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 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*

Retinal neurons are highly vulnerable to hypoxia/ischemia. Excitotoxicity and free radical injury have been proposed as the major mechanisms of ischemic retinal injury have been proposed as the major mechanisms of ischemic retinal neuronal death. In the present study, we examined these possibilities in retinal cultures. Exposure of these cultures to hypoxia for 48 hr induced selective death of neurons. Addition of an antioxidiant trolox markedly attenuated hypoxiainduced retinal neuronal death, whereas addition of glutamate antagonists, MK-801 or CNQX,did not. Morphologically, hypoxic neuronal death in cultures was accompanied by cell body swelling, a feature of necrosis, yet simultaneously exhibited some features of apoptosis such as TUNEL positivity and protection by cycloheximide. However, unlike in classical programmed cell death, adding buthionine sulfoximine, a potent inhibitor of glutathione synthesis, completely reversed the protective effect of cycloheximide. The results have demonstrated that free radical injury is the main mechanism of neuronal death in the present retinal culture, and suggest an intriguing possibility that free redical injury may become a prominent mechanism, when excitotoxic injury is masked.
Animals ; Anoxia ; Apoptosis ; Buthionine Sulfoximine ; Cell Death ; Cycloheximide ; Dizocilpine Maleate ; Excitatory Amino Acid Antagonists ; Glutathione ; In Situ Nick-End Labeling ; Masks ; Necrosis ; Neurons ; Rats* ; Retinal Neurons* ; Retinaldehyde*

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

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

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

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*