Abstract
Purpose: :
To investigate the effects of light protection and light exposure on the correlation between cataract frequencies, age-related lens light scattering profiles and the intensity of lens discoloration in religious communities in Ireland.
Methods: :
Following induction of mydriasis with tropicamide, the anterior eye segments of a subset of 257 retired nuns from the INES cohort were monitored with the Pentacam HR® Scheimpflug Camera (Oculus, Wetzlar, Germany) and Retroillumination images of the lens were recorded with the Neitz cataract screener. In addition lens nuclear colour was graded using a handheld slit lamp microscope (Carl Zeiss, Jena, Germany) and LOCS III. A light exposure index was calculated for each nun with a detailed questionnaire, based on the religious rules of the convent, the professional indoor and outdoor activities and the solar UV- index for the region where they spent most of their active community life (missionary/ contemplative/teaching). Before inclusion into the study, informed consent was obtained from all nuns.
Results: :
Cortical cataracts were the most frequent type of cataract in this cohort (70%), followed by mixed forms of nuclear and cortical cataracts (16,25%). There were no sub- capsular cataracts and 8% of the cohort had normal lenses, unaffected by any cataract development. Independent of this observation, age-related light scattering increased more markedly in the deep cortex than in the anterior nuclear region than in posterior nucleus or cortex. Yellowing of the lens proved to be more correlated to nuclear density and age, than to exposure index.
Conclusions: :
Light protection had a more pronounced effect on the development of light scattering in distinct layers of the lens and on frequencies of cataract than on lens discoloration. The absence of anterior or posterior sub-capsular cataracts points to an efficient protection against UV-irradiation damage in this cohort.
Keywords: cataract • clinical (human) or epidemiologic studies: prevalence/incidence • radiation damage: light/UV