Follow-up to the earlier post that pointed to the large environmental contribution to the increase in myopia in modern populations, here is a report on a pending paper that gives a very high heritability for myopia:

By mathematically modeling the differences in the eye sizes, Hammond found that genes accounted for 89 percent of nearsightedness, farsightedness, and other refractive vision problems....

...Hammond scanned the entire genome of the fraternal twins and found four sections linked to the eye problem. The most strongly linked segment contains 44 genes, including one specified as PAX6, which is already well-known to vision researchers.