Genetic factors notoriously play a role in the development glaucoma, but a study in this month's Ophthalmology journal has found that the weather where is also a big factor. Temperature and sun exposure were found to increase incidences of exfoliation syndrome (ES), an eye condition that is a major cause of glaucoma as well as a risk factor for cataracts and complications from cataract surgery. The study looked at 120,000 Americans; those in the central part of the country had a 47 percent lower risk of developing ES than those in the north. Southerners had a 75 percent lower risk. This follows international statistics that say that 20 percent of Icelanders over the age of 60 develop ES, as do 23 percent of Swedes. However, the disease affects just 1 percent of Australians and 3 percent of Indians. Women were also found to be more at risk of developing ES.