What is dry eye syndrome?
"Dry eye syndrome" is a name that encapsulates a number of different conditions, all of which share eye dryness. It's like "headache"; there are many different types of headaches and causes of a headache, but they all share the same general symptoms of pain in and around the head region. The different types of dry eye are classified into dryness that has to do with inadequate production of tears, what we call tear-deficient dry eye, and dry eye syndrome that is due to enhanced loss (or evaporation) of the tears. We don't know exactly what percentage of people with dry eye syndrome have each type, and this issue is complicated by the fact that many people have both types of dryness at the same time.
The one thing that all of these patients have in common is a sensation of burning and dryness on their eye, which can be quite debilitating in moderate to severe dry eye.
How common is dry eye syndrome?
It affects far more women as compared to men in all age groups. There are many theories regarding that. But, the overarching hypothesis is that the differences are due to sex hormones.
Male sex hormones, like androgens or testosterone, tend to inhibit many, but not all, forms of immune and inflammatory responses. [Inflammation contributes to dry eye.] And consequently, because women have a much lower amount of circulating testosterone as compared to men, that might be an important factor in predisposing women to dryness. It's theorized that dry eye is more common in women after menopause because there is a decrease in androgens as well as estrogen.
