Purpose: To investigate the nature of capsular opacification after cataract-intraocular lens (IOL) surgery in rabbit eyes, we immunohistochemically located extracellular matrix components in lens capsules after the surgery using light microscopy. The study was conducted also to compare the extracellular matrix components in rabbit capsules with those previously reported in the human eve.Methods: Twenty-seven eyes of 17 Japanese albino rabbits were lensectomized by phacoemulsification. and IOLs were implanted. Using immunohistochemical methods, the lens capsules were examined immediately after surgery, and 1, 2, 4, and 8 weeks after surgery.Results: In all cases at each time point, the edge of the anterior capsulotomy had contracted and was found to adhere to the inner surface of the posterior capsule, with both IOL haptics remaining in the capsular bag. Collagen types I and III were detected around the adhesion between the anterior capsulotomy edge and posterior capsule during all stages of healing and also observed on the central posterior capsules I or more weeks after surgery. Immunoreactivity for cellular fibronectin was seen around the adhesion between the anterior capsulotomy edge and posterior capsule during all stages of healing. It was also detected on the posterior capsules 2 and 4 weeks after surgery, but disappeared 8 weeks after surgery.Conclusion: Extracellular matrix components such as collagen types I and III and cellular fibronectin were expressed inside the residual lens capsular bag. Cellular fibronectin may play a role in the early wound healing process in the postoperative posterior capsule because the immunoreactivity in the central posterior capsule disappears in the later phase of healing. (C) 2002 Japanese Ophthalmological Society.

Purpose: To determine whether silicone intraocular lenses (IOLs) are readily affected by capsule shrinkage.Setting: Department of Ophthalmology, Wakayama Medical College, Wakayama, japan.Methods: A D-shaped incision was made in the anterior capsule of 38 eyes of 20 white rabbits. One of 2 IOL types was implanted in the capsular bag: 3-piece silicone or single-piece all-poly(methyl methacrylate) (PMMA). Twenty-eight eyes were evaluated for IOL rotation and optic decentration.Results: The extent of postoperative decentration and rotation observed with the silicone IOLs did not significantly exceed that of the PMMA IOLs.Conclusions: Our results, coupled with the advantages of small incision surgery, indicate that a silicone IOL is an effective choice. (C) 1999 ASCRS and ESCRS.

PURPOSE:We used immunohistochemistry to characterize cellular and proteinaceous deposits on the surfaces of explanted posterior chamber intraocular lenses (PC-IOLs).METHODS:A total of 30 PC-IOLs were immunostained for the alpha- or beta-subunits of prolyl 4-hydroxylase, which is involved in collagen biosynthesis; cellular fibronectin; alpha B crystalline; and CD68, a macrophage marker, to characterize the cellular deposits that adhere to the IOL surfaces and to evaluate the distribution of cells involved in the deposition of extracellular matrix on IOLs.RESULTS:Cellular or proteinaceous deposits were observed on all 30 PC-IOLs. Cells that showed positive staining for alpha B crystallin were classified as lens epithelial cells; CD68-positive cells were considered to be of macrophagic origin. Positivity for cellular fibronectin, including the macrophages and related cells, appeared to be responsible for the accumulation of fibronectin on the surfaces of PC-IOLs. Prolyl 4-hydroxylase-positive cells were involved in the deposition of collagen on PC-IOLs.CONCLUSION:Immunohistochemical study revealed that macrophages, foreign-body giant cells, and lens epithelial cells adhered to explanted PC-IOLs. Such adherent cells are responsible for the deposition of extracellular matrix on the surfaces of PC-IOLs and may regulate the assembly of the extracellular matrix, influencing the biocompatibility of PC-IOLs.

PURPOSE:To evaluate the role of lens epithelial cells (LECs) in posterior capsule opacification. SETTING:Departments of Ophthalmology and Pathology, Wakayama Medical College, Department of Anatomy, Kansai Shinkyu College, and Department of Ophthalmology, Kobe Kaisei Hospital, Japan. METHODS:We examined the presence of degenerated LECs on the capsules of the eyes of rabbits and a patient after intraocular lens (IOL) implantation. Phacoextraction of a crystalline lens and IOL implantation were done in 5 albino rabbits under general anesthesia. The animals were killed after 2 months. Lens capsules were removed and fixed. During vitreous surgery, a lens capsule with an IOL was removed from a patient. Ultrathin sections of specimens were studied by transmission electron microscopy. RESULTS:Presumed LECs proliferated between the posterior capsule and the IOL in association with collagenous matrix. Debris from the degenerated cells and destroyed intracellular organelles was also seen. CONCLUSION:Lens epithelial cells proliferating on the posterior capsule cannot survive indefinitely.

Lens capsules become fibrotic after the extraction of a cataract. To understand this phenomenon, we evaluated the immunolocalization of prolyl 4-hydroxylase (an enzyme involved in procollagen hydroxylation), and extracellular matrix components and cytoskeletal components in a normal human lens capsule and in others with intraocular lenses. Lens capsules containing intraocular lenses were removed from a patient with proliferative vitreoretinopathy and three with proliferative diabetic retinopathy during vitreous surgery. Two circular sections of the anterior capsules with lens epithelial cells were obtained by anterior capsulotomy during cataract surgery. In addition, a lens capsular bag was obtained immediately after phacoemulsification. The lens capsules were processed for light microscopic immunohistochemical detection of the alpha and beta subunits of prolyl 4-hydroxylase, extracellular matrix components (including collagen types, laminin and cellular fibronectin) or cytoskeletal components (such as cytokeratin, vimentin and alpha-smooth muscle actin). Monolayer lens epithelial cells were seen on the inner surface of the normal anterior capsules. Each intraocular lens was found to be fixed in the capsular bag. Light microscopic immunohistochemistry showed that these proliferating cells expressed vimentin and alpha-smooth muscle actin; in contrast, quiescent lens epithelial cells did not stain for alpha-smooth muscle actin. Marked immunostaining for subunits of prolyl 4-hydroxylase was detected in lens epithelial cells proliferating on the capsules, while no or only faint prolyl 4-hydroxylase immunoreactivity was detected in quiescent lens epithelial cells immediately after phacoemulsification. Collagen types I, III and VI and cellular fibronectin were observed diffusely in accumulated connective tissue on a capsule with an intraocular lens. Type IV collagen immunoreactivity was seen both in the capsules and in the connective tissue accumulation on the capsules. Collagen V and laminin were detected in association with cellular proliferation. Collagen VII and VIII and laminin 5 were not seen. We concluded that during wound healing of the lens capsule after cataract extraction, the lens epithelial cells that proliferate on the inner surface of the capsule transform it into a myofibroblastic phenotype, expressing prolyl 4-hydroxylase and alpha-smooth muscle actin. These proliferating cells are involved in the production of collagen on the lens capsule. This results in a postoperative fibrotic process and contraction of the lens capsule.

• Purpose: To examine the deposition of extracellullar matrix on silicone intraocular lenses (IOLs) implanted experimentally into rabbit eyes by electron microscopy and to determine the immunolocalization of extracellular matrix components, including collagen types and cellular fibronectin, on these IOLs. • Methods: We performed phacoemulsification and aspiration of the crystalline lens and implanted a foldable silicone IOL in the capsular bag of one eye of each of 26 adult albino rabbits under general anesthesia. After 8 weeks the animals were killed and the eyes were enucleated. The silicone IOLs were processed for electron microscopy and for immunohistochemical detection of collagen types I, III, and IV and cellular fibronectin. • Results: Electron microscopy revealed deposition of a presumed cell matrix complex on the optic portion of all silicone IOLs, as well as the adhesion of presumed macrophages and foreign-body giant cells. Cellular deposits showed immunoreactivity for cellular fibronectin. Fibrous or membranous deposits exhibited immunoreactivity for cellular fibronectin and collagen types I and III. A few type IV collagen-immunoreactive deposits were also seen. • Conclusion: Deposits of extracellular matrix components were observed on silicone IOLs. These deposits may form the scaffolding for the adhesion and proliferation of cells. These matrix components appeared to be the products of cells adhering to the surfaces of IOLs, including lens epithelial cells, macrophages and foreign-body giant cells, indicating that the process of granulation was incomplete.

• Background: We examined by transmission electron microscopy the accumulation of extracellular matrix on intraocular lenses (IOLs) implanted experimentally into rabbit eyes, and evaluated the immunolocalization of such extracellular matrix components as collagen types I, III, and IV, and cellular fibronectin on these IOLs. • Methods: Phacoemulsification and aspiration of the crystalline lens were performed and an IOL was implanted into the capsular bag of each eye of each of 16 adult albino rabbits under general anesthesia. After up to 12 weeks, the animals were killed and the IOLs were removed. Specimens were processed for transmission electron microscopy or for immunohistochemical detection collagen types I, III, and IV, and cellular fibronectin. • Results: Transmission electron microscopy revealed an accumulation of extracellular matrix between the residual anterior lens capsule and the surface of an IOL explanted 4 weeks after surgery. Collagen types I and III and cellular fibronectin were detected immunohistochemically on each IOL in association with cellular deposits. Type IV collagen-immunoreactive matrix was not seen on the optic portion, but was detected on the haptic portion of one of six IOLs examined. • Conclusion: Each component of the extracellular matrix that is deposited on the IOL supplies scaffolding for the adhesion and proliferation of cells. These components are considered to be produced by cells such as lens epithelial cells and macrophages that adhere to the IOL surface.

A patient with posterior lens capsule rupture caused by blunt trauma and in whom the anterior capsule and the remainder of the eyeball structure was intact had phacoemulsification and aspiration of the crystalline lens with implantation of a posterior chamber intraocular lens. Further rupture of the capsule was prevented by the fibrosis, which tightened the margin of the ruptured capsule. This case shows that blunt trauma can rupture the posterior lens capsule, leaving the anterior capsule intact.

PURPOSE:To use light microscopy to evaluate the presence and distribution of cells that proliferate on the outer surface of the anterior capsule after experimental lens extraction in rabbit eyes.SETTING:Research Laboratory, Department of Ophthalmology, Wakayama Medical College, Wakayama, Japan.METHODS:Extracapsular lens extraction, with or without implantation of a poly(methyl methacrylate) intraocular lens, was performed in 10 adult albino rabbits under general anesthesia. Animals were killed 1 month postoperatively. Each eye was embedded in paraffin and examined by light microscopy.RESULTS:A capsular bag composed of the anterior and posterior capsules was observed. Mononuclear cells, presumed to be lens epithelial cells (LECs), had proliferated in the space between the capsules as well as on the outer surface of the anterior capsules, in association with an accumulation of extracellular matrix.CONCLUSION:After lens extraction, LECs migrated to and proliferated on the anterior surface of the anterior capsule.

Purpose: To examine postoperative changes in the lens capsules of rabbit eyes after phacoemulsification and aspiration of the crystalline lens and implantation of posterior chamber intraocular lenses (IOLs) using light and scanning electron microscopy. Setting: Research Laboratory, Department of Ophthalmology, Wakayama Medical College, Japan. Methods: The crystalline lens was emulsified and aspirated and an IOL implanted in the capsular bag or ciliary sulcus of each eye in adult albino rabbits under general anesthesia. Animals were killed after 4 weeks, and the lens capsules were removed. The specimens were observed under phase-contrast microscopy and processed for light and scanning electron microscopy. Results: Phase-contrast microscopy revealed presumed lens epithelial cells (LECs) on the central posterior capsules in association with regenerating lenticular fibers and Elschnig pearls in the peripheral capsules. Scanning electron microscopy showed the accumulation of fibrous extracellular matrix on the surface of the posterior capsule in eyes in which the IOL was implanted in the ciliary sulcus. Deposition of packed material attached to the surface of IOLs and of Soemmering’s ring were observed in eyes with in-the-bag IOL fixation. At a higher magnification, a parallel arrangement of lenticular fibers was seen in the regenerated lens structure on posterior capsules. An identical structure was observed under light microscopy. Outgrowth of presumed LECs from residual anterior lens capsules and adhesion of macrophages and giant cells were observed on the IOL surface. Conclusion: Two types of postoperative changes were observed in lens capsules after implantation of IOLs: accumulation of fibrous extracellular matrix and newly formed lenticular fibers. These changes are attributed to the proliferation of LECs and can induce posterior capsule opacification after IOL implantation.

Purpose: To evaluate the presence and distribution of lens epithelial cells (LECs) and extracellular matrix on intraocular lenses (IOLs) implanted in the capsular bag in rabbit eyes. Setting: Department of Ophthalmology, Wakayama Medical College, Wakayama, Japan. Methods: Five adult albino rabbits had phacoemulsification and IOL implantation in both eyes. Two or 11 months later, the animals were killed by intravenous pentobarbital. The IOLs were removed and observed under scanning and transmission electron microscopy. Results: In addition to the macrophages and giant cells on the IOLs, all eyes had a monolayer of flattened cells growing out from the residual anterior lens capsule and a fibrous meshwork of extracellular matrix. Unlike those of a macrophagic origin, these cells had no central cytoplasmic elevation of nuclei and few cell surface microvilli and were considered to be proliferating LECs. Conclusion: Lens epithelial cells are involved in the eye's cellular reaction to IOLs and in the formation of extracellular matrix on IOLs. Further study of LEC behavior on IOLs should be done to improve IOL biocompatibility.

In-the-bag hyphema, the collection of blood in the endocapsular space between the posterior capsule and the intraocular lens (IOL), is a rare postoperative complication of IOL implantation in the capsular bag. We report three cases. In Case 1, the hyphema did not obscure the visual axis and thus no treatment was given; the hyphema reabsorbed spontaneously within 3 months Case 2 was successfully treated with a neodymium:YAG (Nd:YAG) laser capsulotomy. Although a fibrin membrane on the IOL's anterior surface in Case 3 made it difficult, an Nd:YAG capsulotomy was performed followed by subsequent YAG laser dissection of the fibrin membrane. We believe that for improved simplicity, safety, and efficacy in such a case, membrane dissection should be done at the time of the capsulotomy.

We performed phacoemulsification and aspiration of the crystalline lens and implanted a silicone intraocular lens in the capsular bag in rabbits. The posterior capsules were then observed under transmission electron microscopy 2 or 4 months after the surgery. Lens epithelial cells proliferated between the posterior capsule and the optic portion of the silicone intraocular lens, accompanied with the accumulation of collagenous extracellular matrix.

Purpose: To localize the enzyme prolyl 4-hydroxylase in the crystalline lens and determine the ability of lens epithelial cells (LECs) to synthesize procollagen.Setting: Research laboratory, Department of Ophthalmology, Wakayama Medical College, Wakayama, Japan.Methods: Phacoemulsification and aspiration of the crystalline lens followed by implantation of a poly(methyl methacrylate) intraocular lens (IOL) were performed in 1 eye each of 6 albino rabbits; the eye was enucleated 1 or 2 months later. Crystalline lenses were also extracted from the eyes of 2 rabbits. These samples were processed for immunohistochemical detection of the alpha- and beta-subunits of prolyl 4-hydroxylase.Results: A monolayer of LECs was detected on the inner surface of the intact anterior capsule. Antibodies directed against both subunits of prolyl 4-hydroxylase reacted strongly to LECs proliferating on capsules with IOLs, whereas little or no reaction was observed in quiescent LECs or in the regenerated lenticular structure.Conclusion: The presence of prolyl 4-hydroxylase in LECs proliferating on the inner surface of the lens capsule suggests that these cells are involved in the production of procollagen and fibrosis during capsular injury and repair. Suppression of prolyl 4-hydroxylase activity may prevent the capsule opacification that results from cataract removal and IOL implantation.

We examined the distribution of extracellular matrix components in the proteinaceous matrix on explanted IOLs using immunohistochemistry to clarify the nature of proteinaceous deposits on the surfaces of IOLs. We examined 15 polymethylmethacrylate (PMMA) IOLs and one silicone IOL explanted from patients. The IOLs were immunostained for cellular fibronectin, types I and IV collagen, and vitronectin. Various amounts of fibronectin, types I and IV collagen, and vitronectin were detected in the extracellular matrix on all IOLs with cellular deposits. Types I and IV collagen and cellular fibronectin were present in the extracellular matrix and were probably the products of cells adhering to the IOLs. Vitronectin in the fibrous extracellular matrix appeared to represent an adsorption material derived from the aqueous humor. These proteinaceous deposits associated with cellular deposits indicate unsuccessful formation of granulation tissue and could influence IOL biocompatibility.

We studied the ultrastructure of giant cells derived from macrophages that are found on the surface of implanted polymethylmethacrylate intraocular lenses (IOLs) in rabbits and the immunolocalization of vimentin in these cells in order to study the rearrangement of the intermediate filaments in multinucleated cells, In adult Japanese albino rabbits, the crystalline lens was extracted and an IOL was inserted into the residual lens capsule, IOLs were removed after 7 days, and the specimens were processed for ultrastructural observation or for immunostaining for vimentin. Macrophages and multinucleated cell were detected on the surfaces of IOLs by both light and transmission electron microscopy. Nuclei of the large multinucleated cells showed a circular distribution with the center of the cytoplasm occupied by cytoplasmic vacuoles. Vimentin intermediate filaments were observed in the cytoplasm of both macrophages and multinucleated cells. Vimentin in giant cells showed a radial distribution. Results indicate that vimentin intermediate filaments become reorganized after the fusion of macrophages. Experimental implantation of an IOL into the animal eye is a useful method for obtaining larger giant cells derived from macrophages.

Most posterior chamber intraocular lenses (IOLs) in common use today measure 13.5 mm to 14.0 mm in diameter. Some investigators recommend using smaller lenses (e.g., 12.0 mm to 12.5 mm). To investigate the effect of smaller lenses, experimental phacoemulsification procedures were performed in 16 eyes of white rabbits using two intraocular lens sizes: 14.0 mm and 12.5 mm. Each lens was evaluated for its effects on posterior capsule opacification and optic decentration, two of the most common complications of modern cataract surgery and intraocular lens implantation. The 12.5 mm lens showed a slightly smaller amount of decentration than the larger lens and a comparable amount of posterior capsule opacification.