Ординатура / Офтальмология / Английские материалы / Clinical Ocular Pharmacology 5th edition_Bartlett, Jaanus_2008

314 CHAPTER 18 Drugs for Retinal Diseases

Mordenti J, Cuthbertson RA, Ferrara N, et al. Comparisons of the intraocular tissue distribution, pharmacokinetics, and safety of 125I-labeled full-length and Fab antibodies in rhesus monkeys following intravitreal administration. Toxicol Pathol 1999;27:536.

Rich RM, Rosenfeld PJ, Puliafito CA, et al. Short-term safety and efficacy of intravitreal bevacizumab (Avastin) for noevascular age related macular degeneration. Retina 2006;26:495.

Rosenfeld PJ. An OCT-guided variable dosing regimen with Lucentis™ (ranibizumab) in neovascular AMD: one year results from the PrONTO Study. Program and Abstracts of the 24th Annual American Society of Retina Specialists and ^th Annual European Vitreoretinal Society Meeting. September 9-13, 2006; Cannes, France.

Rosenfeld PJ, Intravitreal Avastin: the low cost alternative to Lucentis? Am J Ophthalmol 2006;142:141.

Rosenfeld PJ, Brown DM, Heier JS, et al. Ranibizumab for neovascular age-related macular degeneration. The MARINA Study Guide. N Engl J Med 2006;355:1419.

Rosenfeld PJ, Heier JS, Hantsbarger G, et al. Tolerability and efficacy of multiple escalating doses of ranibizumab (Lucentis) for neovascular age-related macular degeneration. Ophthalmology 2006;113:623.

Rosenfeld PJ, Fung AE, Puliafito CA. Optical coherence tomography findings after an intravitreal injection of bevacizumab (Avastin) for macular edema from central retinal vein occlusion. Ophthalmic Surg Lasers Imaging 2005;36:336.

Rosenfeld PJ, Moshfeghi AA, Puliafito CA. Optical coherence tomography findings after an intravitreal injection of bevacizumab (Avastin) for neovascular age-related macular degeneration. Ophthalmic Surg Lasers Imaging 2005;36:331.

Spaide RF, Laud K, Fine HF, et al. Intravitreal bevacizumab treatment of choroidal neovascularization secondary to age-related macular degeneration. Retina 2006;26:383.

Tolentino MJ, Husain D, Theodosiadis P, et al. Angiography of fluoresceinated anti-vascular endothelial growth factor antibody and dextrans in experimental choroidal neovascularization.Arch Ophthalmol 2000;118:78.

Intravitreal Triamcinolone Acetonide

Bakri SJ, Beer PM. The effect of intravitreal triamcinolone acetonide on intraocular pressure. Ophthalmic Surg Lasers Imaging 2003;34:386.

Ip MS, Gottlieb JL, Kahana A, et al. Intravitreal triamcinolone for the treatment of macular edema associated with central retinal vein occlusion.Arch Ophthalmol 2004; 122:1131.

Jager RD,Aiello LP, Patel SC, et al. Risks of intravitreous injection: a comprehensive review. Retina 2004;24:676.

Nelson ML, Teeeant MT, Sivalingam, et al. Infectious and presumed noninfectious endophthalmitis after intravitreal triamcinolone acetonide injection. Retina 2003;23:686.

Reichle ML. Complications of intravitreal steroid injections. Optometry 2005;76:450.

Ta CN. Minimizing the risk of endophthalmitis following intravitreous injections. Retina 2004;24:699.

Intravitreal Corticosteroid Implants

Anonymous. Fluocinolone acetonide ophthalmic—Bausch & Lomb: fluocinolone acetonide Envision TD Implant. Drugs R&D 2005;6:116.

Anonymous. Retisert. Retrieved April 10, 2006 from www.bausch.com/retisert_pi.pdf

Bakri SJ, Beer PM. Intravitreal triamcinolone for the treatment of macular disease. Compr Ophthalmol 2005;6:143.

Bethke W. Present and future retinal implants. Rev Ophthalmol 2006;13(8):39.

Jaffe GJ, Martin D, Callanan D, et al. Fluocinolone acetonide implant (Retisert) for noninfectious posterior uveitis. Fluocinolone acetonide implant (Resisert) for noninfectious posterior uveitus. Fluocinolone Acetonide Uveitis Study Group. Ophthalmology 2006;113:1020.

Tranos PG,Wickremasinghe SS, Stangos NT, et al. Macular edema. Surv Ophthalmol 2004;49:470.

Anecortave Acetate

Augustin AJ, D’Amico DJ, Meier WF, et al. Safety of posterior juxtascleral depot administration of the angiostatic cortisene anecortave acetate for treatment of subfoveal choroidal neovascularization in patients with age-related macular degeneration. Graefe’s Arch Clin Exp Ophthalmol 2005;243:9.

Chakravarthy U, Soubrane G, Bandello F, et al. Evolving European guidance on the medical management of neovascular age related macular degeneration. Br J Ophthalmol 2006; 90:1188.

D’Amico DJ, Goldberg MF, Hudson H, et al. Anecortave acetate as monotherapy for the treatment of subfoveal lesions in patients with exudative age-related macular degeneration (AMD): interim (month 6) analysis of clinical safety and efficacy. Anecortave Acetate Clinical Study Group. Retina 2003; 23:14.

D’Amico DJ,Goldberg MF, Hudson H, et al. Anecortave acetate as monotherapy for treatment of subfoveal neovascularization in age-related macular degeneration: twelve-month clinical outcomes. Ophthalmology 2003;110:2372, discussion 2384–2385.

Penn JS, Rajaratnam VS, Collier RS, et al. The effect of an angiostatic steroid on neovascularization in a rat model of retinopathy of prematurity. Invest Ophthalmol Vis Sci 2001; 42:283.

Schmidt-Erfurth U, Michels S, Michels R, et al. Anecortave acetate for the treatment of subfoveal choroidal neovascularization secondary to age-related macular degeneration. Eur J Ophthalmol 2005;15:482.

Slakter JS, Bochow T, D’Amico DJ, et al. Anecortave acetate (15 milligrams) versus photodynamics therapy for treatment of subfoveal neovascularization in age-related macular degeneration. Ophthalmology 2006;113:3.

VEGF Trap

Bergsland EK. Update on clinical trials targeting vascular endothelial growth factor in cancer. Am J Health-Syst Pharm 2004;61(Suppl 5):S12.

Cursiefen C, Cao J, Chen L, et al. Inhibition of hemangiogenesis and lymphangiogenesis after normal-risk corneal transplantation by neutralizing VEGF promotes graft survival. Invest Ophthalmol Vis Sci 2004;45:2666.

NGUYEN QD. C.L.E.A.R.-IT 1: a phase I safety tolerability, and bioactivity study of intravitreal VEGF Trap in patients with noevascular AMD. Program and Abstracts of the 24th Annual American Society of Retina Specialists and 6th Annual

European Vitreoretinal Society Meeting. September 9-13, 2006; Cannes, France.

Ngyuen QD, Shah SM, Hafiz G, et al. A phase I trial of a IV-administered vascular endothelial growth factor trap for treatment in patients with choroidal nonvascularization due to age-related macular degeneration. CLEAR-AMD 1 Study Group. Ophthalmology 2006;113:1522.

Saishin Y, Saishin Y, Takahashi K, et al. VEGF-TRAP (R1R2) suppresses choroidal neovascularization and VEGF-induced breakdown of the blood-retinal barrier. J Cell Physiol 2003; 195:241.

Weigand SJ, Zimmer E, Nork TM, et al. VEGF trap both prevents experimental choroidal neovascularization and causes regression of established lesions in non-human primates. ARVO abstract 2005;1411/B180.

Zhao L, Liu T, Li Y, et al. Complete inhibition of neovascularization by VEGF trap in a Matrigel CNV model. ARVO abstract 2005;5300/B503.

Squalamine

Akhter S, Nath SK, Tse CM, et al. Squalamine, a novel cationic steroid, specifically inhibits the brush-border Na+/H+ exchanger isoform NHE3. Am J Physiol 1999;276(1 Pt 1):C136.

Anonymous. Evizon shows promise as treatment for macular degeneration. Many macular degeneration patients maintained or improved vision with Evizon [press release 2005]. Retrieved April 3, 2006 from http://vision.about.com/ od/maculardegeneration/a/evizon.htm

Ciulla TA, Criswell MH, Danis, RP, et al. Squalamine lactate reduces choroidal neovascularization in a laser-injury model in the rat. Retina 2003;23:808.

Garcia CA, Quiroz-Mercado H, Uwaydat S, et al. A phase I/II trial of intravenous squalamine lactate for treatment of choroidal neovascularization in age related macular degeneration (ARMD).ARVO Abstract 2004;2362.

Garcia CA, Connelly B, Thomas E, et al. A phase 2 multi-dose pharmacokinetic study of MSI-1256F (squalamine lactate) for

the treatment of subfoveal choroidal neovascularization associated with age-related macular degeneration (AMD). ARVO Abstract 2005;206/B180.

Higgins RD, Yan Y, Geng Y, et al. Regression of retinopathy by squalamine in a mouse model. Pediatr Res 2004;56:144.

Sills AK Jr,Williams JI,Tyler BM, et al. Squalamine inhibits angiogenesis and solid tumor growth in vivo and perturbs embryonic vasculature. Cancer Res 1998;58:2784.

Ruboxistaurin

Aiello LP. The potential role of PKC β in diabetic retinopathy and macular edema. Surv Ophthalmol 2002;47(Suppl 2): S263.

Aiello LP, Bursell SE, Clemont A, et al.Vascular endothelial growth factor-induced retinal permeability is mediated by protein kinase C in vivo and suppressed by an orally effective beta-isoform-selective inhibitor. Diabetes 1997;46:1473.

Aiello LP, Cahill MT, Cavallerano JD. Growth factors and protein kinase C inhibitors as novel therapies for the medical management diabetic retinopathy. Eye 2004;18:117.

Duh E, Aiello LP. Vascular endothelial growth factor and diabetes: the agonist versus antagonist paradox. Diabetes 1999; 48:1899.

Frank RN. Potential new medical therapies for diabetic retinopathy: protein kinase C inhibitors. Am J Ophthalmol 2002; 133:693.

Gardner TW, Antonetti DA. Ruboxistaurin for diabetic retinopathy. Ophthalmology 2006;113:2135.

The PKC-DRS Study Group. The effect of ruboxistaurin on visual loss in patients with moderately severe to very severe nonproliferative diabetic retinopathy: initial results of the Protein Kinase C β Inhibitor Diabetic Retinopathy Study (PKC-DRS) multicenter randomized clinical trial. Diabetes 2005;54:2188.

The PKC-DRS2 Group. Effect of ruboxistaurin on visual loss in patients with diabetic retinopathy. Ophthalmology 2006; 113:2221.

Synthetic local anesthetics enable the practitioner to perform numerous diagnostic or surgical procedures in the office while keeping the patient comfortable and avoiding the relative risk and inconvenience of general anesthesia. Because most procedures involving the eye and its adnexa are of short duration and can be accomplished with local anesthesia, they present almost no risk to the patient’s general health.

TOPICAL ANESTHESIA

Topical application represents the most common route of administration of local anesthetics for procedures involving the eye. Topically applied anesthetics are surface-acting drugs that produce a reversible inhibition of the sensory nerve endings within the corneal and conjunctival epithelium, producing transient local anesthesia of the corneal and conjunctival surfaces.

Although most commonly used topical anesthetics are similar in onset, duration, and depth of anesthesia (see Chapter 6), several important differences exist. For diagnostic and treatment procedures requiring topical anesthesia, the clinician essentially has two choices: tetracaine or proparacaine. Both provide rapid onset of anesthesia within 10 to 20 seconds and last approximately 10 to 20 minutes. If prolonged anesthesia is required, it may be accomplished by repeated application.Tetracaine may cause more discomfort upon instillation than proparacaine and typically results in more corneal compromise. In general, proparacaine 0.5% has a low incidence of hypersensitivity reactions and is the anesthetic of choice for topical anesthesia in ophthalmic applications. Other anesthetics that have occasional topical application are cocaine (4% to 10%) and lidocaine (4%).

After the instillation of most topical anesthetics, many patients report a heaviness of the eyelids that frequently lasts for several minutes after the return of corneal sensation. Conjunctival hyperemia and mild lacrimation sometimes occur after the application of most topical anesthetics. Rarely, the reflex action associated with discomfort may cause the fellow eye to become hyperemic

when the anesthetic is placed in only one eye. In addition to these direct effects, many topically applied anesthetics produce various indirect effects, such as increasing corneal permeability to subsequently applied drugs, occasionally desquamating corneal epithelium, and retarding the mitosis and migration processes associated with corneal epithelial regeneration.

Clinical Use

The following general guidelines should be observed to facilitate the safe and effective use of topical anesthetics:

1.For routine diagnostic procedures, such as applanation tonometry and gonioscopy, topical anesthetics render the eye vulnerable to accidental damage during the period of anesthesia.The protective blink reflex is inhibited, and abnormal drying of the cornea can occur. Because minute foreign bodies can cause corneal damage if brushed across the hypoesthetic cornea, the patient should be advised against rubbing the eye during the period of anesthesia, usually lasting 20 to 30 minutes after the diagnostic procedure.

2.It is beneficial to instill the topical anesthetic into both eyes before routine diagnostic procedures, such as gonioscopy, applanation tonometry, and fundus contact lens biomicroscopy. Bilateral usage of anesthetic inhibits the blink reflex of the fellow eye, facilitating the diagnostic procedure on the eye under examination. This practice also reduces examination time, because drug instillation into both eyes occurs before beginning the procedure.

3.The mild local stinging or burning sensation after instillation of the anesthetic is transient, and treatment requires only patient reassurance.

4.Because topically applied anesthetics may cause transient irregularity of the corneal epithelium, corneal disruption can interfere with subsequent procedures requiring critical visualization inside the eye, such as fundus photography. Ideally, photographic procedures should be performed without application of a topical anesthetic.

5.Corneal integrity should be assessed before instillation of a topical anesthetic because of the epithelial disruption that may occur. For this same reason, tear breakup time should be measured before topical anesthesia.

6.Topical anesthetics are ineffective on skin surfaces and are, therefore, ineffective for dermatologic procedures, such as removal of verrucae.

7.Ideally, resumption of contact lens wear should be delayed for at least 60 minutes after application of the anesthetic.

8.Epinephrine or other vasoconstrictors have no significant effect on the duration of topical anesthesia and should never be combined with commercially available topical anesthetics.

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, conjunctiva, and nasolacrimal system.

Diagnostic Procedures

One or two drops of 0.5% proparacaine are sufficient for most ophthalmic diagnostic procedures requiring topical anesthesia. Most often, procedures are performed bilaterally, and it is most efficient if the anesthetic is instilled in both eyes before beginning the procedure. Because the duration of action is 10 to 20 minutes, it is not necessary to reapply anesthetic before beginning the procedure on the second eye. If a procedure is to be performed on one eye only, it is still recommended that anesthetic be instilled in both eyes to inhibit the blink reflex in the fellow eye. Examples of diagnostic procedures that require topical anesthesia on all or some occasions are listed in Box 19-1.

Box 19-1 Diagnostic Procedures Associated With

Topical Anesthesia

Applanation tonometry A-scan ultrasonography B-scan ultrasonography Contact lens fitting Cultures

Cytology

Dilation and irrigation of nasolacrimal system Forced duction test

Fundus contact lens biomicroscopy Gonioscopy

Pachymetry Pre–drug instillation

Schirmer I tear flow test (basal secretion measurement)

Applanation Tonometry

Use of a solution of benoxinate-sodium fluorescein (Fluress) or proparacaine-sodium fluorescein allows simultaneous application of the required anesthetic and sodium fluorescein dye. This method increases the efficiency of the procedure by eliminating the need for separate applications of the anesthetic and dye, but it has the disadvantages of irritation from the benoxinate and excessive instillation of dye. On occasion, a few seconds must elapse to allow tears and excess dye to dissipate before accurate tonometry can be performed. Notably, the differences in the results of tonometry using either benoxinate or proparacaine are not clinically significant.

Cultures

Microbiologic culture studies are useful for bacterial identification, especially when an ocular infection fails to respond to treatment. Cultures are often obtained from the eyelids, the conjunctiva, 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 solid 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.

Evaluation of Superficial Abrasions

Because repeated applications of a topical anesthetic to an injured cornea may seriously delay or prevent regeneration of the epithelium, the practitioner should refrain from the liberal instillation of topical anesthetics in cases of corneal abrasions, foreign bodies, or other superficial injuries. Often, however, the blepharospasm, lacrimation, and pain accompanying the corneal injury prevent adequate examination of the eye. In such cases one or two drops of 0.5% proparacaine frequently relieve the pain enough to allow slit-lamp evaluation of the injury. The patient, however, should never be given a topical anesthetic for self-administration at home. Very serious corneal damage may result (see Chapter 6). Instead, any pain associated with the injury should be treated with cycloplegics, a bandage contact lens, topical nonsteroidal anti-inflammatory agents, and/or systemic analgesics (see Chapter 7).

Forced Duction Test

The forced duction test is used to investigate anomalous ocular movements to differentiate between deficiencies due to neurogenic or myogenic weakness from those caused

by muscle restrictions, such as in Graves’ ophthalmopathy. The practitioner can detect a mechanical limitation (restrictive myopathy) if in the attempt to move the globe actively considerable resistance prevents movement of the eye. On the other hand, a neurogenic cause is suspected if the globe moves freely on forced duction testing. Two methods of performing this test are commonly used: the traditional technique, involving attempted movement of the globe with toothed forceps, or a less traumatic technique, involving attempted movement of the globe with a cotton-tipped applicator positioned at the limbus.

In the forceps technique the practitioner uses the forceps to grasp the insertion of the rectus muscle to be investigated and attempts to move the globe in a direction opposite the field of action of that muscle (Figure 19-1A). Most commercially available topical anesthetics fail to

A

B

Figure 19-1 Forced duction test. (A) Traditional technique involving attempted movement of the globe with toothed forceps. (B) Technique involving attempted movement of the globe with cotton-tipped applicator positioned at limbus.

eliminate completely the patient’s awareness of the forceps. Although this awareness is not particularly painful, the sensation of the eye being touched often increases patient apprehension, provokes blepharospasm, and prevents adequate investigation of the muscle being tested. Using a 4% solution of topical lidocaine as the anesthetic can greatly reduce or eliminate this problem. A cotton-tipped applicator, moistened with this solution, should be applied to the surface of the conjunctiva at the site overlying the rectus muscle insertion to be investigated.The applicator should be applied for 1 to 2 minutes. The depth of topical anesthesia achieved using this method has been found to be far more satisfactory than the more routinely used anesthetics, such as tetracaine or proparacaine. Alternatively, after topical anesthesia with 0.5% proparacaine, movement of the globe is attempted by placing a cotton-tipped applicator at the limbus (Figure 19-1B). This latter technique allows the practitioner to detect a mechanical limitation of the globe without subjecting the patient to the discomfort associated with toothed forceps.

Pachymetry

Using ultrasound technology, a corneal pachymeter determines the central corneal thickness. The procedure is accomplished by first instilling one or two drops of 0.5% proparacaine into both eyes.The pachymeter probe is then placed perpendicular to the central cornea (Figure 19-2). The Goldmann applanation tonometer is calibrated for a central corneal thickness of approximately 530 mcm. Any deviation from 530 mcm produces an artifact in the intraocular pressure measurement. A thicker cornea results in a measured intraocular pressure reading that is too high, whereas a thinner cornea measures lower than actuality. Pachymetry is also a standard procedure in determining whether a patient is a suitable candidate for laser refractive surgery.The residual thickness of the stromal bed must be sufficient to prevent corneal ectasia. Calculation of this value is dependent on the flap thickness, the patient’s refractive error, and the ablation size. Pachymetry is also useful in measuring the degree of corneal edema that may result from contact lens wear or other corneal conditions, such as corneal dystrophies.

Ultrasonography

A-scan ultrasonography determines the axial length of the globe, which is an important consideration in selecting the correct power of an intraocular implant for patients undergoing cataract surgery. The A-scan probe is applied perpendicularly to the apex of the cornea after topical anesthesia. B-scan ultrasonography may be performed by applying the probe directly to the conjunctiva and cornea.Topical anesthesia should be instilled in both eyes before performing the procedure. B-scan ultrasound should not be performed on an eye that may have sustained an open globe.

322 CHAPTER 19 Topical and Regional Anesthesia

A

B

Figure 19-2 After topical anesthesia, corneal pachymetry is performed by placing the probe perpendicular to the central cornea.

Schirmer No. 1 Test

Schirmer No. 1 test is used as a quantitative test of aqueous tear production.To eliminate the neurogenic component of tear secretion, Schirmer’s test can be performed after the application of a topical anesthetic, thus allowing a more accurate assessment of basal aqueous secretion. The conjunctival sac should be dried with a cottontipped applicator after administration of the anesthetic. This maneuver absorbs any reflex tearing that may result from irritation by the anesthetic and also prevents falsenegative findings from strip wetting by the anesthetic itself.The average Schirmer’s test result, after topical anesthesia in a patient with a normal lacrimal system, is approximately 15 mm of strip wetting at 5 minutes.

Lacrimal Drainage Procedures

Increasing patient comfort during lacrimal dilation and irrigation (see Chapter 24) requires the application of a

Figure 19-3 Anesthetic-soaked cotton pledget may be applied to the punctum for 1 to 2 minutes before procedures involving the nasolacrimal system.

topical anesthetic, such as 0.5% proparacaine. One or two drops are instilled topically. To enhance patient comfort, an anesthetic-soaked cotton-tipped applicator is placed over the punctum for 1 to 2 minutes (Figure 19-3). The dilation and irrigation procedures can begin 1 or 2 minutes after instillation of the anesthetic.

Contact Lens Fitting

To evaluate the eye’s normal physiologic responses to contact lens wear, contact lenses should be fitted without topical anesthesia. However, certain limited circumstances may justify the use of topical anesthetics in contact lens evaluations.Topical anesthesia allows a rigid lens to be easily placed on the cornea and readily tolerated by the patient during the initial diagnostic evaluation.Topical anesthesia may also be used in fitting infants and very young children with rigid contact lenses.

Pre–Drug Instillation

Because topical anesthetics increase permeability of the corneal epithelium to subsequently applied drugs, the clinical effectiveness of mydriatics and cycloplegics may be enhanced.

Miscellaneous Treatments

Requiring Topical Anesthesia

Box 19-2 lists other treatments that require topical anesthesia, elucidated below.

Superficial Foreign Body Removal

As with the evaluation of corneal abrasions, the application of one or two drops of 0.5% proparacaine is often necessary to allow adequate examination of the eye with a corneal or conjunctival foreign body. It is advisable to obtain informed consent, preferably written, before proceeding with any minor surgical procedure.

Box 19-2 Miscellaneous Procedures That May

Require Topical Anesthesia

Anterior stromal puncture

Continuous ocular irrigation systems (e.g., Morgan lens)

Corneal debridement Punctal plug insertion Subconjunctival injection

Superficial foreign body removal Suture barb removal

Acquiring consent is especially prudent when the foreign body overlies the visual axis or in cases where Bowman’s membrane has been penetrated. Before removing superficial foreign bodies, an additional one to two drops of topical anesthetic loosen the epithelium. The additional topical anesthetic also allows somewhat deeper anesthesia for removal of corneal foreign bodies in the deep epithelium or superficial stroma.The limbal area, however, is often difficult to anesthetize, and a solution of 4% lidocaine applied with a cotton-tipped applicator may achieve adequate anesthesia. Topical anesthetics must never be prescribed for self-administration by the patient at home. If topical anesthesia is needed to examine an eye suspected of having a penetrating or perforating injury, a nonpreserved anesthetic should be used to decrease the risk of corneal endothelial damage. Nonpreserved agents include tetracaine, 0.5%, in a 1-ml unit-dose formulation.

Subconjunctival Injection

Various ocular conditions may benefit from medication delivered via a subconjunctival injection. Applications include recalcitrant uveitis, cystoid macular edema, failing trabeculectomy, and severe corneal ulcer in a noncompliant 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).

Minor Surgery of the Conjunctiva

The excision of small superficial conjunctival lesions, such as concretions, can usually be achieved with topical anesthesia alone.Two or three drops instilled at 1-minute intervals allow sufficient anesthesia for this purpose.

Alternatively, a cotton pledget or cotton-tipped applicator soaked in anesthetic solution may be applied for 1 to 2 minutes before surgery.This local application allows anesthesia of deeper portions of the conjunctiva.

Before infiltration anesthesia for chalazion resection, 4% lidocaine solution can be applied to the tarsal conjunctiva using a cotton-tipped applicator. This procedure

Figure 19-4 Lifting the conjunctiva with tissue forceps exposing the subconjunctival space before injection is better tolerated if an anesthetic-soaked cotton pledget is applied to the area first.

effectively reduces the pain of chalazion surgery without additional side effects.

Punctal Plug Insertion

Although not always required, one or two drops of topically applied 0.5% proparacaine and an anesthetic-soaked cotton-tipped applicator placed over the punctum for 1 to 2 minutes improve patient comfort for the insertion of collagen implants and other forms of punctal and canalicular occlusion (see Chapter 24).

Corneal Epithelial Debridement

Topical anesthesia not only provides adequate surface anesthesia before debridement, it also has the beneficial effect of loosening the corneal epithelium. If both tetracaine and proparacaine are on hand, tetracaine is the preferred agent due to its greater effect on the corneal epithelium. Debridement may be accomplished with either a moistened cotton-tipped applicator or an

Algerbrush. Both techniques effectively remove loose and damaged epithelial tissue. Debridement should be followed by irrigation and management of the corneal defect as an abrasion (see Chapter 26).

REGIONAL ANESTHESIA

Some minor surgical procedures involving the eye and adnexa, including papilloma and eyelid lesion removal, chalazion incision and drainage, electrohyfrecation for trichiasis, and repair of eyelid lacerations, require a deeper and more prolonged anesthesia than can be achieved with topically applied anesthetics. Such cases require injectable anesthetics,such as lidocaine or bupivacaine,for increased duration of anesthesia. Preparations may include epinephrine, in a concentration of 1:100,000 or less, to produce a longer acting block, to decrease systemic side effects of the anesthetic, and to provide for local hemostasis.

Local Infiltrative Injection

Infiltrative anesthesia is the major type of local anesthesia used in eyelid surgery. It can be subdivided into two forms: a pretarsal subcutaneous block and a retrotarsal block. A pretarsal subcutaneous block provides excellent anesthesia to the anterior lamella,including skin,orbicularis muscle, orbital septum,and the anterior tarsal surface.When anesthesia is needed for surgery on the palpebral conjunctiva or posterior tarsal surface, a retrotarsal block is indicated.

Regional Nerve Block Anesthesia

In most minor surgical procedures of the eye, local infiltrative anesthesia is adequate. However, patients having multiple lesion removal or those exceptionally sensitive to pain may require a more complete regional anesthesia using an orbital nerve block.Nerve blocks provide excellent regional anesthesia without distortion of tissues but do not allow local epinephrine-induced hemostasis.

Administration of an orbital nerve block requires intimate familiarity with both the anatomic locations of the sensory nerve fibers of the orbit (Figure 19-5) and the sensory distribution of these nerve branches (Figure 19-6). A description of orbital nerve blocks and distribution of regional anesthesia associated with these injections is included in Table 19-1. Care must be taken to avoid nerve laceration that may manifest as severe pain or paresthesias during needle insertion.

PRESURGICAL EVALUATION

Preparing the patient for minor eye surgery is an important aspect of care.Areas of concern that may affect anesthesia

Figure 19-5 Sensory nerves of the eyelids. (From Remington LA. Clinical anatomy of the visual system, 2e, Butterworth Heinemann, 2005.)

Supratrochlear

Supraorbital

Zygomatic

Infratrochlear

Lacrimal

Infraorbital

Nasal

Figure 19-6 Distribution of area for regional anesthesia blocks. (Adapted from Wilson RP. Anesthesia. In: Spaeth GL, ed. Ophthalmic surgery:principles and practice. Philadelphia: Saunders, 1990: 81.)

are the patient’s age, systemic health history, current medications, allergies, and level of apprehension.

Local anesthesia of the eye may be used in cooperative children as young as 6 years of age.Younger or uncooperative patients require general anesthesia.

The patient’s systemic health should be reviewed to determine physical status and ability to tolerate local anesthetic procedures. A careful history should include possible bleeding diatheses (e.g., easy bruising, hemorrhaging during previous surgical procedures or dental extractions) and unstable systemic disease (e.g., hypertension, diabetes, and cardiac arrhythmia). For example, elevation of blood pressure may result in excessive bleeding. The presence of significant liver dysfunction may increase the risk of anesthesia by limiting drug metabolism. The patient should also be asked about and examined for keloid formation.Answers to questions regarding prior anesthesia and any family history of problems with anesthesia aid in assessing the patient’s suitability for local anesthesia.

Patients should also be questioned about the use of any medications that might impair clotting. These might include prescription medications such as warfarin or over-the-counter medications such as aspirin. Even dietary supplements such as ginkgo biloba may have potential impact on bleeding. Consultation with the patient’s physician is necessary to approve discontinuation of any prescribed anticoagulation agent.

Allergic reactions to commonly used amide anesthetics are rare. To identify patients with true allergic reactions, a careful history should be recorded regarding prior anesthesia. Attention should be placed on the offending drug, route of administration, concurrent medications,

Lateral to the supraorbital

notch to a depth of 1.25 inches along the roof of the orbit (avoids orbital hemorrhage from vessel damage in supraorbital notch)

Just above the medial canthal ligament to a depth of 1 inch

Along the upper outer wall of the orbit to a depth of 1 inch

2 ml of anesthetic at the mouth of the infraorbital foramen located as a palpable, small depression in the maxilla, two-thirds of an inch inferior to the midpoint of the lower eyelid

vasoconstrictors, and preservatives. Patients with a proven history of an allergic reaction can often be given a preservative-free anesthetic of unrelated structure. More commonly, adverse reactions related to systemic toxicity are usually secondary to overdosage, rapid systemic absorption, or inadvertent intravascular injection.

Most patients experience some apprehension regarding surgery. Preoperative counseling regarding the anticipated sequence of events can minimize this apprehension. Some patients may require a mild sedative, such as 5 to 10 mg of diazepam by mouth 60 minutes before surgery.

CLINICAL APPLICATIONS: MINOR SURGICAL PROCEDURES

Technique of Local Infiltrative Injection

Written informed consent must be obtained before any minor surgical procedure. Patient safety and comfort during the procedure must be maximized. Controlling the patient’s movement and continually reassuring the patient can accomplish this objective.

The surgical area should be cleaned with either 70% isopropyl alcohol or povidone-iodine solution.The skin is then allowed to dry. Marking the affected area with a skin marker to aid in identification of the site can be useful because infiltration of the anesthetic may distort the appearance of the site.

A Jaeger plate may be used to decrease the likelihood of penetrating the globe while the injection is performed (Figure 19-7). A drop of topical anesthetic should be

instilled before inserting the Jaeger plate. Typically, a 25to 27-gauge needle on a tuberculin syringe is used for a local infiltrative injection. The needle should be positioned with the bevel up and the skin pulled taut to reduce resistance. The needle is inserted using a gentle stabbing motion, angled about 15 degrees to the skin surface (Figure 19-8). The plunger of the syringe should be withdrawn slightly to ensure no intravascular penetration, which would be seen as a “flash”of blood as it enters the base of the needle. The patient should be asked to move the eye to ensure the needle has not impaled or penetrated the globe before the injection.

Approximately 0.2 to 0.6 ml of anesthetic should be injected by simultaneously expressing the plunger and slowly withdrawing needle. Slow and steady infiltration can minimize the pain of the injection. Care should be taken to check if anesthetic is following a line instead of diffuse filling.A linear infiltration is an indication that the needle may have penetrated a small vessel. Continued injection of the anesthetic could cause a cardiac arrhythmia. The procedure should be halted and the patient monitored for 5 to 10 minutes while checking the heart rate and heart rhythm.

Two to three injection sites may be needed to provide adequate anesthesia. For minor surgical procedures of the eyelid, the volume of anesthetic required would be far less than the maximum dose of most local anesthetics (e.g., procaine, lidocaine, and mepivacaine)—approxi- mately 500 mg as a 1% or 2% solution.A ring block or field block may be used to anesthetize around the area of the surgical site in a circumferential manner without injecting