Purpose: In the Nordic countries 2 to 4% of the population squint or have been squinting. Since strabismus is one of the major causes of amblyopia early detection and treatment is important for preventing this development. For centuries it has been recognized that strabismus is hereditary. Identifying individuals with a family history of squinting could give access to a risk population for a selective screening.
Methods and results: 1,571 children were selected for this study. All children that took part in a voluntary eye examination at one year of age (born 1978-1983) in the city of Vasteras, Sweden and that had a family history of strabismus were selected together with controls. The study was a 6-year follow-up from 1 to 7 years of age. Parental knowledge of squint among relatives and measured high hyperopia (>3.0 D) present at 1 year of age were each and in combination evaluated as a risk indicator for development of strabismus between 1 to 7 years of age.
Conclusion: The study indicates that a family history of squint in combination with measured high hyperopia can be used in a selective screening to identify a population with an increased risk of 4 to 6 times for developing strabismus. Among the children with parental knowledge of squint among several relatives of both the parents, those with high hyperopia developed strabismus in almost every second case while this was the case in only approximately 10% of those with low hyperopia. Finally, heredity is an important risk indicator that can be used for selective screening purpose. Its potential as a risk indicator is substantially increased when combined with a high hyperopia.