Okada M

Müller cells in detached human retina express glial fibrillary acidic protein and vimentin

We investigated the expression of vimentin and glial fibrillary acidic protein (GFAP) within Müller cells in normal human retinas and in detached human retinas of proliferative vitreoretinopathy (PVR) cases using the immunogold method. Muller cells in normal retinas showed vimentin immunoreactivity and faint GFAP immunoreactivity; however, in detached retinas they showed distinct GFAP immunoreactivity as well as vimentin immunoreactivity. Immunoelectron microscopic observation revealed that intermediate filaments (IF) within Müller cells in normal retinas showed vimentin immunoreactivity and that those within Müller cells in detached retinas showed both vimentin and GFAP immunoreactivity. Double staining for vimentin and GFAP showed that in detached retinas, these two protein immunoreactivities were observed in the same filaments. These results indicate that IF of human Müller cells consist of vimentin under normal conditions and that Müller cells in detached retinas contain different IF, which consist of vimentin and GFAP.

Prognostic Factor Analysis in Pars Plana Vitrectomy for Retinal Detachment Attributable to Macular Hole in High Myopia: A Multicenter Study

PURPOSE To detect the prognostic factors associated with initial reattachment after primary pars plana vitrectomy (PPV) with gas tamponade for retinal detachment attributable to macular hole (MHRD). DESIGN Retrospective, multicenter, interventional case series. METHODS This study included 49 eyes of 48 patients with MHRD in high myopia (axial length more than 28.0 mm). All eyes underwent PPV with gas tamponade. We retrospectively reviewed the medical records and performed univariate analysis to detect the presence of any difference between eyes with a successful initial reattachment and those that failed. We performed multivariate logistic regression analysis to assess the influence of each preoperative factor on initial success. RESULTS Success rate of initial reattachment was 69%. Postoperative best-corrected visual acuity (BCVA) of 34 eyes with initial success was significantly better than those of 15 eyes with initial failure (P < .05); preoperative BCVA was not significantly different (P = .43). The axial length of eyes with initial success (29.26 +/- 0.94 mm) was shorter than that of eyes with initial failure (30.04 +/- 1.49 mm) with borderline significance (P = .049). There were no significant differences noted for other factors such as use of ILM peeling (P = .43) or type of tamponade gas (P = .99). Multiple logistic regression analysis using preoperative factors indicated that only axial length was significantly associated with initial success (odds ratio, 0.49; 95% confidence interval, 0.26 to 0.93; P < .05). CONCLUSIONS Initial reattachment is important for visual prognosis, and axial length is a prognostic factor for initial reattachment after PPV with gas tamponade for MHRD in high myopia.

Epiretinal Membrane of Proliferative Diabetic Retinopathy: An Immunohistochemical Study

Nineteen cases of epiretinal membrane (ERM) in proliferative diabetic retinopathy were studied using immunohistochemical methods. Antibodies against type I-IV collagen, fibronectin (FN), glial fibrillary acidic protein (GFAP), vimentin and the monoclonal antibody (MAB) against human Müller cells were used to examine the membranes. Type II collagen was found on one side of the ERMs in 95% of the cases. The other types of collagen, FN and vimentin were also identified in most cases. Müller cells (GFAP- and MAB-positive) were found in 2/19 cases (11%), and astrocytes (GFAP-positive but MAB-negative) were found in 10/19 cases (53%). These results suggest that type II collagen (vitreal collagen) may act as a scaffolding in the formation of ERMs and that glial elements of the ERMs consist mainly of astrocytes.

HISTOLOGICAL AND IMMUNOHISTOCHEMICAL STUDY OF IDIOPATHIC EPIRETINAL MEMBRANE

We used electron microscopy and light-microscopic immunohistochemistry of cellular and extracellular markers to characterize the cellular and extracellular components of 15 surgically resected idiopathic epiretinal membranes (IEMs). Ten specimens from the eyes with posterior vitreous detachment (PVD) consisted of inner limiting membrane, collagen layer and a flattened cell layer. Six out of the 10 specimens were also examined immunohistochemically, and fibronectin and type I, II, III and IV collagens were identified in a characteristic lamellar construct in the IEMs. On the other hand, 5 specimens obtained from the eyes without PVD consisted mainly of a thick layer of collagen fibrils with or without a flattened cell layer. Two of the 5 specimens were also examined immunohistochemically, and the collagen fibrils in the specimens were identified as type II collagen. Glial cells (glial fibrillary acidic protein-immunoreactive cells) were also identified in 3 specimens. These results indicate that there are some variations in the IEMs.

A Morphological and Morphometrical Study of the Retina in Aging SAM Mice

We investigated whether neuronal cell loss occurred as a part of normal aging of the retina in the Senescence-Accelerated Mouse, strains SAMP1 and SAMR1, and in the BALB/c mouse. All three strains showed age-related atrophy of the retina after histologically normal development. Morphometrical study revealed the following facts. The rate of loss of photoreceptor cells in the peripheral retina was greater than in the central retina in all three strains. In the central retina, the rate of loss of photoreceptor cells was greater in the SAMP1 and SAMR1 mice than in the BALB/c mice. In the peripheral retina, the SAMR1 and SAMP1 strains had fewer cells than the BALB/c strain at all ages, but the rate of loss of these cells did not differ among the three strains. The rate of loss of ganglion cells did not differ between the peripheral and central retinas in the three strains. The SAMR1 and SAMP1 strains had fewer ganglion cells in the peripheral retina than the BALB/c strain at all ages. Because the rate of age-related loss of these cells in SAMP1 mice was not accelerated, and they were short-lived, SAMP1 mice did not show marked age-related loss. On the contrary, the SAMR1 mice showed a marked loss of photoreceptor cells and ganglion cells late in life because of their longer life span, and we propose that this strain is a suitable animal model for the study of mechanisms of age-related loss of neuronal cells in the retina.

Intravitreal Neovascular Tissue of Proliferative Diabetic Retinopathy: An Immunohistochemical Study

Intravitreal neovascular tissue in 8 cases of proliferative diabetic retinopathy was investigated using immunohistochemical techniques. All 8 cases yielded positive immunoreactivity for type II collagen (vitreous collagen). The intravitreal neovascular tissue was classified into two groups (A or B), depending upon the distribution of type II collagen. In group A (3 cases), blood vessels were entirely surrounded by vitreous collagen, and in group B (5 cases), the vessels proliferated on one side of a mass of vitreous collagen. Type I and III collagens were distributed diffusely within the extracellular space of the tissue, whereas type IV collagen and fibronectin (FN) formed a basement membrane-like foundation for the newly formed vessels. Glial fibrillary acidic protein (GFAP)-immunoreactive cells were not clearly detected in any of the cases. Neovascular tissue typically proliferated on the posterior vitreous surface (as found in group B), but was also found to penetrate the vitreous gel (as found in group A). As neovascular tissue proliferation proceeded, types I, III and IV collagens and FN were produced. Glial cells (GFAP-positive cells) were not essential for neovascular tissue formation.

Involvement of fibronectin in in vitro regeneration of retinal pigment epithelium

Argon laser photocoagulation was placed on the confluent monolayer of cultured chick retinal pigment epithelial cells as a model of the regeneration process of retinal pigment epithelium after laser burn. The intense fibrillar net immunofluorescent pattern of fibronectin appeared on the burnt area from 2 h after the laser application, before the beginning of tissue reconstruction. Fibronectin was observed for several days, then became undetectable before the complete regeneration of retinal pigment epithelial cells. This indicates that fibronectin is involved in the early regeneration process of retinal pigment epithelium.

Retinal pigment epithelial cells produce fibronectin.

Antichick fibronectin antiserum, noncross-reactive to bovine fibronectin, was prepared to determine the production of fibronectin by cultured chick retinal pigment epithelial cells which were grown in the presence of fetal bovine serum. The typical fibrillary net pattern of fibronectin was observed by an indirect immunofluorescent technique when this specific antiserum reacted with cultured chick retinal pigment epithelial cells. Cultured chick retinal pigment epithelial cells were shown to produce fibronectin.

Subretinal strands. Tissue culture and histological study

Subretinal strands in proliferative vitreoretinopathy removed during vitreous surgery in ten cases were studied histologically; tissue culture was taken from five of the ten cases to obtain more material for investigation. Tissue culture was successful in all five cases. The cultured tissue just next to the original strand preserved the characteristics of the original tissue, whereas the portion distal from the original strand did not. Definite and/or suspected retinal pigment epithelial cells (RPE) were found in seven of ten original strands and four of five samples of cultured material. RPE were considered to be a predominant component of subretinal strands.

Large blunt scleral rupture without retinal detachment.

Eyes with scleral rupture after blunt trauma are often complicated by proliferative vitreoretinopathy. A 56-year-old man sustained blunt trauma to his left eye. Visual acuity was light perception. The fundus was obscured by hyphema. Computed tomography imaging and the presence of extensive subconjunctival hemorrhage suggested scleral rupture. Prompt primary surgery to repair a 25-mm scleral rupture was performed under general anesthesia. No retinal detachment developed. Two years postoperatively, visual acuity increased to 12/20. This case shows that retinal detachment and proliferative vitreoretinopathy may not complicate extensive scleral ruptures under certain circumstances.