It would not hurt to have her eyes checked, and have some tests performed. A slightly dry eye (KCS) in cats can be a secondary sequellae to a Herpes infection. Herpes infections are very common upper respiratory and eye infections in cats.
Mild dehydration may also cause a tear problem. The dehydration can be sub-clinical i,e, may not even show up in blood or urine tests, and can be caused by a diet that includes dry food. Feline diets should be all wet or canned diets that are grain free.
Thank you for the information. We'll be visiting the vet in the morning and the local pet health store in the meantime. My siamese eat a can of wet food each per day supplemented with dry food, dry food to be eliminated. Lately the female in question has been drinking noticeably more water than the male (who is nearly twice her size), seeming to indicate that she isn't getting enough water from her food.