The effects of gender and birth control pill use on spontaneous blink rates.
BACKGROUND
Two major reference works suggest that men and women blink spontaneously at different rates, but they disagree with regard to which gender blinks faster.


METHODS
Spontaneous blink rates of 59 males and 86 females, 44 of whom were taking birth control (BC) pills, were measured for 5 consecutive minutes. Schirmer test results and tear break-up times (TBUTs) were also obtained.


RESULTS
Females taking BC pills blinked at a mean rate of 19.6 times per minute, females not taking birth control pills blinked 14.9 times per minute, and males blinked 14.5 times per minute. There were very large differences between blink rates for individuals in each of the groups. No strong associations were found between spontaneous blink rates and a history of contact lens use, tear break-up time, Schirmer test results, temperature or humidity in the examination room, subject age, or menstrual cycle phase.


CONCLUSIONS
The 32 percent increase in mean blink rate for females taking BC pills suggests that the pills affect at least one of the mechanisms that control spontaneous blinking, but it is unclear how they accomplish this.
Yolton
D P
DP
Pacific University College of Optometry, Forest Grove, OR 97116.
Yolton
R L
RL
López
R
R
Bogner
B
B
Stevens
R
R
Rao
D
D
D000328:Adult; D001767:Blinking / Q000187:drug effects / Q000502:physiology*; D003278:Contraceptives, Oral, Hormonal / Q000494:pharmacology*; D005260:Female; D006801:Humans; D008297:Male; D012727:Sex Characteristics; D013666:Tears / Q000737:chemistry
D003278:Contraceptives, Oral, Hormonal