 25 mL/min, vacuum settings min: –120 to max: –350.

Phaco-emulsification of the lens fragments was carried out using specially designed phaco tips. The particular advantage of this new generation of phaco tips lies in its edgeless and non-sharp design. The aperture of the tip is situated more on the side of the ultrasound tip, which makes the procedure safer with regard to protecting the lens capsule. In addition, the side-orientated opening provides greater suction of the lens material. Therefore, it is no longer necessary to cut the lens material.

FIGURE 7

(FIGURE 7) Shark™ phaco tips.

Epinucleus and cortex removal was done with the same phaco needle followed by irrigation/aspiration with a bimanual technique (Geuder, Heidelberg, Germany).

Analyses and results

Analyses

We compared results concerning different parameters obtained by the viscosplit technique (n=200) with results obtained with the standard phaco technique, bimanual (n=83) and one-handed (n=50). Values were compared using two-sample t-tests.

Results

In the viscosplit group (see Table 1) mean BSS volume during phaco was only 12.0 mL; the other two groups needed 35 mL (one-handed) and 65 mL (bimanual).

Both ultrasound time and energy were reduced by between 60% and 80% with viscosplit compared with conventional phaco-emulsification techniques.

All patients had a BCVA of 20/25 or better, and reading speed showed considerable amelioration. BCVA was significantly better in the viscosplit group the day after surgery. At 6 weeks, BCVA showed no difference between the groups.

There was very little endothelial cell loss 6 weeks postoperatively, and no significant difference between viscosplit and the two conventional surgery groups.

Table: Viscosplit versus standard phaco

TABLE 1: Viscosplit versus standard phaco. All values are mean (standard deviation) unless otherwise stated.

Viscosplit group
Shark tip
(n=200)

Standard phaco group; bimanual phacofracture
Mini cobra tip
(n=83)

Standard phaco group; one-handed phacofracture
Mini cobra tip
(n=50)

Pulse mode 30 Hz
Incision size
1.9–2.0 mm

Pulse mode 30 Hz
Incision size
2.0–2.2 mm

Pulse mode 30 Hz
Incision size
1.9–2.0 mm

25.0 (5.0)

80.5 (11)

62.0 (10)

12.0 (3.0)

65.0 (6.0)

35.0 (4.0)

14.3 (2.1)

44.3 (3.1)

31.3 (3.5)

3.1 (0.2)

8.0 (0.2)

4.0 (0.3)

1.0

0.63 (0.1)

0.7 (0.1)

1.0 (0.05)

1.0 (0.05)

1.0 (0.1)

<0.1

<1.5

<1.0

Discussion and summary

Discussion and summary

We have demonstrated excellent results for this innovative procedure in 200 patients, which were compared with the results of two control groups that were treated using conventional procedures.

Our findings suggest the minicoaxial phaco-emulsification technique using the VSC procedure to be an energy- and time-saving method. Owing, presumably, to better flow dynamics and to not grooving the nucleus, this method has advantages over all bimanual methods. Comparing the results from this series of patients with those from former patients whose surgery used bimanual chopping methods by the same surgeon, we noticed faster recovery and better initial results.

We can show that the technique described here has considerable advantages. First, the protective effect of the viscoelastics, e.g., behind the lens nucleus. Second, manipulation is easy because of the rotation and manoeuverability of the lens nucleus. These factors are central to the safety of this procedure and implicate no zonular stress, which is important for example in cases of l-week zonular fibres, such as zonular dehiscence and pseudoexfoliation.

This technique has a similar reduction in ultrasound energy to the femto-assisted phaco procedure,^6,7 which is another advantage of the technique presented here.

Last but not least, the cost/benefit ratio should be considered, which comes out in favour of our technique compared with the femtosecond laser.

Another point to consider is the rate of complications. We observed no rupture of the anterior or posterior capsule in any of our groups.

The femtosecond laser seems to be beneficial, with significantly reduced phaco time and power; further studies are needed to compare the advantages and disadvantages of each fragmentation pattern in relation to the size of the phaco tip and the system used. Our shark-tip design, which I'd like to name the ‘femtotip’, may contribute to a further reduction of the energy levels, further optimising the procedures used and perfectly restoring the vision of our patients.

References

References

ESCRS femtosecond laser-assisted cataract surgery (FLACS) study. Available at www.eurequo.org/new/flacs.asp [accessed 15 April 2016].

Presentation at ESCRS 2010 meeting.

D.F. Chang, ed. Phaco Chop: Mastering Techniques, Optimizing Technology and Avoiding Complications. 2004, Slack, Inc: Thorofare, New Jersey.

I.H. Fine. J. Cataract Refract. Surg. 1991; 17: 366-371.

I.H. Fine, M. Packer and R.S. Hoffman. J. Cataract Refract. Surg. 2001; 27: 188-197.

D.V. Palanker et al., Sci. Transl. Med. 2010; 2 (58): 58ra85.

M. Moshirfar, D.S. Churgin and M. Hsu. Middle East Afr. J. Ophthalmol. 2011; 18 (4): 285-291. doi: 10.4103/0974-9233.90129.