Incidence of retinal detachment following Nd:YAG capsulotomy after cataract surgery John A. Van Westenbrugge, M.D., F.R.C.S.(C), Howard V. Gimbel, M.D. , F.R.C.S.(C), Julianne Souchek, Ph.D. , Debbie Chow, C.O.M.T. ABSTRACT In a retrospective study, we reviewed 218 consecutive Nd:YAG laser posterior capsulotomies performed at the Gimbel Eye Centre between June 1987 and November 1989 for the incidence of retinal detachment (RD) following treatment. Matched controls were found for 198 YAG cases. The median post-surgical follow-up for the YAG cases was 49.5 months; for the controls, 50.0 months. The median time between cataract extraction and YAG laser posterior capsulotomy was 24.8 months. The median follow-up after YAG was 24.2 months. Two of the 198 YAG cases (1.0%) and one of the 198 controls (0.5%) had RD. In the YAG cases, RD occurred 54.8 and 36.5 months after cataract surgery; in the control cases, 51.8 months after cataract surgery. Retinal detachment occurred at 15.0 and 17.0 months after YAG capsulotomy. These rates were lower than those reported in the literature. We feel that the surgical techniques of continuous circular capsulorhexis and in-the-bag IOL placement reduce the risk ofRD following Nd:YAG posterior capsulotomy. Key Words: continuous circular capsulorhexis, Nd:YAG secondary capsulotomy, retinal detachment
Retinal detachment (RD) is still a common sightthreatening complication associated with cataract extraction. 1 ,2 The established popularity of extracapsular cataract surgery and the increasing popularity of in-situ phacoemulsification is based in part on the belief that preserving the posterior lens capsule results in fewer postoperative complications. However, a resultant problem occasionally associated with extracapsular (ECCE) or phacoemulsification cataract extraction is secondary opacification of the posterior capsule or development of a secondary cataract, most commonly treated using the Nd:YAG laser. Previous studies show that a secondary knife/ needle capsulotomy or a YAG laser posterior capsulotomy may increase the risk of RD.1-4 We
report on a retrospective case-control study designed to determine if YAG laser capsulotomy following capsulorhexis and in-situ phacoemulsification predisposes to development of RD. SUBJECTS AND METHODS A retrospective study was designed to document the incidence ofRD following Nd:YAG laser posterior capsulotomy after phacoemulsification cataract surgery and to compare it with the incidence of RD in a control group from the same population of patients who did not receive YAG laser capsulotomy. A consecutive series of 218 cases with Nd:YAG capsulotomy, who had cataract surgery between
From the Gimbel Eye Centre, Calgary, Canada (Westenbrugge, Gimbel, Chow) and the Center for Clinical Research, Department of Ophthalmology, University of Illinois at Chicago (Souchek). Analysis of the data was performed by the Center for Clinical Research. Reprint requests to Howard V. Gimbel, M.D. , F.R.G.S. (C), Gimbel Eye Centre, Suite 450, 4935-40thAvenue, N. W., Calgary, Alberta , Canada T3A 2Nl. 352
J CATARACT REFRACT SURG-VOL 18, JULY 1992
January 1984 and March 1988, were studied. March 1988 was chosen as a cut-off date so all patients would have the potential for at least three years postsurgical follow-up. Surgical techniques, including continuous tear capsulorhexis, phacoemulsification, and in-the-bag fixation of the IOL, were consistent throughout the period. Control patients to match YAG cases by sex and date of surgery were sought. Controls for 198 of the YAG cases (93%) were found. Among the 198 case-control pairs, 94% were matched by day of surgery, 2 % were matched within one week, 2 % were matched within two weeks, and 2 % were matched within four weeks of date of surgery. The following data were extracted from charts: date of cataract surgery, date of Nd:YAG posterior capsulotomy, whether the patient had experienced RD, and date of first occurrence of RD or the last date when it was known that the patient did not have RD. Follow-up was calculated from surgery and/or YAG laser to the date oflast patient contact or the date of the RD occurrence. Patient age and sex and axial length were recorded. If the required data could not be obtained from the patient chart, the data were obtained via telephone contact with the referring physician or from the patient. As an endpoint, this study used symptomatic, clinically significant RD that would be apparent to the patient or referring eye-care provider. However, determination of that endpoint did not depend on patient or primary eye-care-provider initiative. Patients were actively followed by the investigator. RESULTS One hundred ninety-eight YAG cases and 198 controls were available for analysis. Cataract surgeries occurred between January 1984 and March 1988. Neodymium: YAG procedures occurred between June 1987 and November 1989. The median follow-up after surgery was 49.5 months for YAG cases and 50.0 months for controls. Ninety-one percent of all participants had at least 36 months of
follow-up after cataract extraction and 56% had at least 48 months of follow-up. The median followup after YAG was 24.8 months. There were no significant differences between YAG cases and controls in sex distribution of the sample or in age, axial length, or length of followup after cataract surgery. Characteristics of the sample are presented in Table 1. Two of the YAG cases (l.0%) and one control (0.5%) experienced RD during the study period. Table 2 provides descriptive data on the patients experiencing RD. Only 7% of the YAG cases (excluding RD cases) and 4% of the controls (excluding the RD) had axial lengths of 25 mm or more. Axial length in the two YAG cases that had RD were 25.33 mm and 26.75 mm; axial length in the control experiencing RD was 23.47 mm. The number ofRDs was too small to assess any potential association with axial length. One of the two RD patients who had YAG capsulotomy had RD in the fellow eye 18 years earlier, which was repaired. None of the three patients with RD had vitreous loss or capsular rents at surgery, which would predispose to subsequent RD. Retinal detachment in the two patients having YAG capsulotomy occurred 15.0 months and 17.0 months after the capsulotomy and 54.8 and 36.5 months after cataract surgery, respectively. Retinal detachment occurred 5l.8 months after cataract surgery in the control patient. Rates ofRD were very low among YAG cases and controls; the rates were not significantly different between YAG cases and controls. No RDs occurred within the first three years of follow-up after cataract surgery in YAG cases or controls. DISCUSSION The RD incidence in this series of patients was lower than expected based on the literature. We expected 3% ofYAG patients (6 of 198) and 1 % of controls (2 of 198) to experience RD. The expected rates were based on the results of several studies of postoperative RD following ECCE. Coonan et al. 1
Table 1. Characteristics of cases and controls.
Group Capsulotomy n = 198 Control n = 198
Sex (% Male)
Age (years)*
Axial Length (mm)*
Follow-up After Cataract Surgery (months)*
34
75.9 ± 10.3
23.3 ± 1.4
51.0 ± 11.9
32
75.9 ± 10.8
23.3 ± 1.0
51.7 ± 12.5
* Mean ± S.D. J CATARACT REFRACT SURG-VOL 18, JULY 1992
353
Table 2. Data on patients who had RD. YAG-RD Group (n = 2) Case 1
Case 2
Control Group (n = 1)
65 Female
67 Female
63 Female
11/20/84 25.33 39.8 54.8 15.0
1/05/87 26.75
5/16/85 23.47
Age, years Sex Date of surgery Axial length,mm Time between surgery and YAG, months Time between surgery and RD, months Time elapsed between YAG and RD, months
reported the results of a prospective study of 842 consecutive ECCEs on 650 patients performed between October 1973 and October 1983. The proportion of patients with RD in the entire group was 1.4%. The incidence ofRD in the eyes having YAG capsulotomy was 3.2% (three of95 eyes). This was three times higher than the 1 % incidence of RD when the posterior capsule remained intact (six of 615 eyes). Yearly rates were not given, but at least two-thirds of the cases occurred within the first year after surgery. Smith et al. 2 reviewed 3,065 consecutive cases of ECCE with posterior chamber lens implantation. The percentages of cases with RD was 1.4 % overall and 1.7% in the group of eyes followed for at least one year. Age, gender, and axial length were correlated with RD. Younger patients, males, and eyes with axial length greater than 25 mm were more likely to experience RD . Sixty-four percent of cases ofRD occurred within one year of cataract surgery. A retrospective study of 1,000 cases that had Nd:YAG laser posterior capsulotomy after cataract surgery was performed by Dardenne and coauthors.3 Patients were followed up to four years after the capsulotomy. The authors found that 1.6% of cases had RD and that RD was correlated with axial length greater than 25 mm and younger patients. They did not show RD to be correlated with laser parameters or method of cataract surgery (extracapsular or phacoemulsification). Most RDs occurred within nine months after laser treatment. Rickmann-Barger and coauthors 4 reviewed the records of 397 patients who had Nd: YAG posterior capsulotomy from July 1983 to August 1988. Thirteen (3.6%) of the 366 eyes followed for three months or more developed RD. Eleven of the 13 (84.6%) occurred in the first year after YAG capsulotomy. The incidence ofRD was higher among males. Patients who had one or more of the risk 354
19.5 36.5 17.0
51.8
factors (axial length greater than or equal to 25 mm, lattice degeneration, or previous RD in the fellow eye) were more likely to experience RD. Of the four studies reviewed, only the one by Coonan et al. 1 presented the proportion of cases with RD among patients who did and did not have secondary posterior capsulotomy. These studies did not report incidence rates of RD by length of follow-up. Loss to follow-up was also not clearly documented. In our study, RD rates in patients requiring YAG capsulotomy and in a group of controls matched to the cases by sex and date of surgery were compared. The two groups did not differ significantly in age, axial length, or length of follow-up, variables known to be correlated with RD after cataract surgery. Retinal detachment was ascertained by active follow-up through investigator-initiated contact with patients. We feel that the surgical technique of continuous tear capsulotomy, which provides a more intact capsule and ensures in-the-bag placement of the IOL, leads to a reduction of postoperative complications. The placement of an IOL entirely in the capsular bag is particularly important if a secondary posterior capsulotomy is required. In a previous study 6 we showed that early postoperative pressure rises following YAG capsulotomy seen in sulcus-fixated cases were not seen with bag-fixated cases. We believe that this pressure rise may be due to particulate matter, which a bag-fixated implant may shield agains,t. Bag fixation appears to preserve the separation of anterior and posterior segments of the eye and may protect against RD. The bag-fixated implant physically occupies the space left by the removed crystalline lens, providing a barrier to the vitreous and maintaining the anterior support for the vitreous cavity. With earlier techniques of capsu)otomy, when a posterior
J CATARACT REFRACT SURG-VOL 18, JULY 1992
capsulotomy was performed the plane of separation between the anterior chamber and the vitreous cavity was not maintained due to communication of vitreous around the margins of the lens implant through the capsulotomy. Gradual leaking and loss of the more soluble components of the vitreous may contribute to increased breakdown of the vitreous and traction on the retina. Small continuous tear capsulotomy ensures firm enclosure of the lens implant within the capsule. Even after posterior capsulotomy, it is possible that there is no escape of more soluble vitreous components because of the firm adherence and overlap of the anterior capsule margin on the lens implant. These factors may lead to a reduced incidence of RD, which could theoretically equal the incidence in eyes with intact posterior capsules. We feel that our low incidence ofRD is partly due to the surgical technique of continuous curvilinear capsulorhexis and in-the-bag IOL implantation.
REFERENCES 1. Coonan P, Fung WE, Webster RG Jr, et al. The incidence of retinal detachment following extracapsular cataract extraction: a ten-year study. Ophthalmology 1985; 92:1096-1101 2. Smith PW, Stark WJ, Maumenee AE, et al. Retinal detachment after extracapsular cataract extraction with posterior chamber intraocular lens. Ophthalmology 1987; 94:495-504 3. Dardenne M-U, Gerten G-J, Kokkas K, Kermani O. Retrospective study of retinal detachment following neodymium:YAG laser posterior capsulotomy. J Cataract Refract Surg 1989; 15:676-680 4. Rickman-Barger L, Florine CW, Larson RS, Lindstrom RL. Retinal detachment after neodymium:YAG laser posterior capsulotomy. Am J Ophthalmol1989; 107: 531-536 5. Kalbfleisch JD, Prentice RL. The Statistical Analysis of Failure Time Data. New York, John Wiley, 1980 6. Gimbel HV, Van Westenbrugge JA, Sanders DR, Raanan MG. Effect of sulcus vs capsular fixation on YAG-induced pressure rises following posterior capsulotomy. Arch Ophthalmol 1990; 108:11261129
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355
Retinal detachment (RD) is still a common sightthreatening complication associated with cataract extraction. 1 ,2 The established popularity of extracapsular cataract surgery and the increasing popularity of in-situ phacoemulsification is based in part on the belief that preserving the posterior lens capsule results in fewer postoperative complications. However, a resultant problem occasionally associated with extracapsular (ECCE) or phacoemulsification cataract extraction is secondary opacification of the posterior capsule or development of a secondary cataract, most commonly treated using the Nd:YAG laser. Previous studies show that a secondary knife/ needle capsulotomy or a YAG laser posterior capsulotomy may increase the risk of RD.1-4 We
report on a retrospective case-control study designed to determine if YAG laser capsulotomy following capsulorhexis and in-situ phacoemulsification predisposes to development of RD. SUBJECTS AND METHODS A retrospective study was designed to document the incidence ofRD following Nd:YAG laser posterior capsulotomy after phacoemulsification cataract surgery and to compare it with the incidence of RD in a control group from the same population of patients who did not receive YAG laser capsulotomy. A consecutive series of 218 cases with Nd:YAG capsulotomy, who had cataract surgery between
From the Gimbel Eye Centre, Calgary, Canada (Westenbrugge, Gimbel, Chow) and the Center for Clinical Research, Department of Ophthalmology, University of Illinois at Chicago (Souchek). Analysis of the data was performed by the Center for Clinical Research. Reprint requests to Howard V. Gimbel, M.D. , F.R.G.S. (C), Gimbel Eye Centre, Suite 450, 4935-40thAvenue, N. W., Calgary, Alberta , Canada T3A 2Nl. 352
J CATARACT REFRACT SURG-VOL 18, JULY 1992
January 1984 and March 1988, were studied. March 1988 was chosen as a cut-off date so all patients would have the potential for at least three years postsurgical follow-up. Surgical techniques, including continuous tear capsulorhexis, phacoemulsification, and in-the-bag fixation of the IOL, were consistent throughout the period. Control patients to match YAG cases by sex and date of surgery were sought. Controls for 198 of the YAG cases (93%) were found. Among the 198 case-control pairs, 94% were matched by day of surgery, 2 % were matched within one week, 2 % were matched within two weeks, and 2 % were matched within four weeks of date of surgery. The following data were extracted from charts: date of cataract surgery, date of Nd:YAG posterior capsulotomy, whether the patient had experienced RD, and date of first occurrence of RD or the last date when it was known that the patient did not have RD. Follow-up was calculated from surgery and/or YAG laser to the date oflast patient contact or the date of the RD occurrence. Patient age and sex and axial length were recorded. If the required data could not be obtained from the patient chart, the data were obtained via telephone contact with the referring physician or from the patient. As an endpoint, this study used symptomatic, clinically significant RD that would be apparent to the patient or referring eye-care provider. However, determination of that endpoint did not depend on patient or primary eye-care-provider initiative. Patients were actively followed by the investigator. RESULTS One hundred ninety-eight YAG cases and 198 controls were available for analysis. Cataract surgeries occurred between January 1984 and March 1988. Neodymium: YAG procedures occurred between June 1987 and November 1989. The median follow-up after surgery was 49.5 months for YAG cases and 50.0 months for controls. Ninety-one percent of all participants had at least 36 months of
follow-up after cataract extraction and 56% had at least 48 months of follow-up. The median followup after YAG was 24.8 months. There were no significant differences between YAG cases and controls in sex distribution of the sample or in age, axial length, or length of followup after cataract surgery. Characteristics of the sample are presented in Table 1. Two of the YAG cases (l.0%) and one control (0.5%) experienced RD during the study period. Table 2 provides descriptive data on the patients experiencing RD. Only 7% of the YAG cases (excluding RD cases) and 4% of the controls (excluding the RD) had axial lengths of 25 mm or more. Axial length in the two YAG cases that had RD were 25.33 mm and 26.75 mm; axial length in the control experiencing RD was 23.47 mm. The number ofRDs was too small to assess any potential association with axial length. One of the two RD patients who had YAG capsulotomy had RD in the fellow eye 18 years earlier, which was repaired. None of the three patients with RD had vitreous loss or capsular rents at surgery, which would predispose to subsequent RD. Retinal detachment in the two patients having YAG capsulotomy occurred 15.0 months and 17.0 months after the capsulotomy and 54.8 and 36.5 months after cataract surgery, respectively. Retinal detachment occurred 5l.8 months after cataract surgery in the control patient. Rates ofRD were very low among YAG cases and controls; the rates were not significantly different between YAG cases and controls. No RDs occurred within the first three years of follow-up after cataract surgery in YAG cases or controls. DISCUSSION The RD incidence in this series of patients was lower than expected based on the literature. We expected 3% ofYAG patients (6 of 198) and 1 % of controls (2 of 198) to experience RD. The expected rates were based on the results of several studies of postoperative RD following ECCE. Coonan et al. 1
Table 1. Characteristics of cases and controls.
Group Capsulotomy n = 198 Control n = 198
Sex (% Male)
Age (years)*
Axial Length (mm)*
Follow-up After Cataract Surgery (months)*
34
75.9 ± 10.3
23.3 ± 1.4
51.0 ± 11.9
32
75.9 ± 10.8
23.3 ± 1.0
51.7 ± 12.5
* Mean ± S.D. J CATARACT REFRACT SURG-VOL 18, JULY 1992
353
Table 2. Data on patients who had RD. YAG-RD Group (n = 2) Case 1
Case 2
Control Group (n = 1)
65 Female
67 Female
63 Female
11/20/84 25.33 39.8 54.8 15.0
1/05/87 26.75
5/16/85 23.47
Age, years Sex Date of surgery Axial length,mm Time between surgery and YAG, months Time between surgery and RD, months Time elapsed between YAG and RD, months
reported the results of a prospective study of 842 consecutive ECCEs on 650 patients performed between October 1973 and October 1983. The proportion of patients with RD in the entire group was 1.4%. The incidence ofRD in the eyes having YAG capsulotomy was 3.2% (three of95 eyes). This was three times higher than the 1 % incidence of RD when the posterior capsule remained intact (six of 615 eyes). Yearly rates were not given, but at least two-thirds of the cases occurred within the first year after surgery. Smith et al. 2 reviewed 3,065 consecutive cases of ECCE with posterior chamber lens implantation. The percentages of cases with RD was 1.4 % overall and 1.7% in the group of eyes followed for at least one year. Age, gender, and axial length were correlated with RD. Younger patients, males, and eyes with axial length greater than 25 mm were more likely to experience RD . Sixty-four percent of cases ofRD occurred within one year of cataract surgery. A retrospective study of 1,000 cases that had Nd:YAG laser posterior capsulotomy after cataract surgery was performed by Dardenne and coauthors.3 Patients were followed up to four years after the capsulotomy. The authors found that 1.6% of cases had RD and that RD was correlated with axial length greater than 25 mm and younger patients. They did not show RD to be correlated with laser parameters or method of cataract surgery (extracapsular or phacoemulsification). Most RDs occurred within nine months after laser treatment. Rickmann-Barger and coauthors 4 reviewed the records of 397 patients who had Nd: YAG posterior capsulotomy from July 1983 to August 1988. Thirteen (3.6%) of the 366 eyes followed for three months or more developed RD. Eleven of the 13 (84.6%) occurred in the first year after YAG capsulotomy. The incidence ofRD was higher among males. Patients who had one or more of the risk 354
19.5 36.5 17.0
51.8
factors (axial length greater than or equal to 25 mm, lattice degeneration, or previous RD in the fellow eye) were more likely to experience RD. Of the four studies reviewed, only the one by Coonan et al. 1 presented the proportion of cases with RD among patients who did and did not have secondary posterior capsulotomy. These studies did not report incidence rates of RD by length of follow-up. Loss to follow-up was also not clearly documented. In our study, RD rates in patients requiring YAG capsulotomy and in a group of controls matched to the cases by sex and date of surgery were compared. The two groups did not differ significantly in age, axial length, or length of follow-up, variables known to be correlated with RD after cataract surgery. Retinal detachment was ascertained by active follow-up through investigator-initiated contact with patients. We feel that the surgical technique of continuous tear capsulotomy, which provides a more intact capsule and ensures in-the-bag placement of the IOL, leads to a reduction of postoperative complications. The placement of an IOL entirely in the capsular bag is particularly important if a secondary posterior capsulotomy is required. In a previous study 6 we showed that early postoperative pressure rises following YAG capsulotomy seen in sulcus-fixated cases were not seen with bag-fixated cases. We believe that this pressure rise may be due to particulate matter, which a bag-fixated implant may shield agains,t. Bag fixation appears to preserve the separation of anterior and posterior segments of the eye and may protect against RD. The bag-fixated implant physically occupies the space left by the removed crystalline lens, providing a barrier to the vitreous and maintaining the anterior support for the vitreous cavity. With earlier techniques of capsu)otomy, when a posterior
J CATARACT REFRACT SURG-VOL 18, JULY 1992
capsulotomy was performed the plane of separation between the anterior chamber and the vitreous cavity was not maintained due to communication of vitreous around the margins of the lens implant through the capsulotomy. Gradual leaking and loss of the more soluble components of the vitreous may contribute to increased breakdown of the vitreous and traction on the retina. Small continuous tear capsulotomy ensures firm enclosure of the lens implant within the capsule. Even after posterior capsulotomy, it is possible that there is no escape of more soluble vitreous components because of the firm adherence and overlap of the anterior capsule margin on the lens implant. These factors may lead to a reduced incidence of RD, which could theoretically equal the incidence in eyes with intact posterior capsules. We feel that our low incidence ofRD is partly due to the surgical technique of continuous curvilinear capsulorhexis and in-the-bag IOL implantation.
REFERENCES 1. Coonan P, Fung WE, Webster RG Jr, et al. The incidence of retinal detachment following extracapsular cataract extraction: a ten-year study. Ophthalmology 1985; 92:1096-1101 2. Smith PW, Stark WJ, Maumenee AE, et al. Retinal detachment after extracapsular cataract extraction with posterior chamber intraocular lens. Ophthalmology 1987; 94:495-504 3. Dardenne M-U, Gerten G-J, Kokkas K, Kermani O. Retrospective study of retinal detachment following neodymium:YAG laser posterior capsulotomy. J Cataract Refract Surg 1989; 15:676-680 4. Rickman-Barger L, Florine CW, Larson RS, Lindstrom RL. Retinal detachment after neodymium:YAG laser posterior capsulotomy. Am J Ophthalmol1989; 107: 531-536 5. Kalbfleisch JD, Prentice RL. The Statistical Analysis of Failure Time Data. New York, John Wiley, 1980 6. Gimbel HV, Van Westenbrugge JA, Sanders DR, Raanan MG. Effect of sulcus vs capsular fixation on YAG-induced pressure rises following posterior capsulotomy. Arch Ophthalmol 1990; 108:11261129
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355
