Einflussgrößen auf die Applanationstonometrie - ein praxisorientierter Überblick

Comparison of intraocular pressure measurements obtained by icare pro tonometer, non-contact tonometer and Goldmann applanation tonometer in healthy individuals

PURPOSE

The goal of this paper was to compare the intraocular pressure (IOP) measurements obtained via iCare Pro rebound (IRT), non-contact tonometry (NCT), and Goldmann applanation (GAT) tonometry in healthy subjects.

MATERIALS AND METHODS

One hundred and twenty-five healthy individuals were included in this study. The participants' IOP measurements were obtained via non-contact tonometry. After routine ophthalmic examination, central corneal thickness (CCT) was measured with a topography device. Intraocular pressure was measured via iCare Pro rebound tonometry. After waiting for 5minutes, three measurements were taken with GAT under topical anaesthesia, and their means were recorded. Interdevice agreement was evaluated with the intraclass correlation coefficient (ICC) and Bland-Altman analysis.

RESULTS

The mean IOP measurements for NCT, IRT, and GAT were 15.97±2.99, 17.47±2.86, and 16.46±2.68mmHg, respectively. The mean difference between NCT and GAT was -0.49± 1.89mmHg, the mean difference between IRT and GAT was 1.01±1.90mmHg, and the mean difference between NCT and IRT was -1.50±2.02mmHg. Agreement between devices was found to be >0.8 for each tonometry ICC. There were significant positive correlations between the measurements obtained via these three instruments and CCT.

CONCLUSION

In this study, IOP was measured slightly lower with NCT than GAT, but it was about 1mmHg higher with IRT than GAT on average. All three devices appeared to be affected by CCT, with NCT being the most affected in this regard. The three instruments can be used for routine inspection and screening. However, considering the differences in the measurements obtained by using them, it is clear that following up IOP measurements with GAT measurements is beneficial in advanced glaucoma patients.

Meta-analysis of the concordance of Icare® PRO–based rebound and Goldmann applanation tonometry in glaucoma patients

Background:

The Icare® PRO rebound tonometer is being promoted as a patient-friendly device for glaucoma detection and monitoring, allowing rapid and accurate intraocular pressure measurement avoiding anaesthesia. The aim of this systematic review was to examine the concordance of Icare® PRO and Goldmann applanation tonometry in glaucoma patients.

Methods:

The German and English literature research was carried out using PubMed and Cochrane Library between January 2010 and March 2018. Method comparison trials in a paired sample study design were identified. Search criteria were ‘Icare PRO’, ‘Rebound’, ‘Goldmann’ and ‘Applanation’. Adult patients with glaucoma of any aetiology were included. The intraindividual intraocular pressure deviation between Icare® PRO and Goldmann applanation tonometry (mm Hg) served as primary endpoint, parameterized by the reported mean differences. For each study, an asymptotic 95% confidence interval was derived. The overall intraocular pressure meta-difference (Icare® PRO-Goldmann applanation tonometry) and 95% confidence interval were estimated using the random effect model.

Result:

Of 147 publications, 6 studies (672 eyes) were included after reviewing. Four studies showed an intraocular pressure underestimation by the Icare® PRO, two an overestimation. The meta-difference (Icare® PRO-Goldmann applanation tonometry = −0.14 mm Hg; 95% confidence interval: (−0.43 mm Hg; 0.15 mm Hg)) indicated a non-significant, clinically irrelevant mean deviation (p = 0.335). The devices showed good agreement, but there was a strong heterogeneity between the studies (I² = 77%): two studies presented a significant difference (Icare® PRO-Goldmann applanation tonometry), however, with deviations in opposite directions.

Conclusion:

Although the manufacturer advertises the Icare® PRO as a ‘tonometer with superior accuracy’, the present review could neither confirm nor deny considerable agreement between Goldmann applanation tonometry and Icare® PRO in glaucomatous patients.

[Ease of handling of first and second generation rebound tonometers]

PURPOSE

To evaluate the ease of handling of two rebound tonometers, which are designed for self-measurement of intraocular pressure (IOP) in a clinical setting by untrained patients.

METHODS

After self-measurement of the IOP with the rebound tonometers iCare ONE and iCare HOME, participants were asked to complete a questionnaire containing different subitems concerning ease of operation using a visual analog scale (1 = very good to 5 = very poor). Moreover, the feasibility and duration of measurement were tested.

RESULTS

A total of 147 subjects participated in this study. The mean score for general handling ability was 2.79 ± 1.01 for the iCare ONE and 1.85 ± 0.87 for the iCare HOME (p < 0.001). The evaluation of the subitems sense of safety (iCare ONE: 2.71 ± 1.03 and iCare HOME: 1.87 ± 0.81, p < 0.001) and comfort of measurement (iCare ONE: 2.07 ± 1.01 and iCare HOME: 1.66 ± 0.72, p < 0.001) also showed a significant discrepancy between the two tonometers. Participants needed significantly less time for a single valid measurement when using the iCare HOME tonometer (mean 66.14 ± 61.54 s) compared to the iCare ONE tonometer (mean 81.54 ± 69.51 s, p < 0.001).

CONCLUSIONS

A better handling of the iCare HOME rebound tonometer in comparison to the iCare ONE tonometer can be deduced on the basis of the subjective assessments of patients and the shorter duration of measurements. Moreover, the iCare HOME received a significantly better evaluation for all subitems. The accuracy of measurements using the iCare HOME still needs to be clarified.

[Medicinal glaucoma therapy. What can we learn from large randomized clinical trials?]

The prospective multicenter randomized controlled clinical trials (RCTs) Ocular Hypertension Glaucoma Treatment Study (OHTS), Early Manifest Glaucoma Trial (EMGT), Advanced Glaucoma Intervention Study (AGIS), Collaborative Initial Glaucoma Treatment Study (CITGS) and Collaborative Normal Tension Glaucoma Study (CNGTS) are often named as landmarks for glaucoma management as the results of these studies provided the evidence for numerous therapeutic decisions in clinical practice. The studies confirmed the consensus that reduction of intraocular pressure reduces the risk of glaucoma progression covering the whole spectrum of glaucoma from ocular hypertension to advanced glaucoma. Furthermore, the identification of new risk factors allows a higher precision of assessment of the risk of progression. The RCTs achieved the main goal of high level of evidence, thus making progress in the understanding of glaucoma and its treatment and bridging consensus-based and evidence-based decisions. However, the implementation of the results into clinical practice needs adequate and accurate interpretation of the results.

Intracameral air following pneumatic noncontact tonometry in a recently post-perforating keratoplasty patient

PURPOSE

The purpose of this report is to highlight the potential risk of noncontact tonometry after routine uncomplicated penetrating keratoplasty (PK).

CASE REPORT

After uncomplicated PK for keratoconus, routine noncontact tonometry was performed on the second postoperative day. In spite of the adequately closed wound and the tight suture, temporary wound dehiscence occurred, and two-thirds of the anterior chamber was occupied by air. The running suture remained intact, and the Seidel test was negative. One week postoperatively, the patient's corrected distance visual acuity was 0.4 (0.4 logMAR), and the air bubble had absorbed.

CONCLUSION

This is the first report to conclude that noncontact tonometry may not be sufficiently safe in the early postoperative period in normal PK cases. To prevent possible wound opening, we suggest the use of other tonometry methods during the first several months after PK.