In eyes with normal corneas, DCT allows suitable and reliable IOP measurements which are in good concordance with GAT. Comparison of DCT with intracameral manometry is desirable in the future.

In cases with higher difference between DCT-GAT, the difference is reproducible and even present in the fellow eye. We, therefore, assume that the differences are not caused by chance, but by differing biomechanical corneal properties.

Short- and long-term reproducibility of DCT is comparable to that of GAT. GAT is more affected by CCT than DCT, measuring higher IOPs in eyes with higher central corneal thickness.

Thirty healthy volunteers were nasally exposed to control air and urban dust (SRM 1649a) in concentrations of 150 and 500 microg/m3 for 3 hours. Thirty minutes, 8 hours, and 24 hours after exposure, nasal cytologies were obtained, and nasal secretion levels of interleukin (IL)-1beta, IL-6, IL-8, tumor necrosis factor-alpha, epithelial neutrophil activating protein-78, monocyte chemoattractant protein-1, and substance P were determined. Twenty-four hours after exposure to 500 microg/m3, nasal secretion levels of IL-1beta increased 72.3% (0-150.2%, P=0.002), levels of IL-6 increased 42.2% (-28-161.9%,P=0.01), and levels of IL-8 increased 19.7% (-20.3-60.5%, P=0.03; median and 95% confidence interval). These cytokines correlated closely with nasal inflammatory cell counts. No exposure-related changes of tumor necrosis factor-alpha, monocyte chemoattractant protein-1, epithelial neutrophil activating protein-78, and substance P levels were observed. These results provide experimental support for recent epidemiological observations that short-term increase of outdoor particulate matter concentration increases the frequency of upper respiratory diseases.

Purpose: To investigate the corneal hysteresis (CH), the corneal resistance factor (CRF) and the corneal compensated intraocular pressure (IOPcc) of subjects with normal corneas and with corneal pathologies with the Ocular Response Analyzer (ORA). Methods: IOP was measured using Goldmann applanation tonometry (GAT), dynamic contour tonometry (DCT) and ORA in 102 subjects with normal corneas and in patients with keratoconus (KC, n=32), Fuchs endothelial corneal dystrophy (FD, n=34) and penetrating keratoplasty (KP, n=50). Additionally central corneal thickness (CCT) and CH were quantified. Results: CH and CRF were significantly reduced in all groups with corneal pathologies in comparison to the normal group (CH: 7.7 (KC), 8.9 (KP), 7.3 (FD) versus 10.3 (N), CRF: 6.4 (KC), 9.3 (KP), 8.2 (FD) versus 10.8 (N) mmHg). High significant differences were also observed in mean IOP between the control group and the groups with corneal pathologies. There was a significant correlation between CH and CCT for normal corneas and corneas with KC and KP. Conclusions: CH and CRF are significantly decreased in patients with KC, FD and KP compared to subjects with normal corneas. Patients with corneal pathologies showed a substantial variability of mean IOP‐values evaluated by using different methods of IOP‐measurement in comparison to subjects with normal corneas suggesting that corneal properties strongly influence the validity of IOP‐measurements.

Elevated IOP after LASIK can lead to fluid accumulation in the interface. In this case applanation tonometry can underestimate the intraocular pressure. Even when steroid therapy is stopped, the elevated pressure can persist. This complication after LASIK is very rare and can cause severe damage if not diagnosed.

Purpose: The accuracy of Goldmann applanation tonometry (GAT) has been shown to depend on several biomechanical properties of the cornea. Newer tonometry devices (e.g., the Dynamic Contour Tonometer PASCAL ® [DCT] and the Tono-Pen ® XL [TP]) have been designed to accurately measure intraocular pressure (IOP) independent of corneal thickness (CCT) and pathology. This study investigates the influence of corneal pathologies on the accuracy of these IOP measuring devices, and compares this accuracy to that of direct intracameral IOP measurement. Methods: 8 eyes of 8 patients suffering from corneal pathologies scheduled for penetrating keratoplasty, and 10 eyes of 10 patients scheduled for cataract surgery (control group) were examined. Before surgery, the anterior chamber was cannulated at the temporal corneal limbus. In a closed system, the intraocular pressure (IOP) was directly set to 10, 20, and 30 mmHg with a manometric water column. Intraocular pressure measurements taken by GAT, DCT, and TP were compared to intracameral measurements obtained by a precision reference pressure sensor. Results: Control group: All three methods showed good agreement with the intracameral readings (mean deviation of all three devices, −0.9 mmHg). Group with corneal pathologies: The TP yielded the most exact IOP values in the group with corneal pathologies when taking all diagnoses into account. The mean deviations from the intracameral IOP measurements were −0.9 mmHg ± 3.2 mmHg (mean ± SD) for TP, −2.9 mmHg ± 3.3 mmHg for GAT, and −5.0 mmHg ± 7.9 mmHg for DCT. For bullous keratopathy, the most exact IOP readings were obtained by the TP (mean deviation −0.2 mmHg ± 3.5

Purpose: The Ocular Response Analyser (ORA) is a novel device for the measurement of intraocular pressure (IOP), corneal hysteresis (CH) and the corneal resistance factor (CRF). We compared the ORA with Dynamic Contour Tonometry (DCT) and Goldmann Applanation Tonometry (GAT). Methods: We examined 63 eyes of 63 glaucoma patients (primary open angle glaucoma (POAG) n=26, normal tension glaucoma (NTG) n=10, ocular hypertension (OHT) n=15, pseudoexfoliation glaucoma (PEXG) n=12). After assessment of corneal thickness (CCT) by Orbscan, IOP was measured in a randomized order with the ORA, DCT and GAT. For each device mean IOP and for the ORA mean IOP, CH and CRF were calculated and assessed for potential dependency on CCT. Results: Mean IOP in mmHg was 20.6 (±6.1 SD) for the ORA, 18.2 (±4.2 SD) for DCT and 16.5 (±4.4 SD) for GAT. Bland‐Altman‐Analysis showed a good agreement between DCT and GAT, while the ORA showed a tendency to higher values in patients with higher IOP. None of the devices showed a dependency on CCT (GAT: r²=0.12, DCT: r²=0.07, ORA: r²=0.08). There was no correlation between CH and CCT (r²=0.01), but a weak correlation between CRF and CCT (r²=0.2). Patients with NTG had a significantly (p=0.005) thinner CCT (506±55μm) than patients with POAG (567±53μm). As could be expected, OHT‐patients showed higher CCT values (592±41μm). CRF was significantly higher in the OHT (11.6±2.2) than in the POAG group (9.6±2.0) (p=0.006). For CH, we observed no difference between groups. Conclusions: The ORA showed a good agreement with DCT and GAT for “normal” IOP, but we observed higher results compared to the other methods for high IOP‐values. We observed no correlation between CCT and IOP, but a weak positive correlation between CRF and CCT.