THE EFFECTS OF INTRACAMERAL ANESTHESIA ON THE CORNEAL ENDOTHELIUM IN RABBITS

Newer methods of ocular anesthesia have emerged to complement the advanced techniques and instrumentation of modern - day cataract surgery. Local anesthesia has become preferable to general anesthesia for cataract surgery. The advantages of local anesthesia are well known and include: more rapid arnbulation, the ability to perform the procedure a" an outpatient. avoidance of complications associated with general anesthesia, and quicker surgery (Patel et al., 1996).
Methods of local anesthesia for cataract extraction include: retrobulbar, peribulbar.
subconjunctival, and sub-Tenon application of local anesthetic solution (Ducker et al., 1991). Retrobulbar anesthesia has been associated with a number of potentially serious complications including inadvertent globe perforation, retrobulbar
hemorrhage, orbital infection, central retinal artery occlusion, damage to the optic nerve, intravascular or intrathecal injection, postoperative diplopia and ptosis (Morgan et al., 1988). Peribulbar anesthesia eliminates the risk of optic nerve trauma, and lessens the chance of retrobulbar hemorrhage. However, the risk of globe perforation still remains (Kimble et al., 1987). Topical and intracameral anesthesia are new options for pain control in modern cataract surgery. Topical anesthesia has been shown to be a safe and effective alternative to retrobulbar and p«.ibulbar anesthesia (Duguid et al., 1995). Topical anesthesia provides adequate anesthesia for phacoemulsification, with immediate recovery of visual acuity after surgery. However, the significant downfall of this technique lies in its failure to provide adequate motor and sensory anesthesia, when only topical drops are used. This may lead to an increased risk of intraoperative complications due to unrestricted eye movement and insufficient pain control. The lack of optic nerve blockade may also result in  intolerance of the microscopic light (Fukasaku and Marron, 1994; Kreshner, 1993). Subconjunctival and peribulbar anesthesia have been recommended as supplements to topical anesthesia. (Anderson, 1995).