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Visco-fracture technique for phacoemulsification
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LETTERS
consideration. In the meantime, although the studies by M€ onestam and Behndig3 and Miyata et al.4 provide reliable and important data, we recently experienced 6 cases in which visual function improved by replacing the Acrysof IOL (Alcon, Inc.), which had high surface scatter, with a new IOL that does not have surface scatter. The Acrysof IOLs were implanted 7 to 15 years ago, and the patients experienced deterioration of their visual function until the replacement. An article about 1 of these cases will be published soon. In Japan, the same site follows patients continuously after cataract surgery and this may lead to easier detection of visual function change and surface scatter. Considering this, whitening may have small effects on visual function in many cases but have unignorable effects in others because of individual differences and the implantation period. We are currently looking at the factors that influence visual function and methods to better determine which cases require a replacement. dHiroyuki Matsushima, MD, PhD REFERENCES 1. Matsushima H, Mukai K, Nagata M, Gotoh N, Matsui E, Senoo T. Analysis of surface whitening of extracted hydrophobic acrylic intraocular lenses. J Cataract Refract Surg 2009; 35: 1927–1934 2. Nishihara H, Yaguchi S, Onishi T, Chida M, Ayaki M. Surface scattering in implanted hydrophobic intraocular lenses. J Cataract Refract Surg 2003; 29:1385–1388 € nestam E, Behndig A. Impact on visual function from light scat3. Mo tering and glistenings in intraocular lenses, a long-term study. Acta Ophthalmol (Oxf) 2010 Jan. 8; [Epub ahead of print] 4. Miyata K, Otani S, Nejima R, Miyai T, Samejima T, Honbo M, Minami K, Amano S. Comparison of postoperative surface light scattering of different intraocular lenses. Br J Ophthalmol 2009; 93:684–687
Visco-fracture technique for phacoemulsification Malavazzi and Nery1 recently described the viscofracture technique, which uses the high viscosity of an ophthalmic viscosurgical device to separate the lens fibers. The previously reported hydro-chop technique described by Braga-Mele and Khan,2 and subsequently adopted by Fukasaku with his 23-gauge vertically flattened-tip cannula, relies on the same concept.3 There are multiple stress lines from the posterior to the anterior lens surface due to the particular morphology of the human lenticular fibers running meridionally along the equator of the lens and forming the characteristic posterior and anterior Y-sutures.4,5 Both hydro-chop and visco-fracture techniques create vector forces along these stress lines, splitting the nucleus into halves and quadrants.
I strongly agree that novice cataract surgeons might encounter difficulty in cracking soft lenses, and for this reason our trainees are guided step-by-step in their learning curve.Although I believe the proposed technique is effective, I respectfully do not agree that ophthalmic trainees would find it simple to use for 2 reasons. First, a blunt hydrodissection cannula, generally a 26-gauge cannula, has to go deep into the nucleus by applying firm pressure, as shown in the video that illustrates the technique. Trainees might apply much more pressure to deepen the cannula in the nucleus than required or than used by the more experienced authors. Second, the machine settings recommended for this technique were “55 cc/min of aspiration flow rate, 360 mm Hg of vacuum.” Although the authors state that the technique is “ideal for teaching the beginning surgeon,” I challenge them to agree that the proposed machine’s flow parameter produces strong and rapid anterior chamber currents and an extremely short rise time. A longer rise time gives a novice more time to react in case of inadvertent incarceration of iris, capsule, or other unwanted material in the aspiration port. Gianluca Carifi, MD Manchester, United Kingdom REFERENCES 1. Malavazzi GR, Nery RG. Visco-fracture technique for soft lens cataract removal. J Cataract Refract Surg 2011; 37:11–12 2. Braga-Mele R, Khan BU. Hydro-chop technique for soft lenses. J Cataract Refract Surg 2006; 32:18–20 3. Alio JL, Jorge L, Fine IH, eds. Minimizing Incisions and Maximizing Outcomes in Cataract Surgery. New York, NY: Springer, 2010; 31 4. Kuszak JR, Sivak JG, Weerheim JA. Lens optical quality is a direct function of lens sutural architecture. Invest Ophthalmol Vis Sci 1991; 32:2119–2129. erratum 1992; 33: 2076–2077. Available at: http://www.iovs.org/cgi/reprint/32/7/2119. Accessed February 17, 2011 5. Taylor VL, al-Ghoul KJ, Lane CW, Davis VA, Kuszak JR, Costello MJ. Morphology of the normal human lens. Invest Ophthalmol Vis Sci 1996; 37:1396–1410. Available at: http://www.iovs. org/cgi/reprint/37/7/1396. Accessed February 17, 2011
REPLY: I would like to respond to Carifi's 2 concerns. About the first concern, the video clearly shows firm pressure on the nucleus because we selected a grade 2 nucleus to show how far the hardness of a nucleus can be fractured by the ophthalmic viscosurgical device. In my experience, that is the limit and the trainee surgeon should try only grade 1 nuclei. Regarding the second concern, I agree that the machine settings shown in the video were my personal settings. Although effective and with a negative rise time of minus 2 (50% less after the occlusion), 55 cc/ min of aspiration flow rate is too much and a lower
J CATARACT REFRACT SURG - VOL 37, MAY 2011
LETTERS
consideration. In the meantime, although the studies by M€ onestam and Behndig3 and Miyata et al.4 provide reliable and important data, we recently experienced 6 cases in which visual function improved by replacing the Acrysof IOL (Alcon, Inc.), which had high surface scatter, with a new IOL that does not have surface scatter. The Acrysof IOLs were implanted 7 to 15 years ago, and the patients experienced deterioration of their visual function until the replacement. An article about 1 of these cases will be published soon. In Japan, the same site follows patients continuously after cataract surgery and this may lead to easier detection of visual function change and surface scatter. Considering this, whitening may have small effects on visual function in many cases but have unignorable effects in others because of individual differences and the implantation period. We are currently looking at the factors that influence visual function and methods to better determine which cases require a replacement. dHiroyuki Matsushima, MD, PhD REFERENCES 1. Matsushima H, Mukai K, Nagata M, Gotoh N, Matsui E, Senoo T. Analysis of surface whitening of extracted hydrophobic acrylic intraocular lenses. J Cataract Refract Surg 2009; 35: 1927–1934 2. Nishihara H, Yaguchi S, Onishi T, Chida M, Ayaki M. Surface scattering in implanted hydrophobic intraocular lenses. J Cataract Refract Surg 2003; 29:1385–1388 € nestam E, Behndig A. Impact on visual function from light scat3. Mo tering and glistenings in intraocular lenses, a long-term study. Acta Ophthalmol (Oxf) 2010 Jan. 8; [Epub ahead of print] 4. Miyata K, Otani S, Nejima R, Miyai T, Samejima T, Honbo M, Minami K, Amano S. Comparison of postoperative surface light scattering of different intraocular lenses. Br J Ophthalmol 2009; 93:684–687
Visco-fracture technique for phacoemulsification Malavazzi and Nery1 recently described the viscofracture technique, which uses the high viscosity of an ophthalmic viscosurgical device to separate the lens fibers. The previously reported hydro-chop technique described by Braga-Mele and Khan,2 and subsequently adopted by Fukasaku with his 23-gauge vertically flattened-tip cannula, relies on the same concept.3 There are multiple stress lines from the posterior to the anterior lens surface due to the particular morphology of the human lenticular fibers running meridionally along the equator of the lens and forming the characteristic posterior and anterior Y-sutures.4,5 Both hydro-chop and visco-fracture techniques create vector forces along these stress lines, splitting the nucleus into halves and quadrants.
I strongly agree that novice cataract surgeons might encounter difficulty in cracking soft lenses, and for this reason our trainees are guided step-by-step in their learning curve.Although I believe the proposed technique is effective, I respectfully do not agree that ophthalmic trainees would find it simple to use for 2 reasons. First, a blunt hydrodissection cannula, generally a 26-gauge cannula, has to go deep into the nucleus by applying firm pressure, as shown in the video that illustrates the technique. Trainees might apply much more pressure to deepen the cannula in the nucleus than required or than used by the more experienced authors. Second, the machine settings recommended for this technique were “55 cc/min of aspiration flow rate, 360 mm Hg of vacuum.” Although the authors state that the technique is “ideal for teaching the beginning surgeon,” I challenge them to agree that the proposed machine’s flow parameter produces strong and rapid anterior chamber currents and an extremely short rise time. A longer rise time gives a novice more time to react in case of inadvertent incarceration of iris, capsule, or other unwanted material in the aspiration port. Gianluca Carifi, MD Manchester, United Kingdom REFERENCES 1. Malavazzi GR, Nery RG. Visco-fracture technique for soft lens cataract removal. J Cataract Refract Surg 2011; 37:11–12 2. Braga-Mele R, Khan BU. Hydro-chop technique for soft lenses. J Cataract Refract Surg 2006; 32:18–20 3. Alio JL, Jorge L, Fine IH, eds. Minimizing Incisions and Maximizing Outcomes in Cataract Surgery. New York, NY: Springer, 2010; 31 4. Kuszak JR, Sivak JG, Weerheim JA. Lens optical quality is a direct function of lens sutural architecture. Invest Ophthalmol Vis Sci 1991; 32:2119–2129. erratum 1992; 33: 2076–2077. Available at: http://www.iovs.org/cgi/reprint/32/7/2119. Accessed February 17, 2011 5. Taylor VL, al-Ghoul KJ, Lane CW, Davis VA, Kuszak JR, Costello MJ. Morphology of the normal human lens. Invest Ophthalmol Vis Sci 1996; 37:1396–1410. Available at: http://www.iovs. org/cgi/reprint/37/7/1396. Accessed February 17, 2011
REPLY: I would like to respond to Carifi's 2 concerns. About the first concern, the video clearly shows firm pressure on the nucleus because we selected a grade 2 nucleus to show how far the hardness of a nucleus can be fractured by the ophthalmic viscosurgical device. In my experience, that is the limit and the trainee surgeon should try only grade 1 nuclei. Regarding the second concern, I agree that the machine settings shown in the video were my personal settings. Although effective and with a negative rise time of minus 2 (50% less after the occlusion), 55 cc/ min of aspiration flow rate is too much and a lower
J CATARACT REFRACT SURG - VOL 37, MAY 2011