- Email: [email protected]
Risk factors for and management of dropped nucleus during phacoemulsification
Risk factors for and management of dropped nucleus during phacoemulsification Murali K. Aasuri, MD, Viswanadh B. Kompella, MS, Ajit B. Majji, MD ABSTRACT Purpose: To study the risk factors and management of posteriorly dislocated crystalline lenses during phacoemulsification at a teaching institution. Setting: L.V. Prasad Eye Institute, Hyderabad, India. Methods: This retrospective analysis included all phacoemulsification procedures performed by experienced and inexperienced surgeons over 7 years. The incidence, risk factors for, role of surgical experience, mode of management, and the final outcome of posteriorly dislocated lens nuclei were evaluated. Results: Of a total 11 343 phacoemulsification procedures performed between 1993 and 1999, the nucleus was dropped in 38 eyes (0.3%). Two patients with a dropped nucleus were referred from an outside practice. The incidence of dropped nucleus with experienced surgeons (22/8671; 0.2%) was significantly less than that with inexperienced surgeons (16/2672; 0.6%) (P ⫽ .007). Sixteen of the 22 cases of dropped nucleus (72.7%) in the experienced group and 1 of 16 (6.3%) in the inexperienced group had risk factors (P ⫽ .0005). Nucleus removal was performed using vitreoretinal procedures in 39 eyes; 1 eye with a dropped epinucleus was managed conservatively. The final best corrected visual acuity was 20/40 or better in 21 eyes (53.8%). Conclusions: The incidence of dropped nucleus was more frequent with inexperienced surgeons, even though experienced surgeons had more cases with predisposing risk factors. Modern vitreoretinal procedures reduce morbidity and improve the visual outcome. J Cataract Refract Surg 2001; 27:1428 –1432 © 2001 ASCRS and ESCRS
P
osterior dislocation of the lens nucleus is a major intraoperative complication of ultrasonic phacoemulsification.1 The incidence, which is difficult to assess, has been reported to be between 0.4% and 4.0%.1,2 Although the rate of dropped nucleus has risen in the past 2 decades as more surgeons have converted to phacoemulsification, its occurrence is inversely related to surgeon experience.2 Realization of the risks of
Accepted for publication January 19, 2001. Reprint requests to Murali K. Aasuri, MD, Consultant, Cornea Services, L.V. Prasad Eye Institute, L.V. Prasad Marg, Banjara Hills, Hyderabad–500 034, India. E-mail: [email protected]. © 2001 ASCRS and ESCRS Published by Elsevier Science Inc.
attempting nuclear removal by a limbal approach and of the merits of applying advanced vitreoretinal techniques has significantly improved the outcome in these cases. Surgeons are particularly prone to this complication during the learning curve,3 and institutions offering phacoemulsification training are more likely to have a higher rate of dropped nucleus. We report the incidence and management of dropped nucleus over 7 years at a comprehensive eyecare center in Southern India.
Patients and Methods The medical records of all patients who had phacoemulsification at the L.V. Prasad Eye Institute between 0886-3350/01/$–see front matter PII S0886-3350(01)00784-2
DROPPED NUCLEUS DURING PHACOEMULSIFICATION
1993 and 1999 were reviewed. Patients with a dropped nucleus were identified and evaluated in detail. The morphology of the cataract, previous ocular surgery, type of anesthesia, surgeon experience, intraoperative complications contributing to dropped nucleus, number of dislocated nuclear quadrants, the timing of intervention, intraocular lens (IOL) implantation, complications, the mode of management, and final outcomes were analyzed. Lens characteristics such as nuclear hardness (grade 1 to 4), posterior polar opacity, total cataract, subluxation, and pseudoexfoliation were noted. A cataract with a nucleus of grade 3 or 4 was considered to be hard. Phacoemulsification was performed by faculty, fellows, and trainees. Surgeons were categorized as experienced or inexperienced based on their phacoemulsification skills and knowledge. The fellows and trainees were categorized as inexperienced as they had a relatively short exposure to phacoemulsification. Faculty members were subjectively categorized as experienced or inexperienced at different times by a faculty member (M.K.A.) familiar with the individual surgeons. All inexperienced surgeons were well trained in extracapsular cataract extraction and related microsurgery. Surgeries performed before and after 1996 were compared in terms of visual recovery and complications to ascertain whether increasing experience in managing dropped nucleus influenced the outcome.
Results Of the 11 343 phacoemulsification procedures performed between 1993 and 1999, 8671 (76.4%) were performed by experienced surgeons and 2672 (23.6%) by inexperienced surgeons. Dropped nucleus occurred in 38 eyes (0.3%), 22 (57.9%) with experienced surgeons and 16 (42.1%) with inexperienced surgeons. In addition, 2 patients with dropped nucleus were referred from an outside practice, and the surgeon’s phacoemulsification expertise in these cases was unknown. The annual incidence of dropped nucleus is shown in Table 1. Fifteen cases (37.5%) were in right eyes and 25 (62.5%), in left eyes. The incidence of dropped nucleus in the experienced group was 0.2% (22/8671), significantly less than that in the inexperienced group (16/2672; 0.6%) (P ⫽ .007).
Table 1. Annual incidence of dropped nucleus.
Year
Phaco Procedures Performed
Cases of Dropped Nucleus
1993
88
0
1994
1200
2
1995
1444
11
1996
1863
3
1997
2359
5
1998
2318
9
1999
1613
8
The risk factors for dropped nucleus other than surgeon experience are shown in Table 2. Sixteen of 22 eyes (72.7%) with dropped nuclei in the experienced group and 1 of 16 (6.3%) in the inexperienced group had risk factors (P ⫽ .0005). The most common surgical steps contributing to posterior capsule dehiscence and subsequent dropped nucleus were an inability to gauge the depth during sculpting, perforating the nuclear plate at the 6 o’clock position during trenching, and continued aspiration after fragment removal. Posterior polar cataract predisposed to dropped nucleus in 8 eyes. The entire nucleus was dropped in 2 of these eyes immediately after hydrodissection. Details of the surgical procedure were not available for the 2 eyes having surgery elsewhere. In most eyes (n ⫽ 24), the whole nucleus dislocated into the vitreous. In the remaining eyes, 1 (n ⫽ 3), 2 (n ⫽ 7), or 3 (n ⫽ 5) nuclear quadrants dropped posteriorly. In 1 eye, half the epinucleus dislocated posteriorly after all the nuclear fragments were removed. The details of the intraoperative efforts of the surgeon to retrieve the nucleus were not adequately recorded for analysis. Table 2. Factors predisposing to dropped nucleus.
Risk Factor
Experienced Inexperienced Group Group
Posterior polar cataract
7
1
Hard cataract (grade 3 or 4)
2
0
Total cataract
1
0
Radial tears in capsulorhexis
2
0
Topical anesthesia
3
0
Vitrectomized eye
1
0
J CATARACT REFRACT SURG—VOL 27, SEPTEMBER 2001
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DROPPED NUCLEUS DURING PHACOEMULSIFICATION
Posterior capsule dehiscence was central in 32 eyes and peripheral in 8 eyes. Preoperative retinal evaluation was normal in 34 eyes; in the remaining eyes, optic disc pallor (n ⫽ 3), diabetic retinopathy (n ⫽ 2), and myopic chorioretinal degeneration (n ⫽ 1) were noted. A pars plana vitrectomy with nucleus removal was performed in 39 eyes by surgeons experienced in vitreoretinal procedures on the same day (14 eyes), within 1 week (16 eyes), or after 1 week (9 eyes) of the occurrence of dropped nucleus. After adequate vitrectomy, the nuclear fragments were removed with an Ocutome in 23 eyes and with a fragmatome in 9 eyes. In 7 eyes in which the nuclear mass was hard, perfluorocarbon liquid (PFCL) was used to float the nucleus, which was finally delivered through a limbal incision. In the eye with a dropped epinucleus, only anterior vitrectomy (ie, no vitreoretinal intervention) was done. The epinucleus cleared spontaneously over 2 months. Intraocular lens implantation was primary in 15 eyes, secondary in 16 eyes, and was deferred in 9 eyes. Of the 31 IOLs implanted, 25 were posterior chamber and 6, anterior chamber. The mean follow-up was 9.3 months (range 1 week to 3 years). There were no postoperative complications in 30 eyes. Two eyes had corneal edema, 4 eyes had glaucoma, and 1 eye each had macular scar, macular hemorrhage, optic atrophy, or retinal detachment. Scleral buckling was done in the eye with retinal detachment, resulting in a best corrected visual acuity (BCVA) of 20/25. A BCVA of 20/40 or better was achieved in 21 eyes and of 20/50 to 20/125 in 12 eyes. One patient was lost to follow-up shortly after surgery. In the remaining 6 eyes, BCVA was 20/200 or worse because of persistent corneal edema (n ⫽ 1), glaucoma (n ⫽ 2), proliferative diabetic retinopathy (n ⫽ 1), or vitritis (n ⫽ 2). The number of cases of dropped nucleus between 1994 and 1996 (17/4507; 0.37%) and that between 1997 and 1999 (21/6290; 0.33%) was not significantly different (P ⫽ .836). Visual acuity was worse than 20/200 in 3 eyes in each group, and the postoperative complications were similar between the groups.
Discussion Posterior dislocation of nucleus is a serious complication of phacoemulsification because of the morbidity 1430
to the patient and the “embarrassment” to the surgeon. Even so, postoperative complications are minimal and visual recovery is satisfactory after appropriate intervention by a vitreoretinal surgeon.4 We analyzed the data from our phacoemulsification training center to understand which factors contribute to dropped nucleus and complications and to evaluate the management and final outcome of the event. Overall, the incidence of dropped nucleus at our center (0.3%) was less than the incidence reported in the literature (0.4% to 4%).1 The higher rates of dropped nucleus occurred when phacoemulsification was still evolving. State-of-the-art phaco machines, improved surgical skills, and an increased awareness of the factors predisposing to dropped nucleus have contributed to its decreasing incidence. All surgeons performing phacoemulsification at our center are proficient in extracapsular cataract surgery. Studies show that during the learning curve, surgeons are more likely to encounter a dropped nucleus.3,5 Our study confirmed these findings; a significant proportion of cases of dropped nucleus occurred in the hands of inexperienced surgeons. However, the complication can happen even to experienced surgeons as they are more likely to perform difficult surgeries and tend to postpone conversion to an extracapsular technique under unfavorable situations. In our analysis, more risk factors predisposing to dropped nucleus were noted in eyes having phacoemulsification by an experienced surgeon. Nuclear procedures such as trenching, chopping, and quadrant removal were the most common surgical steps resulting in posterior capsule dehiscence and subsequent dropped nucleus. Both preoperative and intraoperative risk factors predispose to dropped nucleus. Posterior polar cataracts were noted in 8 eyes; in 2 of these, the surgeon suspected posterior capsule dehiscence soon after hydrodissection. That posterior polar cataracts predispose to posterior capsule dehiscence is well established.6 Hydroprocedures performed before nuclear emulsification dissect the posterior polar opacity, which is firmly adherent to the posterior lens capsule, resulting in posterior capsule dehiscence. The risk of dropped nucleus is significantly greater in such cases. In patients with posterior polar opacities, we currently avoid hydrodissection and use hydrodelamination to separate the nucleus from the epinucleus, leaving the
J CATARACT REFRACT SURG—VOL 27, SEPTEMBER 2001
DROPPED NUCLEUS DURING PHACOEMULSIFICATION
posterior capsule undisturbed during nucleus emulsification. Measures to reduce complications in the presence of posterior polar opacities have been described.7,8 Hard and total cataracts create problems during capsulorhexis and nuclear emulsification, which increases the risk of dropped nucleus, as evidenced in 3 patients in our series. Radial tears in the capsulorhexis occurring during nuclear emulsification resulted in 2 dropped nuclei in our series. Lu and coauthors3 report 3 cases of dropped nucleus resulting from radial tears in the capsulorhexis. In these eyes, the tears extended to the equator after repeated anterior chamber fluctuations. Postvitrectomy eyes can be a challenge to phacoemulsification surgeons. The chamber in these eyes is unusually deep, the zonules are weak, and the posterior capsule is excessively flaccid secondary to reduced vitreous support. Pinter and Sugar9 report nuclear fragment dislocation in postvitrectomy eyes having phacoemulsification. One case of dropped nucleus in our series occurred in a vitrectomized eye. Topical anesthesia was considered a risk factor in 3 eyes in our series. Inadequate surgical experience with topical anesthesia, poor patient cooperation, and eye movement during key surgical steps were thought to be contributing factors. Surgical intervention was done in all except 1 eye, which had a dropped epinucleus. The eye had transient secondary glaucoma that was managed medically, and the epinucleus cleared spontaneously over 2 months. Peyman and coauthors6 report spontaneous resorption of small cortical or nuclear fragments (⬍25% of the lens material). However, even small fragments can cause cystoid macular edema, persistent uveitis, and glaucoma.10 Hence, careful follow-up is essential until all lens material is cleared. Surgical intervention should be instituted when complications such as those mentioned above are encountered. Nuclear material was removed using standard vitreoretinal procedures as described in the literature. In 30 eyes in our series, the procedure was done in the first postoperative week. The presence of transient corneal edema and postoperative inflammation delayed surgical intervention beyond 1 week in 9 eyes. Although the best timing of vitrectomy for retained lens matter continues to be debated,11,12 several reports in the literature show no difference in final visual recovery between patients having early vitrectomy and those having late vitrec-
tomy.4,5,10 We advocate early intervention in eyes without complications. The presence of corneal edema, intraocular inflammation, or secondary glaucoma may require initial medical control followed by vitrectomy. Retaining the anterior capsulorhexis during vitreous surgery is important in rehabilitating the patient as it permits placement of a posterior chamber IOL. In our initial cases, the dropped nucleus was managed by vitrectomy after the nuclear fragments were removed with an Ocutome, fragmatome, or PFCL. As our experience in managing these cases increased, we could remove even hard nuclei with a fragmatome, sparing the anterior capsulorhexis. The final BCVA was 20/40 or better in 21 eyes (53.8%). In a study of retained lens fragments after phacoemulsification, Kim et al.4 report a visual acuity of 20/40 or better in 68% of patients. Poor visual recovery was attributable to primary ocular pathology (macular scar, optic atrophy, or proliferative diabetic retinopathy) or secondary pathology resulting from improper management at the time the nucleus was dropped, resulting in persistent corneal edema, intractable glaucoma, or vitritis. In our series, there were no complications in 30 eyes. The complications in the other 10 eyes were similar to those reported in the literature.3,4 Complications in cases of dropped nucleus are often the result of nuclear retrieval attempts by anterior segment surgeons who wish to prevent posterior dislocation. Such maneuvers can place traction on the vitreous base, causing retinal tears. However, we did not analyze this aspect because of inadequate data. In conclusion, the rate of dropped nucleus was lower in the experienced phaco surgeon group than in the inexperienced group, even though the experienced surgeons had more difficult cases. Pars plana vitrectomy and removal of retained lens fragments achieved good outcomes in most patients with a dropped nucleus.
References 1. You TT, Arroyo JG. Surgical approaches for the removal of posteriorly dislocated crystalline lenses. Int Ophthalmol Clin 1999; 39(1):249 –259 2. Stilma JS, van der Sluijs FA, van Meurs JC, Mertens DAE. Occurrence of retained lens fragments after phaco-
J CATARACT REFRACT SURG—VOL 27, SEPTEMBER 2001
1431
DROPPED NUCLEUS DURING PHACOEMULSIFICATION
3.
4.
5.
6.
7. 8.
emulsification in The Netherlands. J Cataract Refract Surg 1997; 23:1177–1182 Lu H, Jiang YR, Grabow HB. Managing a dropped nucleus during the phacoemulsification learning curve. J Cataract Refract Surg 1999; 25:447– 450 Kim JE, Flynn HW Jr, Smiddy WE, et al. Retained lens fragments after phacoemulsification. Ophthalmology 1994; 101:1827–1832 Kapusta MA, Chen JC, Lam W-C. Outcomes of dropped nucleus during phacoemulsification. Ophthalmology 1996; 103:1884 –1187; discussion by AJ Brucker, 1187 Peyman GA, Raichand M, Goldberg MF, Ritacca D. Management of subluxated and dislocated lenses with the vitrophage. Br J Ophthalmol 1979; 63:771–778 Vasavada A, Singh R. Surgical techniques for difficult cataracts. Curr Opin Ophthalmol 1999; 10:46 –52 Vasavada A, Singh R. Phacoemulsification in eyes with posterior polar cataract. J Cataract Refract Surg 1999; 25:238 –245
1432
9. Pinter SM, Sugar A. Phacoemulsification in eyes with past pars plana vitrectomy: case-control study. J Cataract Refract Surg 1999; 25:556 –561 10. Gilliland GD, Hutton WL, Fuller DG. Retained intravitreal lens fragments after cataract surgery. Ophthalmology 1992; 99:1263–1267; discussion by TM Topping, 1268 –1269 11. Blodi BA, Flynn HW Jr, Blodi CF, et al. Retained nuclei after cataract surgery. Ophthalmology 1992; 99:41– 44 12. Wong D, Briggs MC, Hickey-Dwyer MU, McGalliard JN. Removal of lens fragments from the vitreous cavity. Eye 1997; 11:37– 42 From Sight Saver’s Cornea Training Centre and Srimati Kanuri Santamma Retina Vitreous Centre, L.V. Prasad Eye Institute, Hyderabad, India. Presented as a poster at the annual meeting of the American Academy of Ophthalmology, Orlando, Florida, USA, October 1999.
J CATARACT REFRACT SURG—VOL 27, SEPTEMBER 2001
P
osterior dislocation of the lens nucleus is a major intraoperative complication of ultrasonic phacoemulsification.1 The incidence, which is difficult to assess, has been reported to be between 0.4% and 4.0%.1,2 Although the rate of dropped nucleus has risen in the past 2 decades as more surgeons have converted to phacoemulsification, its occurrence is inversely related to surgeon experience.2 Realization of the risks of
Accepted for publication January 19, 2001. Reprint requests to Murali K. Aasuri, MD, Consultant, Cornea Services, L.V. Prasad Eye Institute, L.V. Prasad Marg, Banjara Hills, Hyderabad–500 034, India. E-mail: [email protected]. © 2001 ASCRS and ESCRS Published by Elsevier Science Inc.
attempting nuclear removal by a limbal approach and of the merits of applying advanced vitreoretinal techniques has significantly improved the outcome in these cases. Surgeons are particularly prone to this complication during the learning curve,3 and institutions offering phacoemulsification training are more likely to have a higher rate of dropped nucleus. We report the incidence and management of dropped nucleus over 7 years at a comprehensive eyecare center in Southern India.
Patients and Methods The medical records of all patients who had phacoemulsification at the L.V. Prasad Eye Institute between 0886-3350/01/$–see front matter PII S0886-3350(01)00784-2
DROPPED NUCLEUS DURING PHACOEMULSIFICATION
1993 and 1999 were reviewed. Patients with a dropped nucleus were identified and evaluated in detail. The morphology of the cataract, previous ocular surgery, type of anesthesia, surgeon experience, intraoperative complications contributing to dropped nucleus, number of dislocated nuclear quadrants, the timing of intervention, intraocular lens (IOL) implantation, complications, the mode of management, and final outcomes were analyzed. Lens characteristics such as nuclear hardness (grade 1 to 4), posterior polar opacity, total cataract, subluxation, and pseudoexfoliation were noted. A cataract with a nucleus of grade 3 or 4 was considered to be hard. Phacoemulsification was performed by faculty, fellows, and trainees. Surgeons were categorized as experienced or inexperienced based on their phacoemulsification skills and knowledge. The fellows and trainees were categorized as inexperienced as they had a relatively short exposure to phacoemulsification. Faculty members were subjectively categorized as experienced or inexperienced at different times by a faculty member (M.K.A.) familiar with the individual surgeons. All inexperienced surgeons were well trained in extracapsular cataract extraction and related microsurgery. Surgeries performed before and after 1996 were compared in terms of visual recovery and complications to ascertain whether increasing experience in managing dropped nucleus influenced the outcome.
Results Of the 11 343 phacoemulsification procedures performed between 1993 and 1999, 8671 (76.4%) were performed by experienced surgeons and 2672 (23.6%) by inexperienced surgeons. Dropped nucleus occurred in 38 eyes (0.3%), 22 (57.9%) with experienced surgeons and 16 (42.1%) with inexperienced surgeons. In addition, 2 patients with dropped nucleus were referred from an outside practice, and the surgeon’s phacoemulsification expertise in these cases was unknown. The annual incidence of dropped nucleus is shown in Table 1. Fifteen cases (37.5%) were in right eyes and 25 (62.5%), in left eyes. The incidence of dropped nucleus in the experienced group was 0.2% (22/8671), significantly less than that in the inexperienced group (16/2672; 0.6%) (P ⫽ .007).
Table 1. Annual incidence of dropped nucleus.
Year
Phaco Procedures Performed
Cases of Dropped Nucleus
1993
88
0
1994
1200
2
1995
1444
11
1996
1863
3
1997
2359
5
1998
2318
9
1999
1613
8
The risk factors for dropped nucleus other than surgeon experience are shown in Table 2. Sixteen of 22 eyes (72.7%) with dropped nuclei in the experienced group and 1 of 16 (6.3%) in the inexperienced group had risk factors (P ⫽ .0005). The most common surgical steps contributing to posterior capsule dehiscence and subsequent dropped nucleus were an inability to gauge the depth during sculpting, perforating the nuclear plate at the 6 o’clock position during trenching, and continued aspiration after fragment removal. Posterior polar cataract predisposed to dropped nucleus in 8 eyes. The entire nucleus was dropped in 2 of these eyes immediately after hydrodissection. Details of the surgical procedure were not available for the 2 eyes having surgery elsewhere. In most eyes (n ⫽ 24), the whole nucleus dislocated into the vitreous. In the remaining eyes, 1 (n ⫽ 3), 2 (n ⫽ 7), or 3 (n ⫽ 5) nuclear quadrants dropped posteriorly. In 1 eye, half the epinucleus dislocated posteriorly after all the nuclear fragments were removed. The details of the intraoperative efforts of the surgeon to retrieve the nucleus were not adequately recorded for analysis. Table 2. Factors predisposing to dropped nucleus.
Risk Factor
Experienced Inexperienced Group Group
Posterior polar cataract
7
1
Hard cataract (grade 3 or 4)
2
0
Total cataract
1
0
Radial tears in capsulorhexis
2
0
Topical anesthesia
3
0
Vitrectomized eye
1
0
J CATARACT REFRACT SURG—VOL 27, SEPTEMBER 2001
1429
DROPPED NUCLEUS DURING PHACOEMULSIFICATION
Posterior capsule dehiscence was central in 32 eyes and peripheral in 8 eyes. Preoperative retinal evaluation was normal in 34 eyes; in the remaining eyes, optic disc pallor (n ⫽ 3), diabetic retinopathy (n ⫽ 2), and myopic chorioretinal degeneration (n ⫽ 1) were noted. A pars plana vitrectomy with nucleus removal was performed in 39 eyes by surgeons experienced in vitreoretinal procedures on the same day (14 eyes), within 1 week (16 eyes), or after 1 week (9 eyes) of the occurrence of dropped nucleus. After adequate vitrectomy, the nuclear fragments were removed with an Ocutome in 23 eyes and with a fragmatome in 9 eyes. In 7 eyes in which the nuclear mass was hard, perfluorocarbon liquid (PFCL) was used to float the nucleus, which was finally delivered through a limbal incision. In the eye with a dropped epinucleus, only anterior vitrectomy (ie, no vitreoretinal intervention) was done. The epinucleus cleared spontaneously over 2 months. Intraocular lens implantation was primary in 15 eyes, secondary in 16 eyes, and was deferred in 9 eyes. Of the 31 IOLs implanted, 25 were posterior chamber and 6, anterior chamber. The mean follow-up was 9.3 months (range 1 week to 3 years). There were no postoperative complications in 30 eyes. Two eyes had corneal edema, 4 eyes had glaucoma, and 1 eye each had macular scar, macular hemorrhage, optic atrophy, or retinal detachment. Scleral buckling was done in the eye with retinal detachment, resulting in a best corrected visual acuity (BCVA) of 20/25. A BCVA of 20/40 or better was achieved in 21 eyes and of 20/50 to 20/125 in 12 eyes. One patient was lost to follow-up shortly after surgery. In the remaining 6 eyes, BCVA was 20/200 or worse because of persistent corneal edema (n ⫽ 1), glaucoma (n ⫽ 2), proliferative diabetic retinopathy (n ⫽ 1), or vitritis (n ⫽ 2). The number of cases of dropped nucleus between 1994 and 1996 (17/4507; 0.37%) and that between 1997 and 1999 (21/6290; 0.33%) was not significantly different (P ⫽ .836). Visual acuity was worse than 20/200 in 3 eyes in each group, and the postoperative complications were similar between the groups.
Discussion Posterior dislocation of nucleus is a serious complication of phacoemulsification because of the morbidity 1430
to the patient and the “embarrassment” to the surgeon. Even so, postoperative complications are minimal and visual recovery is satisfactory after appropriate intervention by a vitreoretinal surgeon.4 We analyzed the data from our phacoemulsification training center to understand which factors contribute to dropped nucleus and complications and to evaluate the management and final outcome of the event. Overall, the incidence of dropped nucleus at our center (0.3%) was less than the incidence reported in the literature (0.4% to 4%).1 The higher rates of dropped nucleus occurred when phacoemulsification was still evolving. State-of-the-art phaco machines, improved surgical skills, and an increased awareness of the factors predisposing to dropped nucleus have contributed to its decreasing incidence. All surgeons performing phacoemulsification at our center are proficient in extracapsular cataract surgery. Studies show that during the learning curve, surgeons are more likely to encounter a dropped nucleus.3,5 Our study confirmed these findings; a significant proportion of cases of dropped nucleus occurred in the hands of inexperienced surgeons. However, the complication can happen even to experienced surgeons as they are more likely to perform difficult surgeries and tend to postpone conversion to an extracapsular technique under unfavorable situations. In our analysis, more risk factors predisposing to dropped nucleus were noted in eyes having phacoemulsification by an experienced surgeon. Nuclear procedures such as trenching, chopping, and quadrant removal were the most common surgical steps resulting in posterior capsule dehiscence and subsequent dropped nucleus. Both preoperative and intraoperative risk factors predispose to dropped nucleus. Posterior polar cataracts were noted in 8 eyes; in 2 of these, the surgeon suspected posterior capsule dehiscence soon after hydrodissection. That posterior polar cataracts predispose to posterior capsule dehiscence is well established.6 Hydroprocedures performed before nuclear emulsification dissect the posterior polar opacity, which is firmly adherent to the posterior lens capsule, resulting in posterior capsule dehiscence. The risk of dropped nucleus is significantly greater in such cases. In patients with posterior polar opacities, we currently avoid hydrodissection and use hydrodelamination to separate the nucleus from the epinucleus, leaving the
J CATARACT REFRACT SURG—VOL 27, SEPTEMBER 2001
DROPPED NUCLEUS DURING PHACOEMULSIFICATION
posterior capsule undisturbed during nucleus emulsification. Measures to reduce complications in the presence of posterior polar opacities have been described.7,8 Hard and total cataracts create problems during capsulorhexis and nuclear emulsification, which increases the risk of dropped nucleus, as evidenced in 3 patients in our series. Radial tears in the capsulorhexis occurring during nuclear emulsification resulted in 2 dropped nuclei in our series. Lu and coauthors3 report 3 cases of dropped nucleus resulting from radial tears in the capsulorhexis. In these eyes, the tears extended to the equator after repeated anterior chamber fluctuations. Postvitrectomy eyes can be a challenge to phacoemulsification surgeons. The chamber in these eyes is unusually deep, the zonules are weak, and the posterior capsule is excessively flaccid secondary to reduced vitreous support. Pinter and Sugar9 report nuclear fragment dislocation in postvitrectomy eyes having phacoemulsification. One case of dropped nucleus in our series occurred in a vitrectomized eye. Topical anesthesia was considered a risk factor in 3 eyes in our series. Inadequate surgical experience with topical anesthesia, poor patient cooperation, and eye movement during key surgical steps were thought to be contributing factors. Surgical intervention was done in all except 1 eye, which had a dropped epinucleus. The eye had transient secondary glaucoma that was managed medically, and the epinucleus cleared spontaneously over 2 months. Peyman and coauthors6 report spontaneous resorption of small cortical or nuclear fragments (⬍25% of the lens material). However, even small fragments can cause cystoid macular edema, persistent uveitis, and glaucoma.10 Hence, careful follow-up is essential until all lens material is cleared. Surgical intervention should be instituted when complications such as those mentioned above are encountered. Nuclear material was removed using standard vitreoretinal procedures as described in the literature. In 30 eyes in our series, the procedure was done in the first postoperative week. The presence of transient corneal edema and postoperative inflammation delayed surgical intervention beyond 1 week in 9 eyes. Although the best timing of vitrectomy for retained lens matter continues to be debated,11,12 several reports in the literature show no difference in final visual recovery between patients having early vitrectomy and those having late vitrec-
tomy.4,5,10 We advocate early intervention in eyes without complications. The presence of corneal edema, intraocular inflammation, or secondary glaucoma may require initial medical control followed by vitrectomy. Retaining the anterior capsulorhexis during vitreous surgery is important in rehabilitating the patient as it permits placement of a posterior chamber IOL. In our initial cases, the dropped nucleus was managed by vitrectomy after the nuclear fragments were removed with an Ocutome, fragmatome, or PFCL. As our experience in managing these cases increased, we could remove even hard nuclei with a fragmatome, sparing the anterior capsulorhexis. The final BCVA was 20/40 or better in 21 eyes (53.8%). In a study of retained lens fragments after phacoemulsification, Kim et al.4 report a visual acuity of 20/40 or better in 68% of patients. Poor visual recovery was attributable to primary ocular pathology (macular scar, optic atrophy, or proliferative diabetic retinopathy) or secondary pathology resulting from improper management at the time the nucleus was dropped, resulting in persistent corneal edema, intractable glaucoma, or vitritis. In our series, there were no complications in 30 eyes. The complications in the other 10 eyes were similar to those reported in the literature.3,4 Complications in cases of dropped nucleus are often the result of nuclear retrieval attempts by anterior segment surgeons who wish to prevent posterior dislocation. Such maneuvers can place traction on the vitreous base, causing retinal tears. However, we did not analyze this aspect because of inadequate data. In conclusion, the rate of dropped nucleus was lower in the experienced phaco surgeon group than in the inexperienced group, even though the experienced surgeons had more difficult cases. Pars plana vitrectomy and removal of retained lens fragments achieved good outcomes in most patients with a dropped nucleus.
References 1. You TT, Arroyo JG. Surgical approaches for the removal of posteriorly dislocated crystalline lenses. Int Ophthalmol Clin 1999; 39(1):249 –259 2. Stilma JS, van der Sluijs FA, van Meurs JC, Mertens DAE. Occurrence of retained lens fragments after phaco-
J CATARACT REFRACT SURG—VOL 27, SEPTEMBER 2001
1431
DROPPED NUCLEUS DURING PHACOEMULSIFICATION
3.
4.
5.
6.
7. 8.
emulsification in The Netherlands. J Cataract Refract Surg 1997; 23:1177–1182 Lu H, Jiang YR, Grabow HB. Managing a dropped nucleus during the phacoemulsification learning curve. J Cataract Refract Surg 1999; 25:447– 450 Kim JE, Flynn HW Jr, Smiddy WE, et al. Retained lens fragments after phacoemulsification. Ophthalmology 1994; 101:1827–1832 Kapusta MA, Chen JC, Lam W-C. Outcomes of dropped nucleus during phacoemulsification. Ophthalmology 1996; 103:1884 –1187; discussion by AJ Brucker, 1187 Peyman GA, Raichand M, Goldberg MF, Ritacca D. Management of subluxated and dislocated lenses with the vitrophage. Br J Ophthalmol 1979; 63:771–778 Vasavada A, Singh R. Surgical techniques for difficult cataracts. Curr Opin Ophthalmol 1999; 10:46 –52 Vasavada A, Singh R. Phacoemulsification in eyes with posterior polar cataract. J Cataract Refract Surg 1999; 25:238 –245
1432
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J CATARACT REFRACT SURG—VOL 27, SEPTEMBER 2001