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Second instrument tip breaks during phacoemulsification
Second instrument tip breaks during phacoemulsification Fariba Nazemi, MD, FRCSC; Silvia Odorcic, BA; Rosa Braga-Mele, MD, Med Ed, FRCSC; David Wong, MD, FRCSC ABSTRACT • RÉSUMÉ
Background: Second instrument tip breaks during phacoemulsification are complications that are anecdotally recalled, yet little information exists on why and how often they occur, whether they are consistently tracked, and how they are managed. They may be an underreported, but potentially serious, complication of phacoemulsification. Methods: We surveyed 114 cataract surgeons in Ontario to determine reported rates of second instrument tip breaks, their management, and presumed etiology. We reviewed 4 Toronto cataract centres for incident reports, instrument sterilization processes, and purchase histories. Using scanning electron microscopy (SEM), we compared the characteristics of a broken Sweeney tip to new and used second instruments. Results: Of the 35 surgeons responding to the survey, 34% had experienced a second instrument tip break during their careers. Approximately 73% (16 cases) of the 22 cases reported were managed successfully during the procedure by the primary surgeon, 14% (3 cases) required imaging by computerized tomography or x-ray, and another 14% (3 cases) required pars plana vitrectomy for tip retrieval. Purchase histories revealed that 1 Sweeney hook was exchanged monthly, equivalent to 100 to 150 surgeries. SEM of new and used second instruments revealed signs of metal fatigue on both new and used second instruments. Interpretation: Although both physicians and hospitals lack a method for ensuring quality control of second instruments, approximately one third of cataract surgeons encounter second instrument tip breaks during the course of their careers. Although most cases are managed intraoperatively, consistent hospital tracking records and standardized instrument inspection by institutions and surgeons are needed to determine how these complications occur and to establish protocols for complication reporting and management. Contexte : Les bris de l’extrémité des instruments secondaires pendant la phacoémulsification sont des complications qui font l’objet d’anecdotes, mais peu d’information en précise les raisons et la fréquence, si on a en fait constamment un relevé et comment on les gère. Elle ne sont peut-être pas suffisamment signalées, mais elles peuvent présenter des complications graves de la phacoémulsification. Méthodes : Nous avons interrogé 114 chirurgiens de la cataracte de l’Ontario pour établir dans quelle mesure ils signalaient les bris de l’extrémité des instruments secondaires, comment ils géraient la situation et en présumaient l’étiologie. Nous avons visité 4 centres de traitement de la cataracte de Toronto pour voir les dossiers d’incidents, les procédures de stérilisation des instruments et les dossiers des achats. À l’aide du microscope électronique à balayage (SEM), nous avons comparé les caractéristiques d’une extrémité brisée d’un Sweeney avec des instruments secondaires neufs et usagés. Résultats : Parmi les 35 chirurgiens qui ont répondu, 34 % avaient eu un bris d’extrémité d’instrument secondaire dans leur carrière. Environ 73 % (16 cas) des 22 cas signalés ont été gérés avec succès pendant la procédure par le chirurgien principal, 14 % (3 cas) ont requis une imagerie par tomographie informatisée ou rayon x, un autre 14 % (3 cas) ont requis une vitrectomie par la pars plana pour récupérer l’extrémité. Pour ce qui est des achats, on a relevé un remplacement du crochet Sweeney par mois, l’équivalent de 100 à 150 chirurgies. L’examen SEM des instruments secondaires nouveaux et usagés a révélé des signes d’usure sur les deux types d’instrument. Interprétation : Bien que les médecins et les hôpitaux n’aient pas de méthode pour assurer le contrôle de la qualité des instruments secondaires, environ le tiers des chirurgiens de la cataracte voient se briser l’extrémité de leurs instruments secondaires dans leur carrière. Bien que la plupart des cas soient résolus pendant l’opération, les hôpitaux ont besoin de tenir des dossiers cohérents de suivi. Les institutions et les chirurgiens ont aussi besoin d’inspections standardisées des instruments pour savoir comment surviennent ces complications et établir des protocoles de signalement et de gestion des complications. From the Department of Ophthalmology, University of Toronto, Toronto, Ont. Originally received Mar. 21, 2008. Revised June 6, 2008 Accepted for publication July 15, 2008 Published online Nov. 17, 2008
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Correspondence to Fariba Nazemi, MD, Department of Ophthalmology, University of Toronto, 147 Church Ave., Toronto ON M2N 4G4; [email protected] This article has been peer-reviewed. Cet article a été évalué par les pairs. Can J Ophthalmol 2008;43:702–6 doi:10.3129/i08-148
Second instrument tip breaks during phacoemulsification—Nazemi et al.
S
econd instrument tip breaks during phacoemulsification are complications that are anecdotally recalled, yet little information exists on why and how often they occur, whether they are consistently tracked, and how they are managed. The origin and nature of intraocular metallic fragments during, and following, phacoemulsification have received a fair amount of attention but little consensus. Braunstein et al.1 suggested instrument tip touch during phacoemulsification as the cause, whereas Martinez-Toldos et al.,2 by studying resulting fragments using scanning electron microscopy (SEM) and x-ray dispersive energy spectroscopy, demonstrated that prolonged vibration of the phaco needle can cause particles to chip off the hand piece. Several case reports point to a manufacturing defect, with fragments originating from a defect of the phacoemulsification tip sleeve and the silver from the brazing of the irrigation tube as it enters the hand piece shell on its inner diameter.3,4 Recent case reports highlight the occurrence of overt second instrument tip breaks intraoperatively. Pelosini et al.5 report 3 cases of mushroom manipulator tip breakage. Two tips were found floating in the capsular bag and 1 tip came off its stem, embedding into the side port as the instrument was being taken out of the eye. The tips were successfully removed with suction or retrieved with vitreous forceps. Microscopic examination revealed wear around the manipulator stem and decreased neck thickness. The authors concluded that repeated inadvertent contact caused tip breakage with minimal stress, although the exact mechanism of breakage remains unclear. Similarly, Manjunatha et al.6 report a case of a large metallic fragment found postoperatively in the inferior angle that was removed using gonioscopy and forceps. Although the tip of the second instrument appeared missing at the end of lens removal, the fragment was missed by the surgeon and remained undetected after x-rays of the orbits. Second instrument tip breaks may be an underreported, but potentially serious, intraoperative complication of phacoemulsification. To determine their reported frequency of occurrence, etiology, and management, we surveyed 114 cataract surgeons in Ontario in addition to reviewing the records of 4 Toronto cataract centres for instrument purchase histories and cleaning protocols. To understand how these complications occur, we examined a broken Sweeney tip and both new and used second instruments from one of the centres using SEM.
Survey of 4 cataract centres in Toronto, Ont.
We searched through the hospital records of 4 major teaching hospitals affiliated with the University of Toronto for incident reports of second instrument tip breaks during postphacoemulsification. We reviewed purchase histories and surveyed all 4 centres for second instrument cleaning and sterilization protocols. Scanning electron microscopy of new and used second instruments
We examined the surfaces of a broken Sweeney tip, a gently used chopper and Sweeney, and a new chopper. SEM was performed in a metallurgy laboratory at the University of Toronto under ×50, ×100, and ×200 magnifications. RESULTS Survey on incidence, management, and possible causes of second instrument tip breaks
Of the 35 surgeons (31% response rate) who responded to the questionnaire, 51% used the chopper, 26% the Sweeney, and 23% other devices (Rosen paddle, Sinskey hook, Drysdale spatula, or iris spatula) as their second instrument. Twenty-seven surgeons (77% of responders) reported that the Sweeney hook or the chopper was their second instrument of choice, and all reports of broken tips involved these 2 second instruments. Fifty-one percent reported routinely inspecting the second instrument tip and hand piece before use. Thirty-four percent responded that they had witnessed a second instrument tip break (range 1–4 times) during their careers. Of the 22 instances of tip break reported, 73% (16 cases) were managed through surgeon visualization and tip retrieval, 14% 1. What is your favorite second instrument for phacoemulsification? a. Chopper
b. Sweeney
c. Other _____________(please name)
2. Do you or your scrub nurse routinely inspect the instrument’s tip prior to using it? a. Yes
b. No
3. Has it ever happened to you that the instrument’s tip broke during phacoemulsification? a. No b. Yes (state how many times)_______________
4. When it did break a. Able to see and retrieve the tip b. You needed imaging (x-ray or CT)
METHODS Questionnaire survey of cataract surgeons in Ontario
An email questionnaire was sent out to the 114 cataract surgeons in Ontario listed in the Canadian Ophthalmological Society directory (Fig. 1). No compensation was provided. The survey inquired about the surgeon’s favourite second instrument, inspection prior to use, and management and presumed etiology of tip breaks.
c. You referred the patient to a retinal surgeon
5. Why do you think this complication happens? (mark all that apply) a. Phaco tip touch b. Multiple use and metal fatigue c. Not being properly used
Fig. 1—Email questionnaire surveying 114 Ontario cataract surgeons for self-reported second instrument tip break incidence, management, and presumed etiology. CAN J OPHTHALMOL—VOL. 43, NO. 6, 2008
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Second instrument tip breaks during phacoemulsification—Nazemi et al. (3 cases) required imaging with either computerized tomography (CT) or x-ray because they were not found in the eye or on the surgical field after extensive searching, and 14% (3 cases) were referred to a retinal surgeon for pars plana vitrectomy (PPV) and foreign body removal. Thirtysix percent (8 cases) were attributed to a combination of phaco tip touch and metal fatigue, whereas 18% (4 cases) were attributed to phaco tip touch, metal fatigue, and improper use (Table 1). A belief in single modality causation was not as widely held. Survey of hospital records
There were no incident reports of second instrument tip breaks available in the hospital records of the 4 University of Toronto–affiliated institutions we surveyed because of a lack of a standardized reporting system. Purchase histories in 2 hospitals indicated that approximately 1 Sweeney hook was exchanged monthly, equivalent to 100 to 150 surgeries. The majority of these tips were replaced by processing staff before being handled by the surgeon. Although 3 of the hospitals had tracking systems in place for the instrument tray being used, there was no means of tracking a single instrument for its use prior to tip break. Interestingly, the 1 centre that used ultrasound (Neosonic, Amadent, Cherry Hill, N.J.) for 25 minutes for instrument cleaning before autoclaving with dry heat had neither reported nor anecdotal incidents of second instrument tip break. In this centre, the Rosen paddle was used routinely as the second instrument. The other 3 centres used neutral pH cleansers followed by dry heat for sterilization as their cleaning protocol. The dry heat sterilization technique uses temperatures of 65.6 to 121.1 °C (150–250°F), well below the heating threshold for steel. Metallurgic light microscopy in centralized instrument processing was used to detect surface defects in all 4 hospitals. Table 1—Survey results: reported second instrument preference, and presumed etiology of second instrument tip break and its management by 35 Ontario cataract surgeons Survey result
Scanning electron microscopy of new and used second instruments
The second instruments surveyed were 420-grade centre ground, a combination of carbon, chromium, silicone manganese, phosphorus, sulfur, and nickel. The handle measured 0.05 cm, whereas the shaft at the tip was 0.015 thousandths of a cm. With allowed variance, this value could be as small as 0.010 thousandths of a cm. The stainless steel is resistant to the heat used during sterilization, a range of 65.6 to 137.8 °C (150–280°F). With SEM, we examined the broken tip of a Sweeney (Fig. 2), a gently used Sweeney (Fig. 3), a gently used chopper (Fig. 4), and a brand new chopper (Fig. 5). These instruments were chosen because they were the 2 second instruments used most widely by the surgeons responding to our survey. In Fig. 2, the broken surface of the Sweeney shows signs of metal fatigue and sudden stress. The gently used instruments in Figs. 3 and 4 also harboured small cracks. Strikingly, even the new chopper had a small crack (Fig. 5).
Fig. 2—Scanning electron micrograph of broken Sweeney tip surface (original magnification ×500).
No. of surgeons (%)
Second instrument preference among Ontario surgeons, n = 35 Chopper
18 (51)
Sweeney
9 (26)
Other*
8 (23)
Presumed etiology of second instrument tip break among Ontario surgeons, n = 22 Phaco tip touch + metal fatigue
8 (36)
Phaco tip touch + metal fatigue + improper use
4 (18)
Phaco tip touch only
3 (14)
Centralized instrument processing mishandling
3 (14)
Metal fatigue + improper use
2 (9)
Metal fatigue only
2 (9)
Management of reported second instrument tip breaks by Ontario surgeons, n = 22 Intraoperative tip retrieval
16 (73)
Imaging with CT or x-ray
3 (14)
Referral to retina for PPV
3 (14)
*Other: Rosen paddle, Sinskey hook, Drysdale or iris spatula. Note: CT, computed tomography; PPV, pars plana vitrectomy.
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Fig. 3—Scanning electron micrograph of gently used Sweeney (original magnification ×50).
Second instrument tip breaks during phacoemulsification—Nazemi et al. INTERPRETATION
Although many surgeons can recount an experience with metallic-appearing intraocular foreign bodies (IOFBs) on biomicroscopy postoperatively, or even overt tip breaks during surgery, the frequency with which these complications occur, how they are managed, and how they occur remain unknown. Unrecognized tip breaks or instrument damage during surgery could have significant implications. During phacoemulsification, a lodged broken tip may lead to zonular instability, and possibly a broken capsule. A serious long-term complication of a retained iron-containing metal IOFB is ocular siderosis. Although rare, it can present with a rust-coloured corneal stroma, pupillary mydriasis, uveitis, siderotic cataract, lens subluxation, and secondary glaucoma. A delayed transient macular ischemia due to ocular siderosis has also been reported.7 Although complications of missed or poorly managed tip breaks can have serious consequences, our survey suggests that most surgeons do not routinely inspect their instru-
Fig. 4—Scanning electron micrograph of gently used chopper (original magnification ×50).
Fig. 5—Scanning electron micrograph of brand new chopper (original magnification ×50).
ments. Of our 35 surveyed Ontario cataract surgeons, although 34% reported witnessing second instrument tip breaks, only one half reported routinely inspecting their instruments before use. We acknowledge the possible bias inherent in a voluntary uncompensated survey, including the ability to recall intraoperative tip breaks by a surgeon during the span of a single career, the time frame allotted in our survey, or the possibility that only those experiencing such complications would respond. Our review of hospital records reveals the lack of a standardized system for incident reporting of intraoperative tip breaks, as well as a lack of reliable second instrument tracking. The management of IOFBs or broken tips after phacoemulsification depends largely on the size of the fragment, its magnetic nature, and its location. In our survey, most surgeons managed tip breaks intraoperatively by visualizing and removing the tip, whereas only a minority needed imaging or referral to a vitreoretinal surgeon. Of the 3 cases referred to a vitreoretinal surgeon for tip removal and PPV, 2 tips led to posterior capsule ruptures and the primary surgeon was unable to implant the intraocular lens. Consequently, if the tip is successfully extracted at the time of phacoemulsification, it is important to inspect the capsule for any tears before proceeding. Fourteen percent of cases required imaging to manage the tip break after the tip was not found inside the eye or on the surgical field. These tips might have been broken outside the eye and landed on the floor or instrument tray; or they may be too small, or in a location where the surgeon cannot visualize them. Both CT and x-ray may miss fragments smaller than 1 mm; in these cases, a B-scanner is the modality of choice. B-scanners are also helpful in locating intramural or extrascleral foreign bodies.8 If a tip break occurs or is suspected intraoperatively, thorough examination on biomicroscopy and gonioscopy may be warranted in addition to imaging because metallic-appearing IOFBs have been detected 1 day postoperatively on the iris4 or at the incision tunnel9 even after uneventful surgery. Patients should also be followed closely because occult IOFBs have been reported to present as chronic recalcitrant postoperative inflammation, causing macular epiretinal membrane and cystoid macular edema.10 The precise mechanism of second instrument tip breaks also remains unclear but is likely a combination of factors, such as manufacturing defects, inappropriate use, and progressive weakening from inadvertent tip touch. Of the 22 instances reported in our survey, most surgeons attribute the complication to some combination of phacoemulsification tip touch, metal fatigue, and improper use. Prospective studies of incident reports extracted from established tracking systems may elucidate which of these is the most common cause. Although we could not deduce the etiology of tip breaks using SEMs of a broken Sweeney, as well as new and gently used choppers, both new and used choppers showed slight cracks. We acknowledge that scanning of a variety of second instruments in higher numbers could CAN J OPHTHALMOL—VOL. 43, NO. 6, 2008
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Second instrument tip breaks during phacoemulsification—Nazemi et al. provide additional information and should be a focus of future studies; however, our initial SEM scans emphasize the need for quality control both at the level of the manufacturer and by institutions and surgeons. Based on our survey of cataract surgeons, hospital records, and examination of instruments using SEM, we recommend • careful inspection of instruments before, during, and after surgery by the surgeon and scrub nurse; • the formation of consistent hospital tracking systems to replace fatigued instruments and inspect new ones prior to first use; and • quality control at the level of the manufacturer. Experimental studies to find the breaking threshold for hooks, especially at the necks, might also prove insightful. Recent case reports highlight that second instruments frequently break at the necks, which often become narrow after repeated use.5,6 Second instrument tip breaks appear to be a common, but underreported, intraoperative complication of phacoemulsification. Consistent hospital tracking records and instrument inspection by the manufacturer, institution, and surgeon may help elucidate how these complications occur and establish guidelines to prevent future cases. REFERENCES 1. Braunstein RE, Cotliar AM, Wirostko BM, Gorman BD. Intraocular metallic-appearing foreign bodies after phacoemul-
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sification. J Cataract Refract Surg 1996;22:1247–50. 2. Martinez-Toldos JJ, Elvira JC, Hueso JR, et al. Metallic fragment deposits during phacoemulsification. J Cataract Refract Surg 1998;24:1256–60. 3. Thomas D, McLean C. Retained fragments in the anterior segment following phacoemulsification surgery. Eye 2002; 16:94–5. 4. Arbisser LB. Origin of intraocular metallic foreign bodies during phacoemulsification. J Cataract Refract Surg 2005;31:2423–4. 5. Pelosini L, Richardson EC, Goel R, Hugkulstone CE. Intraoperative breakage of the mushroom manipulator tip during phacoemulsification. Eye 2006;20:1451–2. 6. Manjunatha NP, Deshmukh RR, Kayarkar W. Large metallic fragment found in the angle of anterior chamber after phacoemulsification, and its removal. Eye 2007;21:295–6. 7. Cleary G, Sheth HG, Laidlaw AH. Delayed transient macular ischaemia due to ocular siderosis. Eye 2007;21:1132–3. 8. Wu JT, Lam DS, Fan DS, Lam WW, Tham CC. Intravitreal phaco chopper fragment missed by computed tomography. Br J Ophthalmol 1998;82:460–1. 9. Wadood AC, Dhillon B. Unidentified foreign objects in the wound after clear corneal tunnel phacoemulsification. J Cataract Refract Surg 2002;28:2238–9. 10. Stangos AN, Pournaras CJ, Petropoulos IK. Occult anteriorchamber metallic fragment post-phacoemulsification masquerading as chronic recalcitrant postoperative inflammation. Am J Ophthalmol 2005;139:541–2. Key words: phacoemulsification, siderosis, equipment failure, eye foreign bodies, intraoperative complications
Background: Second instrument tip breaks during phacoemulsification are complications that are anecdotally recalled, yet little information exists on why and how often they occur, whether they are consistently tracked, and how they are managed. They may be an underreported, but potentially serious, complication of phacoemulsification. Methods: We surveyed 114 cataract surgeons in Ontario to determine reported rates of second instrument tip breaks, their management, and presumed etiology. We reviewed 4 Toronto cataract centres for incident reports, instrument sterilization processes, and purchase histories. Using scanning electron microscopy (SEM), we compared the characteristics of a broken Sweeney tip to new and used second instruments. Results: Of the 35 surgeons responding to the survey, 34% had experienced a second instrument tip break during their careers. Approximately 73% (16 cases) of the 22 cases reported were managed successfully during the procedure by the primary surgeon, 14% (3 cases) required imaging by computerized tomography or x-ray, and another 14% (3 cases) required pars plana vitrectomy for tip retrieval. Purchase histories revealed that 1 Sweeney hook was exchanged monthly, equivalent to 100 to 150 surgeries. SEM of new and used second instruments revealed signs of metal fatigue on both new and used second instruments. Interpretation: Although both physicians and hospitals lack a method for ensuring quality control of second instruments, approximately one third of cataract surgeons encounter second instrument tip breaks during the course of their careers. Although most cases are managed intraoperatively, consistent hospital tracking records and standardized instrument inspection by institutions and surgeons are needed to determine how these complications occur and to establish protocols for complication reporting and management. Contexte : Les bris de l’extrémité des instruments secondaires pendant la phacoémulsification sont des complications qui font l’objet d’anecdotes, mais peu d’information en précise les raisons et la fréquence, si on a en fait constamment un relevé et comment on les gère. Elle ne sont peut-être pas suffisamment signalées, mais elles peuvent présenter des complications graves de la phacoémulsification. Méthodes : Nous avons interrogé 114 chirurgiens de la cataracte de l’Ontario pour établir dans quelle mesure ils signalaient les bris de l’extrémité des instruments secondaires, comment ils géraient la situation et en présumaient l’étiologie. Nous avons visité 4 centres de traitement de la cataracte de Toronto pour voir les dossiers d’incidents, les procédures de stérilisation des instruments et les dossiers des achats. À l’aide du microscope électronique à balayage (SEM), nous avons comparé les caractéristiques d’une extrémité brisée d’un Sweeney avec des instruments secondaires neufs et usagés. Résultats : Parmi les 35 chirurgiens qui ont répondu, 34 % avaient eu un bris d’extrémité d’instrument secondaire dans leur carrière. Environ 73 % (16 cas) des 22 cas signalés ont été gérés avec succès pendant la procédure par le chirurgien principal, 14 % (3 cas) ont requis une imagerie par tomographie informatisée ou rayon x, un autre 14 % (3 cas) ont requis une vitrectomie par la pars plana pour récupérer l’extrémité. Pour ce qui est des achats, on a relevé un remplacement du crochet Sweeney par mois, l’équivalent de 100 à 150 chirurgies. L’examen SEM des instruments secondaires nouveaux et usagés a révélé des signes d’usure sur les deux types d’instrument. Interprétation : Bien que les médecins et les hôpitaux n’aient pas de méthode pour assurer le contrôle de la qualité des instruments secondaires, environ le tiers des chirurgiens de la cataracte voient se briser l’extrémité de leurs instruments secondaires dans leur carrière. Bien que la plupart des cas soient résolus pendant l’opération, les hôpitaux ont besoin de tenir des dossiers cohérents de suivi. Les institutions et les chirurgiens ont aussi besoin d’inspections standardisées des instruments pour savoir comment surviennent ces complications et établir des protocoles de signalement et de gestion des complications. From the Department of Ophthalmology, University of Toronto, Toronto, Ont. Originally received Mar. 21, 2008. Revised June 6, 2008 Accepted for publication July 15, 2008 Published online Nov. 17, 2008
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Correspondence to Fariba Nazemi, MD, Department of Ophthalmology, University of Toronto, 147 Church Ave., Toronto ON M2N 4G4; [email protected] This article has been peer-reviewed. Cet article a été évalué par les pairs. Can J Ophthalmol 2008;43:702–6 doi:10.3129/i08-148
Second instrument tip breaks during phacoemulsification—Nazemi et al.
S
econd instrument tip breaks during phacoemulsification are complications that are anecdotally recalled, yet little information exists on why and how often they occur, whether they are consistently tracked, and how they are managed. The origin and nature of intraocular metallic fragments during, and following, phacoemulsification have received a fair amount of attention but little consensus. Braunstein et al.1 suggested instrument tip touch during phacoemulsification as the cause, whereas Martinez-Toldos et al.,2 by studying resulting fragments using scanning electron microscopy (SEM) and x-ray dispersive energy spectroscopy, demonstrated that prolonged vibration of the phaco needle can cause particles to chip off the hand piece. Several case reports point to a manufacturing defect, with fragments originating from a defect of the phacoemulsification tip sleeve and the silver from the brazing of the irrigation tube as it enters the hand piece shell on its inner diameter.3,4 Recent case reports highlight the occurrence of overt second instrument tip breaks intraoperatively. Pelosini et al.5 report 3 cases of mushroom manipulator tip breakage. Two tips were found floating in the capsular bag and 1 tip came off its stem, embedding into the side port as the instrument was being taken out of the eye. The tips were successfully removed with suction or retrieved with vitreous forceps. Microscopic examination revealed wear around the manipulator stem and decreased neck thickness. The authors concluded that repeated inadvertent contact caused tip breakage with minimal stress, although the exact mechanism of breakage remains unclear. Similarly, Manjunatha et al.6 report a case of a large metallic fragment found postoperatively in the inferior angle that was removed using gonioscopy and forceps. Although the tip of the second instrument appeared missing at the end of lens removal, the fragment was missed by the surgeon and remained undetected after x-rays of the orbits. Second instrument tip breaks may be an underreported, but potentially serious, intraoperative complication of phacoemulsification. To determine their reported frequency of occurrence, etiology, and management, we surveyed 114 cataract surgeons in Ontario in addition to reviewing the records of 4 Toronto cataract centres for instrument purchase histories and cleaning protocols. To understand how these complications occur, we examined a broken Sweeney tip and both new and used second instruments from one of the centres using SEM.
Survey of 4 cataract centres in Toronto, Ont.
We searched through the hospital records of 4 major teaching hospitals affiliated with the University of Toronto for incident reports of second instrument tip breaks during postphacoemulsification. We reviewed purchase histories and surveyed all 4 centres for second instrument cleaning and sterilization protocols. Scanning electron microscopy of new and used second instruments
We examined the surfaces of a broken Sweeney tip, a gently used chopper and Sweeney, and a new chopper. SEM was performed in a metallurgy laboratory at the University of Toronto under ×50, ×100, and ×200 magnifications. RESULTS Survey on incidence, management, and possible causes of second instrument tip breaks
Of the 35 surgeons (31% response rate) who responded to the questionnaire, 51% used the chopper, 26% the Sweeney, and 23% other devices (Rosen paddle, Sinskey hook, Drysdale spatula, or iris spatula) as their second instrument. Twenty-seven surgeons (77% of responders) reported that the Sweeney hook or the chopper was their second instrument of choice, and all reports of broken tips involved these 2 second instruments. Fifty-one percent reported routinely inspecting the second instrument tip and hand piece before use. Thirty-four percent responded that they had witnessed a second instrument tip break (range 1–4 times) during their careers. Of the 22 instances of tip break reported, 73% (16 cases) were managed through surgeon visualization and tip retrieval, 14% 1. What is your favorite second instrument for phacoemulsification? a. Chopper
b. Sweeney
c. Other _____________(please name)
2. Do you or your scrub nurse routinely inspect the instrument’s tip prior to using it? a. Yes
b. No
3. Has it ever happened to you that the instrument’s tip broke during phacoemulsification? a. No b. Yes (state how many times)_______________
4. When it did break a. Able to see and retrieve the tip b. You needed imaging (x-ray or CT)
METHODS Questionnaire survey of cataract surgeons in Ontario
An email questionnaire was sent out to the 114 cataract surgeons in Ontario listed in the Canadian Ophthalmological Society directory (Fig. 1). No compensation was provided. The survey inquired about the surgeon’s favourite second instrument, inspection prior to use, and management and presumed etiology of tip breaks.
c. You referred the patient to a retinal surgeon
5. Why do you think this complication happens? (mark all that apply) a. Phaco tip touch b. Multiple use and metal fatigue c. Not being properly used
Fig. 1—Email questionnaire surveying 114 Ontario cataract surgeons for self-reported second instrument tip break incidence, management, and presumed etiology. CAN J OPHTHALMOL—VOL. 43, NO. 6, 2008
703
Second instrument tip breaks during phacoemulsification—Nazemi et al. (3 cases) required imaging with either computerized tomography (CT) or x-ray because they were not found in the eye or on the surgical field after extensive searching, and 14% (3 cases) were referred to a retinal surgeon for pars plana vitrectomy (PPV) and foreign body removal. Thirtysix percent (8 cases) were attributed to a combination of phaco tip touch and metal fatigue, whereas 18% (4 cases) were attributed to phaco tip touch, metal fatigue, and improper use (Table 1). A belief in single modality causation was not as widely held. Survey of hospital records
There were no incident reports of second instrument tip breaks available in the hospital records of the 4 University of Toronto–affiliated institutions we surveyed because of a lack of a standardized reporting system. Purchase histories in 2 hospitals indicated that approximately 1 Sweeney hook was exchanged monthly, equivalent to 100 to 150 surgeries. The majority of these tips were replaced by processing staff before being handled by the surgeon. Although 3 of the hospitals had tracking systems in place for the instrument tray being used, there was no means of tracking a single instrument for its use prior to tip break. Interestingly, the 1 centre that used ultrasound (Neosonic, Amadent, Cherry Hill, N.J.) for 25 minutes for instrument cleaning before autoclaving with dry heat had neither reported nor anecdotal incidents of second instrument tip break. In this centre, the Rosen paddle was used routinely as the second instrument. The other 3 centres used neutral pH cleansers followed by dry heat for sterilization as their cleaning protocol. The dry heat sterilization technique uses temperatures of 65.6 to 121.1 °C (150–250°F), well below the heating threshold for steel. Metallurgic light microscopy in centralized instrument processing was used to detect surface defects in all 4 hospitals. Table 1—Survey results: reported second instrument preference, and presumed etiology of second instrument tip break and its management by 35 Ontario cataract surgeons Survey result
Scanning electron microscopy of new and used second instruments
The second instruments surveyed were 420-grade centre ground, a combination of carbon, chromium, silicone manganese, phosphorus, sulfur, and nickel. The handle measured 0.05 cm, whereas the shaft at the tip was 0.015 thousandths of a cm. With allowed variance, this value could be as small as 0.010 thousandths of a cm. The stainless steel is resistant to the heat used during sterilization, a range of 65.6 to 137.8 °C (150–280°F). With SEM, we examined the broken tip of a Sweeney (Fig. 2), a gently used Sweeney (Fig. 3), a gently used chopper (Fig. 4), and a brand new chopper (Fig. 5). These instruments were chosen because they were the 2 second instruments used most widely by the surgeons responding to our survey. In Fig. 2, the broken surface of the Sweeney shows signs of metal fatigue and sudden stress. The gently used instruments in Figs. 3 and 4 also harboured small cracks. Strikingly, even the new chopper had a small crack (Fig. 5).
Fig. 2—Scanning electron micrograph of broken Sweeney tip surface (original magnification ×500).
No. of surgeons (%)
Second instrument preference among Ontario surgeons, n = 35 Chopper
18 (51)
Sweeney
9 (26)
Other*
8 (23)
Presumed etiology of second instrument tip break among Ontario surgeons, n = 22 Phaco tip touch + metal fatigue
8 (36)
Phaco tip touch + metal fatigue + improper use
4 (18)
Phaco tip touch only
3 (14)
Centralized instrument processing mishandling
3 (14)
Metal fatigue + improper use
2 (9)
Metal fatigue only
2 (9)
Management of reported second instrument tip breaks by Ontario surgeons, n = 22 Intraoperative tip retrieval
16 (73)
Imaging with CT or x-ray
3 (14)
Referral to retina for PPV
3 (14)
*Other: Rosen paddle, Sinskey hook, Drysdale or iris spatula. Note: CT, computed tomography; PPV, pars plana vitrectomy.
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Fig. 3—Scanning electron micrograph of gently used Sweeney (original magnification ×50).
Second instrument tip breaks during phacoemulsification—Nazemi et al. INTERPRETATION
Although many surgeons can recount an experience with metallic-appearing intraocular foreign bodies (IOFBs) on biomicroscopy postoperatively, or even overt tip breaks during surgery, the frequency with which these complications occur, how they are managed, and how they occur remain unknown. Unrecognized tip breaks or instrument damage during surgery could have significant implications. During phacoemulsification, a lodged broken tip may lead to zonular instability, and possibly a broken capsule. A serious long-term complication of a retained iron-containing metal IOFB is ocular siderosis. Although rare, it can present with a rust-coloured corneal stroma, pupillary mydriasis, uveitis, siderotic cataract, lens subluxation, and secondary glaucoma. A delayed transient macular ischemia due to ocular siderosis has also been reported.7 Although complications of missed or poorly managed tip breaks can have serious consequences, our survey suggests that most surgeons do not routinely inspect their instru-
Fig. 4—Scanning electron micrograph of gently used chopper (original magnification ×50).
Fig. 5—Scanning electron micrograph of brand new chopper (original magnification ×50).
ments. Of our 35 surveyed Ontario cataract surgeons, although 34% reported witnessing second instrument tip breaks, only one half reported routinely inspecting their instruments before use. We acknowledge the possible bias inherent in a voluntary uncompensated survey, including the ability to recall intraoperative tip breaks by a surgeon during the span of a single career, the time frame allotted in our survey, or the possibility that only those experiencing such complications would respond. Our review of hospital records reveals the lack of a standardized system for incident reporting of intraoperative tip breaks, as well as a lack of reliable second instrument tracking. The management of IOFBs or broken tips after phacoemulsification depends largely on the size of the fragment, its magnetic nature, and its location. In our survey, most surgeons managed tip breaks intraoperatively by visualizing and removing the tip, whereas only a minority needed imaging or referral to a vitreoretinal surgeon. Of the 3 cases referred to a vitreoretinal surgeon for tip removal and PPV, 2 tips led to posterior capsule ruptures and the primary surgeon was unable to implant the intraocular lens. Consequently, if the tip is successfully extracted at the time of phacoemulsification, it is important to inspect the capsule for any tears before proceeding. Fourteen percent of cases required imaging to manage the tip break after the tip was not found inside the eye or on the surgical field. These tips might have been broken outside the eye and landed on the floor or instrument tray; or they may be too small, or in a location where the surgeon cannot visualize them. Both CT and x-ray may miss fragments smaller than 1 mm; in these cases, a B-scanner is the modality of choice. B-scanners are also helpful in locating intramural or extrascleral foreign bodies.8 If a tip break occurs or is suspected intraoperatively, thorough examination on biomicroscopy and gonioscopy may be warranted in addition to imaging because metallic-appearing IOFBs have been detected 1 day postoperatively on the iris4 or at the incision tunnel9 even after uneventful surgery. Patients should also be followed closely because occult IOFBs have been reported to present as chronic recalcitrant postoperative inflammation, causing macular epiretinal membrane and cystoid macular edema.10 The precise mechanism of second instrument tip breaks also remains unclear but is likely a combination of factors, such as manufacturing defects, inappropriate use, and progressive weakening from inadvertent tip touch. Of the 22 instances reported in our survey, most surgeons attribute the complication to some combination of phacoemulsification tip touch, metal fatigue, and improper use. Prospective studies of incident reports extracted from established tracking systems may elucidate which of these is the most common cause. Although we could not deduce the etiology of tip breaks using SEMs of a broken Sweeney, as well as new and gently used choppers, both new and used choppers showed slight cracks. We acknowledge that scanning of a variety of second instruments in higher numbers could CAN J OPHTHALMOL—VOL. 43, NO. 6, 2008
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Second instrument tip breaks during phacoemulsification—Nazemi et al. provide additional information and should be a focus of future studies; however, our initial SEM scans emphasize the need for quality control both at the level of the manufacturer and by institutions and surgeons. Based on our survey of cataract surgeons, hospital records, and examination of instruments using SEM, we recommend • careful inspection of instruments before, during, and after surgery by the surgeon and scrub nurse; • the formation of consistent hospital tracking systems to replace fatigued instruments and inspect new ones prior to first use; and • quality control at the level of the manufacturer. Experimental studies to find the breaking threshold for hooks, especially at the necks, might also prove insightful. Recent case reports highlight that second instruments frequently break at the necks, which often become narrow after repeated use.5,6 Second instrument tip breaks appear to be a common, but underreported, intraoperative complication of phacoemulsification. Consistent hospital tracking records and instrument inspection by the manufacturer, institution, and surgeon may help elucidate how these complications occur and establish guidelines to prevent future cases. REFERENCES 1. Braunstein RE, Cotliar AM, Wirostko BM, Gorman BD. Intraocular metallic-appearing foreign bodies after phacoemul-
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sification. J Cataract Refract Surg 1996;22:1247–50. 2. Martinez-Toldos JJ, Elvira JC, Hueso JR, et al. Metallic fragment deposits during phacoemulsification. J Cataract Refract Surg 1998;24:1256–60. 3. Thomas D, McLean C. Retained fragments in the anterior segment following phacoemulsification surgery. Eye 2002; 16:94–5. 4. Arbisser LB. Origin of intraocular metallic foreign bodies during phacoemulsification. J Cataract Refract Surg 2005;31:2423–4. 5. Pelosini L, Richardson EC, Goel R, Hugkulstone CE. Intraoperative breakage of the mushroom manipulator tip during phacoemulsification. Eye 2006;20:1451–2. 6. Manjunatha NP, Deshmukh RR, Kayarkar W. Large metallic fragment found in the angle of anterior chamber after phacoemulsification, and its removal. Eye 2007;21:295–6. 7. Cleary G, Sheth HG, Laidlaw AH. Delayed transient macular ischaemia due to ocular siderosis. Eye 2007;21:1132–3. 8. Wu JT, Lam DS, Fan DS, Lam WW, Tham CC. Intravitreal phaco chopper fragment missed by computed tomography. Br J Ophthalmol 1998;82:460–1. 9. Wadood AC, Dhillon B. Unidentified foreign objects in the wound after clear corneal tunnel phacoemulsification. J Cataract Refract Surg 2002;28:2238–9. 10. Stangos AN, Pournaras CJ, Petropoulos IK. Occult anteriorchamber metallic fragment post-phacoemulsification masquerading as chronic recalcitrant postoperative inflammation. Am J Ophthalmol 2005;139:541–2. Key words: phacoemulsification, siderosis, equipment failure, eye foreign bodies, intraoperative complications