Agreement of intraocular pressure measurement with Corvis ST,non-contact tonometer,and Goldmann applanation tonometer in children with ocular hypertension and related factors

AIM:To access the agreement of intraocular pressure(IOP)values obtained from biomechanically corrected tonometer[Corvis ST(CST)],non-contact tonometer(NCT),and Goldmann applanation tonometer(GAT)in children with NCT measured-IOP(NCT-IOP)values of 22 mm Hg or more,and related factors.METHODS:A total of 51 eyes with NCT-IOP≥22 mm Hg in children aged 7 to 14y were examined and IOP was measured by CST,NCT,and GAT.Based on GAT measured IOP(GAT-IOP),ocular hypertension(OHT)group(≥22 mm Hg,24 eyes)and the non-OHT group(<22 mm Hg,27 eyes)were defined.We compared the agreement of the three measurements,i.e.,CST measured IOP(CST-IOP),GAT-IOP,and NCT-IOP,and further analyzed the correlation between the differences in tonometry readings,central corneal thickness(CCT),axial length(AL),optic disc rim volume,and age.RESULTS:Compared with the OHT group,thicker CCT,larger rim volume,and higher differences between NCTIOP and GAT-IOP,were found in the non-OHT group.The differences between CST-IOP and GAT-IOP were lower than the differences between NCT-IOP and GAT-IOP in both groups.The mean differences in CST-IOP and GAT-IOP were 1.26 mm Hg(95%limit of agreement ranged from 0.1 to 2.41 mm Hg,OHT group)and 1.20 mm Hg(95%limit of agreement ranged from-0.5 to 3.00 mm Hg,non-OHT group),and the mean differences in NCT and GAT were 3.90 mm Hg(95%limit of agreement ranged from-0.19 to 9.70 mm Hg,OHT group)and 6.00 mm Hg(95%limit of agreement ranged from 1.50 to 10.50 mm Hg,non-OHT group).The differences between CST-IOP and GAT-IOP were not related to CCT,age,and AL in both groups;while the differences between NCT-IOP and GAT-IOP were related to CCT in the OHT group(r=0.93,P<0.001)and to CCT and AL in the non-OHT group(r=0.66,P<0.001,r=-0.81,P<0.001).CONCLUSION:The accuracy of NCT in the diagnosis of pediatric OHT is low.The agreement of CST-IOP and GATIOP was significantly higher in children with and without OHT than in those with NCT-IOP and GAT-IOP.Therefore,CST can be used as a good alternative for IOP measurement in children.The impacts of CCT and AL on NCT measurement need to be fully considered when managing childhood IOP.

Comparison of intraocular pressure measurements with different contact tonometers in young healthy persons

AIM：To analyze the correlation of Goldmann applanation tonometer（GAT）,I-Care tonometer and Tono-Pen tonometer results in young healthy persons,and to investigate the influence of central corneal thickness（CCT）on intraocular pressure（IOP）measurements recorded with these tonometers.·M ETHODS：We conducted a pilot clinical study in 78eyes of 78 subjects aged 22-28 years old（44 women and34 men;mean age 23.8±1.19y）.IOP was measured using GAT,I-Care and Tono-Pen tonometers,followed by measurements of CCT.Statistical analysis was performed using SPSS 20.0.·RESULTS：The mean IOPs and standard deviation（±SD）for GAT,I-Care and Tono-Pen were 15.62±2.281 mm Hg,16.29±2.726 mm Hg and 16.32±2.393 mm Hg,respectively.The mean CCT was 555.15±29.648μm.Clear positive correlations between GAT and I-Care,GAT and TonoPen,and I-Care and Tono-Pen tonometers were found（=0.867,〈0.001;=0.861,〈0.001;=0.915,〈0.001,respectively）.In comparison between devices,BlandAltman analysis showed a significant mean difference（MD）in the measurements by GAT and I-Care of-0.679 mm Hg and by GAT and Tono-Pen of-0.705 mm Hg（〈0.001）,but there was no significant difference between I-Care and Tono-Pe（〉0.05）.Both non-gold standard tonometers were affected by CCT;that is,both I-Care and Tono-Pen tonometer values were significantly higher with higher CCT means（〉555μm;MD=-1.282,〈0.001;MD=-0.949,〈0.001,respectively）compared with GAT.·CONCLUSION：Both I-Care and Tono-Pen tonometers overestimated IOP compared with the GAT values.Either the I-Care or Tono-Pen tonometer could be used instead of GAT because there was no significant difference between their results.Higher CCT values（〉555μm）were associated with overestimated IOP values.

Intraocular pressure measurement over soft contact lens by rebound tonometer: a comparative study

AIM: To evaluate the intraocular pressure(IOP)measurements by Icare rebound tonometer over a contact lens in comparison with Goldmann applanation tonometry(GAT). METHODS: Fifty patients using contact lens were included in this study. One of the eyes of the patients was selected randomly and their IOP were measured by rebound tonometer with and without contact lens(RTCL,RT respectively) and by GAT, as well as their central corneal thickness(CCT) by optical pachymeter. The results of both methods were compared by correlation analysis, general linear method repeated measure and Bland-Altman analysis.RESULTS: Mean IOP values measured by RTCL, RT and GAT were 15.68 ±3.7, 14.50 ±3.4 and 14.16 ±2.8(P 【0.001), respectively. Mean IOP by RTCL was significantly higher than the measurements implemented by RT and GAT(P 【0.001), while there was no difference between the measurements by GAT and RT(P =0.629). There was a good level of positive correlation between GAT and RTCL as well as RT(r =0.786 P 【0.001, r =0.833 P 【0.001, respectively). We have observed that CCT increase did not show any correlation with the differences of the measurements between RTCL and RT(P =0.329), RTCL and GAT(P =0.07) as well as RT and GAT(P =0.189) in linear regression model.CONCLUSION: The average of the measurements over contact lens by rebound tonometer was found to be higher than what was measured by GAT. Although this difference is statistically significant, it may be clinically negligible in the normal population.

Evaluation of rebound tonometer iCare IC200 as compared with IcarePRO and Goldmann applanation tonometer in patients with glaucoma

Background:This study investigated the agreement between a new rebound tonometer,IC200,and IcarePRO and Goldmann applanation tonometry(GAT).Methods:This was a prospective cross-sectional study.We measured the intraocular pressure(IOP)in 145 eyes of 145 glaucoma patients in the sitting position using GAT,IcarePRO,and IC200.IcarePRO and IC200 measurements were also obtained in the supine position.IC200 measurement was performed using two modes:single six(IC200-single)and automatic(IC200-continuous)six-measurements mode.Results:All tonometers provided high reproducibility in both positions(all intraclass correlation coefficients>0.90),although it was highest with GAT,followed by IC200-continuous and IC200-single and then IcarePRO.In the sitting position,the mean(±SD)IOPs of GAT,IcarePRO,IC200-single,and IC200-continuous were 14.5±2.9 mmHg,13.3±3.2 mmHg,11.6±3.2 mmHg,and 11.5±3.2 mmHg,respectively.IOPs measured with IcarePRO or IC200 were significantly lower than those with GAT,particularly in patients with low IOP.IOPs measured with all tonometers were significantly elevated in the supine position as compared with the sitting position,but this difference was significantly greater with IC200-single and IC200-continuous compared with IcarePRO.IOP elevation was significant in eyes without bleb versus those with bleb,but this finding was not observed when IOP was measured with IcarePRO.The IOPs of the single and continuous modes of IC200 were interchangeable in both positions.Conclusions:GAT,IcarePRO,and IC200 had sufficiently high reproducibility,but measurements with IcarePRO may not be accurate in the supine position.Elevation of IOP in the supine position,especially in eyes with bleb,was more sensitively captured with IC200 than with IcarePRO.

Impact of corneal parameters on intraocular pressure measurements in different tonometry methods

AIM: To evaluate the impact of central corneal thickness(CCT) and corneal curvature on intraocular pressure(IOP) measurements performed by three different tonometers. METHODS: IOP in 132 healthy eyes of 66 participants was measured using three different tonometry techniques: Goldmann applanation tonometer(GAT), Pascal dynamic contour tonometer(DCT), and ICare rebound tonometer(RT). CCT and corneal curvature were assessed. RESULTS: In healthy eyes, DCT presents significantly higher values of IOP than GAT(17.34±3.69 and 15.27±4.06 mm Hg, P<0.0001). RT measurements are significantly lower than GAT(13.56±4.33 mm Hg, P<0.0001). Compared with GAT, DCT presented on average 2.51 mm Hg higher values in eyes with CCT<600 μm and 0.99 mm Hg higher results in eyes with CCT≥600 μm. The RT results were lower on average by 1.61 and 1.95 mm Hg than those obtained by GAT, respectively. Positive correlations between CCT in eyes with CCT<600 μm were detected for all IOP measurement techniques, whereas a similar relationship was not observed in eyes with thicker corneas. A correlation between IOP values and keratometry in the group with CCT<600 μm was not detected with any of the tonometry methods. In thicker corneas, a positive correlation was found for GAT and mean keratometry values(R=0.369, P=0.005). CONCLUSION: The same method should always be chosen for routine IOP control, and measurements obtained by different methods cannot be compared. All analysed tonometry methods are dependent on CCT;thus, CCT should be taken into consideration for both diagnostics and monitoring.

Comparison among Ocular Response Analyzer,Corvis ST and Goldmann applanation tonometry in healthy children

AIM： To explore the relationship between different parameters of Ocular Response Analyzer（ORA） and Corvis ST（CST） in a sample of healthy Iranian school-aged children and the relationship between parameters of these 2 instruments against intraocular pressure（IOP）, measured by the Goldmann applanation tonometer（GAT-IOP）, age and gender, and find possible correlation between ORA and CST with GAT.METHODS： This cross-sectional study included 90 healthy children. A general interview and complete eye examination were performed. Following successful GATIOP measurement, ORA and CST were conducted. The CST parameters were A 1/2 length（A1 L, A2 L）, A 1/2 velocity（A1 V, A2 V）, highest concavity deformation amplitude（HCDA）, radius of curvature（Ro C）, peak distance（PD）, central corneal thickness（CCT） and IOP. The ORA parameters were corneal hysteresis（CH）, corneal resistance factor（CRF）, Goldmann-correlated IOP（IOP-G） and corneal compensated IOP（IOP-CC）. Extracted data was analyzed using the Statistical Package for Social Science software.RESULTS： Totally 39 males with age of 9.08±1.60（6-12）y and 51 females with age of 8.96±1.55（6-13）y were included. Many CST parameters were significantly correlated with CH, CRF, IOP-G and IOP-CC. Some CST parameters had a significant correlation with GAT-IOP, including IOP-CST in both eyes and HCDA, A2 L, PD, and RoC in the left eye, but none with age, except A2 L in the right eye. The CRF measurement showed a significant correlation with GAT-IOP in both eyes and CH in the right eye, yet, none with age. Among all CST and ORA parameters, CCT-CST in both eyes and A1 L in right eye had a significant correlation with gender, although this was a negligible negative correlation. Comparison of mean IOP values by different devices showed a significantly highest IOP overestimation by CST and lowest by IOP-CC compared with GAT. Also, IOP-G versus IOP-CST significantly had the lowest IOP overestimation among others. Overall, either low positive correlation or negligible correlation was found between IOP measurements by 3 instruments.CONCLUSION： The study finds the highest IOP overestimation by CST and lowest by IOP-CC compared with GAT. Overall, either low positive correlation or negligible correlation is found between IOP measurements by the 3 instruments.

Distribution of central corneal thickness and intraocular pressure in emmetropic eyes of healthy children of Palestine: a representative cross-sectional study

AIM: To determine the distributions of central corneal thickness(CCT) and intraocular pressure(IOP) in emmetropic eyes of healthy children of Palestine.METHODS: This representative cross sectional study included a total of 1156 eyes from 578 healthy school children aged 7-15 y. Inclusion criteria included emmetropia, no previous history of ocular or systemic diseases, no previous history of contact lens use, and the availability of both eyes. CCT and IOP were measured using ultrasound pachymeter and Goldmann applanation tonometer, respectively. The relationship of the results with age and gender was investigated.RESULTS: The mean age of school children was 11.13±2.8 y. Mean CCT was 542.2±37.4 and 544.3±39.2 μm for right and left eyes, respectively. Mean IOP was 12.5±2.2 and 12.3±2.2 mm Hg for right and left eyes, respectively. A positive correlation was observed between CCT and IOP of the right eye(P<0.001, R=0.358) and CCT and IOP of the left eye(P<0.001, R=0.324). No significant differences were observed in CCT and IOP due to age or gender(P>0.05). There were significant differences in mean CCT and IOP between right and left eyes(P=0.004, P=0.001, respectively).CONCLUSION: A population profile of CCT and IOP is established in Palestinian children for the first time. Mean CCT is comparable to some studies but differ from others. Mean IOP is considerably lower than that of majority children of other ethnic groups. Intereye difference of more than 36 μm in CCT, and 5 mm Hg in IOP should prompt evaluation for potential ocular disorders.

Rebound Tonometry in Cataract Surgery: Comparison with Goldmann Applanation Tonometry

Purpose: to compare the rebound tonometer ICare? (RT) with the Goldmann applanation tonometer (GAT) in cataract surgery and to assess the influence of central corneal thickness (CCT) on intraocular pressure (IOP) measurements. Design: retrospective, comparative study. Methods: a total of 472 patients underwent IOP measurement using RT (time 0 = RTa). GAT IOP measurement was performed 5 minutes later, followed by a second RT IOP measurement after other 5 minutes (RTa + 10 min = RTb). CCT was obtained by ultrasound pachymetry. In 106 patients IOP was measured by means of RT and GAT before clear corneal cataract surgery (RT1 and GAT1) and at one day postoperatively (RT2 and GAT2). Results: RT IOP values > 5 mmHg were overestimated, while RT IOP values Conclusion: our results showed a good agreement between measurements obtained with RT and GAT in pre and postoperative cataract surgery, although a significant statistically difference was found between RT and GAT measurements performed postoperatively. Moreover, CCT is a parameter to be considered for the IOP measurement, especially for values obtained with RT.