Abstract
Purpose: :
To create an experimental model for investigating the causes of infantile retinal haemorrhage (RH).
Methods: :
14 day old rat pups were anaesthetised with 0.3 µg/kg body weight fentanyl citrate, 10 µg/kg fluanisine injected sub-cutaneously and either: subjected to rapid rotary shaking (RS) for two minutes, bilateral jugular vein ligation (JVL) or used as controls. All pups remained deeply anaesthetised for 30 minutes before receiving a lethal injection of sodium pentobarbitone followed by immediate eye removal. Eyes were placed into phosphate buffered 4% formaldehyde for one hour. The eyes were then stored in PBS. The retinas were flat mounted on slides, incubated in 0.05%DAB/0.01% H2O2 in PBS for 30 minutes to stain red blood cells, washed, dried and coverslipped. The presence of RH and the cross sectional area of hemorrhage per area of retina were recorded.
Results: :
RH was present in all three groups. Mean number of RH in Control retinas was 1.5 (n=6 + 0.74 95% CI) in JVL 2.83 (n=6 + 2.5) in RS 1.83 (n=6 + 1.06). Thus pups undergoing JVL had a greater number of hemorrhage on average but this was not statistically significant. The mean area of RH as a percentage of total retinal area for controls was 0.28 (+ 0.23) for JVL was 0.91 (+ 0.46) and for RS was 1.24 (+ 0.66). Thus our experimental interventions appeared to increase the size of the hemorrhage; one way ANOVA analysis showed a significant difference between experimental groups (p<0.05) but post hoc analysis failed to show significant differences between individual groups.
Conclusions: :
These preliminary findings suggest that it may be possible to increase the incidence and size of RH’s in an experimental animal model. The observation that control groups developed RH may be attributable either to a natural incidence of RH in neonatal rat pups or to relative levels of hypoxia related to general anaesthesia. Both experimental interventions appear to have a sizeable effect indicating that infantile RH could be attributed to either an increase in central venous pressure or violent shaking.
Keywords: retina • pathology: experimental