| BackgroundVitreous hemorrhage is not an independent disease,but a common complication with vision damage caused by the entry of blood into the vitreous cavity after various pathologies.The results of different etiologies are different.The blood absorption is related to the site and volume of hemorrhage,the state of vitreous body,the function of retinal choroid and so on.If the amount of bleeding is less,or pre-retinal hemorrhage,it can absorb quickly.Whereas,if the amount is large,it will lead to difficulty for absorption.However,once vitreous liquefaction or vitrectomy occurs,the absorption could accelerate obviously.The condition can recover effectively only by treating timely and appropriatly,which selected according to the primary disease,volume of vitreous hemorrhage and eyes response.But,there is still controversy over the outcomes of VH and its damage to the retina in the clinic.Objectives1.To analyze the natural outcomes,biomechanical and physicochemical properties and ultrastructural changes of VRI in different stages after experimental VH in rabbits,so as to provide reference evidence for course tracking of VH,selection of operative time and prevention of complications.2.To compare the changes in electroretinogram?ERG?and retinal ultrastructure at different time points in rabbits with experimental VH,in order to analyze the effect on retina function,and further provide a reference for seeking ways to avoid retinal damage and prognosis.Methods1.The autologous blood of 0.2 ml was injected intravitreally to the right eyes of 32 New Zealand white rabbits,and the left eyes as the control groups.The rabbits were divided into four groups randomly,and each group was selected on 3 days,7 days,14 days and 30days after injection for obseaving with slit lamp and ophthalmoscope respectively,and to judge the absorption in different stages by Forrester method.Then the degree of liquefaction and viscosity in the vitreous were measured,followed by analysis biochemical indicators such as electrolyte,total protein,PCT and bFGF,and finally to observe the ultrastructure of VRI by scanning electron microscope.2.To construct the model of VH with 8 New Zealand white rabbits,then the model rabbits were mydriasis fully and dark adaptation for 3 hours on day 3,7,14 and 30 after modeling,respectively.The changes of ERG waveform was recorded with a RETI-Scan Multi-focus videography system.To sacrifice the rabbits soon after and the eyeballs were removed immediately.Finally the specimens of choroidal retina with posterior polar and equatorial regions,2 mm×5 mm,were made and the ultrastructure in each layer of retina was observed under a transmission electron microscope.Results1.Natural course of disease:There was no significant difference between binocular intraocular pressure at each time points by independent sample t test?P>0.05?.Day 3after modeling,the blood coagulated,boundary clearer,and the red reflection disappeared.We found that the vitreous became cloudy which would cause blur of the fundus observation on day 7.Day 14 after modeling,the color of the product pale,visible membrane occurred with vitreous liquefaction and posterior space transparent,the ringed turbidity could be shown in front of retina.Day 30 after modeling,the range of VH reduced and blurred,shown no blood clot and dim slightly.Meanwhile,all experimental eyes was classified according to Forrester classification,grade??for day 3,the day 7and day 14 with grade??based,mostly grade?for day 30.But the controls were mainly by grade?at each stage.2.Biomechanical properties:There were significant differences between binocular degree of liquefaction on day 7,14 and 30 after modeling?P<0.05?.Compared with the degree of liquefaction on day 3,it increased significantly in the latter three time points?P<0.01?.Moreover,there was slight increase trend for the degree of liquefaction in the controls,the differences between day 30 and day 3 were statistically significant by t test?P<0.05?.Through test t,the differences between the length of binocular vitreous gel bundle were statistically significant?P<0.001?.3.Biochemical research:The Fe2+,K+and TP for studied eyes were increased significantly on day 3,and independent sample t test showed that the differences between two eyes was statistically significant?P<0.05?.On day 7,all the above index values rose up to the peak,which recovered and closed to the control ones on day 14 and 30?P>0.05?.The value of bFGF increased gradually and the differences began to be statistically significant on day 14 after modeling?P<0.05?.4.Ultrastructure of VRI under scanning electron microscopy:SEM showed that incomplete PVD accounted for 1/8?12.5%?,2/8?25%?,5/8?62.5%?and 6/8?75%?on day3,7,14 and 30 after modeling respectively,and complete PVD accounted for 0/8,1/8?12.5%?,1/8?12.5%?and 2/8?25%?respectively.However,it was found no PVD among the control eyes at all time points.To analyze the incidence of incomplete PVD in both eyes,it showed that the studied eyes had occurred on day 3 after modeling?1/8?,but the incidence increased distinctly?5/8?on day 14 with a statistically significant for the differences between two eyes?P<0.05?.5.Changes of waveform for Electroretinogram:The ERG waveforms disappeared when stimulated by a standard-flash light condition to the studied eyes on day 3 after modeling,whereas the waveforms could be detected by a strong-flash light condition.With the standard-flash light,amplitudes of ERG-b waves began to appear on day 7,which was73.9%of the control eyes.It recovered gradually,but still lower than that of the control ones on day 14?P<0.05?.The amplitudes of b waves were closed to that of the control eyes on day 30 finally?P>0.05?.The amplitudes of ERG-a waves and b waves for studied eyes both were lower significantly than that of the control groups on day 3 after modeling by bright-flash light conditions?P<0.01?.The amplitudes of a-waves recovered obviously on day 30,which showed no significant difference from the control ones?P>0.05?but statistically differences from that on day 14?P<0.05?.The amplitudes of b-waves began to rise up on day 7,which had no significant difference compared with the control ones?P>0.05?,but statistically differences from that on day 3?P<0.05?,and which closed to normal value on day 14 and 30.6.Ultrastructure of retina under transmission electron microscopy:TEM showed us that there were remnants of necrotic cells under inner limiting membrane,and the mitochondria had been vacuolated denaturation in optic nerve ganglion cells of inner and outer nuclear layer.The structure of photoreceptors of cone and rod cells was loose and the cell nuclear membrane was incomplete.Whereas,there was no obvious abnormality in the control eyes.Conclusions1.Vitreous hemorrhage can cause irreversible damage to the structure and function of vitreous body in rabbit eyes.Changes of characteristics of vitreous body are not obvious within two weeks.But extensive vitreous liquefaction,PVD and PVR formation can be seen after that point,which indicats the ideal timing of surgical treatment.2.It can disturb the retinal function mildly and reversibly about one week after VH.The retinal structure was damaged partially after one month,but it did not affect the recovery of retinal function,which provided a reference for the experiment and clinic to judge the role of vitreous hemorrhage on retina. |
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