TOPICAL VS. BLOCK With topical anesthesia (left), patients should be sedated enough that they feel comfortable and relaxed, but not so sedated that they fall asleep. While blocks (right) have a higher risk for complications, some surgeons still feel they're safer overall.What's the best way to anesthetize cataract patients — topical anesthesia or nerve blocks? Regardless of your preference, intravenous sedation given beforehand helps reduce anxiety and keep patients comfortable. It also helps patients hold relatively still, as long as you don't administer too large of a dose. Administer too much and patients may fall asleep and either snore — moving their heads slightly when they do — or suddenly wake up and jerk their heads, momentarily unaware of their whereabouts. Beyond that, the topical block debate depends on several factors. Let's look at some of the considerations.
Is eye movement OK?
If you choose topical anesthesia, patients will be able to move their eyes, which is fine as far as many surgeons are concerned. The key is that those patients are properly sedated and comfortable. But if you use topical without sedation, you may need to supplement it with an intracameral injection of bupivacaine — an injection within the anterior chamber of the eye. Typically, that's enough to keep patients comfortable, because the procedure will likely be completed well before the anesthetic wears off. On the other hand, surgeons who prefer no eye movement will likely opt for blocks, as will surgeons performing longer or more complex cases. The speed at which the surgeon works is also a consideration. A phacoemulsification with an intraocular lens implant may take anywhere from 10 to 30 minutes.
Block types
Although other types of blocks are also used occasionally — including the Sub-Tenon's (episcleral) block and the van Lint (lid) block — the blocks of choice for cataract surgery remain the retrobulbar and the peribulbar.
- Retrobulbar blocks. They involve injecting local anesthetic inside the muscle cone. They block the ciliary nerves, ciliary ganglion, and cranial nerves III, IV and VI. They're usually deeper than peribulbar blocks and require less volume to attain the goal of no movement and no pain.
- Peribulbar blocks. They're usually injected above or below the orbit. The anesthetic solution is deposited within the orbit, but doesn't enter the muscle cone, which makes them safer overall than retrobulbar blocks.
Incidentally, general anesthesia should probably be used only as a last resort — with pediatric patients and/or with patients who can't tolerate blocks, or who can't hold still. More on that later.
