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Danger of viscous gel anesthetic use prior to povidone–iodine antisepsis: Best practice recommendation
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Figure 1. Unfolding time of clear (left) and tinted (right) 1-piece IOLs to 11.0 mm using warmed OVD (x Z each measurement; C Z mean of 5 measurements; * Z significant difference between the 2 IOLs [Mann-Whitney U test]).
warmed to 20 C or higher (P ! .047, Mann-Whitney U test). Warming the IOL itself also reduced the mean unfolding times: 53 seconds (18 C) to 38 seconds (25 C) with the clear IOL and 62 seconds to 55 seconds with the tinted IOL. The acceleration was less than that achieved with warmed OVD. The temperature of the warmed OVD decreased with time, although it was maintained at 30 C or higher for 4.5 minutes. DISCUSSION Eom et al.4 showed that the unfolding of IOL optics accelerated as the temperature of the OVD and balanced salt solution mixtures increased. They did not, however, examine the IOL length. The results in the current study indicated that using a warmed OVD while the IOL was set into the cartridge effectively accelerated the unfolding. The results also show that using an OVD warmed to 30 C or higher enables contact between the haptic of the 1-piece IOL and the capsule equator within 30 seconds. Slow unfolding has advantages, including manipulation of the trailing haptic and removal of OVD below the IOL. However, it is hard to confirm that the unfolding is complete because the entire capsular bag is rarely observable. Therefore, prompt IOL unfolding is indispensable in the use of toric IOLs. Compared with warming the IOL itself, the use of warmed OVD is more practical and easier to manage. Because of the tiny volume of the IOL, the temperature is more influenced by the surroundings, while the OVD temperature can be sustained at 30 C or higher for a longer period. Hence, covering the IOL with a warmed OVD could make the change in temperature slower and accelerate the unfolding in the capsular bag. The use of OVD warmed to
35 C in Tecnis toric IOL implantation should reduce rotation during the acute and early postoperative periods. Clinical evaluation of this technique will be necessary. REFERENCES 1. Miyake T, Kamiya K, Amano R, Iida Y, Tsunehiro S, Shimizu K. Long-term clinical outcomes of toric intraocular lens implantation in cataract cases with preexisting astigmatism. J Cataract Refract Surg 2014; 40:1654–1660 2. Shah GD, Praveen MR, Vasavada AR, Vasavada VA, Rampal G, Shastry LR. Rotational stability of a toric intraocular lens: Influence of axial length and alignment in the capsular bag. J Cataract Refract Surg 2012; 38:54–59 3. Iwase T, Tanaka N. Unfolding characteristics of a new hydrophobic acrylic intraocular lens, and possible association with complications in triple procedures. Clin Exp Ophthalmol 2007; 35:635–639 4. Eom Y, Lee JS, Rhim JW, Kang S-Y, Song JS, Kim HM. A simple method to shorten the unfolding time of prehydrated hydrophobic intraocular lens. Can J Ophthalmol 2014; 49:382–387 5. Petermeier K, Suesskind D, Altpeter E, Schatz A, Messias A, Gekeler F, Szurman P. Sulcus anatomy and diameter in pseudophakic eyes and correlation with biometric data: Evaluation with a 50 MHz ultrasound biomicroscope. J Cataract Refract Surg 2012; 38:986–991
Danger of viscous gel anesthetic use prior to povidone–iodine antisepsis: Best practice recommendation Richard M. Schroeder, BA, Megan R. Silas, BS, Richard M. Thomson, PhD, William G. Myers, MD In 1984, the use of topical povidone–iodine 5.0% solution was shown by MacRae et al.1 to be the most appropriate method of endophthalmitis prophylaxis before ocular surgery. As a result of the increasing use of topical anesthesia prior to ophthalmic
J CATARACT REFRACT SURG - VOL 41, OCTOBER 2015
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CORRESPONDENCE
procedures, in 2008 Boden et al.2 studied the potential barrier effect of urologic lidocaine gel on the bactericidal action of povidone–iodine. They cautioned that the eye should be treated with povidone–iodine prior to placement of viscous lidocaine gel to achieve proper antisepsis. As povidone–iodine 5.0% is very irritating to an unanesthetized surface, this requires the initial use of a nonviscous topical anesthetic agent such as tetracaine drops. Determining the bactericidal effectiveness of povidone–iodine solutions requires consideration of the barrier effects of the applied agents. Povidone–iodine kills bacteria through the ability of free molecular iodine to attack cell membranes and work as a cytotoxic agent.1 Lidocaine 3.5% in hypromellose gel (Akten) is recommended for topical antisepsis for intravitreal injections and in preparation for operating room procedures such as cataract surgery. Lidocaine 2.0% gel (Uro-Jet) is another less viscous formulation used. We
have been concerned that these viscous lidocaine gels, or even the more liquid tetracaine drops used preoperatively, might reduce the intended antibacterial surface disinfection of povidone–iodine solutions. PATIENTS AND METHODS Following the protocol of Boden et al.,2 blood agar plates were inoculated with Staphylococcus epidermidis, the predominant organism in cases of postsurgical endophthalmitis.3 Blood agar plates covered with 1 105 bacteria per cubic millimeter were subjected to a povidone–iodine 5.0% solution alone. A second group of plates was layered with lidocaine 2.0% or lidocaine 3.5% before the povidone–iodine 5.0% solution was applied. The relative viscosities of lidocaine 3.5% and lidocaine 2.0% were compared on a sloped surface.
RESULTS On the blood agar plates covered with the povidone– iodine 5.0% solution alone, there was complete
Figure 1. The effect of povidone–iodine 5.0%, lidocaine gel 2.0%, lidocaine gel 3.5%, and tetracaine drops on bacterial survival. When lidocaine gel was applied before povidone–iodine, the bactericidal effect was reduced. Tetracaine had no effect on antisepsis with povidone–iodine (PVI Z povidone–iodine).
J CATARACT REFRACT SURG - VOL 41, OCTOBER 2015
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Figure 2. Bacterial growth after applications of topical anesthetic povidone–iodine G5.0% solution. Treatment with viscous lidocaine gel prior to povidone–iodine 5.0% solution allowed widespread bacterial growth; tetracaine alone allowed moderate bacterial growth. The bacteria were completely eradicated when treated with povidone–iodine 5.0% solution alone or when viscous gel was placed after povidone–iodine administration with or without preliminary tetracaine drops (PVI Z povidone–iodine).
eradication of the bacteria. On the layered group of plates, a reduced effect of povidone–iodine 5.0% on the bacterial growth was observed (Figure 1). The comparison of lidocaine 3.5% and lidocaine 2.0% showed that lidocaine 3.5% was more viscous, although the wetting angle of the 2 gels was similar. When povidone–iodine 5.0% solution was used on an inoculated blood agar plate before lidocaine 3.5% or lidocaine 2.0% was applied, complete eradication of bacteria was achieved. A common preoperative practice is to use topical anesthetic drops such as lidocaine or tetracaine before the povidone–iodine 5.0% solution to reduce the severe stinging and burning sensation associated with this concentration. It was therefore confirmed that placing tetracaine drops from a multiuse bottle prior to the povidone–iodine 5.0% did not impede the efficacy of povidone–iodine 5.0% against S epidermidis (Figure 2). To model other current practice, tetracaine drops were applied to the bacterial plate, followed by the povidone–iodine 5.0% solution and then the lidocaine 3.5%. This protocol completely eliminated bacteria on the agar surface. DISCUSSION Although it is safe to use tetracaine drops before povidone–iodine, we continue to investigate whether the concentration of povidone–iodine is low enough to avoid ocular irritation while still acting as a
sufficient bactericidal agent. Based on the personal experience of 1 author (W.G.M.), the level of stinging is decreased when the concentration of povidone– iodine is reduced. Concentrations of povidone– iodine as low as 0.25% have been shown to reduce anterior chamber contamination when applied to the surface of the eye throughout surgery.4 Use of dilute povidone–iodine without the need for a preliminary topical anesthetic followed by topical viscous hypromellose gel would simplify the preoperative regimen for the surgical staff. In summary, the study confirms a best practice of applying povidone–iodine before lidocaine gel in preparation for surgery. Viscous lidocaine gels act as a physical barrier to the povidone–iodine solution. Using topical anesthetic drops beforehand to prevent the burning sensation appears to be safe and effective and also achieves adequate antisepsis. REFERENCES 1. MacRae SM, Brown B, Edelhauser HF. The corneal toxicity of presurgical skin antiseptics. Am J Ophthalmol 1984; 97:221–232 2. Boden JH, Myers ML, Lee T, Bushley DM, Torres MF. Effect of lidocaine gel on povidone iodine antisepsis and microbial survival. J Cataract Refract Surg 2008; 34:1773–1775 3. Vaziri K, Schwartz SG, Kishor K, Flynn HW Jr. Endophthalmitis: state of the art. Clin Ophthalmol 2015; 9:95–108. Available at: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4293922/pdf/ opth-9-095.pdf. Accessed September 11, 2015 4. Shimada H, Arai S, Nakashizuka H, Hattori T, Yuzawa M. Reduction of anterior chamber contamination rate after cataract surgery by intraoperative surface irrigation with 0.25% povidone-iodine. Am J Ophthalmol 2011; 151:11–17
J CATARACT REFRACT SURG - VOL 41, OCTOBER 2015
CORRESPONDENCE
Figure 1. Unfolding time of clear (left) and tinted (right) 1-piece IOLs to 11.0 mm using warmed OVD (x Z each measurement; C Z mean of 5 measurements; * Z significant difference between the 2 IOLs [Mann-Whitney U test]).
warmed to 20 C or higher (P ! .047, Mann-Whitney U test). Warming the IOL itself also reduced the mean unfolding times: 53 seconds (18 C) to 38 seconds (25 C) with the clear IOL and 62 seconds to 55 seconds with the tinted IOL. The acceleration was less than that achieved with warmed OVD. The temperature of the warmed OVD decreased with time, although it was maintained at 30 C or higher for 4.5 minutes. DISCUSSION Eom et al.4 showed that the unfolding of IOL optics accelerated as the temperature of the OVD and balanced salt solution mixtures increased. They did not, however, examine the IOL length. The results in the current study indicated that using a warmed OVD while the IOL was set into the cartridge effectively accelerated the unfolding. The results also show that using an OVD warmed to 30 C or higher enables contact between the haptic of the 1-piece IOL and the capsule equator within 30 seconds. Slow unfolding has advantages, including manipulation of the trailing haptic and removal of OVD below the IOL. However, it is hard to confirm that the unfolding is complete because the entire capsular bag is rarely observable. Therefore, prompt IOL unfolding is indispensable in the use of toric IOLs. Compared with warming the IOL itself, the use of warmed OVD is more practical and easier to manage. Because of the tiny volume of the IOL, the temperature is more influenced by the surroundings, while the OVD temperature can be sustained at 30 C or higher for a longer period. Hence, covering the IOL with a warmed OVD could make the change in temperature slower and accelerate the unfolding in the capsular bag. The use of OVD warmed to
35 C in Tecnis toric IOL implantation should reduce rotation during the acute and early postoperative periods. Clinical evaluation of this technique will be necessary. REFERENCES 1. Miyake T, Kamiya K, Amano R, Iida Y, Tsunehiro S, Shimizu K. Long-term clinical outcomes of toric intraocular lens implantation in cataract cases with preexisting astigmatism. J Cataract Refract Surg 2014; 40:1654–1660 2. Shah GD, Praveen MR, Vasavada AR, Vasavada VA, Rampal G, Shastry LR. Rotational stability of a toric intraocular lens: Influence of axial length and alignment in the capsular bag. J Cataract Refract Surg 2012; 38:54–59 3. Iwase T, Tanaka N. Unfolding characteristics of a new hydrophobic acrylic intraocular lens, and possible association with complications in triple procedures. Clin Exp Ophthalmol 2007; 35:635–639 4. Eom Y, Lee JS, Rhim JW, Kang S-Y, Song JS, Kim HM. A simple method to shorten the unfolding time of prehydrated hydrophobic intraocular lens. Can J Ophthalmol 2014; 49:382–387 5. Petermeier K, Suesskind D, Altpeter E, Schatz A, Messias A, Gekeler F, Szurman P. Sulcus anatomy and diameter in pseudophakic eyes and correlation with biometric data: Evaluation with a 50 MHz ultrasound biomicroscope. J Cataract Refract Surg 2012; 38:986–991
Danger of viscous gel anesthetic use prior to povidone–iodine antisepsis: Best practice recommendation Richard M. Schroeder, BA, Megan R. Silas, BS, Richard M. Thomson, PhD, William G. Myers, MD In 1984, the use of topical povidone–iodine 5.0% solution was shown by MacRae et al.1 to be the most appropriate method of endophthalmitis prophylaxis before ocular surgery. As a result of the increasing use of topical anesthesia prior to ophthalmic
J CATARACT REFRACT SURG - VOL 41, OCTOBER 2015
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CORRESPONDENCE
procedures, in 2008 Boden et al.2 studied the potential barrier effect of urologic lidocaine gel on the bactericidal action of povidone–iodine. They cautioned that the eye should be treated with povidone–iodine prior to placement of viscous lidocaine gel to achieve proper antisepsis. As povidone–iodine 5.0% is very irritating to an unanesthetized surface, this requires the initial use of a nonviscous topical anesthetic agent such as tetracaine drops. Determining the bactericidal effectiveness of povidone–iodine solutions requires consideration of the barrier effects of the applied agents. Povidone–iodine kills bacteria through the ability of free molecular iodine to attack cell membranes and work as a cytotoxic agent.1 Lidocaine 3.5% in hypromellose gel (Akten) is recommended for topical antisepsis for intravitreal injections and in preparation for operating room procedures such as cataract surgery. Lidocaine 2.0% gel (Uro-Jet) is another less viscous formulation used. We
have been concerned that these viscous lidocaine gels, or even the more liquid tetracaine drops used preoperatively, might reduce the intended antibacterial surface disinfection of povidone–iodine solutions. PATIENTS AND METHODS Following the protocol of Boden et al.,2 blood agar plates were inoculated with Staphylococcus epidermidis, the predominant organism in cases of postsurgical endophthalmitis.3 Blood agar plates covered with 1 105 bacteria per cubic millimeter were subjected to a povidone–iodine 5.0% solution alone. A second group of plates was layered with lidocaine 2.0% or lidocaine 3.5% before the povidone–iodine 5.0% solution was applied. The relative viscosities of lidocaine 3.5% and lidocaine 2.0% were compared on a sloped surface.
RESULTS On the blood agar plates covered with the povidone– iodine 5.0% solution alone, there was complete
Figure 1. The effect of povidone–iodine 5.0%, lidocaine gel 2.0%, lidocaine gel 3.5%, and tetracaine drops on bacterial survival. When lidocaine gel was applied before povidone–iodine, the bactericidal effect was reduced. Tetracaine had no effect on antisepsis with povidone–iodine (PVI Z povidone–iodine).
J CATARACT REFRACT SURG - VOL 41, OCTOBER 2015
CORRESPONDENCE
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Figure 2. Bacterial growth after applications of topical anesthetic povidone–iodine G5.0% solution. Treatment with viscous lidocaine gel prior to povidone–iodine 5.0% solution allowed widespread bacterial growth; tetracaine alone allowed moderate bacterial growth. The bacteria were completely eradicated when treated with povidone–iodine 5.0% solution alone or when viscous gel was placed after povidone–iodine administration with or without preliminary tetracaine drops (PVI Z povidone–iodine).
eradication of the bacteria. On the layered group of plates, a reduced effect of povidone–iodine 5.0% on the bacterial growth was observed (Figure 1). The comparison of lidocaine 3.5% and lidocaine 2.0% showed that lidocaine 3.5% was more viscous, although the wetting angle of the 2 gels was similar. When povidone–iodine 5.0% solution was used on an inoculated blood agar plate before lidocaine 3.5% or lidocaine 2.0% was applied, complete eradication of bacteria was achieved. A common preoperative practice is to use topical anesthetic drops such as lidocaine or tetracaine before the povidone–iodine 5.0% solution to reduce the severe stinging and burning sensation associated with this concentration. It was therefore confirmed that placing tetracaine drops from a multiuse bottle prior to the povidone–iodine 5.0% did not impede the efficacy of povidone–iodine 5.0% against S epidermidis (Figure 2). To model other current practice, tetracaine drops were applied to the bacterial plate, followed by the povidone–iodine 5.0% solution and then the lidocaine 3.5%. This protocol completely eliminated bacteria on the agar surface. DISCUSSION Although it is safe to use tetracaine drops before povidone–iodine, we continue to investigate whether the concentration of povidone–iodine is low enough to avoid ocular irritation while still acting as a
sufficient bactericidal agent. Based on the personal experience of 1 author (W.G.M.), the level of stinging is decreased when the concentration of povidone– iodine is reduced. Concentrations of povidone– iodine as low as 0.25% have been shown to reduce anterior chamber contamination when applied to the surface of the eye throughout surgery.4 Use of dilute povidone–iodine without the need for a preliminary topical anesthetic followed by topical viscous hypromellose gel would simplify the preoperative regimen for the surgical staff. In summary, the study confirms a best practice of applying povidone–iodine before lidocaine gel in preparation for surgery. Viscous lidocaine gels act as a physical barrier to the povidone–iodine solution. Using topical anesthetic drops beforehand to prevent the burning sensation appears to be safe and effective and also achieves adequate antisepsis. REFERENCES 1. MacRae SM, Brown B, Edelhauser HF. The corneal toxicity of presurgical skin antiseptics. Am J Ophthalmol 1984; 97:221–232 2. Boden JH, Myers ML, Lee T, Bushley DM, Torres MF. Effect of lidocaine gel on povidone iodine antisepsis and microbial survival. J Cataract Refract Surg 2008; 34:1773–1775 3. Vaziri K, Schwartz SG, Kishor K, Flynn HW Jr. Endophthalmitis: state of the art. Clin Ophthalmol 2015; 9:95–108. Available at: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4293922/pdf/ opth-9-095.pdf. Accessed September 11, 2015 4. Shimada H, Arai S, Nakashizuka H, Hattori T, Yuzawa M. Reduction of anterior chamber contamination rate after cataract surgery by intraoperative surface irrigation with 0.25% povidone-iodine. Am J Ophthalmol 2011; 151:11–17
J CATARACT REFRACT SURG - VOL 41, OCTOBER 2015