Association of Nocturnal BP Dips and Optic Disc Hemorrhage in NTG Patients
American Journal of Ophthalmology, April 2017
Kwon et al. performed a case-control study of patients with normal-tension glaucoma (NTG) to assess whether there is an association between nocturnal dips in blood pressure (BP) and optic disc hemorrhage (OHD). They also evaluated the possible linkage between ODH and visual field progression (VFP). They found that “overdipping” is a significant risk factor for ODH and that the presence of ODH is a strong predictor of VFP.
The study included 349 Korean adults with NTG (698 eyes) who underwent 24-hour monitoring of intraocular pressure (IOP) and ambulatory BP. All patients were examined by optic disc photography every 4-6 months and completed at least 5 reliable visual field tests during follow-up (minimum, 3 years).
The researchers noted that a reduction of nocturnal BP in the range of 10%-20% relative to daytime BP levels is usually observed in normotensive subjects and in the majority of hypertensive patients. For this study, subjects within that range were classified as physiologic dippers; nonphysiologic dippers were defined as overdippers (>20% reduction in nocturnal BP) and nondippers (<10% reduction).
Among all eyes, ODH was detected in 15.3% and VFP in 8.6%. The frequency of ODH was significantly greater among overdippers than either nondippers or physiologic dippers. Throughout follow-up, overdipping remained a significant and independent risk factor for ODH. The rate of VFP was 6% for physiologic dippers, 7% for nondippers, and 24% for overdippers. The cumulative probability of VFP was significantly greater in eyes with 1 episode of ODH than in eyes without ODH, and eyes with recurrent ODH (≥2 episodes) had significantly greater cumulative probability of VFP compared with those that had only 1 episode of ODH.
The researchers concluded that nocturnal overdipping is a risk factor for the occurrence of ODHs during follow-up in NTG eyes. Further, they found that ODH is a potent prognostic factor for glaucomatous VFP. They noted that their findings support the idea that occurrence of ODH may be associated with IOP-independent risk factors and that vascular mechanisms may play an important role in the pathogenesis of OHD.
The original article can be found here.