effect of retrobulbar anaesthesia on intraocular pressure and ocular blood flow

ABSTRACT

To study the effect of retrobulbar anaesthesia on intraocular presssure [lOP] and ocular blood flow [OBF]. Fourty eyes of 40 patients [who were prepared for cataract surgery] received retrobulbar anaesthesia. The patients were divided into 2 groups group I [retrobulbar anaesthesia without hyaluronidase] and group II [retrobulbar anaesthesia with hyaluronidase]. We measured intraocular pressure [by applanation tonometry] as well as blood flow velocity and resistivity index of central retinal artery and short posterior ciliary arteries [by Doppler sonography] just before anaesthesia, I minute after anaesthesia, and 10 minutes after anaesthesia. Both groups showed significant elevations of intraocular pressure after 1 minute of anaesthetia group I [+ 17.9% +/- 3.7%] and group II [+ 15.8% +/- 3.3%]. However, the intraocular pressure nearly returned back to its pre-anaesthetic measurement after 10 minutes of anaesthesia. As well, both groups showed significant reductions of ocular blood flow. Group I patients [retrobulbar anaesthesia without hyaluronidase] showed a significant drop of peak systolic velocity in both central retinal artery [- 26.6% +/- 8.0%] and short posterior ciliary arteries [- 18.8% +/- 5.2%] in the 1 minute post-anaesthetic measures, as well as a significant drop of peak systolic velocity in both central retinal artery [- 30.5% +/- 7.0%] and short posterior ciliary arteries [- 22.1% +/- 13.9%] in the 10 minute post-anaesthetic measures. Group II patients [retrobulbar anaesthesia with hyaluronidase] showed a significant drop of peak systolic velocity in both central retinal artery [- 22,0% +/- 6.9%] and short posterior ciliary arteries [- 15.1% +/- 5.9%] in the 1 minute post-anaesthetic measures, as well as a significant drop of peak systolic velocity in both central retinal artery [- 26.4% +/- 13.9%] and short posterior ciliary arteries [- 17.2% +/- 10.3%] in the 10 minute post-anaesthetic measures, Retrobulbar anaesthesia results in the reduction of both choroidal and retinal blood flows. Retrobulbar anaesthesia might carry the risk of visual loss in patients with compromised ocular blood flow before surgery. It may be safer to use other anaesthetic techniques [e.g. topical or subconjunctival] in patients with ocular vascular compromise