Lunar influence on human visual acuity: Effects during the lunar quarters

We have previously shown that, in an eye affected by macular edema, visual acuity is better at the time of the full moon, with respect to the new moon, whereas there is no difference in the normal eye. In the present paper we report that in both the normal and the edematous eyes visual acuity is affected by the Moon at the lunar quarters. There are both increases and decreases of acuity but they occur rarely, only once or twice in a year. It is necessary for a lunar zero declination to coincide with a quarter for there to be a response. There is correlation between these events and changes in the atmospheric pressure. An increase in atmospheric pressure is associated with a decrease in visual acuity, whereas a decrease in atmospheric pressure correlates with an increase in acuity. These results may be of relevance to many marine animals.