Comparison of the precision of air puff tonometer with the gold standard Goldmann applanation tonometer and Schiotz tonomter in Egyptians

PurposeTo determine the precision of the air-puff tonometer compared to the Goldmann applanation tonometer (GAT) and Schiotz tonometers.MethodsThe study is a descriptive, cross-sectional study that included 410 eyes from 205 primary open-angle glaucoma patients. Intraocular pressure (IOP) was measured with the air-puff tonometer, followed by the GAT, and finally, the Schiotz tonometer. Pachymetry was performed for all patients.ResultsIOP was 20.21 ± 3.63 mm Hg for the air-puff tonometer, 18.73 ± 3.41 mm Hg for GAT, and 18.29 ± 3.92 mm Hg for the Schiotz tonometer, and this difference was not statistically significant. In both eyes, the correlation values between GAT and the air-puff tonometer were greater than 0.8, signifying a strong correlation. Additionally, the Bland-Altman analysis revealed greater agreement between the GAT and the air-puff tonometer than with the Schiotz tonometer.ConclusionWe can be confident that the air-puff tonometer provides accurate measurements close to those obtained by the GAT. Therefore, it can be reliably used for diagnosing, screening, and monitoring glaucoma patients, particularly in rural areas and during epidemics. Additionally, the values obtained from the Schiotz tonometer can be trusted, making it a reliable option for patients under general anesthesia or when other tonometers are unavailable.How to cite this articleKhalil KM, Ghoneim EM, Gab-Alla A, et al. Evaluation of the Accuracy of Air-puff Tonometer Compared to Goldmann and Schiotz Tonometers among Egyptians. J Curr Glaucoma Pract 2025;19(2):75–78.

Purpose: The purpose of this study was to evaluate the role of air puff (AP) tonometer by comparing the measurements of intraocular pressure (IOP) made using this device with those made using a Goldmann applanation tonometer (GAT) at Chittagong Eye Infirmary and Training Complex. Method: An observational and comparative study was carried out at Chittagong Eye Infirmary and Training Complex from January 2016 to January 2017. Two techniques for IOP measurements using the standard GAT and the non-contact tonometer (NCT) were compared. A total of 400 eyes from 200 patients were included in the study. Results: The mean IOP as measured by GAT in the right eye was 14.50±5.59mmHg and in the left eye was 14.87±7.03mmHg while that as measured by NCT in the right eye was 15.97±6.12mmHg and in the left eye was 15.94±6.98mmHg. The mean difference between the two methods of measurement in the right eye was 1.47±0.53mmHg and the left eye was 1.07±0.05mmHg. The readings obtained by NCT were higher than those obtained by GAT. There was no statistically significant difference found in IOP measurements between GAT and NCT according to patient’s age, gender or laterality of eyes. Conclusion: There was a significant difference in the measurement of IOP between GAT and NCT. Goldmann applanation tonometry remains the most suitable and reliable method for measuring IOP.

Purpose: To compare the intraocular pressure (IOP)) measurements in normal subjects, between the newly developed, Transpalpebral tonometer (Diaton®), Goldmann Applanation tonometer (GAT), and Air-puff Tonometer (APT), and to assess agreement between the three devices. Material and Methods: A total of 400 eyes of 200 random subjects were included in this cross-sectional, comparative study. IOP was measured with APT (Canon Full Auto Tonometer TX-F®), followed by Diaton®, and lastly GAT (Haag Streit AT 900® tonometer) in both eyes. The mean IOPs and the differences between IOPs of the tonometers were calculated by the paired t-tests. Their correlations were calculated using the Pearson correlation coefficients, mean differences were analyzed by one-way analysis of variance, and agreement was analyzed by the Bland-Altman method. Results: The mean IOPs noted for Diaton, GAT, and APT were 14.78 ± 3.22, 14.62 ± 3.01, and 14.42 ± 3.22 mm of Hg, respectively. The Pearson’s correlation coefficient (r) between Diaton and GAT was 0.314, between Diaton and APT; 0.334, and between GAT and APT; was 0.745. Hence, the strongest correlation was between GAT and APT, followed by moderate correlation of Diaton with APT, and least between Diaton and GAT. However, correlations between all three tonometers were significant at the 0.01 level. Bland- Altman analysis revealed that the mean differencesbetween Diaton and GAT measurements was 0.16 ± 3.6 mm Hg, between GAT and APT was 0.20 ± 2.2 mm Hg, and between Diaton and APT was 0.36 ± 3.7 mm Hg. The 95 % limits of agreement were smallest between GAT and APT, as compared to the other two pairs. Thus good agreement was observed between GAT and APT, and there was fair agreement of Diaton with both GAT and APT. Conclusion: Measurement of intraocular pressures by all three tonometers was comparable with good correlation in normal adults. There was good agreement between GAT and APT, and fair agreement of Diaton with GAT and APT. APT can be used as a screening device for patients. However, Diaton is not a very useful device for screening purpose, because of wider variations. Key words: Intraocular pressure, Transpalpebral tonometry, Goldmann Applanation tonometer, Air-puff tonometry.

Aim & background : Intraocular pressure (IOP) measured through the sclera has some advantages over IOP measured through cornea. This study aimed to determine the agreement between IOP as estimated by scleral Schiotz (SS) tonometer and Goldmann applanation tonometer (GAT). Methods: In this cross-sectional observational study, IOP was measured by GAT on the cornea and Schiotz tonometer on the temporal sclera. Axial length and central corneal thickness (CCT) were noted. IOP was then estimated from SS IOP as eGAT using a predictive formula. Agreement of IOP corrected for CCT (cGAT) with eGAT and SS IOP were assessed. The effects of age, axial length, refraction, CCT, gender, and ocular and systemic comorbidity on measured IOP were also assessed. Results: The study included 155 patients with a mean age of 54.27 ± 10.02 years. Mean IOP measured by GAT and scleral Schiotz were 16.58 ± 2.76 mm Hg and 16.10 ± 2.96 mm Hg, respectively. The mean IOP by cGAT and eGAT were 16.70 ± 2.80 mm Hg and 17.07 ± 3.10 mm Hg, respectively. Both eGAT & SS IOP had good agreement with cGAT on the Bland-Altmann plot (p = 0.96 & 0.51, respectively). Further, SS IOP showed good agreement even with GAT IOP (p = 0.78). Age, axial length, refraction, central corneal thickness, gender, and ocular and systemic comorbidity did not show significant correlation with IOP measurement. Conclusion: Estimated GAT IOP showed good agreement with measured GAT values. SS IOP also agreed well with GAT IOP. Clinical significance IOP measurement on the sclera using Schiotz can be used as an alternative to GAT.

Purpose: To determine the frequency of accuracy of intraocular pressure (IOP) measured by non-contact (air puff) tonometer compared with Goldmann applanation tonometer.Material and Methods: This comparative study was done from April 2011 to September 2011, 286 patients between 10 to 72 years of age, both male and females coming to eye OPD for refraction and ocular examination included. Selected patients were explained and after informed consent; intraocular pressure was taken by consultant Ophthalmologist with Goldmann applanation tonometer (Haag – streit AT900) and Air puff tonometer (Keeler PT100) between 8 am to 1 pm.Results: Air puff tonometer had an overall accuracy of 49.70% to measure intraocular pressure within ± 2 mm Hg difference compared with Goldmann applanation tonometer. Air puff tonometer is more accurate at low pressure range, 54.40% at 10 – 20 mm Hg and accuracy decreases at higher pressure range, 20% at 51 – 60 mm Hg. At all ranges of intraocular pressures Air puff tonometer measured higher (mean 2.87 mm Hg) values than Goldmann applanation tonometer.Conclusion: Airpuff tonometer is quick, a non-contact method to measure intraocular pressure and is useful for screening purposes but the measurements should be confirmed with Goldmann applanation tonometer for accurate labelling of intraocular pressure.

Purpose: To compare between the intra-ocular pressure (IOP) measured by Goldmann applanation tonometer (GAT) and non-contact air-puff tonometer (APT) considering GAT as gold standard. Study Design: Comparative analytical study Place and Duration of Study: Al-Shifa trust eye Hospital, Rawalpindi from January 2018 to June 2018 Methods: Five hundred individuals, 223 glaucoma patients and 277 non glaucoma control subjects were recruited. After taking a detailed history, slit-lamp examination and fundoscopy was performed to check glaucoma status of the eyes. Retinal nerve fiber layer (RNFL) was checked with optical coherence tomography. Non-contact air-puff tonometry of both eyes were performed. Using a drop of local anesthetic and small amount of fluorescein, intra-ocular pressure was measured with GAT (Haag Streit Diagnostics).Central corneal thickness was measured for correction of IOP measurement with GAT. Paired sample correlations were performed to compare the mean IOP with APT and GAT with and without correction factor. Sensitivity and specificity for measurement of IOP by APT was calculated considering GAT as gold standard. Results: Mean age of the male and female participants was 49.87+18.70years and 45.53+16.91years respectively. Mean IOP in glaucomatous eyes measured by GAT (after applying correction factor) and APT was 16.01+5.57 mmHg and 17.31+7.22 mmHg respectively. The sensitivity and specificity of APT for measuring IOP in glaucomatous eyes were 84.04% and 73.53% respectively. Conclusion: Non-contact air-puff tonometer has good sensitivity and specificity and can be used reliably for measurement of IOP in out-patient department and for mass screening of the population.

Objective: To compare measurement of intraocular pressure between Goldmann Applanation Tonometer and Non-Contact Air Puff Tonometer. Study Design: Clinical Observational Study. Place and Duration of Study: This study was carried out at Out Patient Department of Ophthalmology, Khairpur Medical College Hospital, Khairpur Mir�s from January 2017 to March 2017. Methodology: In this Clinical Observational Study, intra ocular pressures of 400 eyes of 200 patients, Male 125 (250 eyes) and Female 75 (150 eyes) with age ranging from 20 to 70 years, were measured by Goldmann Applanation Tonometer (GAT) and Non-Contact Air Puff Tonometer (APT), results and differences were noted. Results: The mean IOP was 16mmHg (SD = 6 mmHg) measured by APT and 13mmHg (SD = 3 mmHg) measured by GAT. The calculated difference between APT and GAT was 3 � 2.5 mmHg. Pressure taken by APT was slight high (i.e. around 3 mmHg). Conclusion: Air Puff tonometry gives slightly higher results (about 3mmHg) but is safe and easy than Goldmann Applanation tonometer. There is no fear of spread of infection and can be used easily in mass screening programs. Key Words: Goldmann Applanation Tonometer, Air-Puff non-contact Tonometer, Intraocular pressure, Glaucoma.

Background: Intraocular pressure (IOP) is one of the most important parameters in the diagnosis and treatment of glaucoma. Glaucoma has been established as the second leading cause of blindness. The treatment of glaucoma focuses mainly on lowering intraocular pressure (IOP). The target IOP is often set to a level 20% to 30% of IOP reduction, and consequent large IOP reduction beyond 30% or even 40% in cases of advanced glaucoma The different methods of tonometery are: Goldman Applanation tonometery, Noncontact (air-puff) tonometery, Perkins tonometery, Tonopen tonometery, Transpalpebral tonometery.Objective: To determine the frequency of accuracy of intraocular pressure (IOP) measured by non-contact (air puff) tonometer compared with Goldmann applanation tonometer.Methods: This was a non-interventional, cross sectional study conducted at a tertiary care centre of Dhaka, Bangladesh. consecutive subjects attending the BSMMU eye OPD were included in the study. IOP was measured by non-contact (air puff) tonometer and a slit lamp mounted GAT in all the subjects. The study samples were selected by convenience sampling who presented for check-up in the Eye Department of community ophthalmology, Bangabandhu Sheikh Mujib Medical University, Dhaka. Bangladesh. Results:A total of 120 eyes in 60 patients were studied. The mean age of the patients was 41.60 year. study population consisted of 24 (40 %) men and 36 (60 %) women. The mean intraocular pressure was 13.52 &13.72 mmHg for GAT, and 16.64 & 17.44 mmHg for Air puff respectively. The range of measurements by GAT was from 10 to 23 mmHg and by Air puff was 12 to 28mmHg. The difference between IOP measured by two instruments were statistically significant (p=0.000).Conclusion: Airpuff tonometer is quick, a non-contact method to measure intraocular pressure and is useful for screening purposes and postoperative case but the measurements should be confirmed with Goldmann applanation tonometer for accurate labelling of intraocular pressure.

Objective: To compare Goldmann applanation tonometer, air puff tonometer, and tonopen measured IOP Readings in vitrectomized eyes filled with temponading oils and gasses. Study Design: Comparative cross-sectional study. Place and Duration of Study: Armed Forces Institute of Ophthalmology (AFIO), Rawalpindi Pakistan, from Aug 2021 to Feb2022. Methodology: A total of 50 eyes were included in our study. Intraocular pressure was measured by an experienced ophthalmologist between 10am to 4pm on the 7th postoperative day by three devices, Goldmann applanation tonometer (GAT), air puff tonometer, and tonopen. Pearson’s correlation and paired samples t-test was applied to determine correlation and any significant difference between the mean of intraocular pressure measured by three different devices. Results: Out of the 50 people included in study 31(62%) were males and 19(38%) were females. The mean age of study participants was 50.10±11.61 years. Mean intraocular (IOP) pressure measured by the GAT applanation tonometer was 14.59±1.13 mmHg. Mean IOP as calculated by the airpuff tonometer was 15.93±1.88 mmHg, whereas mean IOP as calculated by tonopen was 15.85±1.86 mmHg. All three instrument values showed significant difference as p-value < 0.001. Conclusions: The air puff tonometer overestimates IOP as compared to GAT. Tonopen and air puff tonometer produce IOP measurements that are similar and consistent to each other but not to GAT

Purpose:Post-Descemet stripping endothelial keratoplasty (DSEK) patients are prone for intraocular pressure (IOP) elevations and glaucoma. Corneal characteristics influence various IOP measuring devices in various ways. The aim of this study was to evaluate the agreement between four different IOP measuring devices: Goldmann applanation tonometer (GAT), I-care pro, Tonopen XL, and Schiotz tonometr in patients who underwent DSEK.Methods:This was a prospective comparative study using a convenience cohort of post-DSEK patients with compact grafts. Post-DSEK patients had IOP measured using GAT, I-care Pro, Tonopen XL, and Schiotz tonometer. Measurements were compared and agreement assessed. Wilcoxon signed-rank test was used for comparison of means as variables did not show a normal distribution. Bland–Altman plots were used for assessing agreement.Results:Thirty eyes of 24 patients were included in the study. Mean time from DSEK surgery was 25.31 ± 13.05 months. Mean IOP with GAT, I-care pro, Tonopen XL, and Schiotz tonometer was 13.99 ± 3.76, 13.92 ± 3.36, 13.31 ± 3.89, and 12.83 ± 4.07, respectively. GAT, I-care pro, and Tonopen XL had similar mean IOP measurements (P = 0.135 and P = 0.551, respectively), while Schiotz tonometry measurements were higher (P = 0.046). Bland–Altman plots show good agreement between GAT, Tonopen XL, and I-care pro. GAT and Schiotz tonometry show less agreement, with large variations in the differences of measured IOP.Conclusions:IOP measurements in post-DSEK patients showed good agreement between GAT and either Tonopen XL or I-care pro. Schiotz tonometer has large variations in this patient group. IOP measurements and IOP difference between devices were not dependent on central corneal thickness.

Tonometry is a fundamental procedure in routine ophthalmologic examination. Although regarded as the reference standard, the Goldmann applanation tonometer (GAT) has its limitations. A new portable alternative to the GAT is the iCare rebound tonometer (RT). The aim of the present study was to compare the intraocular pressure (IOP) results obtained using the RT and GAT and then correlate the results with the central corneal thickness (CCT). Moreover, the tolerability and safety of the RT were evaluated. The IOP of 336 patients (672 eyes) was determined by the RT and GAT. The patients were divided into three groups (group A, 7–15 mmHg, n=74; group B, 16–22 mmHg, n=218; and group C, 23–50 mmHg, n=44), based on the GAT IOP readings. Pachymetry and slit lamp inspection were also performed. To establish an agreement between the devices, a Bland-Altman analysis and paired t-test were performed. The correlation between CCT and IOP readings obtained by the two devices were assessed using linear regression correlation analysis. The mean IOP values of the RT and the GAT were 18.30±5.10 and 18.52±4.46 mmHg, respectively. There were no significant differences between them (t=−1.31, P=0.19). The 95% confidence interval of the differences between the two devices was −5.80–6.24 mmHg. The RT readings are correlated well with those of GAT (r=0.806, P=0.001). However, the RT measurements were significantly (t=−2.84, P=0.007) lower (−1.66±3.87 mmHg) than those obtained with GAT when GAT ≥23 mmHg. Both the RT (r=0.390, P=0.001) and the GAT (r=0.191, P=0.001) showed positive correlations with CCT. The IOP measurement with RT was well tolerated. None of the corneal epithelial defects was detected and all subjects denied discomfort. The RT is well tolerated and safe, and can be considered a reliable alternative to GAT for patients in a low to moderate IOP range. However, in patients with high IOP values, the measurements obtained with RT did not correlate well with those obtained by GAT. The RT readings are influenced more by CCT compared to GAT.

The purpose of this study was to compare the intraocular pressure (IOP) values measured with the Tono-Pachymeter NT530P (Tonopachy™) and the iCare® rebound tonometer (iCare®) with those obtained by the Goldmann applanation tonometer (GAT). The right eyes of 105 subjects aged 18 to 82 years (mean age = 29.27 ± 14.67 years) were assessed with the three tonometers. Central corneal thickness (CCT) was measured first using the Tonopachy™ and then IOP was measured by Tonopachy™, iCare® and GAT. The data was analyzed with descriptive statistics, paired t-test, correlation and regression analysis. The Bland-Altman method of analysis was used to evaluate agreements between the sets of data from the three devices. The CCT values ranged from 440 µm to 606 µm (mean= 518.49 ± 33.01 µm). There was little or no correlation between CCT and IOP for any of the instruments used in this study (r = 0.29 for Tonopachy™, r = 0.22 for iCare®, r = 0.17 for GAT). The mean IOP measured with the Tonopachy™ was 14.31 ± 3.57 mmHg (range 8.7 mmHg to 31 mmHg) and 16.64 ± 4.38 mmHg (range 8 mmHg to 32 mmHg) using the iCare®. The mean IOP measured with the GAT was 14.79 ± 3.09 mmHg (range 8.7 mmHg to 29.7 mmHg). Using the Bland-Altman method, the upper and lower limits of agreement between the Tonopachy™ and GAT, iCare® and GAT, iCare® and Tonopachy™ were 5.1 mmHg and –4.2 mmHg, 8.6 mmHg and –4.9 mmHg, 7.5 mmHg and –2.8 mmHg respectively. In 79.1% of the eyes studied, the mean IOP difference between Tonopachy™ and GAT was less than 3 mmHg and in 20.9% of the eyes, the difference was greater than 3 mmHg. However, mean IOP differences of greater than 3 mmHg were obtained by iCare® in comparison with GAT (40%) and Tonopachy™ (34.3%) respectively. Findings of this study suggest that the Tonopachy™ yielded IOP readings that were consistent with those of GAT values while iCare® yielded higher IOP values compared to both GAT and Tonopachy™. (S Afr Optom 2011 70(3) 109-116)

BackgroundTo evaluate differences of intraocular pressure (IOP) measurements performed with Goldmann applanation tonometer (GAT), dynamic contour tonometer (DCT), rebound tonometry (RT), Ocular Response Analyzer (ORA) and Corvis ST (CST) in eyes screened for refractive surgery.MethodsOne eye, only the right one, of 146 patients was included in this study. Each participant was submitted to a corneal analysis with Scheimpflug camera and IOP evaluation with GAT, DCT, RT, ORA and CST. Differences in IOP values obtained thanks to each instruments were compared and then correlations between these discrepancies and morphological features such as mean keratometry (MK) and central corneal thickness (CCT) provided by Pentacam were studied. Software used to run statistical evaluations was SPSS, version 18.0.ResultsStudy participants had a mean age of 33.1 ± 9.2 years old. IOP values observed in this study were 15.97 ± 2.47 mmHg (GAT), 17.55 ± 2.42 mmHg (DCT), 17.49 ± 2.08 mmHg (RT), 18.51 ± 2.59 mmHg (ORA) and 18.33 ± 2.31 mmHg (CST). The mean CCT was 560.23 ± 31.00 μm, and the mean MK was 43.33 ± 1.35 D. GAT provided significant lower values in comparison to all other devices. DCT and RT gave significantly lower intermediate IOP values than those measured with ORA and CST. All the IOP measures and the differences between devices were significantly correlated with CCT.ConclusionsAccording to our data, although our findings should be confirmed in further studies, GAT tonometer cannot be used interchangeably with DCT, RT, ORA and CST.

PurposeTonometry, or measurement of intraocular pressure (IOP), is one of the most important examination procedures in ophthalmic clinics, and IOP is an important parameter in the diagnosis of glaucoma. Because there are numerous types of tonometer available, it is important to evaluate the differences in readings between different tonometers. Goldmann applanation tonometers (GATs) and noncontact air-puff tonometers (APTs) are largely available in ophthalmic clinics. The purpose of this study was to evaluate the role of AP tonometer by comparing the measurements of IOP made using this device with those made using a GAT.Patients and methodsThis study involved 196 eyes from 98 study participants, all of whom were patients attending an ophthalmic outpatient clinic. Each patient’s IOP was measured using both Goldmann applanation tonometry and AP tonometry, and the difference in readings between the two methods was calculated.ResultsThe mean IOP as measured by GAT was 13.06 ± 4.774 mmHg, while that as measured by AP tonometer was 15.91 ± 6.955 mmHg. The mean difference between the two methods of measurement was 2.72 ± 2.34 mmHg. The readings obtained by AP tonometer were higher than those obtained by GAT in 74% of patients, and this difference was most obvious when the GAT measurement of IOP exceeded 24 mmHg. No statistically significant variation in IOP was noted between the devices when the patients’ age, sex, and laterality (right and left eyes) were considered.ConclusionThere is a significant difference in the measurement of IOP between GATs and AP tonometers. Goldmann applanation tonometry remains the most suitable and reliable method for measuring IOP. Because measurements of IOP by AP tonometer are usually higher than those obtained by GAT regardless of the patient’s age, sex, or laterality of eyes, AP tonometry is a suitable method for community or mass screenings of IOP.

To evaluate whether manual upper eyelid elevation (MUEE) affects intraocular pressure (IOP) values obtained with a noncontact tonometer (NT). This cross-sectional study included 122 eyes of 122 non-glaucomatous adults. All patients underwent IOP measurement using both NT and Goldmann applanation tonometer (GAT). The order of measurements was NT without MUEE, NT with MUEE, and GAT. Both eyes of each patient were measured and one of the eyes was randomly selected for inclusion in the study. Central corneal thickness (CCT) and palpebral fissure height (PFH; distance between upper and lower eyelids) was recorded. The patients' mean age was 43.91 ± 12.36 (20-61) years and 62.3% were women. Mean IOP values measured by NT without MUEE, NT with MUEE, and GAT were 15.98 ± 2.39, 15.84 ± 2.53, and 14.33 ± 2.3mmHg, respectively. There was no statistically significant difference in mean IOP between NT without and with MUEE (p = 0.506). Mean IOP values obtained by NT with and without MUEE were significantly higher than those obtained by GAT (p < 0.001). The difference in IOP values measured by NT without and with MUEE was positively correlated with PFH (r = 0.214; p = 0.018). CCT and IOP values obtained by NT without MUEE and GAT were positively correlated (r = 0.300; p = 0.001 and r = 0.311; p = 0.001, respectively). MUEE does not have a significant effect on IOP measurements by NT. The difference between IOP measured by NT without and with MUEE increases with greater PFH.