Systemic Drug Updates
Ocular Implications of Topomax
We are all familiar with the maculotoxic potential of hydroxychloroquine
(Plaquenil) and Tamoxifen (Nolvadex). Anticholinergic drugs,
such as tolterodine tartrate (Detrol, for bladder control),
and numerous anti-psychotic drugs can cause angle-closure
events in eyes with occludably narrow iridocorneal angles.
The latest drug to gain ophthalmic side effect attention is
topiramate (Topamax). In the January, 2004 Ophthalmology, an
article entitled, “Topiramate-associated Acute, Bilateral,
Secondary Angle-closure Glaucoma,” details 115 case reports
of such events, and 17 associated case reports of acute, bilateral
myopia. Note that spontaneous narrow iridocorneal angle-closure
attacks are almost always unilateral, whereas these events
associated with Topamax are almost exclusively BILATERAL.
Topamax is commonly used to treat seizure disorders, but is
gaining popularity in the management of migraine, depression,
neuropathic pain, weight reduction, and bipolar disorder. As
you can readily see, there are millions of patients for which
this drug can be potentially used.
When these rare ocular complications occur, they usually do
so within a few days to two weeks of either drug initiation,
or an increase in the dosage. Therefore, this history is critical
in the diagnostic evaluation.
The first presenting symptom of acute secondary angle-closure
glaucoma in many patients is blurring of vision. The mechanism
of the angle-closure event is not clear, but is thought to
be from supraciliary effusions. This requires the evaluating
optometrist to consider four things:
- Avoid miotics, but rather use cyclopentolate or scopolamine
or homatropine to help reduce ciliary body mass and posture.
- Use an oral CAI and a topical beta-blocker to suppress aqueous
production.
- Stop, or decrease, the causative systemic medicine in concert
with the prescribing physician.
- Do not accomplish, or have accomplished, laser photoiridotomy
as this is unnecessary and unwise.
Simply stopping the Topamax results in an abrupt, marked reduction
in the intraocular pressure.
The acute myopia is most likely caused by either lens thickening,
and/or forward displacement of the lens-iris diaphragm.
In summary, it is so critically important to be current with
the ophthalmic literature so that various articles of this
nature can alert the astute clinician to be vigilant for these
rare, but important clinical events.
The "Statins" and Macular Degeneration
(These HMG Co-Enzyme A reductase Inhibitors are more commonly
known as “the statins”. They are best known by their brand
names of Lipitor, Zocor, Pravachol, and Lescol.)
“Age-related macular degeneration involves accumulation of
lipid-laden concretions in Bruch’s membrane which can lead
to fracture of the membrane and subsequent growth of capillaries
resulting in exudative complications. There is conflicting
epidemiological evidence with respect to the relationship between
cardiovascular disease and AMD. Recently, there has been some
evidence suggesting a beneficial effect between use of statins
and development and progression of AMD; however, further research
is needed. The most recent published article, relating statins
and AMD did not identify a causal relationship in a population-based
cohort followed over five years.
This review was done by Paul Lama, MD, Newark, NJ, Survey
of Ophthalmology, Jan-Feb 2004.
Cholesterol-Lowering Drugs and Risks of Age-Related Maculopathy:
Prospective Cohorts Study With Cumulative Exposure Measurement
(Van Leeuwen, R., et al, British Medical Journal, 2003)
Another Article on ARMD and the "Statins"
The following is a summary review of this article by N. Bahgat,
MD, of Newark, NJ; Survey of Ophthalmology, Jan-Feb 2004.
“The authors of this paper report that cholesterol-lowering
drugs have no effect on the development of age-related maculopathy.
There was also no association even when body mass index, hypertension,
smoking, or peripheral artery disease were taken into consideration.
Cumulative use of cholesterol-lowering drugs when compared
to patients who had never used cholesterol-lowering drugs did
not have protective effects on the risk of ARM. No association
was also found between the use of cholesterol-lowering drugs
and the progression of ARM.
“Future long-term, well randomized, prospective studies with
higher statistical power are needed to either support or refute
the claim of the protective effect of statins or cholesterol-lowering
specific class of drugs.”
Bilberry and Night Vision
Anthocyanoside of Vaccinium Myrtillus (Bilberry) For Night
Vision - A Systematic Review of Placebo-controlled Trials
(Cantor, P. H., and Ernst, E., Survey of Ophthalmology, Jan-Feb
2004)
“Abstract. We have systematically reviewed placebo-controlled
trials of v. myrtillus-extracted anthocyanosides for evidence
of positive effects on night vision. Searches of computerized
databases and citations in retrieved articles identified thirty
trials without outcome measures relevant to vision in reduced
light. The four most recent trials were all randomized-controlled
trials and were negative in outcome. The hypotheses that the
myrtillus anthocyanoside improved normal night vision is not
supported by evidence from rigorous clinical studies. There
was a complete absence of rigorous research into the effects
of the extract on subjects suffering impaired night vision
due to pathological eye conditions.”
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