Ophthalmic Anesthetics

Systemic Side-Effects of Anaesthesia

• Confusion, respiratory depression, convulsions, hypotension, and bradycardia are rare systemic side-effects of anaesthesia

Choice of Anaesthetic in Ocular Surgery

• Depends on the procedure, patient, and surgeon's preference
• Local anaesthesia (LA) is used in 95% of cataract operations
• General anaesthesia (GA) is generally used for children and younger cataract patients, trauma cases, and patients who have trouble keeping still

General Anaesthesia

• Desflurane, isoflurane, nitrous oxide, and sevoflurane are commonly used
• Halothane has been discontinued

Injected Local Anaesthetic

• Used for oculoplastic procedures
• Administered through the lower lid and under the globe (peribulbar/retrobulbar anaesthesia)
• May be associated with serious complications, such as retrobulbar haemorrhage, optic nerve damage, muscle palsy, and cranial nerve damage

Sub-Tenon's Technique

• Involves an anaesthetic drop, a small spring to hold the lids open, a small incision in the conjunctiva, and infiltration of the agent
• Patients may feel a burning or stinging sensation

Ophthalmic Anaesthetics

• Act locally to block pain signals at the nerve endings in the eyes
• Available as eye drops, ointments, and gels
• Used to numb the eyes before surgery or for certain tests and procedures
• Used for measurement of intraocular pressure using applanation tonometry and in ocular surgery

Drops

• Lidocaine hydrochloride, oxybuprocaine hydrochloride, proxymetacaine hydrochloride, and tetracaine hydrochloride are commonly used
• Used for initial assessment for minor trauma, removal of conjunctivitis, and corneal foreign bodies
• Contraindicated in patients with hypersensitivity
• Administration involves a brief stinging sensation on application
• Tetracaine produces a more profound anaesthesia, but repeated administration should be avoided due to its effects on corneal epithelial cell healing

Injected Anaesthetics

• Lidocaine hydrochloride, bupivacaine, and cocaine are commonly used
• Used for minor operations, oculoplastic surgery, anterior segment, and cataract surgery
• Contraindicated in patients with refusal or concurrent medical conditions preventing correct positioning
• Administration involves subconjunctival, peribulbar, and retrobulbar injections
• Ocular side-effects are rare if correctly administered