A series of 109 like-sexed twin pairs in the age group 30–31 years (54 monozygotic and 55 dizygotic) with one or both members of the twins with myopia was found in the Finnish Twin Cohort. The series was based on a random sample of 1,200 twins in one age stratum of the cohort. The twins received a questionnaire on their health status with special reference to eye diseases and symptoms. The refractive status of the twin pairs was ascertained by asking the twins to send their latest prescription for glasses to the authors or the refraction was obtained from the ophthalmologists or opticians of the twins. The mean difference in refraction between the monozygotic twins was 1.19 dptr in the right eyes and 1.15 dptr in the left eyes. The difference between dizygotic pairs was 2.34 dptr in the right eyes and 2.47 dptr in the left eyes. Analysis of variance showed that the difference in refraction between the two eyes of a twin pair was not significant. The mean difference in refraction between the monozygotic twins was significantly lower than that between dizygotic twins (p ≤ 0.001). The intrapair variances were doubled among dizygotic twin pairs compared to monozygotic twin pairs in the male group. The intrapair variance in the female group was 4-fold among dizygotic twin pairs as compared to monozygotic twin pairs. Heritability of myopia was 0.58 (0.74 for males and 0.61 for females) when myopia was considered a dichotomous variable. This result suggests that inheritance has a substantial effect on the etiology of myopia.
ABSTRACT.Purpose: Animal research and observational studies in man suggest a protective effect of antioxidant vitamins in the development of age-related maculopathy (ARM). Methods: The ATBC study, a population-based, controlled clinical trial of alpha-tocopherol and beta carotene to prevent lung cancer, took place in Finland between 1984 and 1993. Over 29,000 smoking males aged 50 to 69 years were randomly assigned to alpha-tocopherol (AT; 50 mg/day), beta-carotene (BC; 20 mg/day), both of these, or placebo. We performed an end-of-trial ophthalmological examination on a random sample of 941 participants aged 65 years or more from two of the fourteen study areas, to discover if the five to eight-year intervention with alpha-tocopherol and/or beta-carotene had been associated with a difference in ARM prevalence. Age-related maculopathy was assessed using colour photographs of the macula. Results: Altogether, 269 cases of ARM were found; there were more cases in the AT group (32%; 75/237), BC group (29%; 68/234), and combined antioxidant group (28%; 73/257) than in the placebo group (25%; 53/213). However, neither substance was significantly associated with the risk of ARM in a logistic regression analysis controlling for possible risk factors. Conclusions: No beneficial effect of long-term supplementation with alpha-tocopherol or beta-carotene on the occurrence of ARM was detected among smoking males.
Objective-To examine the eVect of tocopherol and carotene supplementation on the incidence of age related cataract extraction. Setting-The Conclusion-Supplementation withtocopherol or carotene does not aVect the incidence of cataract extractions among male smokers. (J Epidemiol Community Health 1998;52:468-472) Animal studies have shown that deprivation or overprovision of certain vitamins and micronutrients can aVect the development of cataract.
The incidence of acute closed-angle glaucoma was studied in 1796 patients derived from the hospital discharge registry of Finland for the years 1973-1982 (469 males and 1327 females). The average incidence was 3.8 cases/100,000 per year. The incidence showed a steep rise with age. The highest incidence was observed in both sexes in the group 80 years of age and older. The incidence was higher (Chi-square 7.81, df = 1, P less than 0.01) among women (5.3/100,000 per year) than among men (2.0/100,000 per year). The age-adjusted incidence for the whole period of 1973-1982 showed no statistically significant rise. The seasonal variation of incidence was statistically significant (P less than 0.001). In winter (December, January, February) and in autumn (September, October, November) the incidences were higher compared to spring (March, April, May) and summer (June, July, August). This association was greater (P less than 0.001) among females than among males (P less than 0.05). Mean sunshine hours showed a reverse association with the incidence of acute glaucoma. The association was statistically significant when both sexes were pooled together (P less than 0.001). There was no sex interaction with regard to the association of incidence of acute glaucoma and mean sunshine hours.
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