Diurnal Variation of Intraocular Pressure in the Normal Eye

Abstract

Diurnal variation of intraocular pressure has been the subject of considerable interest and speculation since Maslenikow¹ first called attention to it in 1904. Many authors writing on this subject have suggested that exaggeration of the normal diurnal pressure fluctuation is characteristic of early chronic open-angle glaucoma. As recently pointed out by Leydhecker,² however, there seems to be little agreement as to the upper limit of "normal" diurnal variation, the value cited by various authors ranging between 2 and 10 mm Hg (Table 1). Moreover, only a few authors have presented convincing evidence to substantiate their opinions. The most pertinent study is that of Drance,³ who measured the intraocular pressure in 404 eyes without glaucoma in a general hospital, recording tensions with the Schiøtz tonometer at 6, 9, and 11:30 am, and 2, 5, and 10 pm during the day. Diurnal variation in these patients ranged from 0