Purpose:
To evaluate the effect of intravenous methylprednisolone on IOP during OCS.
Methods:
Thirty-three Sprague-Dawley rats were randomly divided into 3 treament groups: intravenous saline, moderate dose methylpredisolone (5mg/kg), and high dose methylprednisolone (30mg/kg) every 6 hours (hrs) for 24 hrs. The rats were treated with isoflurane, ketamine/ace coctail 0.1ml/100g, and topical Alcaine to ensure adequate anesthesia. A 27 gauge needle on a 1cc TB syringe were used to draw 0.8 cc of autologous blood. Indirect ophthalmoscopy was used to visualize the optic nerve and retinal arteries. A 25 gauge needle was then used to inject autologous blood into the retroorbital space until cessation of flow within the retinal arteries was noted. The right orbit of each animal was injected. Following creation of the OCS, the assigned treatment regimen was started. Intraocular pressure was assessed before injection, 5 minutes after injection, at 90 minutes, 6 hrs, and 24 hrs using a Medtronic Tonopen. Isoflurane was used for all measurements to ensure accuracy. Statistical analysis of IOP was performed using two-way ANOVA.
Results:
The mean IOP was 7.0 ± 3.3 mm Hg (p=0.554) prior to injection and 49.1 ± 20.7 mm Hg (p=0.949) following injection. There were no statistically significant differences in IOP as measured at 90 minutes (p=0.866), 6 hours (p=0.454), and 24 hours (p=0.701) between treatment groups. Table 1 lists the average IOP for treatment groups. The mean weight of each rat was 465 ± 204g (p=0.966).
Conclusions:
There was no statistically significant difference of IOP after treatment with moderate or high-dose methylprednisolone in orbital compartment syndrome
Keywords: trauma • intraocular pressure • drug toxicity/drug effects