Effect of Volumes of Solutions on Intraocular Pressure During Intravitreal Injection of Low Dose Gentamicin in Horses With Recurrent Uveitis: A Randomized Controlled Study.

This research study investigated the impact of different solution volumes on intraocular pressure (IOP) when treating horses with recurrent uveitis using low dose gentamicin. It concluded that the smaller volume of 5 mL of lidocaine is preferable for retrobulbar block for intravitreal injections while the volumes of 0.15 and 0.30 mL for gentamicin can be used indifferently.

Study Design

• This study is a randomized controlled trial, which is one of the most rigorous designs in clinical research. Horses with recurrent uveitis were treated with low dose gentamicin injections under sedation.
• The study investigated how different volumes of anesthetic solution (lidocaine) and gentamicin can affect intraocular pressure (IOP). This is particularly important as acute increases in IOP can result in secondary retinal degeneration.

Study Findings

• Based on results from a multivariate regression, it was identified that IOP was significantly lower in the pathologic (diseased) eye both at baseline and after sedation. This suggests that the treatment has an effect on reducing IOP.
• However, the study also found that IOP was significantly higher after a 10 mL block, but the impact was very small.
• No significant difference was observed in IOP with the use of either 0.15 or 0.3 mL solution of gentamicin. So, both the volumes were found to be effective.
• The study also notes that there was no significant combined effect of the volume of local anesthetic used for the block and the volume of the gentamicin solution. This indicates that changing the volume of the solutions doesn’t affect the IOP.

Recommendations

• The study found that despite the changes in volumes, desired anesthetic effects were met in all cases. As such, it concludes that the smaller volume of 5 mL of lidocaine solution would be preferable for retrobulbar block for intravitreal injections. This could potentially reduce the risks associated with larger volumes.
• Regarding gentamicin injection, the research determined that the volumes of 0.15 and 0.30 mL can be used indifferently. This allows for flexibility in treatment.

Implications

• The findings from this research can potentially guide veterinarians in choosing the appropriate volume of lidocaine for retrobulbar block and gentamicin for injection when treating horses with recurrent uveitis. This can also be particularly helpful in controlling complications like secondary retinal degeneration due to acute increase in IOP.