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. 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

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*

We investigated fifteen men and twenty one women, who were diagnosed to have asteroid hyalosis between June, 1997 and November, 1997 at Seoul National University Hospital. After obtaining their medical history a complete eye examination was performed. Specimen was examined by light microscope in one case. Funduscopic examination revealed bilateral involvement in 5 cases. Twenty six patients were diabetic and 12 were hypertensive. There was a significant association with diabetes. Light microscopic exam showed variable sized spherical structures with brown rim. Further decrease in visual acuity due to asteroid hyalosis was not observed in 35 cases in which follow-up exams were possible. In conclusion, asteroid hyalosis rarely caused visual loss and were likely to be monocular and to occur in old age.
Female ; Follow-Up Studies ; Humans ; Male ; Seoul ; Visual Acuity

We reviewed 71 cases of silicone oil injection for retinal detachment surgery with advanced proliferative vitreoretinopathy following failed vitrectomy between November 1982 and March 1986 in order to identify the anatomic and functional success rate and its complications. The causes of vitrectomy were as follows: advanced proliferative vitreoretinopathy after retinal detachment surgery and retinal vascular diseases(34 eyes), giant dialysis(10 eyes), severe perforating injuries and intraocular foreign bodies(17 eyes), and traction retinal detachments associated with proliferative diabetic retinopathy(10 eyes). In 71 cases of silicone oil injection, anatomic success rate was 34.8%(23/66) and functional success rate was 16.9%(16/71) and its complications were lens opacities(28.1%, 9/32) in phakia and corneal opacities(20.5%. 8/39) and increased intraocular pressure(17.9%, 7/39) in aphakia.
Aphakia ; Retinal Detachment* ; Retinaldehyde* ; Silicone Oils* ; Traction ; Vitrectomy* ; Vitreoretinopathy, Proliferative*

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

Diabetic maculopathy which is the major cause of blindness in nonproliferative diabetic retinopathy, has been treated clinically with laser photocoagulation. We reviewed 21 cases(26 eyes) of diabetic maculopathy which were treated by focal laser treatment and followed up for more than 6 months from January 1984 to December 1988. The results were as follows: 1. There was improvement of the visual acuity in 19 eyes(71.1%), no changes in 5 eyes(19.2%), and only two eyes(7.7%) showed worsened visual acuity. 2. The two eyes which showed worsened visula acuity after treatment showed stage IV of diabetic maculopathy.
Blindness ; Diabetic Retinopathy ; Light Coagulation ; Visual Acuity

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

In the process of closing a scleral wound caused by various conditions, incarceration af the conjunctiva, Tenon's capsule or vitreous in the wound can occur unexpectedly. We created such conditions experimentally to determine their intraocular complications. The experimental, materials were 12 albino rabhits(24 eyes) and the rabbits were divided into two groups(I and II). Group I rabbits(12 eyes) received no vinectormy and group II rabbits(12 eyes) received a vitrectormy. After the conjunctiva and Tenon's capsule flap was made, the tissue flap was inserted into the vitreous cavity through the sclerotomy site- Fundus examination with an indirect ophthalmoscope and enucleation for histology were performed at 3 days, 1 week, 3 weeks, 6 weeks, 3 months and 6 months after the experiment. The results were as follows: 1, Intraocular fibrovascular proliferation developed in all experimental rabbit eyes. 2. The more vitreous hemorrhage developed, the greater was the fibrovascular proliferation and the degree of fibrovascular proliferation was more marked in group II than group I. 3. The fibrovascular proliferation developed to a band in 3 weeks, then regressed gradually. 4. The fibrovascular band was composed of fibroblasts, stromal matrix and few vessels.
Conjunctiva ; Fibroblasts ; Ophthalmoscopes ; Rabbits ; Tenon Capsule ; Vitreous Hemorrhage ; Wounds and Injuries*