Comparison of intraocular pressure obtained by Goldmann applanation tonometer, Corvis ST and an airpuff tonometer in healthy adults

Purpose To assess the agreement among four types of intraocular pressure (IOP) measurements: IOP obtained by Goldmann applanation tonometer (IOP-GAT),IOP obtained by an air-puff tonometer (Nidek NT-510)(IOP-NCT), the non-corrected IOP obtained by the Corneal Visualization Scheimpflug Technology (IOP-Corvis) and the biomechanically corrected IOP obtained by the Corvis ST (bIOP-Corvis) in healthy patients with a broad spectrum of IOP values. Methods: This prospective, observational study recruited 113 healthy individuals. Each patient underwent IOP evaluation via GAT, Nidek NT-510 and Corvis ST. Difference in mean in IOP readings was assessed by one-way repeated-measures analysis of variance (ANOVA).Tonometer intermethod agreement was assessed by the Bland-Altman method. The difference between the four IOP measurements was correlated against corneal (CCT) and age with Pearson’s correlation test. Results: IOP-Corvis showed the highest values (16.59 ± 3.08 mmHg),followed by IOP-NCT (16.05 ± 3.43 mmHg), IOP-GAT (15.62 ± 3.08 mmHg) and bIOP-Corvis (15.10 ± 2.67 mmHg).There were statistically significant differences in IOP measurements among all the ANOVA pairwise comparisons except between IOP-GAT and bIOP-Corvis ( p = 0.07),as well as between IOP-GAT and IOP-NCT ( p = 0.25). Bland Altman analysis revealed a notable bias (all p < 0.05) among IOP-GAT and bIOP-Corvis, IOP-GAT and IOP-Corvis, IOP-GAT and IOP-NCT, bIOP-Corvis and IOP-Corvis, bIOP-Corvis and IOP-NCT,IOP-Corvis and IOP-NCT of 0.51, −0.97, −0.43, −1.49, −0.95, 0.53 mmHg respectively. We observed a strong correlation of the difference between bIOP-Corvis and IOP-Corvis with CCT and patient age. Conclusion: Compared with GAT and Nidek NT-510, the Corvis-derived IOPs were recorded either the highest as IOP-Corvis or the lowest as bIOP-Corvis. Even if the differences among the tonometers were relatively small, the IOP values obtained with the Corvis ST, NCT and GAT were not interchangeable.

Ocular Response Analyzer versus Goldmann Applanation Tonometer for Measurement of Intra-Ocular Pressure

Background Goldmann applanation tonometry (GAT) has been the gold standard for intraocular pressure(IOP) measurement ,since its appearance in clinical practice around 50 years ago.(1) In spite of being almost unchallenged, the last few years have become a sustained search for a new standard method for IOP measurement,. One such recently marketed instrument is the Ocular Response Analyzer (ORA), which able to detect the corneal biomechanics. Aim of the Work is to compare the IOP measurement estimated by Goldmann applanation tonometer to that of ORA and detect the effect of state of refraction, corneal topography and central corneal thickness (CCT) on these measurements. Patients and Methods This cross-sectional study was done from March 2018 to October 2018 on 65 eyes of patients visiting the outpatient clinic. Results The mean GAT IOP was 15.938 ± 6.041 while the mean ORA (IOPcc) and (IOPg) were 19.711 ± 7.59 and 17.242 ± 7.35 mm Hg respectively. There is a strong positive relationship between GAT IOP & ORA IOPg measurement (r = 0.880 – p = &lt;0.001*). Also finding a weak yet significant correlation between IOPg and CCT (r = 0.385, p = 0.001). None of the pressure measurements was affected by refraction or corneal curvature significantly. Conclusion In conclusion, our results suggest that mean IOPs obtained by ORA were significantly higher than that of GAT with different influencing factors that are not completely understood. caution has to be sought when using the ORA, the values obtained ought not to be used interchangeably with the values obtained by 1 GAT, despite the presence of a positive correlation between these values. This underlines the importance of using one and only method of evaluation of the IOP for every patient in successive follow-up visits.

A study to compare intraocular pressure using Perkins and Schiotz tonometer with respect to Goldmann applanation tonometer as a gold standard in a tertiary health care centre, Navi Mumbai

To compare IOP measurement of Perkin’s tonometer and Schiotz tonometer with respect to Goldmann applanation tonometer (GAT).100 eyes of 50 patients aged 18 to 65 years presenting to Ophthalmology OPD were selected by randomization and detailed general and ophthalmic examination was done. IOP was measured using applanation tonometers (Perkin’s and GAT) and indentation tonometer (Schiotz tonometer) in that order. The study population included 38 male eyes and 62 female eyes; 50 right eyes and 50 left eyes. There was a statistically highly significant difference seen for the values between the groups (p&#60;0.01) with higher values in IOP measured by GAT followed by IOP measured by Perkin’s tonometer and least in IOP measured by Schiotz tonometer.There was a statistically non significant difference seen for the values between Perkin’s tonometer and GAT (p&#62;0.05). While there was a statistically highly significant difference seen for the values between GAT and Schiotz tonometer (p&#60;0.01).There was a statistically non significant difference seen for the IOP values between right eye and left eye. There was a statistically non significant difference seen for the IOP values between males and females. Measurement of IOP with Perkin’s was closer to the values obtained by GAT. Perkin’s being portable, easy to use and precise tonometer than Schiotz tonometer, can be considered as an excellent substitute to GAT, for large scale examination, if cost is not a concern.

P69 Intra-ocular pressure measurement in eye casualty: Which is the Fairest of Them All?

Introduction A survey completed by junior doctors who routinely run eye casualty clinics identified Goldmann applanation tonometry (GAT) as the single most time-consuming element of a standard consultation. IOP can be measured with a range of devices in the eye clinic. By identifying the most accurate and time efficient method we can save time in consultations as well as provide better outcomes for the patient. Purpose To compare four tonometry techniques: Goldmann applanation tonometer(GAT), Non-contact tonometer(NCT), Tonopen(TP) and Icare tonometer(ICT) to determine the most accurate and efficient method. Method 20 subjects presenting in the casualty eye clinic were used in the study ranging between 36-75 years. Once undergoing routine ophthalmic examination from the same clinician, IOP was recorded with all devices. Three readings were taken before calculating an average value and time taken for each device for each patient. No patients were excluded from the study. Results The average IOP with GAT, NCT, TP and ICT was 8.5 ± 2.7, 10.3 ± 4.2, 8.6 ± 3.1, and 8.4 ± 4.5 mmHg, respectively. The average time taken with GAT, NCT, TP and ICT was 56, 132, 38 and 23 seconds, respectively. There was no significant difference in IOP measured by GAT and TP and ICT however, NCT (10.3 mm Hg, P &lt; 0.01) measured significantly higher IOPs compared to GAT. Conclusion When compared to Goldmann applanation tonometer, Icare was the most accurate and efficient method. While Tonopen was fairly accurate some patients were unable to tolerate it. NCT was significantly slower compared to other devices.

Estimation of Goldmann applanation tonometer intraocular pressure (IOP) from scleral Schiotz IOP values in eyes with type-1 keratoprostheses

PurposeTo validate estimation of Goldmann applanation tonometer (GAT) intraocular pressure (IOP) from scleral Schiotz IOP measurements using a regression model in normal eyes and eyes with type-1 keratoprostheses.MethodsIn this prospective cross-sectional study, cohort-1 had 253 normal anterior segment eyes, and cohort-2 had 100 eyes with type-1 keratoprostheses. Scleral Schiotz IOP measurements were used (in a non-linear model) to predict GAT IOP values for these eyes. Accuracy of predicted GAT IOP values was assessed using actual GAT IOP values for normal eyes, while for type-1 keratoprosthetic eyes, finger tension (FT) IOP assessments by an experienced glaucoma specialist were used. Primary outcome was agreement between FT IOP (assessed by an experienced glaucoma specialist) and predicted GAT IOP-derived clusters.ResultsThe actual values of GAT IOP measurements in normal eyes (n=253; mean age ±SD, 51.35±15.56 years) ranged between 6 mm Hg and 62 mm Hg (mean=22±10.05 mm Hg). Estimated and actual GAT IOP values for normal eyes were very similar (mean difference=0.05 mm Hg with limits of agreement: −5.39 to 5.5 by Bland-Altman plot). Of the 100 eyes with type-1 keratoprostheses, 68 were classified as having digitally normal IOP, 28 as borderline and 4 as high. The agreement between classification by FT assessment and model-predicted GAT IOP values was substantial (Kappa=0.81, 95% CI 0.69 to 0.93). The accuracy of the model in assessing IOP was found to be 91% (95% CI 0.84 to 0.96).ConclusionScleral Schiotz IOP values along with our predictive model can be an alternative objective method to FT IOP in assessing IOP in eyes with type-1 keratoprostheses.