Many women report changes in contact lens comfort during different phases of their menstrual cycle. Dryness and tearing, decreased visual acuity, swollen lids, foreign body sensations and visual coordination problems are examples of what may occur. This paper is a review of recent and older articles relating changes in contact lens comfort to modifications of the glands, conjunctiva and cornea of the eye during different phases of the menstrual cycle. Both high and low estrogen levels seem to affect the eye differently in various phases of the cycle. Some assumptions and predictions of what may happen to the eye at menopause also will be discussed.