# Non-Toxic Anesthesia for Cataract Surgery
## 4 Discussion  
Several techniques to provide anesthesia in cataract surgery have been developed over the years, in order to reduce patient discomfort and the risk of complications. Nowadays, topical anesthesia, being safe and effective, is the gold standard in cataract surgery [8]. It works blocking the afferent nerves of the cornea and the conjunctiva (long and short ciliary nerves, nasociliary nerves). Today different agents are available for topical anesthesia, like Procaine (1-2-10%), Proparacaine (0.5%), Oxyburocaine (0.4%), Tetracaine (0.5-1%), Bupivacaine (0.25-0.5%), Lidocaine (0.5-1%), Prilocaine (4%), and Ropivacaine (0.2%/1%). All these agents have different time of onset and duration of anesthesia. Although topical anesthetics are widely used for ocular diagnostic and ophthalmic surgery, these are not completely safe as epithelial and endothelial toxicities are reported, even following a single use [9]. Indeed, several studies reported corneal epithelial cells damage after repeated and prolonged usage, demonstrating cytotoxicity and apoptosis-inducing effects of topical anesthetics [10; 11]. Moreover, in subjects with preexistent ocular surface alterations, such as diabetics and dry eye patients, topical mydriatics and anesthetics can disrupt the corneal epithelium leading to punctate keratitis, impaired corneal wound healing and infections [12; 13]. Additionally, high concentrations and prolonged expositions of polydone-iodine during cataract surgery increase the risk of corneal epithelial cells damages [14]. Intracameral techniques have been proposed to reduce the ocular surface damage, improving the anesthetic action on the sensitivity of the iris, the zonule and the ciliary body. [PERSON] et al. in a clinical trial compared the effects of an intracameral combined mydriatic and anesthetic agent to standard topical mydriatics and anesthetics on the ocular surface after cataract surgery, demonstrating a reduced ocular surface damage with decreased corneal epithelial and conjunctival toxicity, and faster recovery of surface integrity in patients treated with intracameral anesthetic [15]. However, intracameral anesthetics may cause adverse events such as corneal thickening, opacification, and significant corneal endothelial cell loss [16]. Alternative techniques have been proposed such as limbal anesthesia, consisting of applying a cellulose ophthalmic sponge, soaked in preservative-free lidocaine hydrochloride 4%, to the limbal area for 45 s immediately before starting surgery pre-medicating with one drop of benoxinate 0.4% [17]. The analgesia achieved with the application of the sponge can be justified with the block of the peri-corneal and annular plexus, explaining the analgesic effect on the entire circumference of the cornea. In this study we described an alternative technique of localized topical corneal anesthesia through a soaked Oxyburocaine hydrochloride 0.4% cotton buds on the corneal access sites. This approach reduced the time of exposition to anesthetic to 10 s, without use of anesthetic drops, reducing the toxic effects on the ocular surface.This may be responsible for a reduced ocular discomfort after surgery; indeed, our findings demonstrated a significant lower OSDI score in patients underwent minimal localized anesthesia compared to those treated under conventional topical anesthesia.Furthermore, the reduced damages of the epithelial corneal and conjunctival cells, improved the tear film stability and T-BUT after cataract surgery. In accordance with our study, [PERSON] et al. applied ropivacaine-soaked sponges in the inferior fornix for 5 min, demonstrating that deep topical anesthesia appeared to be safe and effective as topical anesthesia [18]. Based on the VAS scores, the patients who underwent deep topical anesthesia reported less pain. This resembles the results by [PERSON] et al. who reported a lower pain score in patients receiving topical ropivacaine with respect to topical lidocaine, although their results did not reach statistical significance [19], whereas [PERSON] et al.