Eye surgery

Patient and surgery

Most eye operations are done awake with numbing drops or an injection around the eye; the team guards eye pressure, heart rate and stillness.

Updated Nov 13, 2026

What it is

Eye surgery is mostly short, done on older patients with many illnesses, and usually under local anaesthesia with or without light sedation. The options range from topical drops, enough for most cataract surgery, through a sub-Tenon block given with a blunt cannula, to needle blocks: the peribulbar block outside the muscle cone and the retrobulbar block inside it, which give a still, numb eye. Needle blocks bring rare but serious complications: retrobulbar haemorrhage, perforation of the globe (more likely in a long, myopic eye), optic nerve injury, and brainstem anaesthesia when local anaesthetic spreads along the optic nerve sheath to the cerebrospinal fluid, causing confusion, apnoea and cardiovascular collapse within minutes. The oculocardiac reflex, from traction on the eye muscles or pressure on the globe, can cause sudden bradycardia or asystole, especially in children having squint surgery. General anaesthesia is used for children, long or complex cases and patients who cannot lie still; it must keep intraocular pressure steady, with a smooth induction and emergence without coughing. Two classic warnings complete the picture: after an intraocular gas bubble, nitrous oxide must be avoided for weeks because it expands the bubble, and an open globe injury needs an anaesthetic that protects the eye without forgetting the full stomach.

What changes in this patient

Patients: often older, with diabetes, heart and lung disease, and on anticoagulants that usually continue for low-risk blocks.
Technique: topical, sub-Tenon, peribulbar or retrobulbar anaesthesia, light sedation, or general anaesthesia for selected patients.
Access: the face is under drapes and far from the anaesthetist; oxygen under the drapes adds a fire risk and carbon dioxide can build up.
Reflexes: traction on the extraocular muscles or pressure on the globe can trigger the oculocardiac reflex.
Pressure: intraocular pressure rises with coughing, venous congestion, hypercapnia and suxamethonium, and falls with deep anaesthesia.
Eye drops reach the circulation: timolol can cause bradycardia and bronchospasm, and phenylephrine drops can raise blood pressure.

Anaesthetic plan (and why)

Assess whether the patient can lie flat and still for the whole case — cough, tremor, confusion or orthopnoea may make local anaesthesia unsafe.
Choose topical or sub-Tenon anaesthesia when akinesia is not essential — they avoid most needle-related complications.
Before a needle block, check axial length or myopia and keep the eye in a neutral gaze — a long eye is easier to perforate.
Give the block with full monitoring, intravenous access and resuscitation equipment at hand — brainstem spread and toxicity are sudden.
Keep sedation light so the patient can cooperate — deep sedation causes movement, airway obstruction and confusion.
Watch the ECG during muscle traction and tell the surgeon at once about bradycardia — stopping traction usually ends the reflex.
For general anaesthesia, induce smoothly and avoid coughing at emergence — protects intraocular pressure and the surgical wound.
Avoid nitrous oxide when an intraocular gas bubble may be used, and mark the patient's notes — the bubble expands with nitrous oxide.
Give prophylaxis against nausea and vomiting, especially after squint surgery in children — vomiting raises eye pressure and is common.

Local anaesthesia for eye surgery compared

Technique	How it is given	Akinesia	Main risks
Topical	Drops or gel on the cornea and conjunctiva	None	Discomfort, patient movement
Sub-Tenon	Blunt cannula under Tenon's capsule	Partial to good	Chemosis, subconjunctival bleeding; serious events rare
Peribulbar	Needle outside the muscle cone	Good, slower onset	Haemorrhage, perforation (less than retrobulbar)
Retrobulbar	Needle inside the muscle cone behind the globe	Excellent, fast	Haemorrhage, perforation, optic nerve injury, brainstem anaesthesia

Risks and complications

Retrobulbar haemorrhage: tense, proptosed eye and raised pressure that may need an urgent lateral canthotomy.
Globe perforation or optic nerve injury, with sudden pain, a soft eye or loss of vision.
Brainstem anaesthesia or intravascular injection: confusion, seizures, apnoea, bradycardia or cardiac arrest soon after the block.
Oculocardiac reflex: bradycardia, heart block or asystole during muscle traction.
Patient movement or airway obstruction under sedation; carbon dioxide build-up under the drapes.
Blindness from an expanding gas bubble when nitrous oxide is given; vomiting and coughing that raise eye pressure.

Next step

Observe the patient after a needle block until the block's systemic effects have passed, and check vision and the eye's pressure as the surgeon directs.
Call a senior at once for confusion, apnoea or bradycardia after a block, and start airway support and resuscitation without waiting.
Call the surgeon urgently for a tense, proptosed eye after a block: retrobulbar haemorrhage may need decompression.
Give the patient with a gas bubble a written warning and a wristband about nitrous oxide, and advise on posture and air travel as the surgeon instructs.
Restart usual medicines, including anticoagulants, as planned, and treat nausea and pain early to avoid straining.

Test yourself

Think of the answer, then tap the question to see it.

What is brainstem anaesthesia after a retrobulbar block, and how does it present?

Local anaesthetic spreads along the optic nerve sheath into the cerebrospinal fluid. Within minutes the patient becomes confused or unconscious, stops breathing and may collapse.

Which nerves form the oculocardiac reflex and what is the first response?

The ophthalmic division of the trigeminal nerve carries the afferent signal and the vagus the efferent. The first step is to ask the surgeon to release traction; an anticholinergic follows if needed.

Why must nitrous oxide be avoided after an intraocular gas bubble?

Nitrous oxide diffuses into the bubble faster than the gas leaves, so the bubble expands and intraocular pressure rises, which can occlude the retinal circulation and cause blindness.

Which patients are at higher risk of globe perforation from a needle block?

Those with a long axial length, as in high myopia, or a staphyloma, and patients with previous scleral buckling; a sub-Tenon or topical technique is often safer.

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In Pharmacology8

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Educational content; it does not replace supervised training, your institution's protocols or the anaesthetist's or intensivist's decision. It contains no doses and no ventilator or infusion settings.

Sources: Retrobulbar Block (StatPearls (NCBI Bookshelf), 2024); Local and Regional Anesthesia in Ophthalmology and Ocular Trauma (StatPearls (NCBI Bookshelf), 2023).

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