OBJECTIVETo investigate the injury in the retina of rats exposed to n-hexane.

METHODSThirty-two SD male rats were randomly divided into control group and four n-hexane groups. The rats in the four n-hexane groups inhaled 35.2 g/m3 n-hexane statically for 1, 3, 7 and 14 days respectively (6 rats in every group) while 8 rats in the control group inhaled air. Histopathology and ultrastructure changes of the retina of rats were analyzed.

RESULTSRats in control group had clear layers of retinal structure, stained evenly and with regular cell shape. Retinal degeneration was observed in the rats exposed to n-hexane for 7 d and 14 d, and aggravated by degrees with time exposed to n-hexane. In the rats exposed to n-hexane for 14 d, the outer segments of photoreceptor were arranged in a confusing order, and topically there appeared dissolution; in the inner segments, mitochondria were swollen or disappeared. Pyknotic chromatin and cytoplasmic edema were observed in the outer nuclear layer. There were degeneration of horizontal cells, bipolar cells and amacrine cells in the inner nuclear layer. Cytoplasmic edema and organelle dissolution were observed in ganglionic cells. In the neurofibromas layer, outer and inner plexiform layers, there was neuron cell tuber edema, and the microfilament and vacuole of synapse decreased.

CONCLUSIONThe histopathology and ultrastructure of retina are damaged in the rats exposed to n-hexane, thus leading to ocular fundus disease.

Animals ; Hexanes ; toxicity ; Male ; Rats ; Rats, Sprague-Dawley ; Retina ; drug effects ; pathology ; ultrastructure

To simulate the posterior vitreous detachment (PVD) in the rabbit, 1 IU hyaluronidase and/or 0.2 ml of perfluoropropane gas was intravitreally injected. Ophthalmoscopic, light microscopic examination prepared by cryotechnique, electron microscopic examination, and electroretinogram were done on the 3rd and 28th postoperative days. As a result, the eyes undergone simultaneous intravitreal injection of 1 IU hyaluronidase and 0.2 ml perfluoropropane gas showed membranous structure split from the internal limiting membrane of the superior retina in 3 days after injection. The eyes also demonstrated membranous structure separated from the superior retina after 28 days, simulating vitreous detachment. On the contrary, neither agent alone induced vitreous detachment. No toxic retinal changes associated with simultaneous intravitreal injection of 1 IU hyaluronidase and 0.2 ml perfluoropropane gas were observed. Therefore, with a future support by histologic examination other than cryotechnique and by immunohistochemical analysis, the simultaneous intravitreal injection of perfluoropropane gas and hyaluronidase would be a promising method to induce vitreous detachment in non-vitrectomized eye.
Animals ; Drug Combinations ; Electroretinography ; Eye Diseases/chemically induced/pathology ; Fluorocarbons/*toxicity ; Hyaluronoglucosaminidase/*toxicity ; Injections ; Rabbits ; Retina/drug effects/physiology ; Vitreous Body/*drug effects/pathology

OBJECTIVETo study the effect of Vaccinium uliginosum L., (VU) on the electroretinogram (ERG) and retinal pathological changes in rabbits after light-induced damage.

METHODSTwenty-eight Chinchilla rabbits were randomly divided into four groups: administration beforehand (A), administration after injury (B), light injury without administration (C), and blank (D) groups. After a 4-week administration of VU homogenate at 4.8 g/(kg·d) once a day in group A, ERG in groups A, B and C were recorded according to the standards set by the International Society for Clinical Electrophysiology of Vision (ISCEV). Except for group D, the groups were then exposed to strong light. Just after that, group A stopped receiving VU treatment and group B started to receive it. Then ERGs in all groups were recorded after 1 day, 1 week, and 2 weeks. Throughout the whole process groups which were not fed with VU were fed with normal saline. Finally, the tissues and structures of all the groups were observed and the thickness of the outer nuclear layers (ONL) was measured.

RESULTS(1) After 4-week feeding with VU, the latency time of ERG in group A became shorter than those in the other groups and the amplitude increased. After being exposed to strong light, the latency time lengthened and amplitude decreased in all the injury groups, but comparing at each time point, the measured values in group A were better than those in group C. With the accumulation of VU, the ERG in group B improved, and finally, all of the detected values became better than those in group C. (2) Retinae in group D were normal in histology and the layers were in order but those in group C became disarranged. The injuries in groups A and B were minor compared with those in group C. The thickness of the ONL in group C was significantly thinner than in the other groups (P=0.000), and that in groups A and B was thicker than that in group C, although thinner than in group D. That in group A was thicker than in group B.

CONCLUSIONSVU can relieve the injury to rabbit retinae exposed to normal day and night rhythm, alleviate the harm caused by light when used beforehand, and repair the light damage to the retina.

Animals ; Electroretinography ; Light ; Plant Extracts ; pharmacology ; Rabbits ; Retina ; drug effects ; pathology ; physiopathology ; radiation effects ; Retinal Cone Photoreceptor Cells ; drug effects ; pathology ; radiation effects ; Retinal Rod Photoreceptor Cells ; drug effects ; pathology ; radiation effects ; Time Factors ; Vaccinium ; chemistry

Intravitreal fibrin clots were produced by intravitreal injection of 0.2 ml of autologous plasma in 62 rabbit eyes. The intravitreal injection of 0.25 micrograms or more of tissue plasminogen activator(tPA) resulted in a total clearing of intravitreal fibrin within one day in all treated eyes. This was significantly faster than in the control eyes, in which complete clearing was not seen until 8 days later. This represents the plateau on the dose-response curve in doses ranging from 0.25 to 200 micrograms. With light microscopy and transmission electron microscopy, retinal toxicity was demonstrated in eyes enucleated seven days after injection of 25 micrograms or more of tPA. This study demonstrates that tPA was effective and safe at 12.5 micrograms or less in clearing intravitreal fibrin in an experimental model. These results suggest that low dosages of tPA, probably of 3 micrograms or less, may be useful in the treatment of severe postvitrectomy fibrin formation seen clinically.
Animals ; Disease Models, Animal ; Dose-Response Relationship, Drug ; Fibrinolysis/*drug effects ; Rabbits ; Retina/drug effects/pathology ; Tissue Plasminogen Activator/*toxicity ; *Vitreous Body

BACKGROUNDPhotodynamic therapy (PDT) has been recommended as a main treatment for idiopathic choroidal neovascularization (I-CNV). But the visual results of PDT were inconsistent and variable, and PDT may bring severe damage to the retinal pigment epithelium and choriocapillaries. In recent years, intravitreal ranibizumab therapy, showing favorable visual outcomes, has developed as an advanced treatment for choroidal neovascularization (CNV). Although both methods have been reported to be effective in treating I-CNV, there is no detailed comparative report between the two methods. This study aimed to compare visual outcomes, retinal and choroidal thickness between intravitreal ranibizumab therapy and PDT in the treatment of I-CNV, and investigate the correlation of visual outcomes with retinal and choroidal thickness in each of the two groups.

METHODSThirty-seven eyes of 37 patients with I-CNV were involved in this study; 19 eyes were treated with intravitreal ranibizumab therapy and 18 eyes were treated with PDT. The best corrected visual acuity (BCVA) was recorded before and at each follow-up visit after treatments (logMAR). Enhanced-depth imaging optical coherence tomography (EDI-OCT) was used to evaluate the retinal structural changes, and to measure central retinal thickness (CRT) and central choroidal thickness (CCT).

RESULTSMean BCVA was 0.64 ± 0.27 in PDT group and 0.69 ± 0.22 in ranibizumab group at baseline (P = 0.55). When compared with the baseline, mean BCVA in PDT group was improved significantly at 3-month after PDT (0.41 ± 0.16, P = 0.002), then changed little (0.42±0.25 at 12-month, P = 0.88). Whereas mean BCVA in Ranibizumab group was improved significantly at each follow-up visit. It improved much more obviously in the first month and then remained stable. The mean BCVA in the ranibizumab group was significantly better at each follow-up visit than that in PDT (P < 0.05). When compared with the baseline, mean CRT in PDT group decreased significantly since 3-month visit, whereas mean CRT in ranibizumab group decreased significantly from 1-month visit. Mean CRT at 1-month and 3-month decreased much more in ranibizumab group than that in PDT group, almost in the same period as BCVA improving. When compared with the baseline, mean CCT did not change significantly at each follow-up visit in each group (P > 0.05). The CCT difference was not statistically significant between the two groups at each same time visit (P > 0.05). Mean BCVA was correlated with CRT, but was not correlated with CCT.

CONCLUSIONSBoth intravitreal ranibizumab therapy and PDT are effective for the treatment of I-CNV. It is obvious that ranibizumab therapy is significantly superior to PDT in improving BCVA and decreasing CRT. CRT decreases much more rapidly in ranibizumab group than in PDT group, simultaneously with visual improvement. CRT reduction has significant correlation with the visual outcomes in the recovery of I-CNV, whereas BCVA prognosis may have no correlation with CCT. CCT is not changed significantly after each of the treatments. Both PDT and ranibizumab therapy may have no significant effect on choroid.

Antibodies, Monoclonal, Humanized ; administration & dosage ; therapeutic use ; Choroidal Neovascularization ; drug therapy ; therapy ; Female ; Humans ; Intravitreal Injections ; Male ; Photochemotherapy ; methods ; Ranibizumab ; Retina ; drug effects ; pathology ; Visual Acuity ; drug effects

OBJECTIVETo investigate the effect of carbon disulfide (CS2) on inducible nitric oxide synthase (iNOS) and apoptosis in in the retina of rats.

METHODSTwenty-four male SD rats were randomly divided into 3 groups the control group, the group receiving high-dose CS2 and the group receiving low-dose CS2. After treatment, retina were harvested and made into slice. The thickness of inner retina including outer plexiform layer, inner nuclear layer, ganglion cell layer, optic nerve fiber and inner limiting membrane was measured. Expression of iNOS in retina was measured by NADPH-NDP histochemical assay. Apoptosis was detected by terminal deoxynucleotidyl transferase mediated dUTP nick end labeling (TUNEL).

RESULTS(1) The thickness of inner retina decreased in groups receiving CS2. There was significant difference between control group and groups receiving CS2 (P < 0.05). There was also significant difference between group receiving high-dose CS2 and group receiving low-dose CS2 (P < 0.05). (2) The expression of iNOS increased in groups receiving CS2. There was significant difference between control group and groups receiving CS2 (P < 0.05 or P < 0.01). There was also significant difference between the group receiving high-dose CS2 and the group receiving low-dose CS2 (P < 0.05). (3) Apoptosis was observed in groups receiving CS2. There were significant differences in apoptosis index between the control group and groups receiving CS2 (P < 0.05 or P < 0.01). There was also significant difference between the group receiving high-dose CS2 and the group receiving low-dose CS2 (P < 0.05).

CONCLUSIONSCS2 can evoke the expression of iNOS, and the nitric oxide thus produced can be one of the causes of retina destruction. And apoptosis is also one of the causes of retina destruction.

Animals ; Apoptosis ; drug effects ; Carbon Disulfide ; toxicity ; Male ; Nitric Oxide Synthase Type II ; metabolism ; Rats ; Rats, Sprague-Dawley ; Retina ; drug effects ; enzymology ; pathology

OBJECTIVETo study toxic effects of 2,5-hexanedione (2,5-HD) on pathology and lipid peroxidation in mouse retina.

METHODSForty-eight mice were randomly divided into blank control group (12 mice), negative control group exposed to normal solution (12 mice) and group exposed to 2,5-HD for 2. 4 and 8 weeks, respectively (24 mice) by intraperitoneal injection (2.5% 2,5-HD) at the dose of 400 mg/kg. The pathological changes of mouse retina were examined under light microscope. The activity of superoxide dismutase (SOD) and the level of malondialdehyde (MDA) in mouse retina were detected.

RESULTSThe retinal structure in the blank and negative control groups was normal. In mice exposed to 2,5-HD for 8 weeks, the swelling of outer and inner segments and disorder arrangement of the segments without clear boundary were found. The staining of outer plexiform layers was uneven and the irregular loose structure appeared. The hyperchromatic pyknotic and necrosis nuclei were presented in ganglion cells layer. Compared with the control and blank groups, the activities of SOD gradually and significantly reduced and the concentrations of MDA increased in group exposed to 2,5-HD (P < 0.05).

CONCLUSION2,5-HD can induce the injury of retina tissues of mice, which may be associated with the lipid peroxidation.

Animals ; Hexanones ; toxicity ; Lipid Peroxidation ; drug effects ; Malondialdehyde ; metabolism ; Mice ; Mice, Inbred Strains ; Retina ; drug effects ; metabolism ; pathology ; Superoxide Dismutase ; metabolism

This study was designed to determine the maximal safe drug concentration of intravitreal ciprofloxacin in phakic rabbit eyes. Twenty-two eyes of New Zealand pigmented rabbits received midvitreal ciprofloxacin of 100, 200, 400, 600 or 800 microgram in BSS Plus, or BSS Plus only. Retinal toxicity was dose-dependent as determined with electroretinography, light microscopy, and transmission electron microscopy. At a dose of greater than 400 microgram, disorganization of the outer segments was a main pathological finding in transmission electron microscopy. We evaluated retinal function by measuring the electroretinograms for a graded series of flash intensities and by fitting electroretinogram b-wave amplitudes to the Naka-Rushton equation. At a dose of greater than 600 microgram, Rmax was significantly decreased and log K was significantly increased. N-value tended to decrease. A decrease of b-wave amplitudes caused by retinal toxicity could be detected very sensitively with lower luminance stimuli. Determination of retinal toxicity with lower luminance electroretinography revealed a significant decrease of b-wave amplitudes at a dose of greater than 400 microgram. We concluded that a safe dose of intravitreal ciprofloxacin in phakic rabbit eyes was 200 microgram in phakic eyes.
Animals ; Ciprofloxacin/administration & dosage/*toxicity ; Dose-Response Relationship, Drug ; Electroretinography/drug effects ; Injections ; Lens, Crystalline ; Photic Stimulation ; Rabbits ; Retina/*drug effects/pathology/physiopathology ; Rod Cell Outer Segment/drug effects/pathology ; Vitreous Body

Acetates ; pharmacology ; Animals ; Bicarbonates ; pharmacology ; Drug Combinations ; Endothelium, Corneal ; drug effects ; pathology ; Female ; Glutathione ; pharmacology ; Hydrogen-Ion Concentration ; Minerals ; pharmacology ; Ophthalmic Solutions ; pharmacology ; Rabbits ; Retina ; drug effects ; pathology ; Sodium Chloride ; pharmacology ; Vitreous Body ; drug effects

Animals ; Cells, Cultured ; Ginkgo biloba ; Glutamic Acid ; toxicity ; Immunohistochemistry ; Membrane Potentials ; drug effects ; Mitochondria ; drug effects ; physiology ; Neurons ; drug effects ; Neuroprotective Agents ; pharmacology ; Plant Extracts ; pharmacology ; Rats ; Rats, Sprague-Dawley ; Retina ; drug effects ; pathology