Local anaesthesia in cataract surgery

Abstract

There has been a significant evolution in surgical technique of cataract extraction. The technical advances in phaco machines, phacotips, and availability of ophthalmic viscoelastic devices have played a great role in cataract surgery to be faster and more controlled now than before. Similarly, local anesthesia techniques in cataract surgery have also advanced significantly from retrobulbar, peribulbar, sub-Tenon’s, to topical anaesthesia. Even though, the sub-Tenon’s anesthesia technique reduced the risk of complications of peribulbar/retrobulbar anesthesia but the technique is still associated with a possibility of damage to optic nerve, retrobulbar hemorrhage, and ocular muscle injury. Topical anesthesia is used to block the afferent nerves of the cornea and the conjunctiva (long and short ciliary nerves, nasociliary nerves). This technique eliminates the possible complications of injectable anesthesia. However, it does not eliminate pain sensitivity of the iris, the zonule, and the ciliary body which is achieved by intracameral technique of anesthesia with preservative free 1% lidocaine. In a constantly evolving arena, the sub-Tenon’s block has gained popularity while the deep angulated intraconal (retrobulbar) block has been largely superseded by the shallower extraconal (peribulbar) approach. Hyaluronidase is a useful adjuvant because it promotes local anesthetic diffusion and hastens block onset time but there is a possibility of getting an allergic reaction. Ultrasound-guided eye blocks afford real-time visualization of needle position and local anesthetic spread. An advantage of sonic guidance is that it may eliminate the hazard of globe perforation by identifying abnormal anatomy, such as staphyloma.