Purpose:
Management of glaucoma patients requires longitudinal monitoring of IOP and perimetric visual sensitivity. Detection of disease progression and IOP changes is hampered by non-glaucomatous factors that affect their measurement. Seasonal variations in IOP have been reported. This report examines whether seasonal variations also occur in perimetric mean deviation (MD), and whether these might be associated with seasonal variations in IOP.
Methods:
We analyzed IOP measurements and visual fields (MD) for seasonal variation, from 33,873 visits over 12.5 years (median) by 1,636 participants in the OHTS. The 22 clinics participating in the OHTS were classified into 6 climatically-similar geographic zones (Atlantic, Central, North, Pacific Northwest, Southeast, and West), based on the magnitude and timing of seasonal variations in precipitation, temperature and sunlight hours. Mixed effects regression models were used to identify sinusoidal periodic seasonal variations in IOP and MD.
Conclusions:
IOP and MD were both higher in winter than summer, although there is no evidence of a causative relation. The cause of these seasonal variations in sensitivity is unknown. These findings may help shed light on the disease process, as well as aiding reduce clinical test-retest variability.
Clinical Trial:
http://www.clinicaltrials.gov NCT00000125
Keywords: visual fields • intraocular pressure • clinical (human) or epidemiologic studies: natural history