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Small incision nucleus capture: results of 200 cases
Small incision nucleus capture: Results of 200 cases Sergio C. Sacca´, MD, Germano Patrone, MD, Angelo Macrı´, MD, Maurizio Rolando, MD ABSTRACT Purpose: To compare the learning curve in a series of 200 cataract surgeries performed using small incision nucleus capture with that of phacoemulsification as reported in the literature. Setting: Department of Ophthalmology, University of Genoa, Genoa, Italy. Methods: Two hundred eyes of 163 consecutive patients with cataract had small incision nucleus capture, a relatively new cataract surgery technique that allows small incisions and in-the-bag intraocular lens implantation. Patients were divided into 4 groups of 50 each according to when they had surgery between August 1996 and October 1997. The incidence of intraoperative complications (capsule break with or without vitreous loss, capsulorhexis tears, Descemet’s detachment, transient iris damage) and postoperative complications (raised intraocular pressure, corneal epithelial edema, Descemet’s folds, and permanent iris damage) were evaluated at the different time points. Also recorded was final visual acuity. These results were compared with those obtained with phacoemulsification. Results: The study comprised 92 women and 71 men with an age range of 41 to 93 years. Overall final results showed that the learning curve of nucleus capture is comparable to that of phacoemulsification. Conclusion: Nucleus capture cataract extraction resulted in a low incidence of complications and good visual recovery that was comparable to that obtained with phacoemulsification. J Cataract Refract Surg 1999; 25:969 –974 © 1999 ASCRS and ESCRS
I
n the 1980s, phacoemulsification gained in popularity as a surgical procedure for cataract extraction. To perform proficient phacoemulsification, a long learning curve is needed that is often accompanied by Accepted for publication February 19, 1999. From the Department of Ophthalmology, University of Genoa, Genoa, Italy. None of the authors has a proprietary interest in any material or method mentioned. Reprint requests to Sergio Claudio Sacca´, MD, Clinica Oculistica, Ospedale S. Martino–Pad. 9, 16132 Genoa, Italy. © 1999 ASCRS and ESCRS Published by Elsevier Science Inc.
a high incidence of serious complications, such as posterior capsule breaks, vitreous loss, and dislocation of the nucleus or nuclear fragments into the vitreous.1– 4 The risk of such complications can reduce the quality of final vision, which may deter experienced extracapsular surgeons from switching to phacoemulsification. This is more likely when public health departments do not stress competition among surgeons and in institutions burdened by chronic financial shortfalls. To avoid the high cost of phacoemulsification and reduce the outcome differences between extracapsular 0886-3350/99/$–see front matter PII S0886-3350(99)00086-3
NUCLEUS CAPTURE
cataract extraction (ECCE) and small incision surgery, McIntyre,5 Kansas and Sax,6 Blumenthal,7 and Riccardo Giannetti, MD, developed alternatives to phacoemulsification that also allow small incisions, in-the-bag intraocular lens (IOL) implantation, and quick functional recovery. This study compared the learning curve associated with small incision nucleus capture cataract surgery with that of phacoemulsification as reported in the literature.1–3,8 –10
Patients and Methods Two hundred eyes of 163 consecutive patients with cataract (92 women, 71 men; age range 41 to 93 years) referred to the Department of Ophthalmology, the University of Genoa, Italy, were included in the study. Fourteen eyes presented with open-angle glaucoma, 12 had a peripheral iridotomy, and 8 had posterior synechias. All patients had a complete ophthalmologic examination before and 24 hours postoperatively that included a slitlamp examination without and with pupil dilation, tonometry, and ophthalmoscopy. If needed, a peripheral retinal examination and gonioscopy were performed. Written informed consent was obtained from all patients enrolled in the study. Surgical technique comprised peribulbar anesthesia induced with lidocaine hydrochloride 2%, bupivacaine hydrochloride 0.75% with 1:200 000 epinephrine, and 150 IU of hyaluronidase.11 All surgeries were performed by the same surgeon (S.C.S.), who was experienced in ECCE. A rectilinear 5.2 mm half-thickness scleral (2.0 mm from the limbus) or corneal incision, performed with a 30 degree disposable knife on the astigmatism axis, was made. A 2.0 to 3.0 mm corneal or sclerocorneal tunnel was created using a 3.2 mm precalibrated knife.12 The anterior chamber was reached by lowering the knife edge until it was parallel to the iris plane. To maintain the anterior chamber, it was filled with sodium chondroitin 4.0%–sodium hyaluronate 3.0% (Viscoat威), a high-molecular-weight viscoelastic material. A 6.0 mm continuous curvilinear capsulorhexis (CCC) was created.13,14 If the CCC could not be completed, a can-opener-type capsulotomy was used and surgery proceeded. 970
Hydrodissection of the capsular bag from the lens cortex was done using a 27 gauge anterior chamber cannula and balanced salt solution (BSS威).15 Hydrodelineation of the nucleus was performed by sculpting a rectilinear sulcus from the 12 to the 6 o’clock positions into the anterior cortex down to the nucleus and then injecting BSS to split the nucleus and epinucleus.16 A typical golden ring shape should be observed under the operating microscope. The nucleus was moved into the anterior chamber by injecting a viscoelastic material between the nucleus and the epinucleus. A 90 degree angled hook may be needed to safely perform this maneuver. Nucleus capture was performed after the tunnel was enlarged to 5.2 mm using a bimanual maneuver in which a spoon was introduced under the nucleus and a bent spatula was used over the nucleus. Next, the nucleus was extracted through the tunnel (Figure 1). The anterior chamber then was rinsed to remove epinuclear fragments through the tunnel using a flat 14 gauge anterior chamber cannula. The cortex was aspirated using a McIntyre cannula, and the capsular bag was cleaned with a scraper. A 5.5 mm diameter IOL was implanted in all eyes except 5 cases that received a sulcus-placed 7.0 mm diameter IOL, 7 that had an unstable CCC, and 19 that had high myopia precluding the need for an IOL. The viscoelastic material was aspirated from the anterior chamber. One 10-0 nylon suture was usually placed in eyes with a clear corneal tunnel.17 At the completion of surgery, a subconjunctival injection of gentamicin and dexamethasone was given. The day after surgery, topical tobramycin and dexamethasone eyedrops were prescribed 5 times daily for 4 weeks. The pupil was dilated twice a day for 7 days by tropicamide 1% eyedrops. Ophthalmologic examination (i.e., slitlamp examination without and with pupil dilation, tonometry, and ophthalmoscopy) was performed after 1 week and 1 and 3 months. Based on the date of surgery, the patients were divided into 4 groups of 50 eyes each: Group 1 had surgery from August to November 1996; Group 2, from December 1996 to March 1997; Group 3, from April to June 1997; and Group 4, from July to October 1997. The results obtained using the nucleus capture technique during the 4 time periods were compared with the learning curve of phacoemulsification reported in the
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Figure 1. (Sacca´) Nucleus capture performed by the bimanual maneuver using a spoon and a bent spatula. A: The nucleus is moved into the anterior chamber after being separated from the epinucleus. B: A spoon is introduced through the tunnel and placed under the nucleus. In a second maneuver using the other hand, the surgeon introduces a bent spatula through the tunnel laterally with respect to the nucleus. When the spatula is completely over the nucleus, the spatula is shifted toward the center over the nucleus and aligned with the spoon. It is important that the spoon and the spatula are well aligned to avoid breaking the nucleus during extraction. C: The nucleus is extracted through the tunnel in a continuous maneuver. D: The nucleus is completely removed from the anterior chamber. (Courtesy of R. Giannetti, MD)
literature. The learning curve associated with nucleus capture was evaluated according to the frequency of intraoperative and postoperative complications during the time periods as well as the final visual acuity. Data distribution was studied. To compare intraoperative and postoperative complications during the time periods, the Friedman and Dunn multiple comparison tests were used. The chi-square test was used to compare the final visual acuity among the 4 patient groups. Graphpad 2.0 software was used for statistical evaluation.
Results The learning curve associated with nucleus capture was comparable to the reported learning curve of phacoemulsification (Table 1). Intraoperative complications were significantly different among the 4 groups (Friedman statistic ⫽ 9.571; P ⫽ .012; Dunn test not signif-
icant) (Table 2). Postoperative complications were also significantly different among the 4 groups (Friedman statistic ⫽ 11.77; P ⬍ .0001); the Dunn test showed a significant difference between Groups 1 and 3 (P ⬍ .01) (Table 3). The chi-square value was 1.56, showing no significant difference in final Snellen visual acuity among the 4 groups (Table 4). Intraoperative Complications Table 2 shows the intraoperative complications associated with nucleus capture. In Group 1, 3 posterior capsule breaks occurred. In the first 2 cases, the pupil had not been adequately dilated because of posterior synechias and because vitreous loss occurred when the nucleus was moved into the anterior chamber. An anterior vitrectomy was performed, and a 7.0 mm diameter optic IOL was placed in the sulcus in front of the capsulorhexis after tunnel enlargement. In the third case,
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Table 1. Results of cataract surgery with and without IOL implantation during the learning curve: comparison of the literature.
Study*
Level of Surgeon
Number of Patients
Surgical Technique
Vitreous Loss† (%)
Visual Acuity >20/40 (%)
Straatsma20
Resident
144
ECCE
6.9
88.0
Browning21
Resident
130
ECCE
9.0
89.0
Senior
400
Phaco
1.5
92.5
Resident
181
Phaco
5.5
93.0
Allinson
Resident
136
Phaco
14.7
73.7
Tabandeh10
Senior
160
Phaco
3.8
88.0
Senior
360
Phaco
4.2
100.0
Senior
51
Phaco
13.7
94.0
1
Seward Cruz
2 8
9
Heaven
3
Thomas Present
Senior
200
NC
‡
1.5
93.5
IOL ⫽ intraocular lens; ECCE ⫽ extracapsular cataract extraction; Phaco ⫽ phacoemulsification; NC ⫽ nucleus capture *Only first author given † Defined as rupture of the posterior capsule or zonule accompanied by rupture of the vitreous face with presentation of the vitreous anterior to the plane of the posterior capsule ‡ Posterior capsule breaks in 3% of overall sample
the capsule break happened during cortical aspiration; an IOL was inserted in the bag without vitrectomy. In Group 2, 1 posterior capsular break occurred because of an inappropriate maneuver (too much viscoelastic material was introduced between epinucleus and capsular bag) when the nucleus was moved into the anterior chamber. Anterior vitrectomy was performed in this eye, and an IOL was implanted in the sulcus. In Groups 3 and 4, 2 capsule breaks without vitreous loss occurred. An IOL was implanted in the sulcus. Nuclear fragmentation into the vitreous chamber did not occur in any group. Six breaks in the CCC occurred in Group 1, 2 in Group 2, and 1 each in Groups 3 and 4. The breaks necessitated using scissors or a cystotome to complete
the anterior capsule removal. In all cases, nucleus capture was performed without further complication. Descemet’s breaks occurred in Groups 1 and 2 in 4 eyes and 1 eye, respectively; they resolved without complications. Permanent iris damage occurred in 1.5% of cases in Groups 1 and 2; temporary damage occurred in 22.0% of cases in all groups, with a higher prevalence in Groups 1 and 2. Postoperative Complications Table 3 shows the postoperative complications associated with nucleus capture. Temporary intraocular pressure (IOP) increases with corneal epithelial edema that required antihypertensive therapy was observed in 23 eyes in Group 1; in 14 of these eyes, 8 with ongoing
Table 2. Intraoperative complications of the nucleus capture technique.
Table 3. Postoperative complications of the nucleus capture Complication Rate, n (%) Complication
Group 1
Group 2
Group 3
Group 4
Capsule break 1 (2)
—
1 (2)
1 (2)
With vitreous loss
2 (4)
1 (2)
—
—
Capsulorhexis tear
6 (12)
2 (4)
1 (2)
1 (2)
Descemet’s detachment
4 (8)
1 (2)
—
—
30 (60)
10 (20)
2 (4)
2 (4)
972
Complication Rate, n (%) Group 1
Group 2
Group 3
Group 4
Transient IOP rise
23 (46)
12 (24)
4 (8)
5 (10)
Corneal epithelial edema
16 (32)
9 (18)
1 (2)
2 (4)
Descemet’s folds
7 (14)
3 (6)
—
2 (4)
Permanent iris damage
2 (4)
1 (2)
—
—
Complication
Without vitreous loss
Iris damage (transient)
technique.
IOP ⫽ intraocular pressure
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Table 4. Final Snellen visual acuities by group. Number (%) Visual Acuity
Group 1
Group 2
Group 3
Group 4
ⱖ20/40
45 (90)
47 (94)
47 (94)
48 (96)
ⱕ20/50
5 (10)
3 (6)
3 (6)
2 (4)
Cystoid macular edema
2 (4)
0
1 (2)
0
Myopic maculopathy
0
1 (2)
2 (4)
1 (2)
Advanced glaucoma
0
1 (2)
0
1 (2)
Idiopathic macular hole
0
1 (2)
0
0
Senile macular degeneration
3 (6)
0
0
0
glaucoma, elevated IOP lasted a mean of 7 days ⫾ 3 (SD). In 12 eyes in Group 2, 6 of which had early signs of glaucoma, the elevated IOP lasted 4 ⫾ 1 days. In Group 3, 4 eyes had transient elevated IOP that lasted 1 day. In 5 eyes in Group 4, transient elevated IOP lasted 4 ⫾ 1 days. In 2 cases, significant corneal stromal edema was present. Final Snellen best corrected visual acuities (BCVAs) are shown in Table 4. Table 5 shows the major causes of postoperative BCVAs worse than 20/50.
Discussion The creation of the sclerocorneal tunnel, CCC, hydrodissection, and hydrodelineation of the nucleus are procedures used in both nucleus capture and phacoemulsification. We found that the same difficulties were present during the learning curves for both techniques. Nevertheless, during phacoemulsification, the capsulorhexis maintains the nucleus inside the capsular bag, while in nucleus capture the capsulorhexis should be wider to allow the nucleus to be moved into the anterior chamber. A wider capsulorhexis is more frequently assoTable 5. Causes of postoperative visual acuity worse than 20/50.
Complication
Visual Acuity (Number of Patients)
Cystoid macular edema
20/80 (2), 20/100 (1)
Myopic maculopathy
20/50 (2), 20/80 (2)
Advanced glaucoma
20/60 (1), 20/80 (1)
Idiopathic macular hole
20/80 (1)
Senile macular degeneration
20/60 (1), 20/80 (2)
ciated with capsule tear. However, a wide capsulorhexis allows easier nuclear luxation into the anterior chamber, which in our experience is the most difficult step of the procedure, especially for the inexperienced surgeon. Hydrodelineation is a fundamental step of nucleus capture in which the nucleus can be separated from the epinucleus.15 The real nucleus is consistently much smaller than the lens, and it is possible to move it from the anterior chamber through a 5.2 mm incision. If the nucleus is hard, luxation into the anterior chamber is easy. In cases in which the nucleus is soft, the procedure is more difficult because the nucleus may break in the anterior chamber when it is captured. This increases the time of nucleus manipulation in the anterior chamber, which increases the risk of iris or capsule damage. Thus, surgeons inexperienced with this technique may choose patients with nuclear sclerotic cataracts for their early cases. Nucleus capture is the most substantial difference between this procedure and phacoemulsification. This is a bimanual step. It seems complicated, but maybe no more than ultrasound nuclear fragmentation because during nuclear extraction, the posterior capsule is protected by the epinucleus and viscoelastic material, which also shields the endothelium. No fluid circulation in the anterior chamber is required at any time during this step, with less potential direct trauma to the endothelial cell, or during viscoelastic removal. Twenty percent of the entire patient population had corneal complications, all transient without a negative effect on final visual recovery. We think that the damage observed during the follow-up was caused by the learning curve and is not a limitation of the nucleus
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capture technique. After the learning period, corneal damage did not occur. Our study did not seek to evaluate the postoperative course of astigmatism. However, it is likely that the results were comparable to those of other small incision techniques.18,19 In summary, our study suggests that in addition to a low incidence of side effects, the nucleus capture cataract extraction technique allows good visual recovery comparable to that obtained with phacoemulsification. Nucleus capture is a completely manual, low-cost technique that can be performed in institutions with low health care budgets.
References 1. Seward HC, Dalton R, Davis A. Phacoemulsification during the learning curve: risk/benefit analysis. Eye 1993; 7:164 –168 2. Cruz OA, Wallace GW, Gay CA, et al. Visual results and complications of phacoemulsification with intraocular lens implantation performed by ophthalmology residents. Ophthalmology 1992; 99:448 – 452 3. Thomas R, Braganza A, Raju R, et al. Phacoemulsification—a senior surgeon’s learning curve. Ophthalmic Surg 1994; 25:504 –509 4. Kelman CD. Phaco-emulsification and aspiration; a new technique of cataract removal; a preliminary report. Am J Ophthalmol 1967; 64:23–35 5. McIntyre DJ. Extracapsular cataract surgery; McIntyre technique. In: Emery JM, McIntyre DJ, eds, Extracapsular Cataract Surgery. St Louis, MO, CV Mosby, 1983; 17–25 6. Kansas PG, Sax R. Small incision cataract extraction implantation surgery using a manual phacofragmentation technique. J Cataract Refract Surg 1988; 14:328 –330 7. Blumenthal M. Manual ECCE, the present state of the art. Klin Monatsbl Augenheilkd 1994; 205:266 –270 8. Allison RW, Metrikin DC, Fante RG. Incidence of vitreous loss among third-year residents performing phacoemulsification. Ophthalmology 1992; 99:726 –730
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9. Heaven CJ, Davison CRN, Boase DL. Learning phacoemulsification; the incidence of complications and the outcome in these cases. Eur J Implant Refract Surg 1994; 6:324 –327 10. Tabandeh H, Smeets B, Teimory M, Seward H. Learning phacoemulsification: the surgeon-in-training. Eye 1994; 8:475– 477 11. Weiss JL, Deichman CB. A comparison of retrobulbar and periocular anesthesia for cataract surgery. Arch Ophthalmol 1989; 107:96 –98 12. Sinskey RM, Stoppel JO. Induced astigmatism in a 6.0 mm no-stitch frown incision. J Cataract Refract Surg 1994; 20:406 – 409 13. Arshinoff S. Mechanics of capsulorhexis. J Cataract Refract Surg 1992; 18:623– 628 14. Gimbel HV, Neuhann T. Development, advantages, and methods of continuous circular capsulorhexis technique. J Cataract Refract Surg 1990; 16:31–37 15. Fine IH. Cortical cleaving hydrodissection. J Cataract Refract Surg 1992; 18:508 –12 16. Koch DD, Liu JF. Multilamellar hydrodissection in phacoemulsification and planned extracapsular surgery. J Cataract Refract Surg 1990; 16:559 –562 17. Gimbel HV, Raanan MG, DeLuca M. Effect of suture material on postoperative astigmatism. J Cataract Refract Surg 1992; 18:42–50 18. Cravy TV. Routine use of a lateral approach to cataract extraction to achieve rapid and sustained stabilization of postoperative astigmatism. J Cataract Refract Surg 1991; 17:415– 423 19. Armeniades CD, Boriek A, Knolle GE Jr. Effect of incision length, location, and shape on local corneoscleral deformation during cataract surgery. J Cataract Refract Surg 1990; 16:83– 87 20. Straatsma BR, Meyer KT, Bastek JV, Lightfoot DO. Posterior chamber intraocular lens implantation by ophthalmology residents; a prospective study of cataract surgery. Ophthalmology 1983; 90:327–335 21. Browning DJ, Cobo LM. Early experience in extracapsular cataract surgery by residents. Ophthalmology 1985; 92:1647–1653
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n the 1980s, phacoemulsification gained in popularity as a surgical procedure for cataract extraction. To perform proficient phacoemulsification, a long learning curve is needed that is often accompanied by Accepted for publication February 19, 1999. From the Department of Ophthalmology, University of Genoa, Genoa, Italy. None of the authors has a proprietary interest in any material or method mentioned. Reprint requests to Sergio Claudio Sacca´, MD, Clinica Oculistica, Ospedale S. Martino–Pad. 9, 16132 Genoa, Italy. © 1999 ASCRS and ESCRS Published by Elsevier Science Inc.
a high incidence of serious complications, such as posterior capsule breaks, vitreous loss, and dislocation of the nucleus or nuclear fragments into the vitreous.1– 4 The risk of such complications can reduce the quality of final vision, which may deter experienced extracapsular surgeons from switching to phacoemulsification. This is more likely when public health departments do not stress competition among surgeons and in institutions burdened by chronic financial shortfalls. To avoid the high cost of phacoemulsification and reduce the outcome differences between extracapsular 0886-3350/99/$–see front matter PII S0886-3350(99)00086-3
NUCLEUS CAPTURE
cataract extraction (ECCE) and small incision surgery, McIntyre,5 Kansas and Sax,6 Blumenthal,7 and Riccardo Giannetti, MD, developed alternatives to phacoemulsification that also allow small incisions, in-the-bag intraocular lens (IOL) implantation, and quick functional recovery. This study compared the learning curve associated with small incision nucleus capture cataract surgery with that of phacoemulsification as reported in the literature.1–3,8 –10
Patients and Methods Two hundred eyes of 163 consecutive patients with cataract (92 women, 71 men; age range 41 to 93 years) referred to the Department of Ophthalmology, the University of Genoa, Italy, were included in the study. Fourteen eyes presented with open-angle glaucoma, 12 had a peripheral iridotomy, and 8 had posterior synechias. All patients had a complete ophthalmologic examination before and 24 hours postoperatively that included a slitlamp examination without and with pupil dilation, tonometry, and ophthalmoscopy. If needed, a peripheral retinal examination and gonioscopy were performed. Written informed consent was obtained from all patients enrolled in the study. Surgical technique comprised peribulbar anesthesia induced with lidocaine hydrochloride 2%, bupivacaine hydrochloride 0.75% with 1:200 000 epinephrine, and 150 IU of hyaluronidase.11 All surgeries were performed by the same surgeon (S.C.S.), who was experienced in ECCE. A rectilinear 5.2 mm half-thickness scleral (2.0 mm from the limbus) or corneal incision, performed with a 30 degree disposable knife on the astigmatism axis, was made. A 2.0 to 3.0 mm corneal or sclerocorneal tunnel was created using a 3.2 mm precalibrated knife.12 The anterior chamber was reached by lowering the knife edge until it was parallel to the iris plane. To maintain the anterior chamber, it was filled with sodium chondroitin 4.0%–sodium hyaluronate 3.0% (Viscoat威), a high-molecular-weight viscoelastic material. A 6.0 mm continuous curvilinear capsulorhexis (CCC) was created.13,14 If the CCC could not be completed, a can-opener-type capsulotomy was used and surgery proceeded. 970
Hydrodissection of the capsular bag from the lens cortex was done using a 27 gauge anterior chamber cannula and balanced salt solution (BSS威).15 Hydrodelineation of the nucleus was performed by sculpting a rectilinear sulcus from the 12 to the 6 o’clock positions into the anterior cortex down to the nucleus and then injecting BSS to split the nucleus and epinucleus.16 A typical golden ring shape should be observed under the operating microscope. The nucleus was moved into the anterior chamber by injecting a viscoelastic material between the nucleus and the epinucleus. A 90 degree angled hook may be needed to safely perform this maneuver. Nucleus capture was performed after the tunnel was enlarged to 5.2 mm using a bimanual maneuver in which a spoon was introduced under the nucleus and a bent spatula was used over the nucleus. Next, the nucleus was extracted through the tunnel (Figure 1). The anterior chamber then was rinsed to remove epinuclear fragments through the tunnel using a flat 14 gauge anterior chamber cannula. The cortex was aspirated using a McIntyre cannula, and the capsular bag was cleaned with a scraper. A 5.5 mm diameter IOL was implanted in all eyes except 5 cases that received a sulcus-placed 7.0 mm diameter IOL, 7 that had an unstable CCC, and 19 that had high myopia precluding the need for an IOL. The viscoelastic material was aspirated from the anterior chamber. One 10-0 nylon suture was usually placed in eyes with a clear corneal tunnel.17 At the completion of surgery, a subconjunctival injection of gentamicin and dexamethasone was given. The day after surgery, topical tobramycin and dexamethasone eyedrops were prescribed 5 times daily for 4 weeks. The pupil was dilated twice a day for 7 days by tropicamide 1% eyedrops. Ophthalmologic examination (i.e., slitlamp examination without and with pupil dilation, tonometry, and ophthalmoscopy) was performed after 1 week and 1 and 3 months. Based on the date of surgery, the patients were divided into 4 groups of 50 eyes each: Group 1 had surgery from August to November 1996; Group 2, from December 1996 to March 1997; Group 3, from April to June 1997; and Group 4, from July to October 1997. The results obtained using the nucleus capture technique during the 4 time periods were compared with the learning curve of phacoemulsification reported in the
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Figure 1. (Sacca´) Nucleus capture performed by the bimanual maneuver using a spoon and a bent spatula. A: The nucleus is moved into the anterior chamber after being separated from the epinucleus. B: A spoon is introduced through the tunnel and placed under the nucleus. In a second maneuver using the other hand, the surgeon introduces a bent spatula through the tunnel laterally with respect to the nucleus. When the spatula is completely over the nucleus, the spatula is shifted toward the center over the nucleus and aligned with the spoon. It is important that the spoon and the spatula are well aligned to avoid breaking the nucleus during extraction. C: The nucleus is extracted through the tunnel in a continuous maneuver. D: The nucleus is completely removed from the anterior chamber. (Courtesy of R. Giannetti, MD)
literature. The learning curve associated with nucleus capture was evaluated according to the frequency of intraoperative and postoperative complications during the time periods as well as the final visual acuity. Data distribution was studied. To compare intraoperative and postoperative complications during the time periods, the Friedman and Dunn multiple comparison tests were used. The chi-square test was used to compare the final visual acuity among the 4 patient groups. Graphpad 2.0 software was used for statistical evaluation.
Results The learning curve associated with nucleus capture was comparable to the reported learning curve of phacoemulsification (Table 1). Intraoperative complications were significantly different among the 4 groups (Friedman statistic ⫽ 9.571; P ⫽ .012; Dunn test not signif-
icant) (Table 2). Postoperative complications were also significantly different among the 4 groups (Friedman statistic ⫽ 11.77; P ⬍ .0001); the Dunn test showed a significant difference between Groups 1 and 3 (P ⬍ .01) (Table 3). The chi-square value was 1.56, showing no significant difference in final Snellen visual acuity among the 4 groups (Table 4). Intraoperative Complications Table 2 shows the intraoperative complications associated with nucleus capture. In Group 1, 3 posterior capsule breaks occurred. In the first 2 cases, the pupil had not been adequately dilated because of posterior synechias and because vitreous loss occurred when the nucleus was moved into the anterior chamber. An anterior vitrectomy was performed, and a 7.0 mm diameter optic IOL was placed in the sulcus in front of the capsulorhexis after tunnel enlargement. In the third case,
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Table 1. Results of cataract surgery with and without IOL implantation during the learning curve: comparison of the literature.
Study*
Level of Surgeon
Number of Patients
Surgical Technique
Vitreous Loss† (%)
Visual Acuity >20/40 (%)
Straatsma20
Resident
144
ECCE
6.9
88.0
Browning21
Resident
130
ECCE
9.0
89.0
Senior
400
Phaco
1.5
92.5
Resident
181
Phaco
5.5
93.0
Allinson
Resident
136
Phaco
14.7
73.7
Tabandeh10
Senior
160
Phaco
3.8
88.0
Senior
360
Phaco
4.2
100.0
Senior
51
Phaco
13.7
94.0
1
Seward Cruz
2 8
9
Heaven
3
Thomas Present
Senior
200
NC
‡
1.5
93.5
IOL ⫽ intraocular lens; ECCE ⫽ extracapsular cataract extraction; Phaco ⫽ phacoemulsification; NC ⫽ nucleus capture *Only first author given † Defined as rupture of the posterior capsule or zonule accompanied by rupture of the vitreous face with presentation of the vitreous anterior to the plane of the posterior capsule ‡ Posterior capsule breaks in 3% of overall sample
the capsule break happened during cortical aspiration; an IOL was inserted in the bag without vitrectomy. In Group 2, 1 posterior capsular break occurred because of an inappropriate maneuver (too much viscoelastic material was introduced between epinucleus and capsular bag) when the nucleus was moved into the anterior chamber. Anterior vitrectomy was performed in this eye, and an IOL was implanted in the sulcus. In Groups 3 and 4, 2 capsule breaks without vitreous loss occurred. An IOL was implanted in the sulcus. Nuclear fragmentation into the vitreous chamber did not occur in any group. Six breaks in the CCC occurred in Group 1, 2 in Group 2, and 1 each in Groups 3 and 4. The breaks necessitated using scissors or a cystotome to complete
the anterior capsule removal. In all cases, nucleus capture was performed without further complication. Descemet’s breaks occurred in Groups 1 and 2 in 4 eyes and 1 eye, respectively; they resolved without complications. Permanent iris damage occurred in 1.5% of cases in Groups 1 and 2; temporary damage occurred in 22.0% of cases in all groups, with a higher prevalence in Groups 1 and 2. Postoperative Complications Table 3 shows the postoperative complications associated with nucleus capture. Temporary intraocular pressure (IOP) increases with corneal epithelial edema that required antihypertensive therapy was observed in 23 eyes in Group 1; in 14 of these eyes, 8 with ongoing
Table 2. Intraoperative complications of the nucleus capture technique.
Table 3. Postoperative complications of the nucleus capture Complication Rate, n (%) Complication
Group 1
Group 2
Group 3
Group 4
Capsule break 1 (2)
—
1 (2)
1 (2)
With vitreous loss
2 (4)
1 (2)
—
—
Capsulorhexis tear
6 (12)
2 (4)
1 (2)
1 (2)
Descemet’s detachment
4 (8)
1 (2)
—
—
30 (60)
10 (20)
2 (4)
2 (4)
972
Complication Rate, n (%) Group 1
Group 2
Group 3
Group 4
Transient IOP rise
23 (46)
12 (24)
4 (8)
5 (10)
Corneal epithelial edema
16 (32)
9 (18)
1 (2)
2 (4)
Descemet’s folds
7 (14)
3 (6)
—
2 (4)
Permanent iris damage
2 (4)
1 (2)
—
—
Complication
Without vitreous loss
Iris damage (transient)
technique.
IOP ⫽ intraocular pressure
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Table 4. Final Snellen visual acuities by group. Number (%) Visual Acuity
Group 1
Group 2
Group 3
Group 4
ⱖ20/40
45 (90)
47 (94)
47 (94)
48 (96)
ⱕ20/50
5 (10)
3 (6)
3 (6)
2 (4)
Cystoid macular edema
2 (4)
0
1 (2)
0
Myopic maculopathy
0
1 (2)
2 (4)
1 (2)
Advanced glaucoma
0
1 (2)
0
1 (2)
Idiopathic macular hole
0
1 (2)
0
0
Senile macular degeneration
3 (6)
0
0
0
glaucoma, elevated IOP lasted a mean of 7 days ⫾ 3 (SD). In 12 eyes in Group 2, 6 of which had early signs of glaucoma, the elevated IOP lasted 4 ⫾ 1 days. In Group 3, 4 eyes had transient elevated IOP that lasted 1 day. In 5 eyes in Group 4, transient elevated IOP lasted 4 ⫾ 1 days. In 2 cases, significant corneal stromal edema was present. Final Snellen best corrected visual acuities (BCVAs) are shown in Table 4. Table 5 shows the major causes of postoperative BCVAs worse than 20/50.
Discussion The creation of the sclerocorneal tunnel, CCC, hydrodissection, and hydrodelineation of the nucleus are procedures used in both nucleus capture and phacoemulsification. We found that the same difficulties were present during the learning curves for both techniques. Nevertheless, during phacoemulsification, the capsulorhexis maintains the nucleus inside the capsular bag, while in nucleus capture the capsulorhexis should be wider to allow the nucleus to be moved into the anterior chamber. A wider capsulorhexis is more frequently assoTable 5. Causes of postoperative visual acuity worse than 20/50.
Complication
Visual Acuity (Number of Patients)
Cystoid macular edema
20/80 (2), 20/100 (1)
Myopic maculopathy
20/50 (2), 20/80 (2)
Advanced glaucoma
20/60 (1), 20/80 (1)
Idiopathic macular hole
20/80 (1)
Senile macular degeneration
20/60 (1), 20/80 (2)
ciated with capsule tear. However, a wide capsulorhexis allows easier nuclear luxation into the anterior chamber, which in our experience is the most difficult step of the procedure, especially for the inexperienced surgeon. Hydrodelineation is a fundamental step of nucleus capture in which the nucleus can be separated from the epinucleus.15 The real nucleus is consistently much smaller than the lens, and it is possible to move it from the anterior chamber through a 5.2 mm incision. If the nucleus is hard, luxation into the anterior chamber is easy. In cases in which the nucleus is soft, the procedure is more difficult because the nucleus may break in the anterior chamber when it is captured. This increases the time of nucleus manipulation in the anterior chamber, which increases the risk of iris or capsule damage. Thus, surgeons inexperienced with this technique may choose patients with nuclear sclerotic cataracts for their early cases. Nucleus capture is the most substantial difference between this procedure and phacoemulsification. This is a bimanual step. It seems complicated, but maybe no more than ultrasound nuclear fragmentation because during nuclear extraction, the posterior capsule is protected by the epinucleus and viscoelastic material, which also shields the endothelium. No fluid circulation in the anterior chamber is required at any time during this step, with less potential direct trauma to the endothelial cell, or during viscoelastic removal. Twenty percent of the entire patient population had corneal complications, all transient without a negative effect on final visual recovery. We think that the damage observed during the follow-up was caused by the learning curve and is not a limitation of the nucleus
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capture technique. After the learning period, corneal damage did not occur. Our study did not seek to evaluate the postoperative course of astigmatism. However, it is likely that the results were comparable to those of other small incision techniques.18,19 In summary, our study suggests that in addition to a low incidence of side effects, the nucleus capture cataract extraction technique allows good visual recovery comparable to that obtained with phacoemulsification. Nucleus capture is a completely manual, low-cost technique that can be performed in institutions with low health care budgets.
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