[Gathnet] Summer sun

[SKM]

All,

            The summer sun is upon us! UV damage to our skin and that of
our patients causes sunburn, wrinkles, skin aging and skin cancer, but
here are some facts you may not be aware of. Relevance to ophthalmology:
lid cancer, pterygia, pingueculae, chronic "conjunctivitis", MS
(multiple sclerosis).

 

1. Many children come in during the summer months with chronically or
acutely injected eyes from sun exposure. A close look shows
interpalpebral injection. The conjunctiva of the eye does not tan!
Chronic sun damage will eventually lead to eye problems such as
pterygia, pingueculae, and Salzman's degeneration. This can be avoided
by getting out of the sun or by using a hat, UV-protecting sunglasses
and swim goggles (many are these days).

 

2. UV exposure is classified in two broad categories, UVA and UVB (see
the graph below). Standard sunblocks (even those protecting against UVA
and B) do not block much of the UVA light: the SPF number refers to the
UVB protection only. There is a new "reflective" sunblock ingredient in
some sunblocks. This microfine zinc oxide is nearly invisible (I put it
on my bald pate every day) but does a much better job protecting against
UVA; an example is the Coppertone’s "Spectra 3" block available from the
Commissary.

 

See http://www.aad.org/pamphlets/SunSkin.html  or
http://www.sunscreens.net/ 

 



 

 

3. The downside to avoiding sun exposure is lack of vitamin D. Simply
stated, you need about twice the RDA and should get this in pill form
(it is cheap). Here are some quotes about the importance of vit D:

 

“Inverse correlations are found for UV-B radiation for a number of
cancers, with those for bladder, breast, endometrial, ovarian, prostate,
and renal cancer, and multiple myeloma and NHL having the strongest
correlations in this and ongoing multicountry ecologic studies. These
studies add further support for the role of UV-B radiation and vitamin D
in reducing the risk of a large number of cancers.” Grant WB. Ecologic
studies of solar UV-B radiation and cancer mortality rates. Recent
Results Cancer Res. 2003;164:371-7. Review. PMID: 12899536
<http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&li
st_uids=12899536&dopt=Abstract>

 

“Intake of vitamin D from supplements was also inversely associated with
risk of MS; the RR comparing women with intake of >or=400 IU/day with
women with no supplemental vitamin D intake was 0.59 (95% CI = 0.38 to
0.91; p for trend = 0.006). No association was found between vitamin D
from food and MS incidence.” Munger KL, Zhang SM, O'Reilly E, Hernan MA,
Olek MJ, Willett WC, Ascherio A. Vitamin D intake and incidence of
multiple sclerosis. Neurology. 2004 Jan 13; 62(1): 60-5. PMID: 14718698
<http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&li
st_uids=14718698&dopt=Abstract>

 

“The recommended adequate intakes for vitamin D are inadequate, and, in
the absence of exposure to sunlight, a minimum of 1000 IU vitamin D/d is
required to maintain a healthy concentration of 25(OH)D in the blood.”
Holick MF. Vitamin D: importance in the prevention of cancers, type 1
diabetes, heart disease, and osteoporosis. Am J Clin Nutr. 2004
Mar;79(3):362-71. PMID: 14985208
<http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&li
st_uids=14985208&dopt=Abstract>

 

 

 

 

 

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