|Year : 1972 | Volume
| Issue : 3 | Page : 95-100
Role of intravitreal air in the resolution of vitreous haemorrhages--a radioisotope study
IS Jain1, RK Singla1, RR Sharma2, SD Gupta1
1 Department of Ophthalmology, Postgraduate Institute of Medical Education and Research, Chandigarh, India
2 Department of Biophysics, Postgraduate Institute of Medical Education and Research, Chandigarh, India
I S Jain
Department of Ophthalmology, Postgraduate Institute of Medical Education and Research, Chandigarh
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Jain I S, Singla R K, Sharma R R, Gupta S D. Role of intravitreal air in the resolution of vitreous haemorrhages--a radioisotope study. Indian J Ophthalmol 1972;20:95-100
| Introduction|| |
The management of vitreous haemorrhage has been a perplexing problem for the ophthalmologists since 1890. We, in India, have to deal with this clinical problem quite frequently and yet there are no effective remedial measures known which can be confidently offered to this catastrophic blinding condition. The natural resolution of vitreous haemorrhage varied from weeks to years leaving behind permanent residual changes in the retina and vitreous. Complete resolution occurs only rarely.
Conflicting views are expressed in the literature as to the mechanism of absorption of vitreous haemorrhages. Similarly, various forms of therapies have been carried out from time to time, but without any consistently encouraging results. These therapies varied from retrobulbar injection of hyalase, to intravitreal injection of hyaluronidase, deferoxamine  intravitreal injection of alpha chymotrypsin and vitreous replacement with cerebrospinal fluid, saline, pooled vitreous or by lyophylyzed vitreous. 
One of us (I.S.J.) was impressed by the very encouraging results of the role of sub-conjunctival air in the treatment of sub-conjunctival haemorrhages.  Thus, the present investigation was undertaken to study the natural course and the possible mechanism of absorption of artificially induced vitreous haemorrhages in rabbits by tagged whole blood with Cr. 51 The authors have also planned to study the role of intravitreal air on the course and rate of absorption of vitreous haemorrhage.
| Material and Methods|| |
For the experimental study, albino rabbits weighing 1-2 Kg were used. Experiments were carried out in the following way.
Crystamycin drops were put in the eyes of the rabbits one day prior to the experiment. 2-3 cc of blood was taken from the ear vein of the rabbit and collected into heparinized tubes under full aseptic precautions. Then according to the procedure described by GRAY AND STERLING  the tagging was done. The heparinized blood was centrifuged and the plasma was separated from the RBC's .20 u.c. of Cr 51 as sodium chromate-Cr 51 was added drop by drop into the RBC's mass and mixed quickly. This was, with occasional mixing, incubated at 30°C for 30-45 minutes. After incubation normal saline was added and centrifuged. The supernatent was thrown away. Again normal saline was added till no activity came in the supernatent. The plasma was added to the cell mass. The physical half life of Cr 51 is 27.8 days. However, 9 percent of the total emissions is in the form of 320 kev gamma rays. This gamma ray emission was counted in the present experiments using a Nal (TI) crystal scintillation counter. The spectrometer was set to include 295 to 345 keg gamma photons. Lysed tagged blood was prepared by exposing whole blood to ultrasonics for 1 minute at 4 microns peak to peak amplitude.
After the tagging, 0.1 ml. of blood was taken in a sterile syringe for injection. The eye was locally anaesthetised with 1 % anethaine drops and vitreous haemorrhage was simulated as follows:
After fixing the eye with fixation forceps, 0.1 ml of vitreous was aspirated from the rabbit's eye by a 26 gauge needle introduced at the pars plana 5 mm away from the limbus in the superotemporal quadrant. Keeping the needle in place and exchanging the syringe 0.1 ml of tagged whole blood was injected. (Group 1)
In another group (Group II) of six rabbits haemolysed blood was injected with the same technique. In group III, along with the whole blood 0.1 ml of sterlized air was also injected. The needle was kept in place for thirty seconds and then taken out slowly. This prevented leakage of air into the subconjunctival space and the intraocular pressure also did not rise.
In all cases the right eye was used for experiments. The animals in which infection occurred were discarded.
In another group (Group IV) of three rabbits, air was injected on the 4th and 5th days of introduction of whole blood.
A collimated scintillation counter was used for daily counts. The length of the collimeter established a 10cm distance between the eye and the crystal detector, thus, obviating the counting error pointed out by BOYER, SURAN, HOGAN, SCOTT AND MC. EWEN.  In their studies crystal detector was placed in contact with the eye, so the diffusion of radioactive material towards the crystal markedly elevated the number of radiation count. The rate of removal of blood (more specifically, haemoglobin, since Cr 51 tags haemoglobin) was calculated according to the following formula:
A=percentage of radio-activity remaining on X days.
C = number of counts minus background on the day of injection.
C1 = number of counts on X days minus background.
S = number of counts of standard minus background on day of injection.
S1 = number of counts of standard minus background on X days. Percentage of absorption= 100-A.
In addition to daily radiation counts periodic ophthalmoscopic examinations were also made.
| Observations|| |
Tracer Study :[Table - 1]. Graphs 1 and 2)
As is shown in Graph I it was found that the average rate of removal of whole blood from the vitreous cavity occured with a half life of 9.5 days and a quarter life of 21.66 days. For haemolysed blood the half life was 1.45 days and a quarter life of 2.75 days. For air with whole blood the half life was 3.03 days and a quarter life 4.94 days. The Graph clearly demonstrates that the lysed blood and the blood plus air leaves the vitreous cavity at a considerably faster rate than whole blood.
In the fourth group where air was injected on the 4th and 5th day of injection of whole tagged blood, when 21.7% absorption had already taken place-the rate of absorption was considerably hastened to 50%, the following day, whereas it took 9.5 days for the same absorption in the control group.
It was found to be statistically significant at 5% level of significance. 75% absorption was noted after 10.33 days i.e. 6 days after injection of air whereas it took 21.66 days in the control group (Graph II).
This was found to be statistically significant at less than 1 % level of significance. The rate of absorption of haemolysed blood was also much faster and had the same significance level. Graphs I and II show graphic representation of the above observations.
For the first 5-10 days the blood remained in a localised clump with fairly well defined borders. The vitreous then became progressively cloudy due to the escape of erythrocytes, haemoglobin and debris. Leucocytes enter the eye contributing to this diffuse turbidity. Fibrous tract formed along the tract of the injection and in some animals fibrous tissue proliferated from the optic papilla and looked like a white fibrous mass in the centre. The clearing of the vitreous started after 20-25 days and that too in the periphery. Alongwith this, it was noted that the colour of the iris changed in almost all cases from transparent to grey in colour on the second day and vascularisation of the iris was also noted in a few rabbits.
In cases of haemolysed blood no localised clumps formed and the vitreous became completely cloudy after 24 hours and the peripheral clearing was early and faster but change in iris colour and vascularisation was noted in some cases.
In rabbits in which the air and whole blood were injected, the vitreous remained clear for a period of two days. Clot was seen in the centre and air could also be seen in the centre of the vitreous. On the third day the whole vitreous became hazy and even air could not be seen. The resolution in the periphery was faster. Proliferation at optic papilla and injection tract was seen in two cases. Iris changes occured in the same way as in other groups of animals. Almost in all cases residual opacities and floaters were seen in the vitreous.
The animals where cataract formed and infection occured were discarded.
| Discussion|| |
The radioactive studies have made it possible to register the progress of absorption of blood in the vitreous. The earlier studies where only ophthalmoscopic examination was relied upon to observe the course of resolution of vitreous haemorrhage was subjective in nature and thus did not give an accurate idea of mechanism of absorption. Our observations indicate that for the first two days there is hardly any absorption of whole blood; the same is seen when air is injected alongwith whole blood; while the lysed blood showed rapid rate of removal even after the first 24 hours. This observation leads us to conclude that haemolysis plays a significant role in the rapid resolution of vitreous haemorrhage. The group of animals where whole blood plus air was injected in the vitreous, showed rapid resolution like the group of animals where haemolysed blood was injected. This only occured after the initial lag of first 2 days. This observation leads us to postulate that air helps in the lysis of the injected whole blood after an initial variable lag period and thus accelerates the resolution of vitreous haemorrhage.
OKSALA AND AHLAS  heve shown experimentally that the injection of air into the normal vitreous of normal bovine eyes produces larger pockets of liquefaction. CIBIS  from his experience of injection of air in animals as well as human eyes supports the conclusion reported by OKSALA AND AHLAS. He believed that the destruction and liquefaction of the vitreous caused by air may be due to its effects of having different surface tension. The air has a tendency to form bubbles which do not escape easily through smaller opening caused by disruption of continuity of the fibrillar frame work of the vitreous body, larger air bubbles would cause larger disruption and larger pools of liquefied vitreous.
GOMBOS AND BERMAN  studied the effect of intravitreal air and other commonly used vitreous substitutes, Dextran 500, Dextran sulphate 500, Hyaluronic acid, whole centrifuged vitreous or the chemical composition of the vitreous. They noted a considerable loss of hyaluronic acid in all the operated eyes regardless of the type of vitreous replacement used. This escape of hyaluronic acid may be as a result of physical destruction of vitreous by air which gives rise to liquefaction.
Since blood diffuses more rapidly through a liquid medium one would expect that in the presence of liquified vitreous haemorrhage would be absorbed more rapidly. This has also been clinically observed by DAvrs. 
HORVEN AND MYHRE  reported from their experimental studies that BBC's cannot be absorbed into the blood stream intact but have to undergo haemolysis before absorption. GREER et a1  are also of the view that particle size is the most important factor in removal of material from the vitreous and that haemolysis is a rate determining step in the absorption of vitreous haemorrhage. Ophthalmoscopic studies also support the above observations, as a blood clot it seen for quite a few days after the injection of whole blood, while the haemolysed blood diffused throughout the vitreous within 2-3 days. The same ophthalmoscopic appearance was recorded after a lapse of 2 days when air was injected alongwith the whole blood.
Our observations lead us to conclude that liquefaction of vitreous is the process which helps in the resolution of vitreous haemorrhage. If it occurs early, the resolution is rapid, if it develops late the resolution time is proportionately increased. We feel that intravitreal injection of air is an effective, safer and cheapest mode of therapy in the management of vitreous haemorrhage.
| Summary|| |
Management of vitreous haemorrhage has been a perplexing problem for the ophthalmologists, as no satisfactory therapeutic measures are available to cure this blinding catastrophy in the eye.
Albino rabbits were used for study. 0.1 cc of blood was injected into the vitreous after tagging it with Cr. 51
Average rate of removal of whole blood from the vitreous cavity was half life of 9.5 days and a quarter life of 21.66 days. For haemolysed blood the half life was 1.45 days and a quarter life of 2.5 days. For whole blood plus air the half life was 3.03 days and a quarter life of 4.94 days.
The effect of air and haemolysis are found to be statistically significant at less than 1 % level. The observations make us feel that intravitreal injection of air is an effective, safe and cheap mode of therapy in the management of vitreous haemorrhages.
| References|| |
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Gray, S. J. and Sterling, K.: The tagging of red cells and plasma proteins with radioactive chromium. 1. Clin. Invest., 29, 1064, 1958.
Greer, D.; Bensons, W. and Spalter, H.: A study of simulated vitreous haemorrhages using labelled blood. Arch. Ophth. 79, 755-758, 1968.
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[Figure - 1], [Figure - 2]
[Table - 1]