Identical twins have identical vision – new study

Published: 25 May 2017 at 10:00

Identical twins

Study into the eyesight of twins shows power of genetics down to the tiniest detail

Optical aberrations in healthy people are caused by genetics rather than environmental or lifestyle factors, according to research by Anglia Ruskin University published in the journal Investigative Ophthalmology and Visual Science.

Researchers discovered the results after examining the vision of 69 sets of twins, 36 of whom are identical twins. The study looked at optical defects found in every eye which slightly alter a person’s vision.

The results of the study showed that identical twins shared identical defects, even in the over-50s where environmental factors may have normally influenced these aberrations through more than half a century.

Non-identical twins, who only share 50% of genes on average, had different ocular defects as a consequence of their genetic difference, compared to identical twins (who share 100% of genes).

The author of the study, Dr Juan Tabernero of Anglia Ruskin University’s Vision and Eye Research Unit (VERU), said: 

“We have shown how tiny optical defects of the eye that respond to imperfections as small as a few micrometres in the lenses of the human eye are extremely similar in identical twins, and not in non-identical twins. 

“This situation illustrated the strong genetic component that affect these defects against the opinion of those who thought that the aberrations were mostly influenced by the environment. 

“Our results were particularly striking if we take into account that our twins were mostly in the 50s and had been ‘using’ their eyes independently from each sibling for such a long time. 

“Larger, common optical defects like myopia or astigmatism were already known to have a strong genetic component. But very little was known about the genetics of these small aberrations and optical defects that everyone has in their eyes. 

“Aberrations are for instance responsible of how everyone see stars in the sky slightly different at night. But now, we can say that only identical twins see identical stars.”

The research was carried out with the Laboratorio de Optica and the Murcia Twin Registry from the University of Murcia, Spain.