Background/aims: To investigate the effect of eyelid manipulation on the measurement of intraocular pressure (IOP) using two different tonometries (rebound tonometry (RT) vs Goldmann applanation tonometry (GAT)).
Methods: 103 patients with primary open-angle glaucoma were prospectively enrolled. For all of the patients, IOP measurements were performed in three different ways: (1) RT with lid manipulation (LM), (2) RT without LM and (3) GAT. The order of the three measurements was randomly selected. Additionally, the palpebral fissure height (PFH; elliptical space between upper and lower eyelids) was measured.
Results: The mean value of IOP measured by GAT was 13.97±2.80 mm Hg, which was not significantly different from that by RT without LM (13.75±2.44 mm Hg; P=0.096), but which was significantly lower than that by RT with LM (15.21±2.91 mm Hg; P<0.001). On a Bland-Altman plot, RT with LM was overestimated relative to GAT (mean: -1.5) and RT without LM (mean: -1.2). Among the high IOPs (>20 mm Hg), interestingly, those measured by RT without LM were significantly lower than those measured by GAT (P<0.001). In the subgroup analysis of PFH, the smaller the PFH, the more exaggerated the IOP difference between GAT (P=0.014) and RT with LM (P<0.001).
Conclusion: RT-measured IOP was significantly exaggerated when manipulation was applied to the eyelid. This overall trend was more pronounced when PFH was small. GAT-measured IOP, meanwhile, showed a good correlation with IOP measured using RT without LM.
Keywords: eye lids; glaucoma; intraocular pressure.
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