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 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*

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

ERG was checked by an instrument set up by authors in eyes with vitreous opacity with and without retinal disorders. It is composed of a preamplifier(frequency response of 0.3Hz~240Hz, gain of 80 decibel), Tektronix 5103N oscilloscope(with 5A18N dual trace amplifier and 5B12N dual time base). Retina was stimulated by Grass P22 photostimulator at settings of 1, 4, 8, and 16 light in tensities. Following findings were obtained; 1. Voltage of a-wave was much increased with little change of b-wave, when intensities of photostimulation was increased. 2. Definite ERG waves were recorded with high intensities of light stimulation, when low intensities failed to produce them. 3. Even in high intensities of light stimulation, oscillatory potentials were not recorded. 4. In case of diffuse retinal damage and vitreous opacities, peak time of a and b wave were markedly delayed as well as decrease of voltages.
Electroretinography* ; Poaceae ; Retina ; Retinaldehyde

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*

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*

Experimental total retinectomy was performed in pigmented rabbit eyes to in vestigate its long-term effects on the operated and nonoperated opposite eyes from both clinical and histological aspects. There was no significant change in intraocular pressure between the preoperative and postoperative measurements during the six months after surgery. Rubeosis iridis, intraocular hemorrhage and phthisis bulbi were not evident in the operated and opposite eyes. Light microscopic examination revealed congestion of the choroidial vessels. There were scattered areas of retinal pigment epithelial cell proliferation. Transmission electron microscopic examination showed apiral mounding of the retinal pigment epithelium. Apical processes were short and reduced in number. Apical processes of the retinal pigment epithelial cells interdigitated with surface processes of the proliferating retinal pigment epithelial cells. There were numerous melanosomes in the cytoplasm of the proliferating retinal pigment epithelial cells. Cell junctions between the retinal pigment epithelial cells were well preserved.
Animals ; Intraocular Pressure ; Longitudinal Studies ; Pigment Epithelium of Eye/ultrastructure ; Prognosis ; Rabbits ; Retina/*surgery

We examined excitotoxicity, putatively a major mechanism of ischemic neuronal death, in primary rat retinal cultures. Retinal cultures were prepared from newborn rats (day 1 or 2). Exposure of these cultures (DIV8-10)to NMDA or kainate induced neuronal death. Furthermore, MK-801 or CNQX each partially attenuated glutamateinduced neuronal death, suggesting that both NMDA and kainate receptors mediate it. Thy-1(+) retinal ganglion neurons, like neurons as a whole, were equally injured by NMDA and by kainate. However, GABA(+) or calbindin (+) neurons of the inner nuclear layer were resistant to NMDA, but highly vulnerable to kainate. These neurons may have AMPA/kainate receptors that are highly permeable to Ca2+, as they take up cobalt with kainate stimulation. These results suggest that the AMPA/kainate receptor, rater than the NMDA receptor, may mediate this pattern of selective neurnonal death.
6-Cyano-7-nitroquinoxaline-2,3-dione ; Animals ; Calbindins ; Cell Death* ; Cobalt ; Dizocilpine Maleate ; GABAergic Neurons ; Ganglion Cysts ; Humans ; Infant, Newborn ; Kainic Acid ; N-Methylaspartate ; Neurons ; Rats ; Receptors, Kainic Acid ; Retinal Neurons* ; Retinaldehyde*