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Ординатура / Офтальмология / Английские материалы / Practical Ophthalmology A Manual for the Beginning Ophthalmology Residents 4th edition_Wilson_1996

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7. If the patient has any contusion

 

or laceration of the globe or its

 

adnexal structures, apply and

 

• tape a fenestrated aluminum

 

(Fox) shield, instead of a pres-

 

sure patch, over the globe, to

 

protect these tissues from fur-

 

ther damage until healing occurs

 

or definitive repair is performed.

 

Rest the shield on the bony

 

superior orbital ridge and zygo-

 

ma (Figure 2). Do not patch an

 

open globe tightly.

Figure 2

Clinical Protocol 14.2

Removing Corneal Foreign Bodies

1.Apply a drop of topical anesthetic to the affected eye.

2.While holding the patient's upper and lower lids apart with your thumb

and index finger, remove a loose, nonembedded foreign body as appro-

'priate in either of the following two ways:

a.Wipe the corneal surface gently with a cotton swab moistened with saline.

b.Perform saline lavage, inspecting the cornea periodically, until the foreign body is no longer apparent (see Clinical Protocol 14.3, "Irrigating the Ocular Surface").

3.Remove a firmly embedded foreign body by careful extraction with a 27gauge needle on a handle or tuberculin syringe under slit-lamp magnification. Use a flicking motion with the needle and avoid pushing the foreign body deeper into the cornea or inserting the needle any deeper into the cornea than is absolutely necessary (Figure 1).

376

4.If a rust ring remains, you can try to curette it with the needle or use one of the commercially available rust-ring burrs. It is not necessary to remove the entire rust ring. It is better to leave a small rust ring in the visual axis than to risk creating a dense stromal scar after the removal.

5.Treat the abrasion resulting from the foreign body as for a typical corneal abrasion.

Figure 1

Clinical Protocol 14.3

Irrigating the Ocular Surface

1.With the patient supine, instill 1 to 2 drops of topical anesthetic solution into the cul-de-sac.

2.Gently keep the eyelids open either manually or with a Desmarres retractor or a lid speculum.

a. Avoid pressure on the globe or forceful eyelid opening if you suspect a ruptured globe.

b.Keeping the eye open with a lid speculum and administering analgesics and topical anesthetics allow effective irrigation with minimal discomfort to the patient.

c.Inspect the ocular surface and conjunctival cul-de-sac quicklv for particulate chemical substances. Remove small particles by rolling a moistened cotton-tipped applicator across the conjunctiva; remove large particles with forceps.

continued

3.Begin irrigating the eye copiously with normal saline solution or other similarly isotonic solution.

a.You may use a squeeze bottle or normal saline drip with plastic tubings, if available.

b.Ask the patient to shift gaze periodically so that the entire cul-de-sac is flushed.

4.After irrigating for at least 15 or 20 minutes using a minimum of 1 liter of fluid, reexamine the eye, especially the fornices, for particulate matter. You may need to evert the upper lid to irrigate or manually remove particulate matter that is lodged there.

5.If particulate matter is found, irrigate further after removing the particles. Continue irrigation until the pH of the conjunctival sac is neutral (ie, 7.4). Urinary pH strips are suitable for this determination.

Clinical Protocol 14.4

Performing Anterior Chamber Paracentesis

1.Place the patient in the supine position on an operating table, in a manner suitable for ophthalmic surgery.

2. Instill a drop of topical anesthetic (eg, proparacaine) in the eye, and hold a cotton-tipped applicator soaked with anesthetic (eg, proparacaine, lidocaine) against the insertion of the medial rectus muscle.

3.Place an eyelid speculum.

4.Under the operating microscope, fixate the eye by grasping the anesthetized tendon of the medial rectus muscle.

5.Using a 30-gauge short needle on a tuberculin syringe, enter the anterior

chamber at the temporal limbus with die bevel of the needle pointing up *•' and with the needle parallel to the iris plane. Keep the tip of the needle over

tbe midperiphery of the iris, and avoid the lens, throughout the procedure.

6.Withdraw fluid from the anterior chamber until you can observe that it shallows slightly (0.1-0.2 cc of aqueous fluid).

7.Withdraw the needle.

Appendix

Common Ocular Medications

Introduction

This appendix presents an abbreviated overview of the most common medications the beginning resident is likely to encounter. Although it is not exhaustive, it includes information on the following categories of medications:

•Anesthetic agents

•Dyes

•

Infection medications

 

:'|:

•

Anti-inflammatory agents

"':

*

•

Mydriatic/cycloplegic agents

j

 

•Glaucoma medications

•Decongestant, vasoconstrictive, and anti-allergy agents

•Lubricating agents and tear substitutes

•Corneal dehydration medications

Ocular medications are used for both ophthalmic diagnosis and treatment. They can be delivered to the eye bv four different routes:

1. As topical drops or ointments

379

380

Appendix: Common Ocular Medications

. • . .

 

 

I

 

 

.•

• ' ; . . > , • <•;

2. As thin drug-containing wafers deposited in the conjunctival sac

;

i '

";

for timed release of medication

 

• :'

' j

''

;

!

v

3. As injectable drugs administered directly subconjunctivally, intravitreally, sub-Tenon's capsule, or into the peribulbar or retrobulbar spaces

4.As systemic medications, especially tor treating serious intraocular, optic nerve, or orbital inflammations and infections

Anesthetic Agents

 

Topical anesthesia is used when performing routine procedures such as

 

measuring intraocular pressure and removing corneal foreign bodies.

 

Instill 1-2 drops in the eve for temporary anesthesia (15-20 minutes)

,.•••:•:.

to facilitate ocular examination. Common agents include tetracaine

•• .

HC1 0.5% (Pontocaine), proparacaine HC1 0.5% (AJcaine, Ophthaine,

.;'•.: •

Ophthetic), benoxinate 0.4% with fluorescein (Fluress), and cocaine

•-.*' •«

l% - 4% . These agents are toxic to the corneal epithelium when used

; -'•', •'

habitually and should never be dispensed to the patient to take home.

Dyes

Certain dyes are useful for ophthalmic diagnosis. Fluorescein is a vel- low-orange dye that emits a green color when exposed to a blue light. It is used topicallv for applanation tonometry and to diagnose corneal abrasions, punctate epithelial erosions, and other epithelial defects. The

'. , dye stains the corneal or conjunctival stroma in areas where the epithelium is absent, and it is used intravenously for fluorescein angiography.

Rose bengal is a red dve that stains devitalized epithelium and mucus. It is picked up by abnormal, but not absent, epithelial cells in diseases such as keratoconjunctivitis sicca.

Infection Medications

-,u

Medications for ocular infections comprise mainly antibacterial,

 

antiviral, and antifungal agents. Antiprotozoal and antiparasitic agents

 

are available but uncommonlv used, and discussion ot them is beyond

Anti-Inflammatory Agents

381

the scope of this manual. T h e names and attributes of common antibacterial, antiviral, and antifungal medications are summarized in Tables A l , A2, and A3, respectively, at the end of this appendix. Topical antibacterial agents should be used judiciously to avoid sensitization and emergence of resistant organisms.

Anti-Inflammatory Agents

Corticosteroids and nonsteroidal anti-inflammatory drugs are used either topically or systemically to reduce ocular inflammation.

Corticosteroids

Topical corticosteroids are used for anterior segment inflammation, including refractory cases of allergic conjunctivitis, iridocyclitis, episcleritis, scleritis, and both noninfectious and infectious keratitis (once the infection has been adequately treated). Many different corticosteroid preparations are available for topical ocular use; some examples in the three most common drug categories are listed below:

1.Prednisolone

•Prednisolone acetate suspension 0.125% (Pred Mild, Econopred)

•Prednisolone acetate suspension 1% (AK-Tate, Econopred Plus, Pred Forte)

•Prednisolone sodium phosphate solution 0.125% (AK-Pred, Inflamase Mild)

•Prednisolone sodium phosphate solution 1 % (AK-Pred, Inflamase Forte)

2.Dexamethasone

•Dexamethasone sodium phosphate solution 0.1% (Decadron Phosphate, AK-Dex, Baldex)

•Dexamethasone sodium phosphate ointment 0.05% (Decadron Phosphate, AK-Dex, Baldex, Maxidex)

•Dexamethasone suspension 0.1% (Maxidex)

3.Progesterone-like agents

• Medrysone 1.0% (HMS Fiquifilm)

• Fluorometholone suspension 0.1 % (FAIL Liquifilm)

WtSt. Appendix: Common Ocular Medications

•Fluorometholone suspension 0.25% (FML Forte Liquifilm)

•Fluorometholone acetate 0.1% (Flarex)

Corticosteroids may also be given by subconjunctival, sub-Tenon's capsule, intravitreal, peribulbar or retrobulbar, and systemic routes. Dosage and route of administration depend on the location and severity of the inflammation. Drops or ointment may be instilled every 1,2, or 4 hours (among other regimens), with tapering according to response. Even brief exposure to topical corticosteroids can worsen herpes simplex epithelial keratitis and fungal keratitis and may provoke severe ulceration or even perforation. In some people, corticosteroid use causes ocular hypertension or glaucoma. Long-term use can cause posterior subcapsular cataracts. Other side effects include delayed wound healing, corneal melting (keratolysis), prolongation of the natural duration of the disease, mydriasis, and ptosis.

Nonsteroidal Anti-Inflammatory Drugs

The nonsteroidal anti-inflammatory drugs (NSAIDs) reduce inflammation primarily by inhibition of the cyclo-oxygenase enzyme, which is involved in prostaglandin synthesis. Topical ophthalmic preparations with widening indications have become available recently. Certain agents such as flurbiprofen (Ocufen) are used topically to reduce pupillary constriction during intraocular surgery. Ketorolac tromethamine (Acular) has been approved for treatment of ocular allergies. Diclofenac sodium (Voltaren) is used for postoperative inflammation.

Mydriatics and Cycloplegics

:v""

'

"

Mydriasis (dilation of the pupil) is obtained either by paralyzing the

*

,/

 

iris sphincter (with parasympatholytic [cycloplegic] agents) or by stim-

 

 

 

ulating the iris dilator (with sympathomimetic [mydriatic] agents).

 

 

 

Maximal mydriasis is achieved by using a combination of both types of

 

 

 

agents. In addition to causing mydriasis, parasympatholytic agents par-

 

 

 

alyze the ciliarv muscle, which controls accommodation. This cyclo-

••••..-

 

plegia is useful when refracting children, whose active accommodation

 

 

 

precludes accurate measurement of refractive errors. Cvcloplegic (but

..%•

( '

 

not mydriatic) agents are also useful for relieving the pain of ciliary

i :-'.;•

 

muscle spasm, which accompanies epithelial defects of the cornea,

:;_;-.

 

corneal inflammation, and intraocular inflammation. Dilating the

•

ViK"

\^

pupils also helps prevent posterior synechiae in patients with anterior

 

 

 

segment inflammation. Agents that dilate the pupil should be used

Glaucoma Medications

383

with caution in patients with narrow anterior chamber angles, as thev can precipitate angle-closure glaucoma. Table A4 at the end of this appendix lists commonly used agents and their characteristics.

Glaucoma Medications

Glaucoma medications lower intraocular pressure to prevent optic nerve damage. Four different classes of drugs are used to treat openangle glaucoma. In addition, hyperosmotic agents are used to lower the intraocular pressure in acute glaucoma. These five classes of glaucoma medications are discussed below and reviewed in Table A5 at the end of this appendix.

Cholinergic Agonists

These agents, also known as miotics or parasympathomimetics, act bv increasing outflow of aqueous humor. Examples include pilocarpine, carbachol, demecarium bromide, echothiophate iodide, and isoflurophate. Ocular side effects include pupillary constriction (which can decrease vision, particularly if the patient has cataract) and ciliary spasm (resulting in brow ache and a myopic shift in refraction). Young people particularly are affected by ciliary spasm.

Adrenergic Agonists

Adrenergic agents, also called sympathomimetics, lower intraocular pressure by reducing the production of aqueous humor and by opening outflow pathways. Examples include epinephrine, dipivefrin (Propine), and apraclonidine (lopidine). Local ocular side effects include rebound hyperemia leading to a red eye, and cystoid macular edema in aphakic patients. Systemic side effects are uncommon but include tachycardia, hypertension, tremor, anxiety, and premature ventricular contractions.

Beta-Adrenergic Antagonists

Beta-adrenergic antagonists, also known as beta blockers, lower intraocular pressure by reducing aqueous production in the ciliary epithelium.

:Timolol maleate (Timoptic) and levobunolol (Betagan) are nonselective

-' beta blockers; betaxolol (Betoptic) selectively blocks beta-1 receptors.

•4$4 Appendix: (Amnion Ocular Medications

 

Systemic side effects include bradycardia, decreased cardiac output,

 

exercise intolerance, bronchiolar spasm, hypotension, syncope,

 

decreased libido, lethargy, and depression. These side effects can be

"' . *

additive to those associated with systemic beta blockers that the patient

 

might be taking for high blood pressure. Selective beta-1 blockers

• : ..

should be less associated witii bronchospasm.

Carbonic Anhydrase Inhibitors

 

 

Carbonic anhydrase inhibitors are given systemically to patients with

 

 

glaucoma who do not respond sufficiently to topical medication. They

 

 

reduce aqueous production by inhibiting the enzyme carbonic anhy-

 

 

drase. They are sulfonamide derivatives and should be avoided in

 

 

patients with sulfonamide allergies. Examples include acetazolamide

• • ; •

• i

(Diamox), methazolamide (Neptazane), and dichlorphenamide

• .

-, ?

(Daranide). Side effects include nausea, tingling of the fingers and

-?..'T'':--

 

toes, anorexia, peculiar taste sensations, hypokalemia, renal lithiasis,

 

 

acidosis, lethargy, loss of libido, depression, and (very uncommonly)

 

 

aplastic anemia. A topical ophthalmic carbonic anhydrase inhibitor,

 

 

dorzolamide (Trusopt), is also available.

Hyperosmotic Agents

Urea, glycerin, isosorbide, and mannitol reduce intraocular pressure by making the plasma hypertonic to aqueous and vitreous humor, with the result that fluid is drawn from the eye into the intravascular space. These agents are used orally or intravenously to lower die intraocular pressure in cases of acute glaucoma, and thev also are used preand postoperatively in selected patients. Caution must be exercised in patients with diabetes mellitus, congestive heart failure, and kidney damage.

Decongestant Vasoconstrictive, and Anti-Allergy Agents

A number of nonprescription ophthalmic preparations are available to reduce ocular redness, itching, and irritation. Most contain ephedrine and naphazoline, tetrahydrozoline, or phenylephrine. Some of these also have an added antihistamine such as pheniramine maleate or antazoline phosphate. ,; :,

1

i

|

Corneal Dehydration Medications

385

' Antihistamine-decongestant combinations include naphazoline HCl 0.025% plus pheniramine maleate 0.3% (AK-Con, Naphcon-A, Opcon-A) and naphazoline HCl 0.05% plus antazoline phosphate 0.5% (Albalon-A, Vasocon-A). Antihistamines (without decongestant) include levocabastine 0.05% (Livostin).

Mast cell stabilizers are used for allergic disorders such as vernal conjunctivitis. These include cromolyn sodium (Crolom), ketotifen fumarate (Zaditen), and lodoxamide tromethamine (Alomide).

Lubricating Medications and Tear Substitutes

•'•: f Many formulations of artificial tears and ointments are useful in patients with dry eyes. These are available over the counter in most cases. Basic ingredients include hypotonic or isotonic buffered solution, surfactants, and viscosity agents such as methylcellulose or ethyl-

• . . , . cellulose, which prolong corneal contact time. In general, ointments and viscous solutions adhere better to the cornea and require less frequent administration, but they have the disadvantage of temporarily degrading vision. Oilv medications (such as ointments) can also destabilize the tear film. Artificial tears often have preservatives (eg, ben/.alkonium chloride, thimerosal), which can cause epithelial toxicity if overused, but preservative-free preparations have been developed. Examples include Celluvisc, Refresh, Refresh Plus, and Cellulresh.

Corneal Dehydration Medications

 

 

Hypertonic medications may be instilled on the eye to clear corneal

 

 

edema osmotically. Patients may be placed on hypertonic sodium chlo-

 

 

ride 2% or 5% (Muro 128, Hypersal, Adsorbanac). For diagnostic pur-

 

 

poses, anhydrous glycerin (Ophthalgan) may be instilled on the cornea

 

 

to clear it

transiently lor visualization

of posterior

structures;

the

-

.

preparation

is so hypertonic as to cause

considerable

pain (thus

the

name, OphtlW^Y/n) if it is instilled without the use first of a topical anesthetic agent.

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