DƯỢC LÍ Goodman & Gilman's The Pharmacological Basis of Therapeutics 12th, 2010

necessary. Rifabutin, if used in conjunction with clarithromycin
or fluconazole for treatment of Mycobacterium avium complex
(MAC) opportunistic infections in human immunodeficiency
virus (HIV)-positive persons, is associated with an iridocyclitis
and even hypopyon. This will resolve with steroids or by stopping
the medication.
Ocular Surface. Isotretinoin (ACCUTANE, others) has a drying effect
on mucous membranes and is associated with dry eye and meibomian
gland dysfunction.
Cornea Coryanghiva and Eyclids . The cornea, the conjunctiva, and
even the eyelids can be affected by systemic medications. One of
the most common drug deposits found in the cornea is from the cardiac
medication amiodarone. It deposits in the inferior and central
cornea in a whorl-like pattern termed cornea verticillata. It appears
as fine tan or brown pigment in the epithelium. Fortunately, the
deposits seldom affect vision, and therefore, this rarely is a cause to
discontinue the medication. The deposits disappear slowly if the
medication is stopped. Other medications, including indomethacin,
atovaquone, chloroquine, and hydroxychloroquine, can cause a similar
pattern.
The phenothiazines, including chlorpromazine and thioridazine,
can cause brown pigmentary deposits in the cornea, conjunctiva,
and eyelids. The deposits generally are found in
Descemet’s membrane and the posterior cornea. They typically do
not affect vision. The ocular deposits generally persist after discontinuation
of the medication and can even worsen, perhaps because
the medication deposits in the skin are slowly released and accumulate
in the eye.
Gold treatments for arthritis (now rarely used) can lead to gold
deposition in the cornea and conjunctiva, which are termed chrysiasis
and are gold to violet in color. With lower cumulative doses (1-2 g),
the deposits are found primarily in the epithelium and anterior stroma.
These deposits usually disappear with discontinuation of the medication.
With higher doses, the gold is deposited in Descemet’s membrane
and posterior stroma and can involve the entire stroma. These
changes can be permanent. The deposits generally do not affect vision
and are not a reason to stop gold therapy.
Tetracyclines can cause a yellow discoloration of the lightexposed
conjunctiva. Systemic minocycline can induce a blue-gray
scleral pigmentation that is most prominent in the interpalpebral
zone (Morrow and Abbott, 1998).
Agents Used to Assist
in Ocular Diagnosis
A number of agents are used in an ocular examination
(e.g., mydriatic agents, topical anesthetics, dyes to evaluate
corneal surface integrity), to facilitate intraocular
surgery (e.g., mydriatic and miotic agents, topical and
local anesthetics), and to help in making a diagnosis in
cases of anisocoria (Figure 64–5) and retinal abnormalities
(e.g., intravenous contrast agents). The autonomic
agents have been discussed earlier. The diagnostic and
therapeutic uses of topical and intravenous dyes and of
topical anesthetics are discussed in “Anterior Segment
and External Diagnostic Uses” and “Posterior Segment
Diagnostic Uses.”
Anterior Segment and External Diagnostic Uses. Epiphora (excessive
tearing) and surface problems of the cornea and conjunctiva
are commonly encountered external ocular disorders. The dyes fluorescein,
rose bengal, and lissamine green are used in evaluating
these problems. Available as a 2% alkaline solution, 10% and 25%
solutions for injection, and an impregnated paper strip, fluorescein
reveals epithelial defects of the cornea and conjunctiva and aqueous
humor leakage that may occur after trauma or ocular surgery.
In the setting of epiphora, fluorescein is used to help determine the
patency of the nasolacrimal system. In addition, this dye is used
as part of the procedure of applanation tonometry (IOP measurement)
and to assist in determining the proper fit of rigid and semirigid
contact lenses. Fluorescein in combination with proparacaine
or benoxinate is available for procedures in which a disclosing
agent is needed in conjunction with a topical anesthetic. Fluorexon
(FLUORESOFT), a high-molecular-weight fluorescent solution, is
used when fluorescein is contraindicated (as when soft contact
lenses are in place).
Rose bengal and lissamine green, available as saturated paper
strips, stain devitalized tissue on the cornea and conjunctiva.
Posterior Segment Diagnostic Uses. The integrity of the blood-retinal
and retinal pigment epithelial barriers may be examined directly by
retinal angiography using intravenous administration of either fluorescein
sodium or indocyanine green. These agents commonly cause
nausea and may precipitate serious allergic reactions in susceptible
individuals.
Agents Used to Treat Retinal
Neovascularization and Macular
Degeneration
Verteporfin (VISUDYNE) is approved for photodynamic
therapy of the exudative form of ARMD with predominantly
classic choroidal neovascular membranes (Fine
et al., 2000; Jager et al., 2008). Verteporfin also is used in
the treatment of predominantly classic choroidal neovascularization
caused by conditions such as pathological
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CHAPTER 64
OCULAR PHARMACOLOGY