Summertime Ultraviolet Exposure of Cataract and Control Patients: a Proposed Model for Testing the Sunshine Hypothesis

Judit Szabó1, Sándor Gáspár2 and László D. Szabó1

1 Frédéric Joliot-Curie National Research Institute for Radiobiology and Radiohygiene, Fodor József National Center for Public Health, Budapest, Hungary
2 Institute of Biophysics and Radiation Biology, Semmelweis University Medical School, Budapest, Hungary

Contributing ophthalmologists: Andrea Facskó3, Katalin Gaál4, Beáta Gáspár5, Ibolya Gulyás6, Miklós Kanyár7, Angela Kovács4, Zoltán Pap8, and Zita Tóth Bagi9

3 Debrecen University Medical School, Debrecen, Hungary
4 Bajcsy-Zsilinszky Hospital, Budapest, Hungary
5 Hungarian Army Hospital, Budapest, Hungary
6 St. János Hospital, Budapest, Hungary
7 Emil Weil Hospital, Budapest, Hungary
8 City Health Service, Debrecen, Hungary
9 St. Imre Hospital, Budapest, Hungary
   
Corresponding author: Dr. Judit Szabó
    Frédéric Joliot-Curie National Research Institute for
    Radiobiology and Radiohygiene
    Fodor József National Center for Public Health
    Telephone:P.O. Box 101, H-1775 Budapest, Hungary
    Tel/ Fax: (+36) 1 229 1911
    E-mail: szj@hp.osski.hu

CEJOEM 1999, Vol.5. No.3-4.:243-260

Key words:
Cataract, cortical opacity, UV-B, biologically effective dose, biodosimetry

Abbreviations:
CUV-B = ultraviolet B radiation
CA = cortical anterior lens opacity
PSC = posterior subcapsular lens opacity
N = nuclear lens opacity
out = all cumulative time spent outdoors
sun = cumulative sunny hours spent outdoors
a.m. = before 11 o'clock 		noon = from 11 up to 15 o'clock
p.m. = after 15 o'clock
s.a.m. = sunny hours a.m.
s.noon = sunny hours noon
s.p.m. = sunny hours p.m.
hudos = uracyl effective dose /H(U)effective/
MED = erythemally weighted dose









Abstract:
Depletion of the ozone layer has been observed over the European continent in the past decades and, as a consequence, an increase in biologically effective solar UV radiation (SUVR) at the ground level has probably occurred. Chronic SUVR exposure gives rise to ocular damage mainly in the form of UV induced cataract.
    Our aim was to prove the known data of the literature, whether the excess SUVR exposure causes mainly cortical type opacity in the lens in our population. The present knowledge of the exact pathway of UV damage to the eye is limited. A proper action spectrum according to a known chromophore is needed for proper risk assessment of UVR exposure. DNA is a prominent target for UV-B radiation (cells of the germinal layer of the lens still contain DNA). We used uracyl thin layer to measure UV-B (sensitivity interval: 250-330 nm) exposure, because i) its action spectrum is very similar to the action spectrum of DNA, and ii) it is suitable for measuring cumulated dose over a longer period (summer of 1996). We assumed that the measured exposure (dosimeter positioned frontally on the chest) represented more or less: i) the individual's usual summertime outdoors behavior (SUVR exposure), and ii) the direction of sunlight similar to the eyes.
    To our best knowledge we were the first to employ personal biodosimetry to monitor SUVR exposure during a clinical (case-control) study. In order to be able to assess the excess risk of SUVR, we determined the risk posed by main cataractogen factors, other than UVR in terms of odds ratios. The reported dose of patients was compared to the measured dose. Altogether 47 cataracts (mean age: 62 years) and 34 controls (mean age: 48 years) participated in the survey. The mean biologically effective uracyl dose (H(U)eff) was 0.110 H(U)eff. Posterior subcapsular (PSC) was the most frequent opacity type. The cortical anterior type cataract patients' mean uracyl effective dose was higher, than that of the former.
    The odds of cataract of patients with higher UV doses (>0.10 H(U)eff) (without hyperglycemia and high blood pressure) was almost two times higher then of those, who had lower doses (gender adjusted OR: 1.86, 95% C.I.: 0.21-16.28).
    We have concluded that these observations support the known data of the literature, that excess SUVR (UV-B) exposure causes mainly cortical type opacity in the lens.

Received:   27 October 1999
Accepted:  09 February 2000
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