LETTERS

Gas-forced infusion prevents endothelial cellloss in phacoemulsification

In their recent study comparing endothelial cellloss in longitudinal and torsional biaxial small-incision phacoemulsification techniques, Gonen et al.1

found no significant difference between the 2techniques. In this context, we would like the authorsto clarify whether gas-forced infusion (air pump)2

was an option in any of these eyes during surgery.The use of gas-forced infusion prevents endothelialcell loss by decreasing the intraoperative surge.2 Agas-forced infusion system is connected througha nitrocellulose membrane air filter to the infusionfluid bottle. The air filter prevents contaminants inthe operating room air from entering the eye. Theair pump produces a positive pressure head abovethe fluid in the bottle, significantly increasing theamount of fluid entering the eye and balancing theexcess outflow occurring when the occlusion isbroken. It also blunts the fluctuations in intraocularpressure. In our prospective study of gas-forcedinfusion in longitudinal phacoemulsification,3 wenoted that the mean endothelial cell loss was lowerin the infusion group than in the control group(6.98% G 8.46% [SD] versus 10.54% G 11.24%,PZ.045).

Gonen et al. used a 19-gauge irrigating chopper forirrigation and a 20-gauge phaco tip for aspiration.The intraoperative vacuum was set at 250 mm Hgand the flow rate at 30 mL/min. However, despitethe claimed anterior chamber stability, the endothe-lial cell loss exceeded 35% in both groups.1 In ourstudy, the cell loss was 6.98% G 8.46% in eyes thathad phacoemulsification with gas-forced infusionbut 10.54% G 11.24% in eyes without gas-forced in-fusion. Gonen et al.1 should have calculated the inci-dence of intraoperative surge, which can affect theendothelial loss. From our experience with phakonit,4

we noted that an air pump deepens the anteriorchamber, increasing the surgical space available formaneuvering, and thus prevents complications suchas posterior capsule tears and corneal endothelialdamage. The phenomenon of surge is neutralizedby rapid inflow of fluid at the time of occlusionbreak. The irrigating chopper and the bimanual irri-gation/aspiration of a 22-gauge will provide betterchamber stability. In our analysis of wound architec-ture, we noted that good endothelial alignment wasseen in eyes with microphakonit (with gas-forcedinfusion) as early as 3 days postoperatively.5 Wewould like to recommend the use of air-forced infu-sion during phacoemulsification. A built-in devicefor pressurized infusion has been adapted in variousphacoemulsification systems.3,6

Q 2013 ASCRS and ESCRS

Published by Elsevier Inc.

Amar Agarwal, MS, FRCS, FRCOphthDhivya Ashok Kumar, MDAthiya Agarwal, MD, DO

Chennai, India

REFERENCES1. Gonen T, Sever O, Horozoglu F, Yasar M, Keskinbora KH.

Endothelial cell loss: biaxial small-incision torsional phacoemulsi-

fication versus biaxial small-incision longitudinal phacoemulsifi-

cation. J Cataract Refract Surg 2012; 38:1918–1924

2. Agarwal A, Agarwal S, Agarwal A. Antichamber collapse.

J Cataract Refract Surg 2002; 28:1085–1086

3. Chaudhry P, Prakash G, Jacob S, Narasimhan S, Agarwal S,

Agarwal A. Safety and efficacy of gas-forced infusion

(air pump) in coaxial phacoemulsification. J Cataract Refract

Surg 2010; 36:2139–2145

4. Agarwal A, Agarwal A, Agarwal S, Narang P, Narang S. Phakonit:

phacoemulsification through a 0.9 mm corneal incision.

J Cataract Refract Surg 2001; 27:1548–1552

5. Agarwal A, Kumar DA, Jacob S, Agarwal A. In vivo analysis of

wound architecture in 700 mm microphakonit cataract surgery.

J Cataract Refract Surg 2008; 34:1554–1560

6. P�erez-Arteaga A. Anterior vented gas forced infusion system of

the Accurus surgical system in phakonit. J Cataract Refract

Surg 2004; 30:933–935

Reply : Surge is one of the important factors thatcause endothelial cell loss during phacoemulsifica-tion.1 Currently, especially with the coaxial method,the intraoperative surge rate has decreased signifi-cantly thanks to enhanced phacoemulsificationsystems.2 However, it can be a problem with the biax-ial method. Several techniques to maintain anteriorchamber stability during biaxial phacoemulsificationhave been described. Gas-forced infusion (air pump)is one that is successfully used to prevent surge.3 Inour study, we did not need this technique to maintainanterior chamber stability. Our preferred phacoemul-sification parameters (vacuum, 250 mmHg; aspirationflow rate, 30 mL/min; bottle height, 110 cm) andinstruments (20-gauge sleeveless phaco tip and19-gauge irrigating chopper) successfully preventedthe intraoperative surge.

As is well known, high ultrasound power, longultrasound time, and high total balanced salt solutionvolumes are the most important intraoperativemachine-related factors in excessive endothelial cellloss after phacoemulsification in healthy eyes with nohistory of intraocular surgery, pseudoexfoliation, orcorneal dystrophy.4 High-density nuclear cataract,increased infusion volume, and a large nucleus areindependent predictors of endothelial cell loss incoaxial torsional phacoemulsification.5 In our study,there was a significant positive linear correlation be-tween endothelial cell loss and total ultrasound time,cumulative dissipated energy, and balanced salt solu-tion volume. Another important cause of excessive

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