Well, it is normal to have glassy eyes when you are pregnancy. For glassy eyes, you should know that when someone have glassy eyes, his eyes will have a feeling of listlessness, and the eyes are unfocused, and without any luster. Some researches have shown that glassy eyes can be caused by pregnancy. Also, eye irritation, dry eyes, eye discomfort, and vision changes may occur, when you are pregnancy.
When you get pregnant, you will find that your eyes pressure is not that stable. The eyes may easily get dry. You could find that your pregnancy will cause your glassy eyes which will make your eyes look watery and shining. The glassy eyes can be a sign of pregnancy. However, you could see that the eyes infection could also cause the glassy eyes.
I don't think glassy eyes is a sign of pregnancy. Pregnancy does have some effect on eyes due to hormone changes during pregnancy. However some people find it very obvious, while some found nothing changes to their eyes. In a word, change of eyes is not a must signal during pregnancy, so we can't tell that glassy eyes is a sign of pregnancy. Glassy eyes make people look tried and listless, which is caused by some complicated factors. Normally it might be caused by high thyroid level or viral infections. Pregnancy might make people get eye infection by increased toleration with wearing contact lenses. But you can see there is no direct connection between glassy eyes and pregnancy. The glassy eyes might be caused by some depress central nervous system medication too.