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Shape of lens epithelial cells after intraocular lens implantation
Shape of lens epithelial cells after intraocular lens implantation Kiyoyuki Majima, MD, Yoshinao Majima, MD ABSTRACT Purpose: To evaluate the morphological behavior of lens epithelical cells (LECs) after human cataract surgery with implantation of a poly(methyl methacrylate) (PMMA) or silicone intraocular lens (IOL). Setting: Department of Ophthalmology, Fujita Health University, Banbuntane Hotokukai Hospital, Nagoya, Aichi, Japan. Methods: Morphological observations of LECs in the patients with IOLs were made by light and transmission electron microscopy. The LECs were from 4 areas: (1) the region below the anterior capsule, touching the IOL; (2) the area between region 1 and the equatorial region; (3) the equatorial region; and (4) the central equatorial region and of the posterior capsule not touching the IOL. Case 1 had implantation of a single-piece IOL with a PMMA optic and haptics. Case 2 had a 3-piece IOL with a PMMA optic and polypropylene haptics. Case 3 had a 3-piece IOL with a silicone optic and polypropylene haptics. Areas 1 and 4 could not be observed in Case 2. Results: The major difference between the patient with a PMMA IOL (Case 1) and the patient with a silicone IOL (Case 3) was that among the 4 areas observed, collagen fibers were present only in area 1 in Case 1 but in areas 2 or 3 as well in Case 3. Conclusions: Fibrous collagen fibers appeared in regions in which LECs adhered and there was capsule contact with the IOL optic. In addition fibrous collagen fibers appeared in more areas in the eye with the silicone IOL than in that with the PMMA IOL, perhaps because IOLs with silicone optics move slightly while in the capsular bag. J Cataract Refract Surg 2001; 27:745–752 © 2001 ASCRS and ESCRS
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econdary cataract occurs in most patients after cataract surgery, although its severity varies. If marked opacification occurs in the central region of the posterior capsule, it can impair visual function and require neodymium:YAG laser treatment or invasive treatment by posterior capsule excision.
Accepted for publication August 9, 2000. From the Departments of Ophthalmology, Fujita Health University, Banbuntane Hotokukai Hospital (K. Majima), and Fujita Health University School of Medicine (Y. Majima), Nagoya, Japan. Reprint requests to Yoshinao Majima, MD, Fujita Health University, Banbuntane Hotokukai Hospital, Otobashi 3-6-10, Nakagawa-ku, Nagoya, Aichi 454-0012, Japan. © 2001 ASCRS and ESCRS Published by Elsevier Science Inc.
Secondary cataracts may include anterior or posterior capsule fibrous opacity, Elschnig pearls, or Soemmering’s rings. Although there are various hypotheses regarding the onset mechanism for secondary cataract,1– 8 the underlying cause is the lens epithelial cells (LECs) that remain in the anterior capsule after surgery. Because the details of the onset mechanism of secondary cataract are unknown, it is important to gain an understanding of the postoperative behavior of LECs. We report 3 patients who had phacoemulsification with intraocular lens (IOL) implantation, after which the IOL, still in the capsular bag, dislocated into the vitreous body. The shapes of the LECs in these patients after surgery were evaluated pathohistologically. 0886-3350/01/$–see front matter PII S0886-3350(00)00685-4
LEC SHAPE AFTER IOL IMPLANTATION
Patients and Methods Case 1 A 58-year-old man had phacoemulsification with IOL implantation in October 1989. The biconvex single-piece IOL had a 6.0 mm diameter poly(methyl methacrylate) (PMMA) optic and PMMA haptics. Five years after surgery, the IOL dislocated with the capsular bag into the vitreous body. The IOL was surgically removed, with care taken not to damage the capsular bag containing the IOL.
mission electron microscopy (TEM) (Hitachi, H-300). Light and transmission electron microscopy were used to observe the LECs in the following 4 areas: (1) below the anterior capsule, touching the IOL; (2) between the region described in 1 and the equatorial region; (3) the equatorial region; (4) the central equatorial region and the posterior capsule, not touching the IOL. These 4 areas are shown in Figure 1, and observations of the areas in each patient are shown in Figure 2.
Results Case 2 A 66-year-old man had phacoemulsification and IOL implantation in July 1994. The biconvex 3-piece IOL had a 6.0 mm diameter PMMA optic and polypropylene haptics. Nine years after surgery, the capsular bag with the IOL inside dislocated into the vitreous body. The capsular bag containing the IOL was removed and observed as in Case 1. Case 3 A 50-year-old man had phacoemulsification and IOL implantation in October 1993. The biconvex 3-piece IOL had a 6.0 mm diameter silicone optic and polypropylene haptics. The capsular bag with the IOL dislocated into the vitreous body 4 years after surgery. The capsular bag and IOL were surgically removed as in Cases 1 and 2. Observations and Analysis It was thought that trauma might be the reason that the capsular bags with the IOLs in place dislocated into the vitreous body in the 3 patients. However, no patient had a medical history of trauma, and the reason for the dislocations remains unknown. Immediately after removal from the capsular bags, the IOLs of all 3 patients were prefixed for about 2 hours in a mixed solution of paraformaldehyde 2% and glutaraldehyde 2.5%. Then, they were postfixed in osmic acid 1% for 1 hour, dehydrated in an ethanol series, and embedded in epoxy resin. Slices approximately 1 m thick were prepared from the resin block, stained with toluidine blue, and observed under light microscopy (LM). Ultrathin slices were prepared from the same block and, after uranyl acetate and lead double staining, were viewed by trans746
Case 1 Light microscopy revealed a single layer of LECs below the anterior capsule in area 1 (Figure 3,A). In area 2, there was a single layer of LECs, with swollen lens fibers directly below (Figure 3,B). In areas 3 and 4, there was a single layer of LECs, with swollen lens fibers in a layer-like formation directly below (Figure 3,C,D). No lens fibers were observed in area 1, but some were found in areas 2, 3, and 4. These fibers appear to be the result of the edge of the IOL optic interfering with the migration of the differentiated lens fibers in the capsular bag. Transmission electron microscopy revealed that in area 1, there was no continuity between LECs; no singlelayer structure was seen, only isolated LECs among collagen fibers (Figure 3,E). In area 2, flat LECs were arranged below the anterior capsule. Directly below was a structure thought to consist of degenerating lens fibers (Figure 3,F). In areas 3 and 4, more 3-dimensional LECs were arranged in a single layer below the anterior capsule, below which was a structure thought to be degenerating lens fibers (Figure 3,G,H).
Figure 1. (Majima) The 4 areas evaluated.
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Figure 2. (Majima) A: Observed areas in Case 1. B: Observed areas in Case 2. C: Observed areas in Case 3.
Case 2 During preparation of the sections of areas 1 and 4 for LM, the LECs separated from the anterior and posterior capsules, making observation of the cells in those areas impossible. In areas 2 and 3, a single layer of LECs was observed, with a mass of lens fibers directly below (Figure 4,A,B). However, unlike in Case 1, no swelling of lens fibers was observed under LM. Although observations of areas 1 and 4 were not possible, TEM of the other areas revealed a single layer of flat LECs arranged under the anterior capsule in area 2. Directly below was a structure thought to be degenerating lens fibers (Figure 4,C). In area 3, a single layer of more 3-dimensional LECs was arranged under the anterior chamber, directly below which was a structure thought to consist of lens fibers (Figure 4,D).
2, 3, and 4, had single layers of LECs under the anterior capsule, with swollen lens fibers in a layer-like structure just below (Figure 5,B,C,D). Transmission electron microscopy showed cell fragments touching the anterior capsule and collagen fibers in area 1, with isolated LECs between the collagen fibers (Figure 5,E). In area 2, LECs and structures of LECs and degenerating lens fibers were below the anterior chamber; collagen fibers were also observed (Figure 5,F). In area 3, a single layer of 3-dimensional LECs was arranged below the anterior chamber, with degenerating lens fibers and collagen fibers directly below (Figure 5,G). Disseminated flat LECs were seen under the anterior capsule in area 4, with an image of degenerating lens fibers directly below. Area 4 had no collagen fibers (Figure 5,H).
Case 3 Under LM, multiple layers of LECs were observed under the anterior capsule in area 1 (Figure 5,A). Areas
Discussion Secondary cataracts are classified as fibrous capsular opacities, Elschnig pearls, or Soemmering’s rings. The
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Figure 4. (Majima) A: A single layer of LECs and a mass of lens fibers (original magnification ⫻400). B: Findings similar to those in A (original magnification ⫻400). C: Flat LECs and degenerating lens fibers. D: Three-dimensional LECs and degenerating lens fibers.
cause of onset of secondary cataract is the proliferation and differentiation of LECs remaining in the anterior capsule after surgery. If these processes could be controlled, formation of secondary cataracts might be prevented, or at least hindered. At present, however, there is no solution. A first step in finding a solution is to investigate the behavior of LECs after IOL implantation. There have been reports of the morphological behavior of LECs after lens excision in rabbit eyes2– 4,9,10 and of cytobio-
logical LEC behavior in human eyes.11,12 However, to our knowledge, there have been no reported morphological comparisons of LEC behavior after human cataract surgery, particularly with implantation of PMMA and silicone IOLs. The present study evaluated 3 patients: One received an IOL with a PMMA optic and haptics, the second had an IOL with a PMMA optic and polypropylene haptics, and the third had an IOL with a silicone optic and polypropylene haptics. In the areas in which
Figure 3. (Majima) A: A single layer of LECs below the anterior capsule. The arrowhead indicates the border region on the equatorial side between areas 1 and 2 in contact with the IOL optic and the anterior capsule (original magnification ⫻400). B: A single layer of LECs and liquefied lens fibers (original magnification ⫻400). A single layer of LECs and liquefied lens fibers in a layer-like formation (original magnification ⫻400). D: Findings similar to those in C (original magnification ⫻400). E: Isolated LECs among collagen fibers (arrows). F: Flat LECs and degenerating lens fibers. G: Three-dimensional LECs and degenerating lens fibers. H: Findings similar to those in G.
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observation was possible, there were no major differences in the shape of the LECs under LM or TEM between the patient with the IOL entirely of PMMA and the patient with the PMMA IOL with polypropylene haptics. However, in the latter patient, aggregations of degenerating lens fibers but no liquefied lens fibers were seen. Future studies of the LEC behavior based on differences in haptic material with a greater number of patients should be done. In Case 1, LM and TEM showed that in area 1 (the area in which the anterior surface of the IOL and the LECs remaining in the anterior capsule come in contact), LECs but no lens fibrocytes were observed. In area 2, there was a single layer of LECs, just below which were lens fibrocytes. Closer study of Figure 2 might help explain these findings. Figure 2,A shows the border between areas 1 and 2, thought to be the region on the equatorial side at which the IOL optic and anterior capsule make contact. This region clearly separates the areas into those with regenerated lens fibrocytes and those without. From these observations, we conclude that the absence of lens fibrocytes results from the IOL optic blocking the invasion of lens fibrocytes into the center region of the pupil. Thus, although the present study shows regenerated lens fibrocytes in areas 2, 3, and 4, the fibrocytes were liquefied or degenerating and appeared grossly as a region of opacification. This indicates that it is more beneficial to visual function if these regenerated lens fibrocytes do not exist and that the presence of the IOL optic helps maintain the transparency of the central region of the pupil. The major difference between the patient with a PMMA IOL and the patient with a silicone IOL in which all 4 areas could be evaluated was that collagen fibers were present only in area 1 in the first patient but also in areas 2 and 3 in the latter patient. Ishibashi et al.13 report that fibrous collagen fibers exist in the incision margin of the anterior capsule after IOL implantation. However, ours is the first report of fibrous collagen fibers in regions other than the anterior capsule incision margin and in areas (2 and 3) that do not appear to be in
contact with the IOL optic. The reason for this may be that IOLs with a silicone optic and polypropylene haptics, even when implanted in the capsular bag, may not become fixated physically. Thus, there is slight movement of the IOL in the capsular bag. The reason that fibrous collagen fibers were observed in areas 2 and 3 may be that contact was made not only in area 1, but also in areas 2 and 3. We hypothesize that one reason for this is that LECs adhere more to silicone optics than to PMMA optics because silicone is hydrophobic.14 Thus, the IOL’s movement in the capsular bag prevents LECs below the anterior capsule from adhering to the optic when the anterior capsule and the IOL optic are in contact. Therefore, it is important to consider the contribution of both the IOL haptic and optic when evaluating IOL fixation.
References 1. McDonnell PJ, Stark WJ, Green WR. Posterior capsule opacification; a specular microscopic study. Ophthalmology 1984; 91:853– 856 2. Kappelhof JP, Vrensen GFJM, Vester CAM, et al. The ring of Soemmerring in the rabbit; a scanning electron microscopic study. Graefes Arch Clin Exp Ophthalmol 1985; 223:111–120 3. Kappelhof JP, Vrensen GFJM, De Jong PTVM, et al. An ultrastructural study of Elschnig’s pearls in the pseudophakic eye. Am J Ophthalmol 1986; 101:58 – 69 4. Kappelhof JP, Vrensen GFJM, De Jong PTVM, et al. The ring of Soemmerring in man: an ultrastructural study Graefes Arch Clin Exp Ophthalmol 1987; 225: 77– 83 5. Frezzotti R, Caporossi A, Mastrangelo D, et al. Pathogenesis of posterior capsular opacification. Part II: histopathological and in vitro culture findings. J Cataract Refract Surg 1990; 16:353–360 6. Apple DJ, Solomon KD, Tetz MR, et al. Posterior capsule opacification. Surv Ophthalmol 1992; 37:73–116 7. Ishibashi T, Araki H, Sugai S, et al. Anterior capsule opacification in monkey eyes with posterior chamber intraoclar lenses. Arch Ophthalmol 1993; 111:1685–1690 8. Ishibashi T, Hatae T, Inomata H. Collagen types in human posterior capsule opacification. J Cataract Refract Surg 1994; 20:643– 646
Figure 5. (Majima) A: Multiple layers of LECs under the anterior capsule (original magnification ⫻400). B: Single layers of LECs and liquefied lens fibers in a layer-like state (original magnification ⫻200). C, D: Findings similar to those in B (original magnification ⫻200). E: Cell fragments, collagen fibers (arrows), and isolated LECs between collagen fibers. F: Lens epithelial cells and degenerating lens fibers. Collagen fibers (arrows) existed in the LECs. G: Three-dimensional LECs, degenerating lens fibers, and collagen fibers (arrows). H: Flat LECs and degenerating lens fibers. No collagen fibers were seen in this area.
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9. Saika S, Ohmi S, Kanagawa R, et al. Lens epithelial cell outgrowth and matrix formation on intraocular lenses in rabbit eyes. J Cataract Refract Surg 1996; 22: 835– 840 10. Saika S, Ohmi S, Tanaka S, et al. Light and scanning electron microscopy of rabbit lens capsules with intraocular lenses. J Cataract Refract Surg 1997; 23:787–794 11. Nagamoto T, Hara E. Lens epithelial cell migration onto the posterior capsule in vitro. J Cataract Refract Surg 1996; 22:841– 846
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12. Nagamoto T, Hara E, Kurosaka D. Lens epithelial cell proliferation onto the intraocular lens optic in vitro. J Cataract Refract Surg 1996; 22:847– 851 13. Ishibashi T, Araki H, Sugai S, et al. [Histopathologic study of anterior capsule opacification in pseudophakic eyes]. [Japanese] Nippon Ganka Gakkai Zasshi 1993; 97:460 – 466 14. Majima K. An evaluation of the biocompatibility of intraocular lenses. Ophthalmic Surg Lasers 1996; 27:946 – 951
J CATARACT REFRACT SURG—VOL 27, MAY 2001
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econdary cataract occurs in most patients after cataract surgery, although its severity varies. If marked opacification occurs in the central region of the posterior capsule, it can impair visual function and require neodymium:YAG laser treatment or invasive treatment by posterior capsule excision.
Accepted for publication August 9, 2000. From the Departments of Ophthalmology, Fujita Health University, Banbuntane Hotokukai Hospital (K. Majima), and Fujita Health University School of Medicine (Y. Majima), Nagoya, Japan. Reprint requests to Yoshinao Majima, MD, Fujita Health University, Banbuntane Hotokukai Hospital, Otobashi 3-6-10, Nakagawa-ku, Nagoya, Aichi 454-0012, Japan. © 2001 ASCRS and ESCRS Published by Elsevier Science Inc.
Secondary cataracts may include anterior or posterior capsule fibrous opacity, Elschnig pearls, or Soemmering’s rings. Although there are various hypotheses regarding the onset mechanism for secondary cataract,1– 8 the underlying cause is the lens epithelial cells (LECs) that remain in the anterior capsule after surgery. Because the details of the onset mechanism of secondary cataract are unknown, it is important to gain an understanding of the postoperative behavior of LECs. We report 3 patients who had phacoemulsification with intraocular lens (IOL) implantation, after which the IOL, still in the capsular bag, dislocated into the vitreous body. The shapes of the LECs in these patients after surgery were evaluated pathohistologically. 0886-3350/01/$–see front matter PII S0886-3350(00)00685-4
LEC SHAPE AFTER IOL IMPLANTATION
Patients and Methods Case 1 A 58-year-old man had phacoemulsification with IOL implantation in October 1989. The biconvex single-piece IOL had a 6.0 mm diameter poly(methyl methacrylate) (PMMA) optic and PMMA haptics. Five years after surgery, the IOL dislocated with the capsular bag into the vitreous body. The IOL was surgically removed, with care taken not to damage the capsular bag containing the IOL.
mission electron microscopy (TEM) (Hitachi, H-300). Light and transmission electron microscopy were used to observe the LECs in the following 4 areas: (1) below the anterior capsule, touching the IOL; (2) between the region described in 1 and the equatorial region; (3) the equatorial region; (4) the central equatorial region and the posterior capsule, not touching the IOL. These 4 areas are shown in Figure 1, and observations of the areas in each patient are shown in Figure 2.
Results Case 2 A 66-year-old man had phacoemulsification and IOL implantation in July 1994. The biconvex 3-piece IOL had a 6.0 mm diameter PMMA optic and polypropylene haptics. Nine years after surgery, the capsular bag with the IOL inside dislocated into the vitreous body. The capsular bag containing the IOL was removed and observed as in Case 1. Case 3 A 50-year-old man had phacoemulsification and IOL implantation in October 1993. The biconvex 3-piece IOL had a 6.0 mm diameter silicone optic and polypropylene haptics. The capsular bag with the IOL dislocated into the vitreous body 4 years after surgery. The capsular bag and IOL were surgically removed as in Cases 1 and 2. Observations and Analysis It was thought that trauma might be the reason that the capsular bags with the IOLs in place dislocated into the vitreous body in the 3 patients. However, no patient had a medical history of trauma, and the reason for the dislocations remains unknown. Immediately after removal from the capsular bags, the IOLs of all 3 patients were prefixed for about 2 hours in a mixed solution of paraformaldehyde 2% and glutaraldehyde 2.5%. Then, they were postfixed in osmic acid 1% for 1 hour, dehydrated in an ethanol series, and embedded in epoxy resin. Slices approximately 1 m thick were prepared from the resin block, stained with toluidine blue, and observed under light microscopy (LM). Ultrathin slices were prepared from the same block and, after uranyl acetate and lead double staining, were viewed by trans746
Case 1 Light microscopy revealed a single layer of LECs below the anterior capsule in area 1 (Figure 3,A). In area 2, there was a single layer of LECs, with swollen lens fibers directly below (Figure 3,B). In areas 3 and 4, there was a single layer of LECs, with swollen lens fibers in a layer-like formation directly below (Figure 3,C,D). No lens fibers were observed in area 1, but some were found in areas 2, 3, and 4. These fibers appear to be the result of the edge of the IOL optic interfering with the migration of the differentiated lens fibers in the capsular bag. Transmission electron microscopy revealed that in area 1, there was no continuity between LECs; no singlelayer structure was seen, only isolated LECs among collagen fibers (Figure 3,E). In area 2, flat LECs were arranged below the anterior capsule. Directly below was a structure thought to consist of degenerating lens fibers (Figure 3,F). In areas 3 and 4, more 3-dimensional LECs were arranged in a single layer below the anterior capsule, below which was a structure thought to be degenerating lens fibers (Figure 3,G,H).
Figure 1. (Majima) The 4 areas evaluated.
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Figure 2. (Majima) A: Observed areas in Case 1. B: Observed areas in Case 2. C: Observed areas in Case 3.
Case 2 During preparation of the sections of areas 1 and 4 for LM, the LECs separated from the anterior and posterior capsules, making observation of the cells in those areas impossible. In areas 2 and 3, a single layer of LECs was observed, with a mass of lens fibers directly below (Figure 4,A,B). However, unlike in Case 1, no swelling of lens fibers was observed under LM. Although observations of areas 1 and 4 were not possible, TEM of the other areas revealed a single layer of flat LECs arranged under the anterior capsule in area 2. Directly below was a structure thought to be degenerating lens fibers (Figure 4,C). In area 3, a single layer of more 3-dimensional LECs was arranged under the anterior chamber, directly below which was a structure thought to consist of lens fibers (Figure 4,D).
2, 3, and 4, had single layers of LECs under the anterior capsule, with swollen lens fibers in a layer-like structure just below (Figure 5,B,C,D). Transmission electron microscopy showed cell fragments touching the anterior capsule and collagen fibers in area 1, with isolated LECs between the collagen fibers (Figure 5,E). In area 2, LECs and structures of LECs and degenerating lens fibers were below the anterior chamber; collagen fibers were also observed (Figure 5,F). In area 3, a single layer of 3-dimensional LECs was arranged below the anterior chamber, with degenerating lens fibers and collagen fibers directly below (Figure 5,G). Disseminated flat LECs were seen under the anterior capsule in area 4, with an image of degenerating lens fibers directly below. Area 4 had no collagen fibers (Figure 5,H).
Case 3 Under LM, multiple layers of LECs were observed under the anterior capsule in area 1 (Figure 5,A). Areas
Discussion Secondary cataracts are classified as fibrous capsular opacities, Elschnig pearls, or Soemmering’s rings. The
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Figure 4. (Majima) A: A single layer of LECs and a mass of lens fibers (original magnification ⫻400). B: Findings similar to those in A (original magnification ⫻400). C: Flat LECs and degenerating lens fibers. D: Three-dimensional LECs and degenerating lens fibers.
cause of onset of secondary cataract is the proliferation and differentiation of LECs remaining in the anterior capsule after surgery. If these processes could be controlled, formation of secondary cataracts might be prevented, or at least hindered. At present, however, there is no solution. A first step in finding a solution is to investigate the behavior of LECs after IOL implantation. There have been reports of the morphological behavior of LECs after lens excision in rabbit eyes2– 4,9,10 and of cytobio-
logical LEC behavior in human eyes.11,12 However, to our knowledge, there have been no reported morphological comparisons of LEC behavior after human cataract surgery, particularly with implantation of PMMA and silicone IOLs. The present study evaluated 3 patients: One received an IOL with a PMMA optic and haptics, the second had an IOL with a PMMA optic and polypropylene haptics, and the third had an IOL with a silicone optic and polypropylene haptics. In the areas in which
Figure 3. (Majima) A: A single layer of LECs below the anterior capsule. The arrowhead indicates the border region on the equatorial side between areas 1 and 2 in contact with the IOL optic and the anterior capsule (original magnification ⫻400). B: A single layer of LECs and liquefied lens fibers (original magnification ⫻400). A single layer of LECs and liquefied lens fibers in a layer-like formation (original magnification ⫻400). D: Findings similar to those in C (original magnification ⫻400). E: Isolated LECs among collagen fibers (arrows). F: Flat LECs and degenerating lens fibers. G: Three-dimensional LECs and degenerating lens fibers. H: Findings similar to those in G.
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observation was possible, there were no major differences in the shape of the LECs under LM or TEM between the patient with the IOL entirely of PMMA and the patient with the PMMA IOL with polypropylene haptics. However, in the latter patient, aggregations of degenerating lens fibers but no liquefied lens fibers were seen. Future studies of the LEC behavior based on differences in haptic material with a greater number of patients should be done. In Case 1, LM and TEM showed that in area 1 (the area in which the anterior surface of the IOL and the LECs remaining in the anterior capsule come in contact), LECs but no lens fibrocytes were observed. In area 2, there was a single layer of LECs, just below which were lens fibrocytes. Closer study of Figure 2 might help explain these findings. Figure 2,A shows the border between areas 1 and 2, thought to be the region on the equatorial side at which the IOL optic and anterior capsule make contact. This region clearly separates the areas into those with regenerated lens fibrocytes and those without. From these observations, we conclude that the absence of lens fibrocytes results from the IOL optic blocking the invasion of lens fibrocytes into the center region of the pupil. Thus, although the present study shows regenerated lens fibrocytes in areas 2, 3, and 4, the fibrocytes were liquefied or degenerating and appeared grossly as a region of opacification. This indicates that it is more beneficial to visual function if these regenerated lens fibrocytes do not exist and that the presence of the IOL optic helps maintain the transparency of the central region of the pupil. The major difference between the patient with a PMMA IOL and the patient with a silicone IOL in which all 4 areas could be evaluated was that collagen fibers were present only in area 1 in the first patient but also in areas 2 and 3 in the latter patient. Ishibashi et al.13 report that fibrous collagen fibers exist in the incision margin of the anterior capsule after IOL implantation. However, ours is the first report of fibrous collagen fibers in regions other than the anterior capsule incision margin and in areas (2 and 3) that do not appear to be in
contact with the IOL optic. The reason for this may be that IOLs with a silicone optic and polypropylene haptics, even when implanted in the capsular bag, may not become fixated physically. Thus, there is slight movement of the IOL in the capsular bag. The reason that fibrous collagen fibers were observed in areas 2 and 3 may be that contact was made not only in area 1, but also in areas 2 and 3. We hypothesize that one reason for this is that LECs adhere more to silicone optics than to PMMA optics because silicone is hydrophobic.14 Thus, the IOL’s movement in the capsular bag prevents LECs below the anterior capsule from adhering to the optic when the anterior capsule and the IOL optic are in contact. Therefore, it is important to consider the contribution of both the IOL haptic and optic when evaluating IOL fixation.
References 1. McDonnell PJ, Stark WJ, Green WR. Posterior capsule opacification; a specular microscopic study. Ophthalmology 1984; 91:853– 856 2. Kappelhof JP, Vrensen GFJM, Vester CAM, et al. The ring of Soemmerring in the rabbit; a scanning electron microscopic study. Graefes Arch Clin Exp Ophthalmol 1985; 223:111–120 3. Kappelhof JP, Vrensen GFJM, De Jong PTVM, et al. An ultrastructural study of Elschnig’s pearls in the pseudophakic eye. Am J Ophthalmol 1986; 101:58 – 69 4. Kappelhof JP, Vrensen GFJM, De Jong PTVM, et al. The ring of Soemmerring in man: an ultrastructural study Graefes Arch Clin Exp Ophthalmol 1987; 225: 77– 83 5. Frezzotti R, Caporossi A, Mastrangelo D, et al. Pathogenesis of posterior capsular opacification. Part II: histopathological and in vitro culture findings. J Cataract Refract Surg 1990; 16:353–360 6. Apple DJ, Solomon KD, Tetz MR, et al. Posterior capsule opacification. Surv Ophthalmol 1992; 37:73–116 7. Ishibashi T, Araki H, Sugai S, et al. Anterior capsule opacification in monkey eyes with posterior chamber intraoclar lenses. Arch Ophthalmol 1993; 111:1685–1690 8. Ishibashi T, Hatae T, Inomata H. Collagen types in human posterior capsule opacification. J Cataract Refract Surg 1994; 20:643– 646
Figure 5. (Majima) A: Multiple layers of LECs under the anterior capsule (original magnification ⫻400). B: Single layers of LECs and liquefied lens fibers in a layer-like state (original magnification ⫻200). C, D: Findings similar to those in B (original magnification ⫻200). E: Cell fragments, collagen fibers (arrows), and isolated LECs between collagen fibers. F: Lens epithelial cells and degenerating lens fibers. Collagen fibers (arrows) existed in the LECs. G: Three-dimensional LECs, degenerating lens fibers, and collagen fibers (arrows). H: Flat LECs and degenerating lens fibers. No collagen fibers were seen in this area.
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9. Saika S, Ohmi S, Kanagawa R, et al. Lens epithelial cell outgrowth and matrix formation on intraocular lenses in rabbit eyes. J Cataract Refract Surg 1996; 22: 835– 840 10. Saika S, Ohmi S, Tanaka S, et al. Light and scanning electron microscopy of rabbit lens capsules with intraocular lenses. J Cataract Refract Surg 1997; 23:787–794 11. Nagamoto T, Hara E. Lens epithelial cell migration onto the posterior capsule in vitro. J Cataract Refract Surg 1996; 22:841– 846
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12. Nagamoto T, Hara E, Kurosaka D. Lens epithelial cell proliferation onto the intraocular lens optic in vitro. J Cataract Refract Surg 1996; 22:847– 851 13. Ishibashi T, Araki H, Sugai S, et al. [Histopathologic study of anterior capsule opacification in pseudophakic eyes]. [Japanese] Nippon Ganka Gakkai Zasshi 1993; 97:460 – 466 14. Majima K. An evaluation of the biocompatibility of intraocular lenses. Ophthalmic Surg Lasers 1996; 27:946 – 951
J CATARACT REFRACT SURG—VOL 27, MAY 2001