This study was conducted to investigate the effect of ascorbic acid on oxidative injury of cultured porcine retinal pigment epithelial (RPE) cells induced by t-butylhydroperoxide. The porcine RPE cells were cultured in Dulbecco's modified Eagle's medium and the culture medium was replaced with one containing 0.01 mM to 5 mM ascorbic acid and/or 0.2 mM t-butylhydroperoxide. After 2 hours incubation, the test medium was replaced with the control medium. The number of cells was counted with a Coulter counter after a 2-day incubation period. The medium was pretreated with 900 U/ml and the previous procedure was repeated to eliminate the toxic effects of hydrogen peroxide induced by ascorbic acid. Not only t-butylhydroperoxide (p < 0.01) but also ascorbic acid (p < 0.01) were found to have dose-dependent cytotoxicity on RPE cells. The cytotoxicity was more significant when both agents were added to the culture media. In the presence of catalase, the cytotoxicity of ascorbic acid became insignificant (p > 0.05). The cytotoxicity of t-butylhydroperoxide decreased when 1 mM and 5 mM of ascorbic acid was added to the culture media with catalase pretreatment (p = 0.0277). These results indicate that ascorbic acid was toxic to RPE cells in our culture model but this cytotoxicity was not detected in the presence of catalase. With catalase pretreatment, ascorbic acid in relatively high concentration provided protection against oxidative injury of t-butylhydroperoxide.
Animals ; Ascorbic Acid/*pharmacology ; Cell Count ; Cell Survival/drug effects ; Cells, Cultured ; Culture Media ; Dose-Response Relationship, Drug ; Free Radicals ; Oxidative Stress/*drug effects ; Peroxides/antagonists & inhibitors/toxicity ; Pigment Epithelium of Eye/cytology/*drug effects ; Reactive Oxygen Species/toxicity ; Swine ; tert-Butylhydroperoxide

Proliferative vitreoretinopathy(PVR) is the most common cause of failure in retinal reattachment surgery. We performed three different procedures in 20 pigmented rabbits to get a simple model to induce experimental PVR. Rabbits were assigned randomly to three groups(I, II and III). Group I rabbits(5 rabbits, 10 eyes) received normal saline into vitreous cavity, after iatrogenic retinal tear was made. In group n rabbits(8 rabbits, 8 eyes), suspension of retinal pigment epithelium(RPE) and choroid of left eye was transferred into vitreous cavity of right eye. In group III rabbits(7 rabbits, 7 eyes), suspension of RPE and choroid of left eye was transferred into vitreous cavity of right eye after iatrogenic retinal tear was made. We observed the fundus for 2 months with, indirect ophthalmoscope. Incidence of retinal detachment of group I was zero(0/10) , that of group II was 37.5%(3/8), and that of group III was 85.7%(6/7). Electron microscopic findings of vitreous strand of one eye of group n showed central melanocytic core, peripheral fibroblast, and intercellular collagen fibril. Electron microscopic finding of one eye of group III revealed subretinal membrane composed of suspected RPE and glial cell.
Choroid ; Collagen ; Fibroblasts ; Incidence ; Membranes ; Neuroglia ; Ophthalmoscopes ; Rabbits* ; Retinal Detachment ; Retinal Perforations ; Retinaldehyde ; Vitreoretinopathy, Proliferative*

proliferative vitreoretinopathy (PVR) is the most common cause of failure in retinal reattachment surgery. Three different procedures were performed in 20 pigmented rabbits to devise a simple model to induce experimental PVR. Rabbits were assigned randomly to three groups (I, II, and III). Group I rabbits (5 rabbits, 10 eyes) rereived normal saline into the vitreous cavity, after an iatrogenic retinal tear was made. In group II rabits (8 rabbits, 8 eyes), a suspension of retinal pigment epithelium (RPE) and choroid from the left eye was transferred into the vitreous cavity of the right eye. In group III rabbits (7 rabbits, 7 eyes), a suspension of RPE and choroid from the left eye was transferred into the vitreous cavity of the right eye after an iatrogenic retinal tear was made. The fundus was observed for 2 months with an indirect ophthalmoscope. The incidence of retinal detachment in group I was zero (O/IO), that of group II was 37.5% (3/8), and that of group III was 85.7% (6/7). Electron microscopic findings of the vitreous strand of one eye of group II showed a central melanocytic core, peripheral fibroblasts, and intercellular collasen fibril. Electron microscopic findings in one eye of group III revealed a subretinal membrane composed of suspected RPE and glial cells.
Animals ; *Disease Models, Animal ; Pigment Epithelium of Eye/pathology ; Rabbits ; Retinal Diseases/*etiology ; Vitreous Body/pathology

Silicone oil is widely used as a retinal tamponade in the treatment of PVR. But reproliferation of membrane can occur under the silicone oil. Formerly, silicone oil was believed to suppress the proliferation of membrane, but recently, there were reports that silicone oil might actually promote proliferation of membrane, and recommended to use long-lasting gas rather than silicone oil. But it is known that proliferation of membrane can also occur in the eye in which intraocular gas has been used. So a careful study to compare the effect of intraocular gas and silicone oil to proliferation of membrane is needed. Rabbits are divided into three groups. Retinal tears were made in all the groups. in control group, no further surgery was done, and in the other two group, perfluoropropane gas was injected into the vitreous cavity. The intraocular gas was left unchanged(gas group), or it was exchanged with silicone oil 3 days later(silicone oil group). The fundus was examined periodically, and the eyeball was removed at 1, 2, 4, and 8 weeks after surgery for histopathologic study with light and electron microscope. Both intravitreal gas and silicone oil were shown to increase the formation of proliferative membrane compared to control group, but there was no statistically significant difference between them.
Membranes ; Rabbits ; Retinal Perforations ; Retinaldehyde ; Silicone Oils*

We performed the intravitreal injection of air and pure perfluoropropane (C3F8) gas in the pigmented rabbits and observed the changes of gas levels by the ultrasonography. We also observed the changes of the intra-ocular gas levels by the ultrasonography and measured the intraocular pressures (lOPs) in 9 patients who had undergone vitrectomy and fluid-gas exchange with 20% sulfur hexafluoride (SF6) and 14% perfluoropropane (C3F8) gases. In the pigmented rabbits, the air was not expanded and completely absorbed within 2 days, and the C3F8 gas was expanded maximally at 3 to 7 days and completely absorbed after 3 weeks. Among nine human eyes treated with vitrectomy and fluid-gas exchange, the intraocular pressures were elevated above 25mmHg at 1 day after operation in 2 eyes, which were controlled with medical therapy. The lOPs were significantly correlated with the amount of the intraocular gases (r=0.3476, p<0.05). The assessment of intraocular gas level by ultrasonography seems to be easier and more objective method than others previously reported.
Absorption* ; Gases ; Humans ; Intraocular Pressure ; Intravitreal Injections ; Rabbits ; Sulfur Hexafluoride ; Ultrasonography ; Vitrectomy

We performed the intravitreal injection of air and pure perfluoropropane(C3F8) gas in the pigmented rabbits and observed the changes of gas levels by the ultrasonography. We also observed the changes of the intra-ocular gas levels by the ultrasonography and measured the intraocular pressures(IOPs) in 9 patients who had undergone vitrectomy and fluid-gas exchange with 20% sulfur hexafluoride(SF6) and 14% perfluoropropane(C3F8) gases. In the pigmented rabbits, the air was not expanded and completely absorbed within 2 days, and the C3F8 gas was expanded maximally at 3 to 7 days and completely absorbed after 3 weeks. Among nine human eyes treated with vitrectomy and fluid-gas exchange, the intraocular pressures were elevated above 25mmHg at 1 day after operation in 2 eyes, which were controlled with medical therapy. The lOPs were significantly correlated with the amount of the intraocular gases(r=0.3476, p<0.05). The assessment of intraocular gas level by ultrasonography seems to be easier and more objective method than others previously reported.
Absorption* ; Gases ; Humans ; Intraocular Pressure ; Intravitreal Injections ; Rabbits ; Sulfur ; Ultrasonography ; Vitrectomy

The retrospective study of 231 eyes which were underwent the vitrectomy for the proliferative diabetic retinopathy was done. The purpose of this study was to identify the factors associated with visual prognosis and to understand the clinical features of traction-rhegmatogenous retinal detachment in diabetic retinopathies. The functional outcome of vitrectomy in these group revealed 44.6% of visual improvement, 40.3% of visual constancy and 15.1% of visual deterioration. Anatomically, 55.8% of eyes in these study showed retinal attachment and clarity of ocular media, postoperatively. The preoperative factors associated with visual outcome were vitreous hemorrhage land retinal detachment. The postoperative factors were hyphema, iatrogenic break formation and rubeosis iridis. Preoperatively and intraoperatively, retinal breaks were found in 43 eyes among 142 eyes of retinal detachment. In 43 eyes, 39 eyes showed only one break. The site of retinal breaks was majorly at posterior pole and the shape of breaks showed no difference between them in frequency. Our clinical data proved that the extent of traction rhegmatogerious retinal detachment was larger than pure traction retinal detachment which has a tendency to be localized at posterior pole. The leading complication after operation was lens opacity(19.3%).
Diabetic Retinopathy* ; Hyphema ; Prognosis ; Retinal Detachment* ; Retinal Perforations ; Retinaldehyde* ; Retrospective Studies ; Traction ; Vitrectomy* ; Vitreous Hemorrhage

Effect of silicone oil in vitreous cavity of the rabbit was studied with electroretinogram. Pars plana vitrectomy was performed bilaterally in nine white rabbits, and they were divided into 3 groups. 1.6~1.7 cc of silicone oil was injected in right eye in 1st group, 0.8 cc of silicone oil was injected in right eye in 2 nd group, and 0.8~1.0 cc of silicone oil was injected in right eye after retinal tear was made in 3 rd group. Left eye in each group was used as a control. Photopic and scotopic electroretinographic studies were performed in both eye of rabbits preoperatively and postoperatively 2 days, 1 week, 2 weeks, 3 weeks, and 4 weeks. In each group, a and b-wave amplitude was decreased in silicone oil injected eye compared to control eye at postoperative 2 days, and was increased to normal amplitude at postoperative 4 weeks in both photopic and scotopic electroretinograms. Implicit time of a and b-wave was not affected in each group. Above results suggest that rabbit electroretinogram is not affected by intravitreal silicone oil until postoperative 4 weeks.
Rabbits ; Retinal Perforations ; Silicone Oils* ; Vitrectomy

To investigate the retinal hemodynamics in branch retinal vein occlusion (BRVO), we measured retinal circulation times using scanning laser ophthalmoscope (SLO) and studied their relationships with clinical findings. Arm-retina time (ART) and arteriovenous passage time (AVP) were measured in 30 eyes of 30 patients. Mean ART was 13.07 seconds. ART showed no difference in relation to sex and systemic diseases, but increased with age. Mean AVPs were 3.00 sec. and 3.39 sec. in superotemporal and inferotemporal BRVO, respectively. AVPs were delayed significantly in occluded branch of retinal veins. AVP was delayed three-fold when the area of capillary nonperfusion was over 6 disc area, but showed no difference according to the duration of disease or macular edema. These results suggest that SLO may be a useful tool for studying retinal hemodynamics in BRVO.
Adult ; Aged ; Blood Circulation ; Female ; Humans ; Lasers/diagnostic use ; Male ; Middle Aged ; Ophthalmoscopes ; Regional Blood Flow ; Retinal Vein Occlusion/complications/*physiopathology ; Retinal Vessels/*physiology

In the process of closing scleral wounds caused by various conditions, incarceration of conjunctiva, Tenon's capsule, or vitreous in the wound can occur unexpectedly. We created such conditions experimentally in order to discover their intraocular complications. The experimental materials consisted of 12 albino rabbits (24 eyes) divided into two groups (Groups I & II). Vitrectomy was performed in the Group I rabbits (12 eyes) but not in the Group II rabbits (12 eyes). Flaps of conjunctiva and Tenon's capsule were made and inserted into the vitreous cavity through the sclerotomy site, which was soon closed. Fundal examination of the rabbits was carried out using an indirect ophthalmoscope at intervals after the procedure; first at 3 days, then at 1, 3, and 6 weeks, and then at 3 months and 6 months, respectively. Enucleation of the rabbits' eyes 4 from two different rabbits at each of these intervals was carried out, and the extracted eyes were examined under a light microscope at each interval. The results are summarized as follows: 1. All rabbit eyes studied showed intraocular fibrovascular proliferation. 2. The extent of tissue proliferation, which was proportional to the amount of vitreous hemorrhage, was greater in Group II than in Group I. 3. The proliferated tissue developed to "band" by three weeks postexperiment, after which it gradually regressed. 4. The fibrovascular band was made of fibroblasts, stromal matrix, and capillaries.
Animals ; Cell Division ; Conjunctiva/pathology ; Eye Injuries/surgery ; Fundus Oculi ; Postoperative Complications ; Rabbits ; Retinal Diseases/pathology ; Retinal Vessels/*pathology ; Sclera/*surgery ; Vitrectomy ; Vitreous Hemorrhage/pathology