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Anterior capsule contraction and intraocular lens dislocation after implant surgery in eyes with retinitis pigmentosa1
Anterior Capsule Contraction and Intraocular Lens Dislocation after Implant Surgery in Eyes with Retinitis Pigmentosa Ken Hay&, MD,’ Hideyuki Fumihiko Hayashi, MD’
Hayashi, MD,’
K&hi
Matsuo,
MD, ’ Fuminori
Nakao, MD, ’
Objective: The purpose of the study was to investigate the extent of anterior capsule contraction, intraocular lens (IOL) decentration, and tilt after implant surgery in eyes with retinitis pigmentosa (RP). Design: A case-control study. Participants: Forty-seven eyes from 47 patients with typical RP and 47 control eyes from 47 age-matched healthy patients were studied. lnterventionr Phacoemulsification surgery with polymethylmethacrylate IOL implantation with continuous curvilinear capsulorrhexis was performed. Main Outcome Measures: The area of the anterior capsule opening obtained with capsulorrhexis and the amount of the decentration and tilt of the IOL were measured using a Scheimpflug photography system at 1 week and 1, 3, 6, 9, and 12 months after surgery. Results: The mean area in the RP group was found to be significantly smaller than that in the control group at 1 month after surgery and later (P < 0.0001). The percent area reduction in the RP group at 6 months was 45.2 ? 25.8% and 4.6 f 13.5% in the control group. Both the decentration length and tilt angle were also greater in the RP group than in the control group. Fourteen (29.8%) of the 47 RP eyes had undergone a neodymium:YAG (Nd:YAG) laser anterior capsulotomy at 12 months after surgery, whereas none of the control eyes had undergone an Nd:YAG. Conclusions: Anterior capsule contraction in the RP eyes was more extensive than in the control eyes, leading to a high Nd:YAG laser anterior capsulotomy rate. Both lens decentration and tilt also were greater in the RP eyes than in the control eyes. Ophthalmology 1998; 105:1239-1243
Previous studies have shown that the area of the anterior capsule opening after continuous curvilinear capsulorrhexis decreases over time,” most likely because of postoperative capsule shrinkage. The anterior capsule contraction is considered to be more extensive in some types of pathologic eyes, such as those with pseudoexfoliation syndrome, than in healthy eyes.‘-” We recently showed diabetes mellitus to be a predisposing factor for extensive anterior capsule contraction.7 Nishi and Nishi’ also reported an eye with retinitis pigmentosa (RP), which had
an extreme degree of severe capsule contraction and eventually resulted
in the complete
closure
of the capsule
opening. Such a severe constriction of the anterior capsule may decrease the patient’s visual acuity.4” Originally received:
October December
Revision
accepted:
’ Hayashi
Eye Hospital,
’ Department slty, Fukuoka, Presented Academy
of Ophthalmology, Japan.
Patients
Japan. School
of Medwne,
in part as a poster at the Annual of Ophthalmology, San Francisco,
The authors have no proprietary m this article.
interest
reduction in the anterior capsule opening as well as the amounts of IOL decentration and tilt in eyes of patients with RP compared to those in the control eyes of patients without RP. We also examined the rate that a neodymium:YAG (Nd:YAG) laser anterior capsulotomy had to be performed to achieve an enlargement of the opening.
10, 1997. 12, 1997.
Fukuoka,
Postoperative capsule shrinkage also is considered to be a cause of dislocation of the implanted intraocular lens (IOL). Similar to anterior capsule constriction, both the IOL decentration and tilt therefore may possibly occur more extensively in pathologic eyes than in healthy eyes. An excessive degree of IOL decentration and tilt unavoidably leads to refractive changes” or an increased degree of glare disability.“’ The purpose of this study was to investigate the area
Fukuoka
Univer-
Meeting of the American California, October 1997.
in any ofthe
Reprint requests to Ken Hayashl, MD, Hayashi Hakataekimae, Hakata-Ku, Fukuoka 8 12, Japan.
materials Eye Hospital,
described 4-7-13
and Methods
We prospectively studied 47 eyes of 47 consecutive patients with RP and 47 control eyes from age-matched healthy patients who had phacoemulsification and implant surgery between April 1, 1996, and September 30, 1996. All eyes had typical RP, and no cases of sector or central type atypical RP were included. In addition in this study, no consideration was given regardinggenetictype of RP. In the eyesoperatedon bilaterally, only the first eye operatedon was includedin the analysis.For
1239
Ophthalmology
Volume 105, Number 7, July 1998
Table 1. Patient Characteristics
No. of eyes Age Sex (M/F) Left/right RI’ = retimtls *’ No statistical
RI’ Group
Control Group
47 60.7 +- 11.6 19128 23124
47 61.6 k 11 5 24123 21126
P 0.7365* 0.3001* 0.6793*
plgmentosa. slgmficance.
pressed in millimeters, whereas the angle of the tilt was shown in degrees. The patient’s best-corrected visual acuity also was measured by decimal charts at all intervals. All measurements using the EAS-1000 system were performed by three ophthalmic technicians, who were not aware of the aims of the study. Statistical analyses were performed to compare the differences in the biometric data between the RP and control groups using the Mann-Whitney U test. Categoric variables also were compared using the chi-square test. Probability values less than 0.05 were considered statistically significant.
Results each eye from the patients with RP, a control eye from a patient without RP was selected within the 5-year age group. The preoperative exclusion criteria were (1) cataracts due to etiologies other than age-related changes or RP or both; (2) a history of ocular surgery or inflammation; (3) ocular pathologies such as pseudoexfoliation syndrome, glaucoma, and diabetes mellitus; and (4) a pupillary diameter after a full mydriasis of less than 6.0 mm. All eyes had one-piece polymethylmethacrylate IOLs implanted with a 6.0-mm round optics (MZ60BD; Alcon Surgical, Inc, Fort Worth, TX). Informed consent was obtained from all patients included in this study. Before surgery, fundus examination, visual field perimetry using a Goldman perimeter, and electroretinogram recordings were performed for all eyes to confirm the diagnosis of typical RP. All surgeries were performed by the same surgeon (KH). The surgical procedures used in this study have been described previously.” Briefly, an arch-shaped Frown incision with a chord length of 6.5 mm was made for implantation of the PMMA IOL. After completing a scleral tunnel incision, the continuous capsulorrhexis measuring approximately 5.5 mm in diameter was performed using a bent needle. After a hydrodissection, phacoemulsification of the nucleus and cortex aspiration was performed. The lens capsule was inflated with sodium hyaluronate, and then the IOL was inserted into the capsular bag. At the end of surgery, the surgeon always confirmed whether the IOLs were placed accurately in the capsular bag using a push-and-pull hook. When the anterior capsule opening was so constricted as to disturb the patient’s vision, a capsulotomy of the anterior capsule using an Nd:YAG laser was performed.4,“,‘2 The basic criterion for performing an anterior capsulotomy was a reduced opening area of less than 10 mm*, because when the opening area became less than 10 mm’, the anterior capsule edge usually covered a portion of the pupillary area, which led to decreased visual acuity or blurred vision. An approximately l-mm length of the anterior capsule edge with subcapsular fibrotic tissue was cut in four cross-directions by the Nd:YAG laser burst of approximately 2 mJ. After undergoing the anterior capsulotomy, the anterior capsule opening area also was excluded from our analysis. Periodic examinations to measure the anterior capsule opening area and the decentration length and tilt angle of the IOL were performed at I week, as well as at 1, 3, 6, 9, and 12 months after surgery using the Anterior Eye Segment Analysis System (EAS-1000; NIDEK, Inc, Gamagori, Japan). The methods for calculating the anterior capsule opening area and the decentration length and tilt angle with the EAS-1000 system have been described in previous studies.2.‘3 The anterior capsule opening area was expressed in square millimeters, and the percent area reduction at I, 3, 6, 9, and 12 months after surgery also was calculated as a percentage of the decreased area from the area at I week. The length of decentration also was ex-
1240
Fundus examinations of all eyes in the RP group showed tindings that were consistent with those of typical RP, including bone spicule-like pigmentation, attenuated vessels, and optic disc atrophy. In addition, all eyes in the RP group showed peripheral visual field loss and either markedly reduced or nonrecordable electroretinogram amplitudes that were compatible with RP. The patient characteristics are listed in Table I. No statistical significances were found between the RP and control groups regarding age, gender, or the ratio of the left and right eyes. In the first slit-lamp biomicroscopic examination after full pupil dilation at 1 week after surgery, all IOLs were confirmed to be placed in the capsular bag. Table 2 lists the changes in the mean area of the anterior capsule opening and the percent reduction in the RP and control groups. The data of the area also are displayed in Figure 1. The Mann-Whitney U test showed no statistical significance in the mean capsulorrhexis area at I week after surgery. However, at I month and later, the mean area in the RP group was significantly smaller than that in the control group (P < 0.0001). In addition, the percent reduction in the RP group also was significantly greater than that in the control group (P < 0.0001). In I8 (38.3%) of 47 RP eyes, the opening area decreased to less than 10 mm*, whereas no eyes in the control group showed such an extensive reduction. The visual acuity loss of these 18 eyes from the best postoperative visual acuity on the decimal charts was as follows: 9 eyes, 2 lines or more; 5 eyes, 1 line; and 4 eyes, no decrease. Table 3 lists the changes in the mean decentration length
Table 2. Changes in the Mean Area of the Anterior Capsule Opening (mm’) and the Percent Reduction in the Retinitis Pigmentosa (RP) and Control Groups RI’ Group Area ( mmL) 1 wk I mo 3 mm 6 mos 9 mos 12 mos Yo reduct10n 1 mo 3 1110s 6 mos 9 mos 12 mos * No statistd ‘/_Statistdly
26.6 20.7 15.2 15.0 14.5 15.1
2 5 ? i -+ t-
4.3 6.0 8.0 8.2 8.2 7.7
22.5 44.5 45.2 46.9 43.4
k 5 2 + t
17.3 25 3 25.9 25.9 26.3
syydicance significant.
Control
Group
27.2 25.9 25.4 26.0 26.2 26.2
-t + + + +k
44 4 3 5.4 5.5 5.6 5.6
4.5 6.7 4.6 3.8 3.6
5 k t 2 +
6.8 13.2 13.5 13.8 13.6
P 0.5732”
t t
Hayashi et al * Anterior Capsule Contraction and IOL Dislocation after Surgery , .
(mm21 P ‘2
* not slgniflcant t Stabstlcally slgnlflcant
(mm, I 0.7 -L * not signlftcant t stailstically significant
40
5
T
T
t
1
-r I
0.1 -0
RP Control 1 week
RP Control 1 month
RP Control 3 months
Postoperative
RP Control 6 months
RP Control 9 months
RP Control 12 months
o-
interval
RP Control 1 week
RP Control 1 month
RP Consol 3 months
RP Control 6 months
Postoperative
Figure 1. Comparison of the mean area for the antenor capsule openmg between the retinitis pigmentosa (RI’) and the control groups. No statistical difference was observed in the capsulorrhexis area at 1 week between the two groups. However, at 1 month and later, the mean area in the RP group was significantly smaller than that m the control group (I’ < 0.0001).
and tilt angle of the two groups. The data of the decentration and tilt also were depicted in Figures 2 and 3, respectively. The mean decentration lengths in the RP group were greater than those in the control group. The differences at 1, 6, 9, and 12 months after surgery showed statistical significance, whereas those differences at 1 week and 3 months were only marginal. The mean tilt angles in the RP group also were larger than those in the control group. The differences at 1, 3, 6, and 12 months were statistically significant. Retroillumination photographs, which show the postoperative changes in the anterior capsule, are displayed in Figures 4A and 4B. In Figure 4A, in which the eye of a patient with RP is shown, the anterior capsule opening after continuous capsulorrhexis was constricted and also showed extensive fibrosis. In Figure 4B, in which the eye of a patient without RP was
RP Control 9 months
RP Controt 12 months
interval
Figure 2. Compauson of the mean amount of decentration between the retinitis pigmentosa (RI’) and the control groups. The decentratton lengths in the RP group were greater than those m the control group. The difference at 1, 6, 9, and 12 months after aurgcry was stattatlcally slgmticant.
shown, only a slight degree of contraction and fibrosis of the anterior capsule occurred over the polymethylmethacrylate optic. A total of 14 eyes (29.8%) of the 47 RP eyes underwent an anterior capsulotomy within 12 months after surgery (Figs 5A, 5B). The opening areas of these eyes were all less than 10 mm*. The average interval between the IOL implant surgery and capsulotomy was 5.92 t 4.03 months. In addition, 12 of these 14 eyes also showed decreased visual acuity from the best postoperative visual acuity. After undergoing the capsulotomy, the patient’s visual acuity virtually returned to the best postoperative visual acuity.
Discussion The contraction of the anterior capsule opening after continuous capsulorrhexis is considered to occur more exten-
Table 3. Changes and Tilt
Angle
in the Mean Decentration of the Retinitis Pigmentosa and Control Groups
Length (RP)
Control
RI’ Groua Decentratton 1 wk 1 trio 3 mos 6 mos 9 mos 12 mos Tilt (“) 1 wk 1 mo 3 mos 6 mos 9 mos 12 mos * No statistical t Statistically
Grow
P
(mm) 0.313 0.346 0.340 0.346 0.421 0.402 3.23 3.29 3.40 3.09 3.29 3.54 significance. sigmficant.
+ 2 t fz + +
0.220 0.203 0.175 0.257 0.258 0.231
+ 2.20 + 2.09 + 2.09 + 1.67 -c2.79 -c2.78
0.262 0.256 0.277 0.281 0.279 0.256
f ? k 2 k +
0.154 0.149 0.140 0.151 0.167 0.137
0.3991* 0.0386t 0.0889* 0.0447t 0.0038% 0.0017t
2.43 2.14 2.31 2.41 2.49 2.46
+ + 2 5 -t t
1.38 1.29 1.39 1.47 1.28 1.23
0.0787" 0.0064t 0.0088t 0.0404t 0.2263* 0.0484t
WC 1 we Postoperative
tntetval
Figure 3.
Comparison of the mean angle of the tilt between the two groups. The tilt angles in the retinitis plgmentosa group were larger than those in the control group. The dlffercnces at 1, 3,6, and 12 months were statistically significant.
1241
Ophthalmology
Volume 105, Number
7, July I998 Non-RP control
Figure 4. Retrodll photogr aphs showmg operate te ch anges m rior capsule. A, an eye of a tlent with retimtls pigment There was prominent fibros the edge of the anterior opening with secondar traction. B, an eye of a control patlent; only degree of constrlcuon brosls in the antenor cap was observed Figure 5. Sht-lamp photc graphs showmg an eye that ha undergone an antenor caps& tomy usmg a neodymmm:YA( (Nd:YAG) laser A, before cap sulotomy; marked fibrosis an constrlctlon of the anterlc capsule openmg. B, after caps” lotomy; Nd:YAG laser bursts have cut the antenor capsule edge m four dIrectIons for approximately 1 mm
sively in certain types of pathologic eyes.4-” Nishi and Nish? reported an eye with RP showing the closure of the capsulorrhexis opening. We also experienced some eyes with RP that showed an extensive contraction of the opening and needed a capsulotomy of the anterior capsule using an Nd:YAG laser. Our study clarified that the anterior capsule contraction with RP eyes was more extensive than that with healthy eyes. The percent area reduction in the RP group at 6 months was 45.2%, whereas it was only 4.6% in the control group. This was the greatest area reduction among the pathologic eyes that we have investigated, including those with diabetes, pseudoexfoliation, glaucoma, uveitis, and atopic cataract. In 38.3% of the RP eyes, the anterior capsule opening area decreased to less than 10 mm2. The opening area of 10 mm2 was almost the same as the pupillary area, and these eyes had clinically significant blurring of vision, Postoperative capsule shrinkage may cause a dislocation of the implanted IOL. Our study also showed that both the decentration and tilt were greater in the RP eyes
1242
I
\
4B
than in the healthy eyes. These results suggest that postoperative capsule shrinkage may be abnormally stronger in RP eyes than in healthy eyes. An excessive degree of IOL dislocation may cause refractive changes” or glare,‘O although this was difficult to quantitate. A possible twofold explanation regarding the extensive anterior capsule contraction and IOL dislocation in eyes with RP is as follows. The first explanation is that some blood-derived cytokines, which can stimulate the lens epithelial cell activity,‘4m’h may be more abundant in the aqueous humor of the RP eyes compared to healthy eyes. Previous studies showed that the blood aqueous barrierI as well as the blood retinal barrier’“,‘” were disrupted in the eyes of the patient with RP. Therefore, the release of blood cytokines into the aqueous humor may be increased in eyes with RP.20 Lens epithelial cells activated by the cytokines may cause the extensive contraction and fibrosis of the anterior capsule in patients with RP. The second explanation is the possible existence of zonular weakness in eyes with RP. Namiki et a12’ assumed that there was a dehiscence of the zonules with RP, but they were unable
Hay&
et al * Anterior Capsule Contraction and IOL Dislocation after Surgery
to prove this assumption. The postoperative capsule constriction is therefore considered to be stronger with RP compared to healthy eyes. In contrast, a morphologic study reported that the lens epithelial cells and the lens capsule in eyes with RP did not appear to be abnormal.22 When the anterior capsule opening area decreased to less than 10 mm2, the patient’s visual acuity usually deteriorated. The contraction of the anterior capsule opening in eyes with RP therefore certainly is clinically significant. In such cases, we performed an Nd:YAG laser capsulotomy. Although an anterior capsulotomy has been shown to cause a slight myopic shift,23 no serious complications have yet been reported to date. However, radial tears in the anterior capsule occasionally extended to the equator after the capsulotomy. A long-term follow-up of the IOL fixation status after an anterior capsulotomy is needed. In conclusion, the contraction of the anterior capsule occurred more extensively in RP eyes than in healthy eyes and also caused a high incidence of deterioration in the patient’s vision. The IOL dislocation also was greater in patients with RP than in healthy subjects. When we perform IOL implant surgery for patients with RP, it might be advantageous to make a larger capsulorrhexis. Surgeons should be aware that patients with RP may have an extensive postoperative capsulorrhexis constriction develop and need the Nd:YAG laser anterior capsulotomy.
References 1. Joo CK, Shin JA, Kim JH. Capsular opening contraction after continuous curvilinear capsulorrhexis. J Cataract Refract Surg 1996;22:585-90. 2. Hayashi K, Hayashi H, Nakao F, Hayashi F. Reduction in the area of the anterior capsule opening after polymethylmethacrylate, silicone, and soft acrylic intraocular lens implantation. Am J Ophthalmol 1997; 123:441-7. 3. Gonvers M, Sickenberg M, van Melle G. Change in capsulorrhexis size after implantation of three types of intraocular lenses. J Cataract Refract Surg 1997;23:231-8. 4. Hansen SO, Crandall AS, Olson RJ. Progressive constriction of the anterior capsular opening following intact capsulorrhexis. J Cataract Refract Surg 1993; 19:77-82. 5. Davison JA. Capsule contraction syndrome. J Cataract Refract Surg 1993; 19582-9. 6. Namiki M, Yamamoto N, Tagami Y, et al. Risk factors for anterior capsule shrinkage in intraocular lens implantation. Jpn J Clin Ophthalmol 1991;45:1828-31. 7. Hayashi H, Hayashi K, Nakao F, Hayashi F. Area reduction in the anterior capsule opening in eyes if diabetes mellitus patients. J Cataract Refract Surg 1998, in press.
8. Nishi 0, Nishi K. Intraocular lens encapsulation by shrinkage of the capsulorrhexis opening. J Cataract Refract Surg 1993; 19:544-5. 9. Nishigaki S, Inaba I, Minami H, et al. The postoperative change of depth of anterior chamber, refraction, and anterior capsulorrhexis size after intraocular lens implantation. J Jpn Ophthalmic Sot 1995; 100:156-8. 10. Miyata A, Nakata M, Yaguchi S, et al. 34 cases of severe anterior capsular shrinkage after continuous circular capsulorrhexis. IOL 1991;5:231-5. 11. Hayashi K, Hayashi H, Nakao F, Hayashi F. The correlationship between incision size and cornea1 shape changes in sutureless cataract surgery. Ophthalmology 1995; 102: 550-6. 12. Hurvitz LM. YAG anterior capsulectomy and lysis of posterior synechiae after cataract surgery. Ophthalmic Surg 1992;23:103-7. 13. Hayashi K, Harada M, Hayashi H, et al. Decentration and tilt of polymethyl methacrylate, silicone, and acrylic soft intraocular lenses. Ophthalmology 1997; 104:793-8. 14. Oliver0 DK, Fucht LT. Type IV collagen, laminin, and fibronectin promote the adhesion and migration of rabbit lens epithelial cells in vitro. Invest Ophthalmol Vis Sci 1993;34:2825-34. 15. Ibaraki N, Lin LR, Reddy VN. Effects of growth factors on proliferation and differentiation in human lens epithelial cells in early subculture. Invest Ophthalmol Vis Sci 1995;36:2304-12. 16. Nishi 0, Nishi K, Fujisawa T, et al. Effects of the cytokines on the proliferation of and collagen synthesis by human cataract lens epithelial cells. Br J Ophthalmol 1996; 80:638. 17. Kato M, Kobayashi R, Ueno M, Watanabe I. Aqueous flare values in eyes of retinitis pigmentosa. Jpn J Clin Ophthalmol 1997;51:299-303. 18. Fishman GA, Cunha-Vaz J, Salzano T. Vitreous fluorophotometry in patients with retinitis pigmentosa. Arch Ophthalmol 1981;99:1202-7. 19. Mallick KS, Zeimer RC, Fishman GA, et al. Transport of fluorescein in the ocular posterior segment in retinitis pigmentosa. Arch Ophthalmol 1984; 102:691-6. 20. Pande MV, Spalton DJ, Marshall J. In vivo human lens epithelial cell proliferation on the anterior surface of PMMA intraocular lenses. Br J Ophthalmol 1996; 80:46974. 21. Namiki M, Tagami Y, Morino I, et al. Findings from slit lamp and histological examination of the anterior capsule in patients with severe anterior capsule shrinkage and opacities after implantation of intraocular lens. J Jpn Ophthalmol Sot 1993;97:716-20. 22. Eshaghian J, Rafferty S, Goossens W. Ultrastructure of human cataract in retinitis pigmentosa. Arch Ophthalmol 1980;98:2227-30. 23. Inoue T, Inaba I, Nishigaki S, Ichioka H. Changes in IOL fixation after relaxing incision of contracted anterior lens capsule. IOL & RS 1995;9:101-4.
1243
Hayashi, MD,’
K&hi
Matsuo,
MD, ’ Fuminori
Nakao, MD, ’
Objective: The purpose of the study was to investigate the extent of anterior capsule contraction, intraocular lens (IOL) decentration, and tilt after implant surgery in eyes with retinitis pigmentosa (RP). Design: A case-control study. Participants: Forty-seven eyes from 47 patients with typical RP and 47 control eyes from 47 age-matched healthy patients were studied. lnterventionr Phacoemulsification surgery with polymethylmethacrylate IOL implantation with continuous curvilinear capsulorrhexis was performed. Main Outcome Measures: The area of the anterior capsule opening obtained with capsulorrhexis and the amount of the decentration and tilt of the IOL were measured using a Scheimpflug photography system at 1 week and 1, 3, 6, 9, and 12 months after surgery. Results: The mean area in the RP group was found to be significantly smaller than that in the control group at 1 month after surgery and later (P < 0.0001). The percent area reduction in the RP group at 6 months was 45.2 ? 25.8% and 4.6 f 13.5% in the control group. Both the decentration length and tilt angle were also greater in the RP group than in the control group. Fourteen (29.8%) of the 47 RP eyes had undergone a neodymium:YAG (Nd:YAG) laser anterior capsulotomy at 12 months after surgery, whereas none of the control eyes had undergone an Nd:YAG. Conclusions: Anterior capsule contraction in the RP eyes was more extensive than in the control eyes, leading to a high Nd:YAG laser anterior capsulotomy rate. Both lens decentration and tilt also were greater in the RP eyes than in the control eyes. Ophthalmology 1998; 105:1239-1243
Previous studies have shown that the area of the anterior capsule opening after continuous curvilinear capsulorrhexis decreases over time,” most likely because of postoperative capsule shrinkage. The anterior capsule contraction is considered to be more extensive in some types of pathologic eyes, such as those with pseudoexfoliation syndrome, than in healthy eyes.‘-” We recently showed diabetes mellitus to be a predisposing factor for extensive anterior capsule contraction.7 Nishi and Nishi’ also reported an eye with retinitis pigmentosa (RP), which had
an extreme degree of severe capsule contraction and eventually resulted
in the complete
closure
of the capsule
opening. Such a severe constriction of the anterior capsule may decrease the patient’s visual acuity.4” Originally received:
October December
Revision
accepted:
’ Hayashi
Eye Hospital,
’ Department slty, Fukuoka, Presented Academy
of Ophthalmology, Japan.
Patients
Japan. School
of Medwne,
in part as a poster at the Annual of Ophthalmology, San Francisco,
The authors have no proprietary m this article.
interest
reduction in the anterior capsule opening as well as the amounts of IOL decentration and tilt in eyes of patients with RP compared to those in the control eyes of patients without RP. We also examined the rate that a neodymium:YAG (Nd:YAG) laser anterior capsulotomy had to be performed to achieve an enlargement of the opening.
10, 1997. 12, 1997.
Fukuoka,
Postoperative capsule shrinkage also is considered to be a cause of dislocation of the implanted intraocular lens (IOL). Similar to anterior capsule constriction, both the IOL decentration and tilt therefore may possibly occur more extensively in pathologic eyes than in healthy eyes. An excessive degree of IOL decentration and tilt unavoidably leads to refractive changes” or an increased degree of glare disability.“’ The purpose of this study was to investigate the area
Fukuoka
Univer-
Meeting of the American California, October 1997.
in any ofthe
Reprint requests to Ken Hayashl, MD, Hayashi Hakataekimae, Hakata-Ku, Fukuoka 8 12, Japan.
materials Eye Hospital,
described 4-7-13
and Methods
We prospectively studied 47 eyes of 47 consecutive patients with RP and 47 control eyes from age-matched healthy patients who had phacoemulsification and implant surgery between April 1, 1996, and September 30, 1996. All eyes had typical RP, and no cases of sector or central type atypical RP were included. In addition in this study, no consideration was given regardinggenetictype of RP. In the eyesoperatedon bilaterally, only the first eye operatedon was includedin the analysis.For
1239
Ophthalmology
Volume 105, Number 7, July 1998
Table 1. Patient Characteristics
No. of eyes Age Sex (M/F) Left/right RI’ = retimtls *’ No statistical
RI’ Group
Control Group
47 60.7 +- 11.6 19128 23124
47 61.6 k 11 5 24123 21126
P 0.7365* 0.3001* 0.6793*
plgmentosa. slgmficance.
pressed in millimeters, whereas the angle of the tilt was shown in degrees. The patient’s best-corrected visual acuity also was measured by decimal charts at all intervals. All measurements using the EAS-1000 system were performed by three ophthalmic technicians, who were not aware of the aims of the study. Statistical analyses were performed to compare the differences in the biometric data between the RP and control groups using the Mann-Whitney U test. Categoric variables also were compared using the chi-square test. Probability values less than 0.05 were considered statistically significant.
Results each eye from the patients with RP, a control eye from a patient without RP was selected within the 5-year age group. The preoperative exclusion criteria were (1) cataracts due to etiologies other than age-related changes or RP or both; (2) a history of ocular surgery or inflammation; (3) ocular pathologies such as pseudoexfoliation syndrome, glaucoma, and diabetes mellitus; and (4) a pupillary diameter after a full mydriasis of less than 6.0 mm. All eyes had one-piece polymethylmethacrylate IOLs implanted with a 6.0-mm round optics (MZ60BD; Alcon Surgical, Inc, Fort Worth, TX). Informed consent was obtained from all patients included in this study. Before surgery, fundus examination, visual field perimetry using a Goldman perimeter, and electroretinogram recordings were performed for all eyes to confirm the diagnosis of typical RP. All surgeries were performed by the same surgeon (KH). The surgical procedures used in this study have been described previously.” Briefly, an arch-shaped Frown incision with a chord length of 6.5 mm was made for implantation of the PMMA IOL. After completing a scleral tunnel incision, the continuous capsulorrhexis measuring approximately 5.5 mm in diameter was performed using a bent needle. After a hydrodissection, phacoemulsification of the nucleus and cortex aspiration was performed. The lens capsule was inflated with sodium hyaluronate, and then the IOL was inserted into the capsular bag. At the end of surgery, the surgeon always confirmed whether the IOLs were placed accurately in the capsular bag using a push-and-pull hook. When the anterior capsule opening was so constricted as to disturb the patient’s vision, a capsulotomy of the anterior capsule using an Nd:YAG laser was performed.4,“,‘2 The basic criterion for performing an anterior capsulotomy was a reduced opening area of less than 10 mm*, because when the opening area became less than 10 mm’, the anterior capsule edge usually covered a portion of the pupillary area, which led to decreased visual acuity or blurred vision. An approximately l-mm length of the anterior capsule edge with subcapsular fibrotic tissue was cut in four cross-directions by the Nd:YAG laser burst of approximately 2 mJ. After undergoing the anterior capsulotomy, the anterior capsule opening area also was excluded from our analysis. Periodic examinations to measure the anterior capsule opening area and the decentration length and tilt angle of the IOL were performed at I week, as well as at 1, 3, 6, 9, and 12 months after surgery using the Anterior Eye Segment Analysis System (EAS-1000; NIDEK, Inc, Gamagori, Japan). The methods for calculating the anterior capsule opening area and the decentration length and tilt angle with the EAS-1000 system have been described in previous studies.2.‘3 The anterior capsule opening area was expressed in square millimeters, and the percent area reduction at I, 3, 6, 9, and 12 months after surgery also was calculated as a percentage of the decreased area from the area at I week. The length of decentration also was ex-
1240
Fundus examinations of all eyes in the RP group showed tindings that were consistent with those of typical RP, including bone spicule-like pigmentation, attenuated vessels, and optic disc atrophy. In addition, all eyes in the RP group showed peripheral visual field loss and either markedly reduced or nonrecordable electroretinogram amplitudes that were compatible with RP. The patient characteristics are listed in Table I. No statistical significances were found between the RP and control groups regarding age, gender, or the ratio of the left and right eyes. In the first slit-lamp biomicroscopic examination after full pupil dilation at 1 week after surgery, all IOLs were confirmed to be placed in the capsular bag. Table 2 lists the changes in the mean area of the anterior capsule opening and the percent reduction in the RP and control groups. The data of the area also are displayed in Figure 1. The Mann-Whitney U test showed no statistical significance in the mean capsulorrhexis area at I week after surgery. However, at I month and later, the mean area in the RP group was significantly smaller than that in the control group (P < 0.0001). In addition, the percent reduction in the RP group also was significantly greater than that in the control group (P < 0.0001). In I8 (38.3%) of 47 RP eyes, the opening area decreased to less than 10 mm*, whereas no eyes in the control group showed such an extensive reduction. The visual acuity loss of these 18 eyes from the best postoperative visual acuity on the decimal charts was as follows: 9 eyes, 2 lines or more; 5 eyes, 1 line; and 4 eyes, no decrease. Table 3 lists the changes in the mean decentration length
Table 2. Changes in the Mean Area of the Anterior Capsule Opening (mm’) and the Percent Reduction in the Retinitis Pigmentosa (RP) and Control Groups RI’ Group Area ( mmL) 1 wk I mo 3 mm 6 mos 9 mos 12 mos Yo reduct10n 1 mo 3 1110s 6 mos 9 mos 12 mos * No statistd ‘/_Statistdly
26.6 20.7 15.2 15.0 14.5 15.1
2 5 ? i -+ t-
4.3 6.0 8.0 8.2 8.2 7.7
22.5 44.5 45.2 46.9 43.4
k 5 2 + t
17.3 25 3 25.9 25.9 26.3
syydicance significant.
Control
Group
27.2 25.9 25.4 26.0 26.2 26.2
-t + + + +k
44 4 3 5.4 5.5 5.6 5.6
4.5 6.7 4.6 3.8 3.6
5 k t 2 +
6.8 13.2 13.5 13.8 13.6
P 0.5732”
t t
Hayashi et al * Anterior Capsule Contraction and IOL Dislocation after Surgery , .
(mm21 P ‘2
* not slgniflcant t Stabstlcally slgnlflcant
(mm, I 0.7 -L * not signlftcant t stailstically significant
40
5
T
T
t
1
-r I
0.1 -0
RP Control 1 week
RP Control 1 month
RP Control 3 months
Postoperative
RP Control 6 months
RP Control 9 months
RP Control 12 months
o-
interval
RP Control 1 week
RP Control 1 month
RP Consol 3 months
RP Control 6 months
Postoperative
Figure 1. Comparison of the mean area for the antenor capsule openmg between the retinitis pigmentosa (RI’) and the control groups. No statistical difference was observed in the capsulorrhexis area at 1 week between the two groups. However, at 1 month and later, the mean area in the RP group was significantly smaller than that m the control group (I’ < 0.0001).
and tilt angle of the two groups. The data of the decentration and tilt also were depicted in Figures 2 and 3, respectively. The mean decentration lengths in the RP group were greater than those in the control group. The differences at 1, 6, 9, and 12 months after surgery showed statistical significance, whereas those differences at 1 week and 3 months were only marginal. The mean tilt angles in the RP group also were larger than those in the control group. The differences at 1, 3, 6, and 12 months were statistically significant. Retroillumination photographs, which show the postoperative changes in the anterior capsule, are displayed in Figures 4A and 4B. In Figure 4A, in which the eye of a patient with RP is shown, the anterior capsule opening after continuous capsulorrhexis was constricted and also showed extensive fibrosis. In Figure 4B, in which the eye of a patient without RP was
RP Control 9 months
RP Controt 12 months
interval
Figure 2. Compauson of the mean amount of decentration between the retinitis pigmentosa (RI’) and the control groups. The decentratton lengths in the RP group were greater than those m the control group. The difference at 1, 6, 9, and 12 months after aurgcry was stattatlcally slgmticant.
shown, only a slight degree of contraction and fibrosis of the anterior capsule occurred over the polymethylmethacrylate optic. A total of 14 eyes (29.8%) of the 47 RP eyes underwent an anterior capsulotomy within 12 months after surgery (Figs 5A, 5B). The opening areas of these eyes were all less than 10 mm*. The average interval between the IOL implant surgery and capsulotomy was 5.92 t 4.03 months. In addition, 12 of these 14 eyes also showed decreased visual acuity from the best postoperative visual acuity. After undergoing the capsulotomy, the patient’s visual acuity virtually returned to the best postoperative visual acuity.
Discussion The contraction of the anterior capsule opening after continuous capsulorrhexis is considered to occur more exten-
Table 3. Changes and Tilt
Angle
in the Mean Decentration of the Retinitis Pigmentosa and Control Groups
Length (RP)
Control
RI’ Groua Decentratton 1 wk 1 trio 3 mos 6 mos 9 mos 12 mos Tilt (“) 1 wk 1 mo 3 mos 6 mos 9 mos 12 mos * No statistical t Statistically
Grow
P
(mm) 0.313 0.346 0.340 0.346 0.421 0.402 3.23 3.29 3.40 3.09 3.29 3.54 significance. sigmficant.
+ 2 t fz + +
0.220 0.203 0.175 0.257 0.258 0.231
+ 2.20 + 2.09 + 2.09 + 1.67 -c2.79 -c2.78
0.262 0.256 0.277 0.281 0.279 0.256
f ? k 2 k +
0.154 0.149 0.140 0.151 0.167 0.137
0.3991* 0.0386t 0.0889* 0.0447t 0.0038% 0.0017t
2.43 2.14 2.31 2.41 2.49 2.46
+ + 2 5 -t t
1.38 1.29 1.39 1.47 1.28 1.23
0.0787" 0.0064t 0.0088t 0.0404t 0.2263* 0.0484t
WC 1 we Postoperative
tntetval
Figure 3.
Comparison of the mean angle of the tilt between the two groups. The tilt angles in the retinitis plgmentosa group were larger than those in the control group. The dlffercnces at 1, 3,6, and 12 months were statistically significant.
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Ophthalmology
Volume 105, Number
7, July I998 Non-RP control
Figure 4. Retrodll photogr aphs showmg operate te ch anges m rior capsule. A, an eye of a tlent with retimtls pigment There was prominent fibros the edge of the anterior opening with secondar traction. B, an eye of a control patlent; only degree of constrlcuon brosls in the antenor cap was observed Figure 5. Sht-lamp photc graphs showmg an eye that ha undergone an antenor caps& tomy usmg a neodymmm:YA( (Nd:YAG) laser A, before cap sulotomy; marked fibrosis an constrlctlon of the anterlc capsule openmg. B, after caps” lotomy; Nd:YAG laser bursts have cut the antenor capsule edge m four dIrectIons for approximately 1 mm
sively in certain types of pathologic eyes.4-” Nishi and Nish? reported an eye with RP showing the closure of the capsulorrhexis opening. We also experienced some eyes with RP that showed an extensive contraction of the opening and needed a capsulotomy of the anterior capsule using an Nd:YAG laser. Our study clarified that the anterior capsule contraction with RP eyes was more extensive than that with healthy eyes. The percent area reduction in the RP group at 6 months was 45.2%, whereas it was only 4.6% in the control group. This was the greatest area reduction among the pathologic eyes that we have investigated, including those with diabetes, pseudoexfoliation, glaucoma, uveitis, and atopic cataract. In 38.3% of the RP eyes, the anterior capsule opening area decreased to less than 10 mm2. The opening area of 10 mm2 was almost the same as the pupillary area, and these eyes had clinically significant blurring of vision, Postoperative capsule shrinkage may cause a dislocation of the implanted IOL. Our study also showed that both the decentration and tilt were greater in the RP eyes
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I
\
4B
than in the healthy eyes. These results suggest that postoperative capsule shrinkage may be abnormally stronger in RP eyes than in healthy eyes. An excessive degree of IOL dislocation may cause refractive changes” or glare,‘O although this was difficult to quantitate. A possible twofold explanation regarding the extensive anterior capsule contraction and IOL dislocation in eyes with RP is as follows. The first explanation is that some blood-derived cytokines, which can stimulate the lens epithelial cell activity,‘4m’h may be more abundant in the aqueous humor of the RP eyes compared to healthy eyes. Previous studies showed that the blood aqueous barrierI as well as the blood retinal barrier’“,‘” were disrupted in the eyes of the patient with RP. Therefore, the release of blood cytokines into the aqueous humor may be increased in eyes with RP.20 Lens epithelial cells activated by the cytokines may cause the extensive contraction and fibrosis of the anterior capsule in patients with RP. The second explanation is the possible existence of zonular weakness in eyes with RP. Namiki et a12’ assumed that there was a dehiscence of the zonules with RP, but they were unable
Hay&
et al * Anterior Capsule Contraction and IOL Dislocation after Surgery
to prove this assumption. The postoperative capsule constriction is therefore considered to be stronger with RP compared to healthy eyes. In contrast, a morphologic study reported that the lens epithelial cells and the lens capsule in eyes with RP did not appear to be abnormal.22 When the anterior capsule opening area decreased to less than 10 mm2, the patient’s visual acuity usually deteriorated. The contraction of the anterior capsule opening in eyes with RP therefore certainly is clinically significant. In such cases, we performed an Nd:YAG laser capsulotomy. Although an anterior capsulotomy has been shown to cause a slight myopic shift,23 no serious complications have yet been reported to date. However, radial tears in the anterior capsule occasionally extended to the equator after the capsulotomy. A long-term follow-up of the IOL fixation status after an anterior capsulotomy is needed. In conclusion, the contraction of the anterior capsule occurred more extensively in RP eyes than in healthy eyes and also caused a high incidence of deterioration in the patient’s vision. The IOL dislocation also was greater in patients with RP than in healthy subjects. When we perform IOL implant surgery for patients with RP, it might be advantageous to make a larger capsulorrhexis. Surgeons should be aware that patients with RP may have an extensive postoperative capsulorrhexis constriction develop and need the Nd:YAG laser anterior capsulotomy.
References 1. Joo CK, Shin JA, Kim JH. Capsular opening contraction after continuous curvilinear capsulorrhexis. J Cataract Refract Surg 1996;22:585-90. 2. Hayashi K, Hayashi H, Nakao F, Hayashi F. Reduction in the area of the anterior capsule opening after polymethylmethacrylate, silicone, and soft acrylic intraocular lens implantation. Am J Ophthalmol 1997; 123:441-7. 3. Gonvers M, Sickenberg M, van Melle G. Change in capsulorrhexis size after implantation of three types of intraocular lenses. J Cataract Refract Surg 1997;23:231-8. 4. Hansen SO, Crandall AS, Olson RJ. Progressive constriction of the anterior capsular opening following intact capsulorrhexis. J Cataract Refract Surg 1993; 19:77-82. 5. Davison JA. Capsule contraction syndrome. J Cataract Refract Surg 1993; 19582-9. 6. Namiki M, Yamamoto N, Tagami Y, et al. Risk factors for anterior capsule shrinkage in intraocular lens implantation. Jpn J Clin Ophthalmol 1991;45:1828-31. 7. Hayashi H, Hayashi K, Nakao F, Hayashi F. Area reduction in the anterior capsule opening in eyes if diabetes mellitus patients. J Cataract Refract Surg 1998, in press.
8. Nishi 0, Nishi K. Intraocular lens encapsulation by shrinkage of the capsulorrhexis opening. J Cataract Refract Surg 1993; 19:544-5. 9. Nishigaki S, Inaba I, Minami H, et al. The postoperative change of depth of anterior chamber, refraction, and anterior capsulorrhexis size after intraocular lens implantation. J Jpn Ophthalmic Sot 1995; 100:156-8. 10. Miyata A, Nakata M, Yaguchi S, et al. 34 cases of severe anterior capsular shrinkage after continuous circular capsulorrhexis. IOL 1991;5:231-5. 11. Hayashi K, Hayashi H, Nakao F, Hayashi F. The correlationship between incision size and cornea1 shape changes in sutureless cataract surgery. Ophthalmology 1995; 102: 550-6. 12. Hurvitz LM. YAG anterior capsulectomy and lysis of posterior synechiae after cataract surgery. Ophthalmic Surg 1992;23:103-7. 13. Hayashi K, Harada M, Hayashi H, et al. Decentration and tilt of polymethyl methacrylate, silicone, and acrylic soft intraocular lenses. Ophthalmology 1997; 104:793-8. 14. Oliver0 DK, Fucht LT. Type IV collagen, laminin, and fibronectin promote the adhesion and migration of rabbit lens epithelial cells in vitro. Invest Ophthalmol Vis Sci 1993;34:2825-34. 15. Ibaraki N, Lin LR, Reddy VN. Effects of growth factors on proliferation and differentiation in human lens epithelial cells in early subculture. Invest Ophthalmol Vis Sci 1995;36:2304-12. 16. Nishi 0, Nishi K, Fujisawa T, et al. Effects of the cytokines on the proliferation of and collagen synthesis by human cataract lens epithelial cells. Br J Ophthalmol 1996; 80:638. 17. Kato M, Kobayashi R, Ueno M, Watanabe I. Aqueous flare values in eyes of retinitis pigmentosa. Jpn J Clin Ophthalmol 1997;51:299-303. 18. Fishman GA, Cunha-Vaz J, Salzano T. Vitreous fluorophotometry in patients with retinitis pigmentosa. Arch Ophthalmol 1981;99:1202-7. 19. Mallick KS, Zeimer RC, Fishman GA, et al. Transport of fluorescein in the ocular posterior segment in retinitis pigmentosa. Arch Ophthalmol 1984; 102:691-6. 20. Pande MV, Spalton DJ, Marshall J. In vivo human lens epithelial cell proliferation on the anterior surface of PMMA intraocular lenses. Br J Ophthalmol 1996; 80:46974. 21. Namiki M, Tagami Y, Morino I, et al. Findings from slit lamp and histological examination of the anterior capsule in patients with severe anterior capsule shrinkage and opacities after implantation of intraocular lens. J Jpn Ophthalmol Sot 1993;97:716-20. 22. Eshaghian J, Rafferty S, Goossens W. Ultrastructure of human cataract in retinitis pigmentosa. Arch Ophthalmol 1980;98:2227-30. 23. Inoue T, Inaba I, Nishigaki S, Ichioka H. Changes in IOL fixation after relaxing incision of contracted anterior lens capsule. IOL & RS 1995;9:101-4.
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