Ocular anesthesia

Brachial plexus anesthesia Buccal anesthesia Caudal anesthesia Cervical plexus anesthesia Dental anesthesia Digital anesthesia Epidural anesthesia Intercostal nerve anesthesia Interpleural anesthesia Intra-articular anesthesia Intradermal anesthesia Intrathecal (spinal) anesthesia Intravenous regional anesthesia Laryngeal anesthesia Lumbar plexus anesthesia Nasal anesthesia Neck anesthesia Obstetric anesthesia Ocular anesthesia Oropharyngeal anesthesia Otic anesthesia Paravertebral anesthesia Perianal anesthesia Peritonsillar anesthesia Respiratory anesthesia Sciatic nerve anesthesia Stellate ganglion anesthesia... 

In addition to complications arising from the local anesthetic used during ocular anesthesia, complications can arise as a direct result of the injection. An arteriovenous fistula has been reported (315). 

Wessels IF, Wessels DA, Zimmerman GJ. The photic sneeze reflex and ocular anesthesia. Ophthalmic Surg Lasers 1999 30(3) 208-11. 

M. Shukr, Formulation, in vitro and in vivo evaluation of lidocaine HCl ocular inserts for topical ocular anesthesia. Arch Pharm Res, 37,882-889,2014. 

Sensory systems Topical ocular anesthesia abuse is often misdiagnosed as acanthamoeba keratitis (a parasitic disease) and early identification to prevent ocular complications including superficial pxmctate keratitis, persistent epithelial defects, stromal/ring infiltrates, comeal oedema, endothelial damage and ocular inflammation is important. Local anesthetics may cause direct toxicity to the comeal epithelium, stroma and endothelium. Preservatives in the anesthetics may also contribute to toxicity. Patient demographics may include a health care association and/or psychiatric illness [25 ]. Evisceration of the eye after persistent topical anesthetic use has been described [26 ]. 

Other reported effects of exposure to carbon disulfide are ocular changes (blind spot enlargement, contraction of peripheral field, corneal anesthesia, diminished pupillary reflexes, nystagmus, and microscopic... 

The transplant of nasal mucosa was first prescribed by Naumann for the treatment of severe and bilateral conjunctival mucous shortages. In a study of 24 patients including 16 victims of a severe eye bum with symblepharons, Naumann has observed an improvement of the condition of the ocular surface in all of the cases. He has then concluded that the transplantation of nasal mucosa is better than the transplant of buccal mucosa. When the ocular damage is bilateral, the transplant of nasal mucosa would be perfectly recommended [11]. The nasal cavities are examined with an endoscope in order to find the zone to be sampled. The graft of nasal mucosa is taken from the septum, from the lower or medium turbinates. Under endoscopy and after local anesthesia, the anterior part of the turbinates is usually sampled. A hemostasis is cautiously operated and a gauze plugging of the cavity is set up. This... 

Adapted from Raj PP Handbook of regional anesthesia. New York Churchill Livingstone, 1985 Bartlett JD, Fiscella R, Jaanus SD, et al., eds. Ophthalmic drug facts. St. Louis Facts and Comparisons, 2005 Crandall DG. Pharmacology of ocular anesthetics. In Duane TD, Jaeger EA, eds. Biomedical foundations of ophthalmology. Philadelphia J.B. Lippincott, 1994 and Sobol WM, McCrary JA. Ocular anesthetic properties and adverse reactions, hit Ophthalmol Chn 1989 29 195-199. 

The ocular effects of cocaine include anesthesia (see Chapter 6), mydriasis, and vasoconstriction. The mydriatic effect of cocaine depends on the presence of a functioning adrenergic innervation. After topical appUcation to the eye, the pupil begins to dilate within 15 to 20 minutes. The maximum effect, which is typically less than 2 mm of dilation, occurs within 40 to 60 minutes, and the pupil may remain dilated for 6 or more hours. The mydriasis is accompanied by vasoconstriction that causes blanching of the conjunctiva. Cocaine is also readily absorbed through the mucous membranes into the systemic circulation. 

Otolar Effeets. Because levobunolol has the same pharmacologic activity as timolol, it has the propensity for the same untoward ocular effects as timolol. The ocular comfort of levobunolol is similar to that of timolol. Corneal anesthesia is not a significant problem with levobunolol, nor does it seem to elicit dry eye symptoms or mydriasis. Although allergic blepharoconjunctivitis can occur with levobunolol, it may also be tolerated in patients in whom timolol elicits an allergic reaction. 

Ocular Effects. Carteolol 1% is less irritating than 0.5% timolol. However, unlike other topical P-blockers, use of carteolol 1% can cause a moderate corneal anesthesia. 

Topical ocular anesthetics have many uses in clinical practice. Most commonly, they are used to improve patient tolerance of various diagnostic procedures. In addition, these drugs often provide sufficient anesthesia for minor operations on the cornea, conjimctiva, and nasolacrimal system. 

Microbiologic culture studies are useful fc>r bacterial identification, especially when an ocular infection foils to respond to treatment. Cultures are often obtained from the eyelids, the conjimctiva, expressed material from the lacrimal sac, and the cornea. Because preserved ophthalmic anesthetics have a bacteriostatic effect, cultures should be obtained if possible before anesthetic instillation. In the case of corneal sampling, it is necessary to provide topical anesthesia for patient comfort. The anesthetic of choice is 0.5% proparacaine because it causes the least bacterial growth inhibition. To enhance the bacterial yield, sterile preservative-free anesthetic may be used. Samples obtained may be inoculated directly onto soUd media plates (e.g., blood agar). Amies without charcoal transport medium (e g., BBL CultureSwab Plus) appears to be an acceptable alternative to direct plating and has the added benefit of convenience. 

Various ocular conditions may benefit from medication delivered via a subconjimctival injection. Applications include recalcitrant uveitis, cystoid macular edema, felling trabeculectomy, and severe corneal ulcer in a noncompli-ant patient. One to two drops of topical anesthesia should be instilled. Additionally, an anesthetic-soaked pledget of 4% lidocaine applied to the area of injection may enhance comfort, particularly if the conjunctiva is to be lifted with forceps before introducing the needle into the subconjunctival space (Figure 19-4). 

Dry eyes have been reported after the systemic or ocular use of timolol (360). A sensation of dryness in the eyes can develop and is usually transitory. There can be a reduction in the Schirmer test and tear film break-up time. Symptomatic superficial punctate keratitis in association with complete corneal anesthesia has been observed (361). 

Lidocaine gel 2% has been compared with 0.5% tetracaine drops for topical anesthesia in cataract surgery in 25 patients (331). There were no corneal epithehal or ocular surface complications, demonstrating the safety of the gel, which may provide a more practical and efficient method of anesthesia, because it needs to be applied only once as opposed to three applications of the drops. 

Wessels IF, Najjar MF. Paroxysmal sneezing during local anesthesia for ocular surgery with thiopentone hypnosis. Can J Anaesth 1999 46(6) 617. 

Topical anesthesia of the ocular surface is used to facilitate diagnostic techniques, such as comeal scraping, conjunctival biopsy, ocular ultrasonography and tonography, and is necessary when placing subpalpebral lavage systems or performing subconjunctival injections. Examination of the bulbar surface of the third eyelid or retrieval... 

The topical anesthetics in general use in the horse are 0.5% proxymetacaine (proparacaine) and 0.5% tetracaine (amethocaine). The rate of onset and duration of clinical anesthesia of the ocular surfaces using these agents in the horse is not known. However, in general, repeated instillations at 30-60 s intervals over a 5 min period will superficially desensitize the normal eye for around 15 min. In the presence of conjunctival hyperemia, there is likely to be accelerated loss of the drug into the systemic circulation and instillation of the anaesthetic agent at shorter intervals for a longer period may be necessary to desensitize the ocular surfaces effectively. 

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