A comparison of iCare and Goldmann applanation tonometry measurements during the COVID-19 pandemic: a retrospective study.

PURPOSE: To evaluate factors associated with differences in intraocular pressure (IOP) readings between iCare and Goldmann applanation tonometry (GAT) in established glaucoma patients. METHODS: This retrospective comparative study included clinical data of 350 eyes from 350 established glaucoma patients who had iCare and GAT IOP measured by an ophthalmic technician and a glaucoma specialist, respectively. The main outcome measure was the difference in IOP measurements of the right eyes with iCare and GAT. RESULTS: The intraclass correlation coefficient (ICC) between GAT and iCare was 0.90. The mean IOP difference between tonometers was - 0.18 ± 2.89 mmHg. Bland-Altman plots indicated a 95% limit of agreement of - 5.8 to 5.5 mmHg. Central corneal thickness (CCT) and age were significantly correlated with the difference in IOPs of the iCare and GAT. GAT-IOP and age were significantly associated with the absolute difference in measured IOP of the two tonometers. The difference in measurements was not significantly associated with prior glaucoma surgery, average global index of optical coherence tomography, axial length, technician years of experience and certification, and IOP range. CONCLUSION: Although there is good agreement between the iCare and GAT mean values, these devices are not interchangeable in glaucoma patients due to the wide range of the limit of agreement.

A comparison of intraocular pressure measurement using SUOER SW-500 rebound tonometer and conventional reusable Goldmann prisms.

Introduction: To determine the agreement between intraocular pressure (IOP) measurements using conventional Goldmann applanation tonometry (GA1,2T) and SUOER SW-500 Rebound Tonometer. Methods: This was a retrospective observational study where 205 eyes of 106 glaucoma patients had their IOPs measured by 2 fellowship trained ophthalmologists. Data were analyzed using the Bland-Altman method of differences. Correlation was measured using the Pearson coefficient. Results: Most of our patients were Chinese (88.7%) and female (51.9%). The average age was 66.9 years. The range of IOPs as measured by GAT was 2 to 58 mm Hg. Using the Bland-Altman method to compare GAT and SUOER SW-500 Rebound Tonometer. The tonometer overestimated the IOP by 0.5 mm Hg in the right eye and underestimated it by 0.1 mm Hg in the left eye. Overall, the tonometer overestimated the IOP by 0.2 mmHg. The Tonometer IOP correlated well with GAT, with a Pearson coefficient of correlation(r) of 0.89 (p < 0.001) for the right eye and 0.86 (p < 0.001) for the left eye, respectively. In patients with GAT IOP ≥ 21 mm Hg (n = 25), the Tonometer underestimated the IOP by 2.96 mm Hg. Discussion: The IOP measurements from the SUOER SW-500 Rebound Tonometer correlates well with the conventional GAT in measuring the IOP within normal ranges of IOP. SUOER SW-500 Rebound Tonometer may be of use, especially if the risk of transmission of infection is high considering that the probes are disposable. It is easy to use and its small size and portability makes it useful in situations where the patient is unable to be examined at the slit lamp.

A Comparative Analysis of Intraocular Pressure Measurement Accuracy With Reused iCare Probes.

PURPOSE: To assess the accuracy of reused iCare probes after disinfection with 70% isopropyl alcohol and ethylene oxide gas compared to new iCare probes and Goldmann applanation tonometry (GAT). DESIGN: Prospective comparative analysis. PARTICIPANTS: A total of 118 eyes from 59 patients recruited from the Aravind Eye Hospital glaucoma clinic in Tirupati, South India. METHODS: Intraocular pressure (IOP) was measured on each eye using a new iCare tonometer probe, an iCare probe previously used and disinfected 1 time prior (once used probe) and 5 times prior (multiply used probe), as well as with GAT. Probes were disinfected after each use with 70% isopropyl alcohol swabs and ethylene oxide sterilization. MAIN OUTCOME MEASURES: Agreement demonstrated with intraclass correlation coefficients (ICCs), mean difference in IOP values with limits of agreement, and Bland-Altman plots among IOP measurement approaches. RESULTS: Compared to new iCare probes, both once used probes (ICC = 0.989, 95% confidence interval [CI] 0.985-0.993) and multiply used probes (ICC = 0.989, 95% CI 0.984-0.992) showed excellent agreement, and the mean difference in IOP was minimal for both once used probes (0.70 mmHg, 95% CI 0.29-1.11) and multiply used probes (0.75 mmHg, 95% CI 0.66-0.82) compared to new probes. Bland-Altman plots demonstrated minimal differences between new and reused probes across the spectrum of IOP. When comparing multiply used probes to once used probes, there was a high level of agreement (0.993) (95% CI 0.990-0.995) and negligible mean IOP difference 0.04 mmHg (95% CI 0.32-0.40). Additionally, ICC values for new probes (0.966, 95% CI 0.951-0.976), once used probes (0.958, 95% CI 0.940-0.971), and multiply used probes (0.957, 95% CI 0.938-0.970) compared to GAT were similar and all showed excellent agreement. Both new and reused iCare probes underestimated IOP by 2 to 3 mmHg compared to GAT. CONCLUSIONS: In this prospective comparative analysis, we found that reusing iCare probes up to 5 times does not compromise the accuracy of IOP measurements when disinfected with 70% isopropyl alcohol swabs and ethylene oxide. Reusing iCare probes has the potential to transform care by reducing cost, decreasing environmental waste, and allowing for glaucoma screening camps and increased glaucoma monitoring in low resource settings leading to earlier identification and treatment of glaucoma. FINANCIAL DISCLOSURE(S): Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.

Even-number measurement bias with Goldmann applanation tonometry in patients with glaucoma and glaucoma suspects.

CLINICAL RELEVANCE: Goldmann applanation tonometry is widely used for the diagnosis and management of glaucoma and its use is considered standard of care. However, the precision of this method may be reduced by a clinician tendency to round to even numbers. BACKGROUND: Studies have previously demonstrated an even-number measurement bias with Goldmann applanation tonometry during examination of a general patient population. Since it has not been determined whether this bias persists among glaucoma suspects and patients with glaucoma, further investigation was conducted. METHODS: A retrospective analysis was conducted on a random sample from a large dataset of >69,000 patients seen during a six-year period at an urban, academic primary eye care service. Patients without suspicion of glaucoma, patients with a suspicion of glaucoma, and patients with glaucoma were selected who had Goldmann tonometry performed. Chart reviews were performed to confirm status, and even/odd-numbered Goldmann tonometry measurement frequencies were compared. RESULTS: The analysis included 961 controls, 506 glaucoma suspects, 159 ocular hypertensives not taking medication, and 314 patients taking medications who carried a diagnosis of glaucoma or ocular hypertension. Among controls the Goldmann tonometry even/odd digit proportions were 62.8%/37.2% (N = 961, p < 0.0001), and the even-number bias persisted among the other groups with specific even/odd distributions being 61.9%/38.1% (N = 506, p < 0.0001) for glaucoma suspects not taking medications, 66.0%/34.0% (N = 159, p < 0.0001) for ocular hypertensives not taking medications, and 64.3%/35.7% (N = 314, p < 0.0001) for glaucoma/ocular hypertension patients taking medications. CONCLUSION: An even-number measurement bias with Goldmann tonometry may be prevalent even when the examiner is aware of there being greater importance for intraocular pressure measurement accuracy.

Comparison of Three Methods of Tonometry in Patients with Inactive Thyroid-Associated Orbitopathy.

INTRODUCTION: Intraocular pressure (IOP) measurement in patients with thyroid-associated orbitopathy (TAO) can be difficult and misleading, particularly in patients with diplopia and eye deviation (esotropia or hypotropia). However, when measuring IOP, it is also necessary to pay sufficient attention to TAO patients without diplopia in primary gaze direction and without motility disorder that might not be readily apparent. PURPOSE: The aim of this study was to evaluate the accuracy of measurement of intraocular pressure (IOP) using three different types of tonometers: the rebound tonometer (iCARE), the Goldmann applanation tonometer (GAT) and the non-contact airpuff tonometer (NCT) in patients with inactive TAO.  Materials and Methods: A total of 98 eyes of 49 adult patients with TAO were examined. The study group included 36 females and 13 males, with an age range of 19-70 years and a median age of 55.0. All the patients had evidence of thyroid disease,  a history of mild to moderate TAO, no clinical signs or symptoms of active disease, and no diplopia in direct gaze direction. In addition to a comprehensive eye examination, all the patients underwent measurement of intraocular pressure with three tonometers: NCT, iCARE, and GAT. The measurements with these three devices were compared. RESULTS: The mean IOP was 18.1 ± 2.4 mmHg (range 13-25 mmHg) with GAT, 22.3 ±5.0 mmHg (range 13-35 mmHg) with NCT, and 18.0 ±2.4 mmHg (range 13.3-26 mmHg) with iCARE. The mean difference between the GAT and iCARE measurements (using the Bland-Altman analysis) was -0.1 ±1.16 mmHg (limits of agreement -2.4 to 2.1). The mean difference between the GAT and NCT measurements was 4.2 ±3.6 mmHg (limits of agreement -2.8 to 11.2). The mean difference between the iCARE and NCT measurements was -4.3 ±3.7 mmHg (limits of agreement -11.6 to 2.9). No significant difference was found between GAT and iCARE (p = 1.000). However, there was a significant difference between GAT and NCT (p < 0.0001), as well as between iCARE and NCT (p < 0.0001).  Conclusions: In patients with TAO, NCT significantly overestimates IOP values compared to the GAT and ICare. By contrast, the iCARE rebound tonometer provides IOP measurements comparable to the gold standard GAT in these patients.

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.

Bilateral interface fluid syndrome and glaucoma progression after laser-assisted in situ keratomileusis.

A 32-year-old male with a past history of bilateral laser-assisted in situ keratomileusis (LASIK), presented with a decrease in vision in both eyes (BE). Clinical examination showed diffuse corneal haze and interface fluid syndrome (IFS), which was confirmed on anterior segment optical coherence tomography. Intraocular pressure (IOP) measurements obtained with Goldmann applanation tonometer (GAT) were low; however, digital tonometry indicated a raised IOP in BE, which was confirmed by measuring IOP with GAT, outside the peripheral edge of the LASIK flap. Treatment with antiglaucoma medications resulted in complete resolution of the interface fluid. However, due to noncompliance with medications, it recurred and glaucoma showed progression. The patient underwent trabeculectomy with mitomycin C in BE, resulting in improvement in the visual acuity, clear cornea, resolution of interface fluid, and normal IOP, till the last follow-up visit. This case had IFS secondary to episodes of raised IOP, which was diagnosed on careful clinical examination. IOP readings using GAT over the central cornea can give spuriously low readings in IFS. Hence, IOP should be measured in the peripheral cornea to obtain correct IOP readings. Early detection of high IOP and its management is essential to halt glaucoma progression.

Analysis of Goldman Applanation Tonometry with and without fluorescein among glaucomatous and nonglaucomatous patients attending Mzuzu Central Hospital in Malawi: A cross-sectional study.

Background and Aim: Goldman Applanation Tonometry (GAT), the gold standard of tonometry, is used without fluorescein in low-resource settings. Nevertheless, corneal biomechanics differ among population groups. Purpose: The aim of the study is to assess the relationship between GAT findings with and without fluorescein among glaucomatous and nonglaucomatous adults in Malawi. Methods: This was a cross-sectional quantitative study involving 22 glaucoma patients and 22 nonglaucoma patients at Mzuzu Central Hospital. We used a purposive sampling technique to select participants into the two groups. Next, we measured intraocular pressure using GAT with and without fluorescein. Then we entered the data into SPSS version 25. We employed the Wilcoxon test to make comparisons based on age and gender. We considered the value of p < 0.05 statistically significant. Results: There is a statistically significant and strong positive correlation between nfGAT and fGAT among both glaucoma (r = 0.989, p < 0.001) and nonglaucoma (r = 0.955, p < 0.001). According to age, there is no significant difference in IOP value measured with nfGAT and fGAT for both glaucomas (p = 0.109) and nonglaucoma subjects (p = 0.076). However, significant differences were observed between nfGAT and fGAT mean IOP according to sex among both glaucomatous and nonglaucomatous subjects (p = 0.017 and p = 0.32, respectively). Conclusion: The study suggests that the merits of intraocular pressure measured using GAT without fluorescein are not speculative, therefore the two techniques can be routinely used interchangeably in diagnosing and managing glaucoma.

Clinical Outcomes of Micropulse Transscleral Cyclophotocoagulation: 2 Years of Experience in Portuguese Eyes.

Aim: This study evaluates the safety and efficacy of micropulse transscleral cyclophotocoagulation (MPTSCPC) in glaucoma patients, with standard parameters, over a 24-month period. Methods: Retrospective analysis of 61 eyes undergoing MPTSCPC from January 2018 to December 2020 was carried out. Patients received 160 seconds of laser, with settings of 2000 mW/cm2 and a duty cycle of 31.3%. Results: A total of 61 eyes were included, arranged in an age distribution of 73.9 ± 10.8 years. The most frequent diagnosis was primary open-angle glaucoma (POAG), with a mean best-corrected visual acuity (BCVA) of 5/10 in the Snellen Visual chart. Around 37.7% of the eyes had undergone at least one glaucoma filtration surgery prior to MPTSCPC. The mean pretreatment intraocular pressure (IOP) was 24.9 ± 8.6 mm Hg. Except for the contrast at 24 months, at every other follow-up visit, there was a significant reduction (p ≤ 0.001) in IOP and in the number of topical drugs required to control IOP, from four (baseline) to three, with oral acetazolamide suspension in most cases. The total success rate (absolute and clinical successes combined) was 81.9% after 1 year of the treatment. There was no drop in visual acuity or cases of serious complications. There is a positive and significant correlation between prior glaucoma surgery and the need for reinterventions (p = 0.028). Conclusions: Micropulse transscleral cyclophotocoagulation (MPTSCPC) is an effective and safe procedure for reducing IOP within a broad spectrum of glaucoma patients. Additional studies are needed to confirm the current indications, widen their scope, and determine the optimal treatment settings on an individual basis. How to cite this article: Basto RC, Almeida J, Roque JN, et al. Clinical Outcomes of Micropulse Transscleral Cyclophotocoagulation: 2 Years of Experience in Portuguese Eyes. J Curr Glaucoma Pract 2023;17(1):30-36.

Evaluation of the agreement and reliability of Transpalpebral Tonometers compared with Goldmann Applanation Tonometer - A systematic Review and Meta-Analysis Protocol.

In 2020, the global prevalence of glaucoma was estimated to be 76 million and it was projected to increase to 111.8 million by 2040. Accurate intraocular pressure (IOP) measurement is imperative in glaucoma management since it is the only modifiable risk factor. Numerous studies have compared the reliability of IOP measured using transpalpebral tonometers and Goldmann applanation tonometry (GAT). This systematic review and meta-analysis aims to update the existing literature with a reliability and agreement comparison of transpalpebral tonometers against the gold standard GAT for IOP measurement among individuals presenting for ophthalmic examinations. The data collection will be performed using a predefined search strategy through electronic databases. Prospective methods-comparison studies published between January 2000 and September 2022 will be included. Studies will be deemed eligible if they report empirical findings on the agreement between transpalpebral tonometry and Goldmann applanation tonometry. The standard deviation and limits of agreement between each study and their pooled estimate along with weights and percentage of error will be reported using a forest plot. Cochrane's Q test and the I2 statistic will be used to assess heterogeneity, and the publication bias will be investigated using a funnel plot, Begg's and Egger's tests. The review results will provide additional evidence on the reliability of transpalpebral tonometers that, in turn, could possibly assist practitioners to make informed decision about using it as a screening or diagnostic device for clinical practice, outreach camps, or home-based screening. Institutional Ethics Committee registration number: RET202200390. PROSPERO Registration Number: CRD42022321693.

Reutilization of disposable rebound tonometer probes: Risk or return?

Purpose: An advantage of rebound tonometry (RT) is its ease of use so that it can also be operated by health care technicians. However, the cost of the disposable measuring probes is high and their reuse carries the risk of infection. Therefore, this study aims to objectify the potential risk of bacterial transmission by RT. Methods: Our experimental setting consisted of two experiments. The first aimed to quantify the number of bacteria on a tonometer probe after immersion in a bacterial suspension in vitro. The experiment was carried out with two different bacteria and compared with results from a Goldmann tonometer probe. The second experiment tested whether bacteria could be transmitted by simulating reuse of a nondisinfected rebound tonometer probe. Results: First experiment: After immersion of the rebound tonometer probe, we measured a bacterial count of 2.43 × 106 Escherichia coli (EC) and 1.12 × 106 Pseudomonas fluorescens. In total, 1.09 × 107 bacteria for EC and 2.61 × 106 for Pseudomonas fluorescens (PF) were measured on the Goldmann tonometer probe. Second experiment: A bacterial transmission could be detected in 36% of cases in which reuse of nondisinfected tonometer probes was simulated. Conclusion: These results show that despite the small surface of the rebound tonometer probe, there is a clear risk of bacterial transmission. Thorough disinfection according to general standards should be mandatory if the tonometer probes are to be reused.

Impact of self-tonometry on glaucoma treatment decision.

PURPOSE: The aim of this study was to examine the impact of self-tonometry on clinicians' decision in glaucoma treatment. MATERIALS AND METHODS: Medical records of 133 patients who had performed self-tonometry using iCare® Home between January and December 2019 were retrospectively reviewed. Inclusion criteria were as follows: age over 18 years, all types of glaucoma, as well as ocular hypertension and glaucoma suspect, compliance with tonometer manufacturer's recommendations and monitoring over at least 2 days. The data consisted of age, gender, diagnosis, visual field index, rate of progression and type of treatment pre- and post-intraocular pressure (IOP) phasing. The following IOP measurements were used to calculate the mean and maximum IOP, and range over each day and consecutive days: Goldmann applanation tonometry (GAT) measurements from referral and training visits and iCare® Home measurements made by the trainers and the patients themselves. A total of 90 patients were included. RESULTS: Clinicians were satisfied with the actual treatment in 54.4% of the cases. There was a statistically significant difference between the clinicians' decision to maintain same treatment or to escalate therapy for all the mean and maximum IOPs measured on each single day and over a 2- or 3-day period (p < 0.002). CONCLUSION: Our results suggest that the presence of high IOP values obtained with self-tonometry supports an intensification of glaucoma treatment. Self-tonometry provides clinicians with an important complement for clinical decision-making, and under- or over-treatment may be avoided for the benefit of patients.

Performance of home-based self-tonometry (iCare HOME (TA022)) for measuring intraocular pressure among healthy and glaucoma patients.

Introduction: The purpose of this study was to compare iCare HOME (TA022) with Goldmann applanation tonometer and to evaluate the self-tonometry measurements among the Indian population. Methods: Eligible patients underwent iCare HOME training through guided demonstration (verbal, pictorial, video) and practised self-tonometry measures using iCare HOME. Certification for independent iCare HOME measure was provided if first iCare HOME intraocular pressure (IOP) measurement fell within ± 5 mmHg of Goldmann applanation tonometer (GAT) measurement which was measured by the trained clinician (principal investigator). Certified participants underwent simulated home self-tonometry measurements using iCare HOME, and agreement with GAT IOP measurements was assessed. Results: Seven of 83 participants (8.43%) failed to complete the study due to difficulty in performing the task, leading to non-certification. Patients who could use the iCare HOME had a mean age of 53 ± 15.55years (53% males; 46% females). Only one in 12 subjects did not qualify to use iCare HOME. The overall mean difference between iCare HOME and GAT was 0.83 mmHg (95%, 3.92 and -2.25). At various pressure ranges, 7-16 mmHg, 17-23 mmHg and >23 mmHg, the mean difference between iCare HOME and GAT was 1.22 mmHg (95%, 4.32 and -1.86), 0.77 mmHg (95%,3.69 and -2.19), -0.11 mmHg (95%, 2.52 and -2.74) respectively. The intra-class correlation coefficient of the iCare HOME device was 0.997(95% CI,0.995-0.998). Conclusions: Patients were able to perform self- tonometry using iCare HOME with good reliability and safety. iCare HOME can be used to address the issue of difficulty in acquiring frequent and diurnal IOP measurements by patients doing self-tonometry from home.

Predictive models for IOPs measured with NCT, GAT, and ORA among patients undergoing SMILE.

Purpose: To develop predictive models for the intraocular pressure (IOP) of patients undergoing small incision lenticule extraction (SMILE) procedures, measured with a noncontact tonometer (NCT), Goldmann applanation tonometry (GAT), and an ocular response analyzer (ORA). Methods: In this prospective study, a total of 104 eyes (-6.23 ± 2.06 diopters) of 52 patients (24.38 ± 4.76 years) undergoing SMILE procedures were included. The intraocular pressure was measured (IOPNCT with NCT, IOPGAT with GAT, and IOPcc and IOPg with ORA) before surgery and at postoperative 6 months. Information on age, preoperative and attempted spherical equivalent (SE), ablation depth, preoperative values and postoperative changes in central corneal thickness (CCT), K1, K2, Km, corneal hysteresis (CH) and corneal resistance factor (CRF) values was collected in order to predict IOPs. Results: All surgeries were uneventful. At postoperative 6 months, the efficacy and safety index were 1.04 ± 0.15 and 1.08 ± 0.18, respectively. Significant decreases were detected in postoperative IOPNCT, IOPGAT, IOPcc, and IOPg compared to preoperative values (all p < 0.001). No relationship was found between any IOP and ablation depth, attempted SE, and preoperative SE, as well as CCTdifference (all p > 0.05). Predictive models for IOPs were constructed to predict preoperative values, and R 2 values were 67.5% (IOPNCT), 64.5% (IOPGAT), 78.7% (IOPcc), and 82.0% (IOPg). The prediction band of IOPNCT and IOPGAT was 7.4-15.1 mmHg and 8-16 mmHg, respectively. Conclusion: Predictive models for IOP measurements after SMILE procedures can be helpful in clinical practice.

A comparison of goldmann applanation tonometry and rebound tonometry measurements among patients attending a glaucoma clinic in Southwest Nigeria.

Background: The accurate measurement of intraocular pressure (IOP) is a fundamental basic examination in daily ophthalmic practice and is important in managing many ophthalmic diseases and conditions such as glaucoma, uveitis, and following trauma. Accurate measurement of IOP is particularly important in glaucoma because the intraocular pressure is the most important modifiable risk factor in its management. Aim: To compare intraocular pressure (IOP) measurements obtained with the Goldmann applanation (GAT) tonometer to intraocular pressure measurements obtained with the iCare rebound tonometer (RBT) and evaluate the suitability of the iCare tonometer for routine clinical use among adult patients attending a glaucoma clinic in Southwest, Nigeria. Patients and Methods: The study was a comparative cross-sectional study. A total of 132 eyes of 132 patients were recruited for the study. Three consecutive IOP measurements were obtained with each of the instruments by the same observer. A difference in IOP of ± 3 mmHg between the two instruments was considered clinically significant in this study. Results: The mean IOP measurement from GAT was 15.18 mmHg (±4.26 mmHg) and 16.32 mmHg (±4.48 mmHg) from RBT. The mean central cornea thickness was 520.66 µm (±33.34). Pearson's correlation (r = 0.84) revealed a strong statistically significant correlation between GAT and RBT measurements and paired student t-test revealed a statistically significant difference in the means of IOP obtained by the GAT and RBT. There was a tendency for RBT to yield higher IOP measurements. Conclusion: The intraocular pressure measurements obtained with iCare RBT and GAT though strongly correlated, showed statistically significant differences in the means. The impact of central cornea thickness on measurements obtained by GAT and RBT was statistically insignificant. The iCare rebound tonometer, cannot replace GAT for routine use in the glaucoma clinic.

Comparison of Non-contact Tonometry and Goldmann Applanation Tonometry Measurements in Non-pathologic High Myopia.

Purpose: To compare intraocular pressure (IOP) values obtained using Goldmann applanation tonometry (IOPGAT) and non-contact tonometry (IOPNCT) in a non-pathologic high myopia population. Methods: A total of 720 eyes from 720 Chinese adults with non-pathologic high myopia were enrolled in this cross-sectional study. Demographic and ocular characteristics, including axial length, refractive error, central corneal thickness (CCT), and corneal curvature (CC) were recorded. Each patient was successively treated with IOPNCT and IOPGAT. Univariate and multivariable linear regression analyses were conducted to detect factors associated with IOPNCT and IOPGAT, as well as the measurement difference between the two devices (IOPNCT-GAT). Results: In this non-pathologic high myopia population, the mean IOPNCT and IOPGAT values were 17.60 ± 2.76 mmHg and 13.85 ± 2.43 mmHg, respectively. The IOP measurements of the two devices were significantly correlated (r = 0.681, P < 0.001), however, IOPNCT overestimated IOPGAT with a mean difference of 3.75 mmHg (95% confidence interval: 3.60-3.91 mmHg). In multivariate regression, IOPNCT was significantly associated with body mass index (standardized ß = 0.075, p = 0.033), systolic blood pressure (SBP) (standardized ß = 0.170, p < 0.001), and CCT (standardized ß = 0.526, p < 0.001). As for IOPGAT, only SBP (standardized ß = 0.162, p < 0.001), CCT (standardized ß = 0.259, p < 0.001), and CC (standardized ß = 0.156, p < 0.001) were significantly correlated. The mean IOPNCT-GAT difference increased with younger age (standardized ß = -0.134, p < 0.001), higher body mass index (standardized ß = 0.091, p = 0.009), higher SBP (standardized ß = 0.074, p = 0.027), thicker CCT (standardized ß = 0.506, p < 0.001), and lower IOPGAT (standardized ß = -0.409, p < 0.001). Conclusion: In the non-pathologic high myopia population, IOPNCT overestimated IOPGAT at 3.75 ± 2.10 mmHg. This study suggests that the difference between the values obtained by the two devices, and their respective influencing factors, should be considered in the clinical evaluation and management of highly myopic populations.

Intraocular Pressure Measurement after Penetrating Keratoplasty.

Assessing the intraocular pressure is a difficult but crucial task in the follow-up of patients that have undergone penetrating keratoplasty. Early recognition of elevated intraocular pressure and/or glaucoma and establishment of the appropriate treatment is essential to ensure the best possible visual outcome for patients dealing with this feared complication. Although Goldmann applanation tonometry is still the gold standard for measuring the intraocular pressure, its limitations in postkeratoplasty eyes, due to postoperative modified corneal morphology, have led to the search for more suitable alternatives. This review is the result of a comprehensive literature search in the MEDLINE database that aims to present glaucoma in the context of perforating keratoplasty, the corneal properties with impact on ocular pressure measurement, and the results achieved with the most important tonometers that have been studied in this pathology. Goldmann applanation tonometry remains the reference for intraocular pressure assessment even in corneas after penetrating keratoplasty. However, some promising alternatives have emerged, the most important of which are the Pascal dynamic contour tonometry, the Tono-Pen XL, the ocular response analyzer, and the iCare. All have advantages and disadvantages but have proved to be appropriate alternatives, especially in cases in which Goldmann applanation tonometry cannot be used.

The effect of central corneal thickness on Goldmann tonometry: a retrospective study.

PURPOSE: To determine the relation between central corneal thickness and intraocular pressure. PATIENTS AND METHODS: This retrospective study investigated 112 eyes from 56 individuals who underwent photorefractive keratectomy in a single private medical center between May 2018 and September 2019. Intraocular pressure readings were obtained with Goldmann applanation tonometry, and central corneal thickness measurements were evaluated preoperatively. All the examinations were repeated at 3 and 6 months postoperative. RESULTS: At 3 and 6 months postoperative, the mean intraocular pressure was only slightly reduced from baseline (mean reduction of 0.6 ± 2.0 mmHg, P < 0.001 and 0.73 ± 2.14 mmHg, P < 0.001, respectively). The change in intraocular pressure following photorefractive keratectomy was not clinically significant, and this change was not correlated with postoperative central corneal thickness at 3 months (p = 0.620, r = 0.047). CONCLUSION: This study showed that the change in intraocular pressure following photorefractive keratectomy was not clinically significant, and ruled out a correlation in this context between the change in central corneal thickness and the delta intraocular pressure. Our results might question the axiom between central corneal thickness and intraocular pressure and may thus challenge the current clinical setting for evaluating glaucoma.

Comparison between different tonometers following intrastromal corneal ring segments implantation.

PURPOSE: To compare different intraocular pressure (IOP) readings in corneas with intrastromal corneal ring segments (ICRS) taken by three different tonometers; Goldmann applanation tonometry (GAT), air puff tonometer, and ocular response analyzer (ORA) corneal-compensated IOP (ORA-IOPcc) and determine the relation of these measurements to different corneal parameters taken by Pentacam. METHODS: An observational cross-sectional analytic study included patients who underwent ICRS keraring implantation at 3 months. In each eye, the two rings were placed using the femtosecond laser assisted technique 5.5 or 6 mm from the center. IOP was measured using three different tonometers; GAT, air puff tonometer, and ocular response analyzer (ORA) corneal-compensated IOP (ORA-IOPcc). RESULTS: Fifty eyes of 30 patients (20 males and 10 females) aged 27.56 ± 6.38 years were included. IOP measurements by GAT, air puff tonometer, and ORA-IOPcc were 13.28 ± 2.13 mmHg, 10.47 ± 2.55 mmHg, and 13.19 ± 2.78 mmHg, respectively. Comparisons between air puff and each of GAT and ORA-IOPcc were statistically highly significant (p-value <0.001). CONCLUSION: IOP measurements taken by air puff tonometer were significantly lower than those taken by GAT and ORA-IOPcc. These differences were not constant across the pressure range but increased as the pressure values determined using GAT and ORA increased. ORA-IOPcc and GAT showed similar readings. No correlation was found between any of the IOP readings taken by the three tonometers and the central corneal thickness.

Differential impact of prostaglandin analogues on agreement of intraocular pressure measurements obtained by Goldmann applanation, rebound, and noncontact tonometry.

BACKGROUND: To evaluate the effect of topical prostaglandin analogues on agreement of IOP measurements obtained by Goldmann applanation tonometry (GAT), rebound tonometry (RBT), and noncontact tonometry (NCT) in eyes with primary open- angle glaucoma (POAG). METHODS: Intraocular pressure measurements were obtained using GAT, RBT, and NCT in patients with POAG with or without prostaglandin analogues. The agreement between each tonometry was analysed using Bland-Altman analyses in those with or without prostaglandin analogues. The effect of average IOP on IOP differences was also evaluated. RESULTS: Among a total of 86 subjects included in the study, 44 patients were using prostaglandin analogues. The difference in IOP measured by GAT and RBT was marginally greater in those with (GAT-RBT: - 0.94 ± 1.63 mmHg) prostaglandin analogues than in those without (- 0.33 ± 1.22 mmHg, P = 0.06). The difference in IOP measured by GAT and NCT was significantly greater in the prostaglandin group (GAT-NCT: 2.40 ± 2.89 mmHg) than in the group without prostaglandin analogues (0.41 ± 1.63 mmHg, P < 0.01). While there was no significant relationship between the average of all tonometries and the difference between tonometries in those without prostaglandin analogues, both RBT and NCT underestimated IOP relative to GAT at higher IOP in those using prostaglandin analogues. CONCLUSION: Intraocular pressure measured by RBT and NCT was similar to that measured by GAT in those without prostaglandin analogues. RBT overestimated and NCT underestimated IOP compared to GAT in those using prostaglandin analogues.