Ophthalmologic Anesthesia: The Open Globe Pressure

If you’re like me, the open globe case is one where you spend more time explaining your anesthetic choice than actually doing the case. The succinylcholine-IOP debate has been taught so dogmatically that "no succs in open globe" has become a reflex — often without the physiological reasoning attached. On the anesthesiology oral boards, you need more than the reflex. You need to explain why, defend the alternative, and — critically — understand that the entire case (not just the intubation) is an IOP management problem.

The scenario almost always involves a full stomach: penetrating trauma happens unexpectedly, and patients rarely injured their eyes while fasting. So you’re managing an aspiration risk and an IOP risk simultaneously. That’s the conflict, and the examiner is watching how you resolve it.

The Core Logic

IOP is determined by aqueous humor production, outflow resistance, and venous episcleral pressure. Any maneuver that increases venous pressure — coughing, straining, Valsalva, fasciculations — acutely raises IOP. In an intact globe, this is tolerable. In an open globe (lacerated cornea or sclera), a sudden IOP spike can force intraocular contents — iris, lens, vitreous — through the wound. This is vitreous extrusion, and it causes permanent, severe vision loss.

The succinylcholine controversy: it raises IOP by 5-10 mmHg for 5-10 minutes via extraocular muscle contracture. A cough or strain during inadequate intubation raises IOP by 30-40 mmHg for a shorter but more intense period. The question is which risk is greater. In a full stomach patient where intubation failure risks aspiration, the argument for high-dose rocuronium (which provides equivalent RSI conditions) is strong — you get the rapid onset without the IOP risk.

How the Examiner Tests This

Standard scenario: 28-year-old with a nail through the right eye, ate lunch 3 hours ago. "How do you plan to manage this airway?" Your answer structures around: RSI to manage the full stomach, rocuronium 1.2 mg/kg to avoid the IOP spike from succinylcholine fasciculations, video laryngoscopy to optimize first-pass success, and adequate induction depth to prevent coughing on laryngoscopy.

Follow-up probe: "What if the airway looks very difficult — would you still avoid succinylcholine?" This is the hardest version. In a truly difficult airway with full stomach risk, succinylcholine becomes more defensible because the RSI failure risk with rocuronium is higher, and a failed intubation with patient movement is a worse IOP event than succinylcholine fasciculations.

The Board Trap

The induction-only focus trap: residents manage the intubation perfectly and then forget about emergence. The eye is still open until the surgeon repairs it. Forty-five minutes into the case, the surgeon is closing the corneal laceration and the anesthesiologist plans to extubate awake. The cough reflex on extubation, even after the eye is repaired but before it’s fully sealed, is a real IOP event. Plan for a smooth emergence — deep extubation or IV lidocaine 1.5 mg/kg before emergence.

The Ketamine trap: ketamine raises IOP through increased extraocular muscle tone and potentially increased aqueous humor production. It’s not a good induction choice for open globe, despite its hemodynamic stability. If the patient is hemodynamically compromised, etomidate or a reduced propofol dose is a safer choice.

Lead-In Phrases

• "My anesthetic priorities for this open globe are smooth RSI to manage the full stomach, avoidance of IOP spikes throughout the case, and a smooth emergence — the eye is at risk until the wound is sealed and beyond."
• "I will use rocuronium 1.2 mg/kg for my RSI — this provides onset conditions equivalent to succinylcholine while avoiding the extraocular contracture that raises IOP with succinylcholine."
• "I will ensure adequate induction depth before laryngoscopy — coughing or struggling on the laryngoscope generates far greater IOP spikes than succinylcholine, and preventing this is the most important intervention."
• "My emergence plan is deep extubation or IV lidocaine 1.5 mg/kg before emergence — a single cough at extubation can undo the surgeon’s repair."
• "I will avoid ketamine — despite its hemodynamic advantages, it raises IOP through extraocular muscle tension and is not appropriate for an open globe case."

FAQs

What if Sugammadex isn’t available and I used rocuronium for RSI?

This is a real practical concern. High-dose rocuronium (1.2 mg/kg) has a duration of 60-90 minutes — if the case takes only 30 minutes, you’re extubating with significant residual block. My plan: Sugammadex is always available when I use high-dose rocuronium for RSI, because the entire justification for using it (rapid, reliable RSI) depends on having rapid, reliable reversal if needed. If Sugammadex availability is genuinely uncertain, this shifts the risk-benefit calculation back toward succinylcholine.

Is any anti-IOP pretreatment warranted before induction?

In elective cases, pretreatment with acetazolamide (carbonic anhydrase inhibitor), timolol (topical beta-blocker), or mannitol can lower baseline IOP. In an emergency full-stomach open globe, there’s rarely time for this. The focus is on technique — smooth induction, video laryngoscopy, adequate depth — rather than pharmacological pretreatment.

Can I use a laryngeal mask airway for an open globe repair?

In a fasted patient with a straightforward open globe, an LMA can be appropriate — it avoids the cough and straining of intubation and extubation. However, in any patient with full stomach risk, an LMA does not provide adequate aspiration protection and is not appropriate for RSI. The airway protection question resolves the LMA debate before the IOP question even comes up.

Open globe management is an IOP problem from induction to emergence. Practice the full case — RSI technique, IOP maintenance, smooth emergence — in Boards Bot until every phase of the anesthetic has a defensible IOP rationale behind it.