This study was designed to evaluate the hypothesis that hormonal
change can affect lower level light-adaptation processes, which are
likely to be retinally based. Foveal visual sensitivities were measured
across several menstrual cycles of four women not using hormonally
acting medication and across several menstrual cycles of three women
using a triphasic oral contraceptive. One woman, diagnosed with
premenstrual syndrome (PMS), was a subject for both groups.
Sensitivities were measured for a series of test wavelengths for 580-nm
backgrounds of 2.0 and 4.0 log td. Of the six individuals tested, one
had clear evidence of visual-adaptation changes occurring in phase with
the menstrual cycle. Prior to using the oral contraceptive, this
individual (the PMS subject) experienced changes of
short-wavelength-sensitive (SWS)-cone-mediated sensitivities of up to
about 1.4 log unit on the 4.0 log td background. Her SWS-cone-mediated
sensitivities tended to be highest near ovulation and lowest
premenstrually. Threshold-versus-illuminance (TVI) curves confirmed
that the rate of sensitivity decrease with increasing background
illuminance (i.e. the TVI slope) was greater premenstrually. The degree
of background-induced desensitization within her
middle-wavelength-sensitive (MWS)/long-wavelength-sensitive (LWS)
cone pathways also appeared to vary cyclically, but the magnitude of
the variation was smaller and the time course appeared to be different.
When this subject began oral contraceptive use, the patterns of
sensitivity change were all altered. None of the other five subjects
experienced changes of SWS-cone-mediated vision that were cyclic and
significantly adaptation-state dependent. However, there was evidence
for a limited degree of cyclic adaptation change within the MWS/LWS
cone pathways of at least one additional subject. We conclude that
hormonal change can—for some unknown proportion of women—be
linked to alterations of retinal function. However, the alterations are
not the same for all visual pathways, and there are pronounced
individual differences. The data also demonstrate that
individuals' visual adaptation capabilities can vary substantially
over periods of weeks.