Soltalk December 2018 | Page 46
Doctor’s notes
Dr Rik Heymans is a general practitioner in Nerja and writes
on developments in the world of medicine
Vitamin D
more outdoors life, walking about, or enjoying the sun on a
terrace!
There appears to be a growing discrepancy between the
observational studies on the benefits of having sufficient levels
of vitamin D, and the randomised clinical trials of vitamin D
intake. For example, the observational studies are showing a
fairly consistent relationship between low blood levels of
vitamin D and an increased risk for heart disease, cancer,
diabetes, and many other chronic diseases.
Contact lens use and infections
Most adult contact lens wearers in the United States who took
part in an online survey from the Centers for Disease Control
and Prevention (CDC) reported at least one type of hygienic
behaviour that put them at risk for an eye infection in 2014. In
addition, approximately one-third of them reported at least
one healthcare visit for a red or painful eye while wearing
contact lenses, researchers reported recently. The survey found
that approximately 40.9 million US adults (an estimated 1 in 6
adults in the United States) wear contact lenses. Nearly all
(93.0%) of them wear soft contact lenses.
Yet, the randomised clinical trials of vitamin D supple-
mentation to date have been generally disappointing. This
includes several randomised trials published over the past few
months, including a large analysis of randomised trials of
vitamin D supplementation showing minimal, if any, benefit
on lowering blood pressure; a trial of high-dose vitamin D
supplementation showing no clear benefit for muscle strength,
bone mineral density, or even the risk for falls; and, most
recently, a randomised trial of vitamin D supplementation
with and without calcium showing no clear benefit in reducing
the risk for colorectal adenomas.
Of the respondents to this survey, approximately 99% reported
at least one risky hygiene behaviour, including ever doing any
of the following: sleeping overnight in contact lenses (50.2%),
napping in contact lenses (87.1%), diluting the disinfecting
solution (55.1%), extending the recommended replacement
frequency of lenses (49.9%) or cases (82.3%), showering (84.9%)
or swimming (61.0%) whilst wearing contact lenses, rinsing
lenses in tap water (35.5%), or even storing lenses in tap water
(16.8%). Of all contact lens wearers, 30.2% reported ever having
a red or painful eye while wearing lenses that required a
doctor’s visit.
Vitamin D is one of these vitamins which is stored in the body,
and accumulates there - unlike Vitamin C or B, where any
excess ingested is easily washed out; so when taking in too high
doses Vitamin D will have toxic effects.
The Institute of Medicine (IOM) and the US Preventive
Services Task Force do not endorse routine universal screening
for vitamin D deficiency. They also recommend more
moderate intakes of vitamin D. For example, the IOM
recommends 600-800 IU a day for adults and also
recommends avoiding daily intakes above 4000 IU, which has
been set as the tolerable upper intake level.
The frequent exposure of contact lenses to water, including
storing or rinsing the lenses in tap water and showering or
swimming while wearing lenses, is especially concerning.
Exposure of lenses to water raises the risk for infection
because bacteria or viruses living in this water can be
transferred to the eye. Even household tap water, although
treated to be safe for drinking, is not sterile and contains
microorganisms that can contaminate lens cases and contact
lenses and cause eye infections. And although some contact
lenses have approval from the US Food and Drug
Administration for
overnight wear, sleeping
in any type of contact
lens increases risk for eye
infection, as obviously
does noncompliance with
lens and case replacement
schedules.
However, some patients may have higher vitamin D
requirements. This may include patients with bone health
problems (osteoporosis, osteomalacia) or poor diets; those who
spend minimal time outdoors; those with malabsorption
syndromes; or those who take medications that may interfere
with vitamin D metabolism (long-term cortisone,
anticonvulsant medications, and antituberculosis drugs). All in
all, here in sunny Spain there would be little need for
additional Vitamin D supplements, since one tends to live a
The final message should
be: focus on keeping all
water away from contact
lenses; discarding used
disinfecting solution from
the case and cleaning
with fresh solution each
day; and replacing
contact lens case every
three months, the authors
conclude.
© Dr RIK HEYMANS
c/ Angustias 24, Nerja.
Tel: 95 252 6775
44
Dr Rik Heymans "running in
the rain" in the Vélez Half
Marathon last month. Not
deterred by the weather
apparently, he plans to run the
Half Marathon in Cordoba
next...