Purpose
To assess changes in the peripapillary retinal pigment epithelium (RPE) in association with an acute intraocular pressure (IOP) elevation provoked by a dark room prone provocative test (DRPPT).
Methods
Nineteen eyes of 14 primary angle-closure suspects with normal optic nerve heads (ONH) showed a rise in IOP of more than 15 mmHg at the end of the DRPPT. Before and at the end of the test, the ONH was imaged by spectral-domain optical coherence tomography (OCT) in a 7-line-scan pattern and in a star-scan pattern. The follow-up tracking mode was applied to detect changes between the first and second image. 26 eyes from 26 patients with IOP increase below 4 mmHg were selected as the control group.
Results
The mean IOP increased by 32.1 ± 9.5 mmHg (17 mmHg to 47 mmHg). 17 (90%) eyes showed morphological changes at the end of the RPE on the peripapillary Bruch's membrane. In comparison, none of the 26 control eyes showed RPE positional change while IOP elevated by 3.0 ± 0.6 mmHg (P<0.001). The changes included a folding of the RPE and a centrifugal sliding of the RPE on Bruch's membrane away from the optic disc. The IOP-rise associated RPE changes could be visualized on at least two scans of the ONH images. The RPE changes were located most often at the temporal side of the ONH (9 o'clock (orientated for right eyes): 14 (82%) eyes; 10 o'clock: 1 (6%) eye), followed by the nasal side (3 o'clock: 2 (12%) eyes; 2 o'clock: 1 (6%) eye. One eye showed RPE changes at both the temporal and the nasal side of the ONH. The two eyes without IOP-rise associated RPE changes showed an RPE line closely associated with the Bruch's membrane line in the OCT image. In all other eyes, the RPE line could easily be distinguished from the Bruch's membrane line. There were no RPE changes at the inferior or the superior optic disc pole.
Conclusions
The observations suggest that the peripapillary RPE may change its morphology in association with an acute rise in IOP in some eyes. The findings may be of interest to elucidate the pathogenesis of parapapillary atrophy in glaucoma.