Circadian fluctuations of macular edema in patients with morning vision blurring:: Correlation with arterial pressure and effect of light deprivation

PURPOSE. This study explored the causes of vision fluctuations in patients with chronic macular edema. METHODS. Fifteen patients ( 16 eyes) with vision blurring at awakening due to post - central retinal vein occlusion (CRVO) macular edema underwent three examination sessions over 24 hours ( at 7 PM, immediately after awakening at 7 AM, and at 7 PM), which comprised assessment of Early Treatment Diabetic Retinopathy Study score and measurement of macular thickness (MT) by optical coherence tomography. Ocular perfusion pressure was calculated from ambulatory arterial pressure measurement. In addition, after the 7 AM measurements, the patients were randomly selected for monocular light deprivation during the day to evaluate the role of retinal illumination in these fluctuations. RESULTS. Circadian fluctuation of MT was documented in all patients. At 7 AM, mean visual acuity (VA) was worse ( mean +/- SD of the difference: 6.5 +/- 7.2 points; P < 0.002) and mean MT was higher (57.4 +/- 34 mu m; P < 0.001) than at 7 PM. Fluctuations of MT were correlated to fluctuation of arterial pressure ( P = 0.05), but were not influenced by monocular light deprivation. CONCLUSIONS. In most patients complaining of visual fluctuations due to macular edema secondary to CRVO, MT and VA were found to undergo a circadian cycle. These short-term anatomic and functional variations were associated with arterial pressure variations ( that is, macular thickening was inversely correlated to the arterial pressure drop during the night), but were not due to light deprivation.