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β-zone peripapillary atrophy (PPA) is known to be associated with glaucoma development and progression. The cause of the development and enlargement of β-zone in association with glaucoma remains to be elucidated. Wang et al. assessed changes in the peripapillary RPE in association with acute IOP elevation provoked by a dark room prone provocative test (DRPPT) in 45 eyes of 35 patients.
The findings of this study suggest the possibility that the development for enlargement of the parapapillary β-zone is influenced by a rise in IOP
They found that 18 out of the 19 eyes with an acute rise in IOP (> 15 mmHg) showed a folding and centrifugal sliding, or both, of the end the RPE layer on the peripapillary Bruch's membrane. The RPE changes were located most often at the temporal pole of the ONH, followed by the nasal pole. The RPE changes were not detected at the inferior or superior disc poles. On the day after the DRPPT, the RPE end moved back to the end of peripapillary Bruch's membrane. None of the eyes who had IOP elevation less than 15 mmHg after the DRPPT showed RPE changes. The findings of this study suggest the possibility that the development or enlargement of the parapapillary β-zone is influenced by a rise in IOP. Since the β-zone PPA is characterized by the absence of RPE, it may be conceived that long-standing IOP induces sustained centrifugal sliding of the RPE, and thereby development of β-zone PPA. However, further study is needed to confirm whether the study finding observed in this study on eyes with acute IOP elevation can substantially explain the development of β-zone PPA, which is a slowly occurring process over a long period. In addition, it is noteworthy that β-zone is also commonly found in glaucomatous eyes with IOP within the statistically normal limit.