Correct patient, correct eye and correct procedure!
Vitreoretinal surgery can usually be performed under local anesthesia (LA). Choices include retrobulbar, peribulbar, sub-Tenon’s and topical anesthesia. Selecting which type depends on personal preference, prior training and at which stage of the surgery it is required. Commonly, the most painful steps of surgery are the insertion of trocars, scleral depression, cryotherapy and scleral buckling. Better akinesia may be an advantage of peri- and retrobulbar blocks (Figure 1.2), but the latter has been associated with a higher risk of globe perforation and brainstem anesthesia. This has led to a reduction in popularity of retrobulbar LA and increased enthusiasm for sub-Tenon’s LA (Figure 1.3), especially in long eyes. Incomplete or insufficient LAs can be supplemented during the surgery. Mild sedation is helpful during insertion of the LA as well as during the procedure.
Commonly used medications for performing LA include combination of 2% lignocaine and 0.75% bupivacaine hydrochloride, or pure 1% ropivacaine hydrochloride.
(Figure 1.1). Both these options offer good efficacy of anesthesia, with no significant differences in volume of anesthetic required, time to onset of block, perioperative pain scores or frequency of adverse events. However, the lower potential for systemic toxicity of ropivacaine compared with bupivacaine may be advantageous.
Indications for general anesthesia (GA) include children, the non-compliant patient (e.g. dementia or mental retardation), involuntary movements (e.g. head tremor), extreme claustrophobia or anxiety, and globe rupture. It may also be safer in extremely high axial myopes to avoid the risk of globe perforation associated with LA. GA is also preferable for longer procedures (e.g. combined vitrectomy / scleral buckling surgery).
Pre-anesthesia baseline readings of blood pressure, oxygen saturation and ECG should be obtained.
McLure HA, Rubin AP, Westcott M, Henderson H. A comparison of 1% ropivacaine with a mixture of 0.75% bupivacaine and 2% lignocaine for peribulbar anaesthesia. Anaesthesia. 1999 Dec;54(12):1178-82. doi: 10.1046/j.1365-2044.1999.01069.x. PMID: 10594416.
A common LA preparation is a 50:50 combination of 2% lignocaine and 0.75% bupivacaine hydrochloride (Marcaine®), or pure 1% ropivacaine hydrochloride (Naropin®). Hyaluronidase (Hylase® e.g. 500 IU) can be added but can be associated with allergic reactions. The solution should be drawn up in a 10ml syringe on a 25-gauge 25mm (peribulbar) needle. The approach may be transconjunctival or through the skin.
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