irrigation and greater cooling, and less potential for the compression of the tip to block irrigation flow. An aspiration bypass tip can avoid excessive increase in temperature at the incision site because of the lack of complete occlusion of the tip and the absence of flow during occlusion. The use of an angled phaco tip, such as the Kelman tip, gives accessibility to the endolenticular material with less tilting of the tip and therefore, greater protection against thermal injury [26] (Fig. 6.38).

6.3.4.7 Surgical Technique

Chopping techniques utilize less ultrasound energy in general, because they use mechanical forces in the form of chopping to disassemble the nucleus compared to ultrasound energy grooving, in preparation for cracking. There are some studies that indicate that biaxial microincision cataract surgery results in increased thermal damage [27, 28]; however, other studies [6, 7, 29–33] have not found a significant difference in the temperature at the incision using a sleeveless technique compared to a sleeved one. Although early irrigating choppers had less flow than conventional coaxial systems, the more modern irrigating choppers and larger lumens have flows that are comparable to coaxial microincision cataract surgery [34] (Fig. 6.39).

6.3.5 Conclusion

In the past, corneal burns during phacoemulsification have represented an important problem, which has partially delayed the complete diffusion of this surgical procedure. To a greater extent, the fault can be placed on the machines which delivered too much energy for too long.

With the improvement of scientific knowledge in ultrasonic emission, it has been possible to have even more efficient machines that are able to use lesser energy[35–40].

For this reason, during recent years, the occurrences of corneal burns has been much more occasional and can no longer be put down to any machine malfunction, but to a series of surgeon’s distractions.

The surgeon who prepares to perform an ultrasonic phacoemulsification must know that, apart from a valid and well-set machine, it is also necessary to pay attention to a number of other factors:

•Tunnel construction in terms of shape and dimension

•The tip to be used

•Using as few ultrasounds as possible by having an excellent knowledge of the foot pedal adopted

•Emptying the anterior chamber from the viscoelastic device before beginning phacoemulsification

•Employing techniques that use more mechanical energy than ultrasonic energy

Fig. 6.39 Irrigation flow guaranteed by an irrigating chopper and an ultrasmall sleeve

19 gauge (1.00 mm) open-ended chopper

19 gauge (1.00 mm)

2 lateral openings

19 gauge (1.00 mm)

3 holes (2 lateral,1 beneath)

* Bottled placed at 140 cm

77.20 cc/min

73.60 cc/min

By observing the points listed above, corneal burns in phacoemulsification can become a thing of the past.

Take Home Pearls

ßIn order to Avoid Thermal Damage due to Corneal Incisions, the following factors should

be paid attention.

ßAccurate incision construction and architecture

ßTip design appropriate for the particular procedure being done

ßUse of power modulations with decreased energy delivered

ßCareful control of the foot pedal to avoid prolonged time in foot position 3

ßNeed to aspirate OVD prior to commencing in foot position 3

ßUsing surgical techniques that depend more on mechanical forces for disassembly of the

nucleus rather than grooving and cracking.

References

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2.Hwang DG, Smith RE (1981) Corneal complications of cataract surgery. Refract Corneal Surg 7:77–80

3.Wirt H, Heisler J-M, Domarus DV (1995) Phacoburns: experimental study for evaluation of risk factors. Eur J Implant Refract Surg 7:275–278

4.Franchini A, Zamma Gallarati B, Vaccari E (2001) 5 anni di esperienza nella erbio facolaseremulsificazione ed altre applicazioni cliniche. Atti della Fondazione G.Ronchi 2:211–237

5.Fishkind WJ (2002) Multisite comparative study of the current Sovereign power control system with the WhiteStar control system. In: Symposium on Cataract, IOL and Refractive Surgery, Philadelphia, PA

6.Donnenfeld ED, Olson RJ, Solomon R et al (2003) Efficacy and wound-temperature gradient of Whitestar phacoemulsification through a 1.2 mm incision. J Cataract Refract Surg 29:1097–1100

7.Soscia W, Howard JG, Olson RJ (2002) Microphacoemulsification with WhiteStar: a wound temperature study. J Cataract Refract Surg 28:1044–1046

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10.Majid MA, Sharma MK, Harding SP (1998) Corneal scleral burn during phacoemulsification surgery. J Cataract Refract Surg 24:1413–1415

11.Sugar A, Schertzer RM (1999) Clinical course of phacoemulsification wound burns. J Cataract Refract Surg 25:688–692

12.Osher RH (2005) Shark fin: a new sign of thermal injury. J Cataract Refract Surg 31:640–642

13.Enest P, Rhem M, Mc Dermott M et al (2001) Phacoemulsification conditions resulting in thermal wound injury. J Cataract Refract Surg 27:1829–1839

14.Fishkind WJ (2000) Phacoemulsification technology: improved power and fluidica. Chapter 9. In: Wallace RB (ed) Refractive cataract surgery and multifocal IOLs. Slack; Thorofare, NJ, p 87

15.Olson MD, Miller KM (2005) In-air thermal imaging comparison of Legacy AdvanTec, Millenium, and Sovereign WhiteStar phacoemulsification systems. J Cataract Refract Surg 31:1641–1647

16.Brinton JP, Adams W, Kumar R et al (2006) Comparison of thermal features associated with 2 phacoemulsification machine. J Cataract Refract Surg 32:288–293

17.Payne M, Waite A, Olson RJ (2006) Thermal inertia associ-

ated with ultrapulse technology in phacoemulsification. J Cataract Refract Surg 32:1032–1034

18.Schaeffer ME (2004) Demonstration of cavitation effects in phacoemulsification devices. In: ASCRS Symposium, San Diego, CA

19.Liu Y, Zeng M, Liu X et al (2007) Torsional mode versus conventional ultrasound mode phacoemulsification. Randomized comparative study. J Cataract Refract Surg 33:287–292

20.Mackool RJ (2007) Phaco arena: to sleeve or not to sleeve; this is the question. In: Course presented at the Congress of the American Society of Cataract and Refractive Surgery, San Diego, CA

21.Boukhny M (2003) Phaoemulsification tips and sleeves. In: Buratto L, Werner L, Zanini M, Apple D (eds) Phacoemulsification principles and techniques, 2nd edn. Slack, Thorofare NJ, pp 247–254

22.Braga-Mele R (2006) Thermal effect of microburst and hyperpulse settings during sleeveless bimanual phacoemulsification with advanced power modulations. J Cataract Refract Surg 32:639–642

23.Olson RJ, Jin Y, Kefalopoulos G et al (2004) Legaci AdvanTec and Sovereign WhiteStar: A wound temperature study. J Cataract Refract Surg 30:1109–1113

24.Takahashi H (2005) Free radical development in phacoemulsification cataract surgery. Nippon Med Sch 72:4–12

25.Franchini A (2007) Signature: discovering new frontiers in creating a stable environment during cataract surgery. In: Paper presented at the XXV Congress of the ESCRS, Stockholm

26.Vasavada AR, Mamidipudi PR, Minj M (2004) Relationship of immediate intraocular pressare rise to phaco-tip ergonomics and energy dissipation. J Cataract Refract Surg 30:137–143

27.Berdahl J, DeStefano J, Kim T (2007) Corneal wound architecture and integrity after phacoemulsification. Evaluation

of coaxial, microincision coaxial and microincision bimanual techniques. J Cataract Refract Surg 33:510–515

28.Vasavada AR (2005) Phaco tip and corneal tissue; histomorphology and immunochemistry reveal the effects of sleeveless and sleeved tip. Cataract Refract Surg Today (Suppl):9–10

29.Alió J, Rodríguez-Prats JL, Galal A et al (2005) Outcomes of microincision cataract surgery versus coaxial phacoemulsification. Ophthalmology 112:1997–2003

30.Assaf A, El-Moatassem Kotb AM (2005) Feasibility of bimanual microincision phacoemulsification in hard cataracts. Eye 21:807–811

31.Soscia W, Howard JG, Olson RJ (2002) Bimanual phacoemulsification through 2 stab incisions; a woundtemperature study. J Cataract Refract Surg 28: 1039–1043

32.Tsuneoka H, Shiba T, Takahashi Y (2001) Feasibility of ultrasound cataract surgery with a 1.4 mm incision. J Cataract Refract Surg 27:934–940

33.Tsuneoka HT, Shiba Takahashi Y (2001) Wound temperature during ultrasmall incision phacoemulsification. Nippon Ganka Gakkai Zasshi 105:237–243

34.Franchini A (2006) Bimanual microphacoemulsification vs. ultra-small incision coaxial phacoemulsification. In: Paper presented at the Congress of ASCRS, San Francisco, CA

35.Alzner E, Grabner G (1999) Dodick laser phacolysis: thermal effects. J Cataract Refract Surg 25:800–803

36.Floyd M, Valentie J., Coombs J et al (2006) Effect of incisional friction and ophthalmic viscosurgery devices on the

heat generation of ultrasound during cataract surgery. J Cataract Refract Surg 32:1222–1226

37.Mackool R, Sirota MA (2005) Thermal comparison of the AdvanTec Legaci, Sovereign WhiteStar, and Millenium phacoemulsification systems. J Cataract Refract Surg 31:812–817

38.Miyajima HB, Shimmura S, Tsubota K (1999) Thermal effect on corneal incisions with different phacoemulsification ultrasonic tips. J Cataract Refract Surg 25:60–64

39.Osher RH, Injev VP (2006) Thermal study of bare tip with various system parameters and incision size. J Cataract Refract Surg 32:867–872

40.Tsuneoka H, Shiba T, Takahashi Y (2002) Ultrasonic phacoemulsification using a 1.4 mm incision: clinical results 22. J Cataract Refract Surg. 28:81–86

6.4Using Ophthalmic Viscosurgical Devices with Smaller Incisions

Steve A. Arshinoff1

Core Messages

ßUnderstanding the rheology of cataract surgery steps greatly facilitates micro incision surgery,

whether coaxial or biaxial.

ßBefore using an ophthalmic viscosurgical device (OVD) in any situation, a clear idea of

the method of removing it at the end of the case, is necessary.

ßOVD techniques need only minor modification to accommodate microincision surgery. Aware-

ness of the actual purpose of each OVD in a given situation is a critical factor.

ßGenerally speaking, smaller incisions seal better, making all OVD techniques more stable

and easier to perform.

ßWhile a single OVD may be excellent in uncomplicated routine cataract surgery, varia-

tions of soft shell and ultimate soft shell techniques make difficult cases much easier.

ßIt is never too early or too late in the cataract procedure to alter or correct an OVD strategy.

6.4.1 Introduction

Routine cataract surgery, by phacoemulsification and intraocular lens implantation, is regarded as a quick, mature and relatively simple procedure. However, when the sequential steps of the procedure are