Adhesion between Amniotic Membrane and Retinal Tissue and Inhibition of Amniotic Membrane on Cell Transformation

PURPOSE: Tissue adhesion rate between the amniotic membrane and the retinal tissue and histological change of the retinal tissue was studied. And the inhibition effect of amniotic membrane on the retinal pigment epithelial cell transformation was evaluated. METHODS: The human amniotic membrane and the porcine retinal tissue flap were used. The sensory retinal flap and the retinal pigment epithelial flap were placed on the amniotic membrane in culture disk. Tissue adhesion was evaluated and graded at 1, 2, 3, 4 and 5 weeks. Glial fibrillary acidic protein immunohistochemical staining and Masson's trichrome staining were performed for histologic study. Transmitted electron microscope examination was performed to study the stabilization effects of amniotic membrane. RESULTS: Tissue adhesion rates showed no significant change until the 4th week, but tend to decrease in the 5th week of organotissue culture. Tissue adhesion rate was higher in the chorion-side than in the amnion-side culture (p=0.000) and was higher in the retinal pigment epithelial than in the retinal flap (p=0.000). The inhibition of cell transformation was higher in the chorion-side culture than in the amnion-side culture. CONCLUSIONS: Amniotic membrane can be used for prevention of proliferative vitreoretinopathy by its mechanical barrier effect and cell stability effect.

The effects of diffusion blur on Snellen and grating acuity and foveal function in amblyopia

In order to verify that the effects of diffusion blur on Snellen and grating acuity in amblyopic eyes resemble those obtained from the peripheral or central retina in normal controls, we conducted the following experiment using a liquid crystal window (Edmund Scientific Co.) to produce diffusion blur on Snellen and grating acuity. Spatial frequencies used for a Snellen chart and Teller acuity card were 3.2, 6.5, 13.0, 26.0 cyc/cm at a working distance of 55 cm. The values of diffusive blur on central and peripheral visual acuity obtained from 20 normal healthy control eyes were compared with those values of central visual acuity in 26 amblyopic eyes. The diffusion blur had a strong negative effect on both Snellen and grating acuity in amblyopic eyes, but it had more potent effects on grating acuity (p 0.05). Snellen acuity obtained from diffusion blur overestimated grating acuity in the normal central acuity group and amblyopic central acuity group. The result of this investigation demonstrated that the liquid crystal diffusion blur had a strong negative effect on both Snellen and grating acuity and suggested that the visual function of an amblyopic retina resembled that of a normal central retina.

Ultrastructural Features of Surgically Excised Idiopathic Subretinal Neovascular Membrane

Subretinal neovascular membrane is the direct cause of visual impairment in various macular lesions. The aim of this study is to understand the pathophysiology of subretinal neovascular membrane by ultrastructural study. Six cases of surgically excised idopathic subretinal neovascular membrane were examined ultrastructurally. The vascular channels, which were lined by endothelial cells and surrounded by pericyte or retinal pigment epithelium, were the main feature of subretinal neovascular membrane. Other cellular components were retinal pigment epithelium, myofibroblast containing melanosome, chronic inflammatory cells including macrophages, histiocytes, plasma cells and lymphocytes, fibrocytes and outer segments of photoreceptor cells. Considereing that the development of subretianl neovascular membrane is similar to the wound healing process, it is suggested that pathophysiology of subretinal neovascular membrane may be a process of abnormal wound healing.

The Results of Delayed Repair for Orbital Wall Fracture

We studied the therapeutic effects on delayed reduction of orbital wall fracture. From December 1991 to December 1996, 20 patients with orbital fracture were delayed repaired at Severance hospital. The common indications for reduction of orbital bone fractures were enophthalmos and critical diplopia. The difference of preoperative exophthalmometry between both eyes was 3.2mm on average, and that of postoperative exophthal-rnometry was 1.4mm on average. Most of the patients showed improveinent of diplopia with good motility except I patient with upward gaze diplopia and 3 patients with downward gaze diplopia. We drew conclusion that delayed reduction of orbital wall fracture would improve syniptoms, even if performed, delayed surgical intervention as late as 2 month after trauma.

Clinical Study of Orbital Wall Fracture

The authors studied 229 patients (236 eyes) diagnosed with orbital wall fracture from April 1991 to December 1995 at Severance hospital with retrospective reviewing of the charts and orbital computed tomographs. Orbital wall fracture occurred most frequently between the ages of 20 and 29 years (mean age 25.7 years). It was more common in male (81.7%) than female (18.3%), about 4.5 times. Most patients were seen for management within 7 days after injury (66.4%). The causes of orbital wall fractures were violence (54.1%), traffic accidents (14.8%), falling down (7.9%) and others in order. Most common coexisting intraocular disease was hyphema (13.5%) and extraocular disease was eyelid laceration (15.3%). The difference between two eyes in initial exophthalmometry was 1.4 mm on average, and the patients with 1mm or less difference between two eyes allowed for the largst proportion of patients (57.2%). The number of patients with the presentation of binocular diplopia was 181 (79.0%), and the most of the complained of mild binocular diplopia (46.3%). As to the location of fracture, inferior wall fractures were most common, followed by fractures of medial (21.6%), inferior and medial (18.6%) and others in order. The number of patients operated for orbital wall fracture was 107 (47.0%), and the most common indication for surgical intervention was binocular diplopia caused by limitation of extraocular motor movement (49 cases, 45.8% of operated case).