[Intraocular pressure elevation after vitrectomy-Goldmann applanation tonometry measures lower intraocular pressure than dynamic contour tonometry].

Background: The dynamic contour tonometer PASCAL (DCT) is a direct noninvasive digital tonometer matching the corneal contour. We compared the DCT with the Goldmann applanation tonometer (GAT).

Methods: A total of 100 eyes were included in this prospective comparative clinical investigation and intraocular pressure (IOP) was measured with GAT and DCT before and after pars plana vitrectomy (ppV). Different intraocular endotamponades, such as gas and silicone oil were used. Preoperative IOP, changes in IOP postoperatively and intertonometer differences were measured.

Results: The preoperative mean IOP was 15.8 ± 5.2 mm Hg measured with the GAT and 17.5 ± 5.9 mm Hg with DCT. On the first postoperative day, in eyes with gas endotamponade the mean IOP rise was 2.5 mm Hg (p = 0.035) and 18 eyes were measured with an IOP of ≥ 25 mm Hg (19.1%; DCT). Postoperative IOP measured by GAT was 2.5 mm Hg lower and in eyes with gas endotamponade the GAT measured the IOP 3.0 mm Hg lower than the DCT. In eyes with a postoperative IOP above 20 mm Hg, the GAT measured the IOP 4.7 mm Hg lower compared to the DCT. Out of 18 eyes 10 with IOP ≥ 25 mm Hg were not recognized as hypertensive (≥ 25 mm Hg) by GAT. In 13% of the eyes the DCT measured at least 6 mm Hg higher IOP levels than GAT on the first postoperative day. In one extreme case with gas endotamponade, GAT underestimated the IOP by 12 mm Hg compared to the DCT.

Conclusion: The IOP spikes after ppV are a feared complication and can lead to irreversible visual loss. Depending on the endotamponade, GAT measures lower IOP than DCT, especially in IOP spikes caused by expansive gas endotamponade. Postoperative IOP measurement is important and readings between GAT and DCT can differ.