Reproducibility and Tolerability of the ICare Rebound Tonometer in School Children

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.

The Impact of Noncontact Tonometry and Icare Rebound Tonometry on Tear Stability and Dry Eye Clinical Practice

The purpose of this study was to investigate the possible effects of the noncontact air puff tonometry (NCT) and Icare rebound tonometry (ICT) on the tear film stability by using the tear stability analysis system (TSAS) and dry eye parameters. Fifteen eyes from fifteen normal healthy subjects were investigated in this study. All subjects underwent TSAS surface regularity index (SRI) examinations, TBUT, and IOP measurements. The mean IOP results measured with NCT were 13.3 ± 1.86 mm Hg, and the mean IOP results measured with ICT were 15.88 ± 3.09 mm Hg (p > 0.05). The mean values of baseline, 5 min, and 10 min of the NCT-SRI and ICR-SRI were tested. There were statistically significant differences between NCT-Baseline SRI, NCT-5 min SRI, and NCT-10 min SRI values (p < 0.05). SRI values significantly increased after NCT. The mean values of the baseline, 5 min, and 10 min of the ICT-SRI were also assessed. There were no statistically significant differences between ICT-Baseline SRI, ICT-5 min SRI, and ICT-10 min SRI values (p > 0.05). The mean TBUT values exhibited a significant decrease at 1 min, 5 min, and 10 min compared with baseline values for the NCT and ICT (p < 0.01). NCT-TBUT and ICT-TBUT values were also compared with each other in the same time period. There were no statistically significant differences between NCT-Baseline and ICT-Baseline TBUT values (p > 0.05). In conclusion, intraocular pressure measurements in routine ophthalmology clinical practices by either NCT or ICT cause deterioration in the tear film stability which might affect tear stability testing when performed soon after IOP measurements. It is best to wait at least for 20−30 min after the IOP measurement before evaluating the tear film and the corneal surface or perform tonometry after the tear film-ocular surface evaluation tests.

24-h intraocular pressure patterns measured by Icare PRO rebound in habitual position of open-angle glaucoma eyes

PURPOSE

To measure the 24-h intraocular pressure (IOP) by Icare PRO rebound in healthy and primary open-angle glaucoma (POAG) eyes and compare it with non-contact tonometry (NCT).

METHODS

Thirty POAG patients, who were under IOP-lowering treatment, and 30 healthy subjects were included. Participants were hospitalized overnight for the 24-h IOP measurement. IOPs were measured by Icare PRO and NCT according to a standard protocol every 2 h during 24 h. The 24-h IOP curve and IOP-related parameters were compared between Icare PRO and NCT groups in POAG and healthy eyes.

RESULTS

The IOPs measured by Icare PRO in habitual position increased notably at 22:00 in the normal group and at 20:00 in the POAG group, reached peak at 0:00, stayed high until 4:00, and then decreased in both groups (all p < 0.05). The POAG patients had higher mean 24-h IOP, peak IOP, IOP fluctuation, and greater IOP change from supine to sitting position in the nocturnal period than those in the normal subjects even after adjusting for eyes, age, gender, CCT, and axial length (all p < 0.05).

CONCLUSIONS

The Icare PRO provides a well-tolerated approach for 24-h IOP monitoring in habitual position. Twenty-four-hour IOP in habitual position is more sensitive for detecting high nocturnal IOP peaks and greater IOP fluctuation for POAG patients.

Obesity, Blood Pressure, and Intraocular Pressure: A Cross-Sectional Study in Italian Children

INTRODUCTION

Several studies in the adult population have shown that obesity is an independent risk factor for elevated intraocular pressure (IOP), whereas data in the paediatric population are sparse and controversial. The purpose of the present study is to investigate the relationship between body mass index (BMI), blood pressure (BP), and IOP in healthy school children.

METHODS

The survey was conducted among a random sample of 8-year-old Italian students. Data were collected on their health status and behaviours related to obesity (physical activity, food and drinking habits, etc.). Physical examinations, conducted at school, included measurements of height, weight, BP, and IOP.

RESULTS

Five hundred and seventy-six subjects were recruited (92.8% response rate); 42.4% were overweight or obese, 58.9% consumed inadequate daily servings of fruit and vegetables, and 87.5% were involved in sedentary activities. Elevated BP/hypertension (HTN) affected 3.6% and high IOP was revealed in 12.5% of the children. In the multivariate analysis, elevated BP/HTN was the only significant determinant of ocular HTN (OR 5.36, 95% CI 1.95-14.73, p = 0.001).

CONCLUSIONS

Our results show that high IOP affects 12.5% of 8-year-old school children and appears to be associated with high BP related to a high BMI.

In vivo measures of anterior scleral resistance in humans with rebound tonometry

PURPOSE

To measure regional variations in anterior scleral resistance (ASR) using a ballistic rebound tonometer (RBT) and examine whether the variations are significantly affected by ethnicity and refractive error (RE).

METHODS

ASR was measured using a RBT (iCare TA01) following calibration against the biomechanical properties of agarose biogels. Eight scleral regions (nasal, temporal, superior, inferior, inferior-nasal, inferior-temporal, superior-nasal and superior-temporal) were measured at locations 4mm from the limbus. Subjects were 130 young adults comprising three ethnic groups whose RE distributions [MSE (D) ± S.D.] incorporated individuals categorised as without-myopia (NM; MSE ≥ -0.50) and with-myopia (WM; MSE < -0.50); British-White (BW): 26 NM + 0.52 ± 1.15D; 22 WM -3.83 ± 2.89D]; British-South-Asian (BSA): [9 NM + 0.49 ± 1.06D; 11 WM -5.07 ± 3.76D; Hong-Kong-Chinese (HKC): [11 NM + 0.39 ± 0.66D; 49 WM -4.46 ± 2.70D]. Biometric data were compiled using cycloplegic open-field autorefraction and the Zeiss IOLMaster. Two- and three-way repeated measures analysis of variances (anovas) tested regional differences for RBT values across both refractive status and ethnicity whilst stepwise forward multiple linear regression was used as an exploratory test.

RESULTS

Significant regional variations in ASR were identified for the BW, BSA and HKC (p < 0.001) individuals; superior-temporal region showed the lowest levels of resistance whilst the inferior-nasal region the highest. Compared to the BW and BSA groups, the HKC subjects displayed a significant increase in mean resistance for each respective region (p < 0.001). With the exception of the inferior region, ethnicity was found to be the chief predictor for variation in the scleral RBT values for all other regions. Mean RE group differences were insignificant.

CONCLUSIONS

The novel application of RBT to the anterior sclera confirm regional variation in ASR. Greater ASR amongst the HKC group than the BW and BSA individuals suggests that ethnic differences in anterior scleral biomechanics may exist.

Distribution of intraocular pressure in healthy Iranian children: the Shiraz Pediatric Eye Study

PURPOSE

To describe the mean and normal range of intraocular pressure (IOP) and its associations in healthy Iranian school children using the noncontact tonometer.

METHODS

In this cross-sectional study as part of the Shiraz Pediatric Eye Study, a stratified random sampling was performed among elementary school children of Shiraz, Iran. Basic demographics and socioeconomic status of households, past medical history, drug history, and eye health history were collected for each eligible student. Children underwent complete ophthalmic examination. Axial length, corneal curvature, and anterior chamber depth were measured using the IOL-Master 500.

RESULTS

Of 2,001 eligible children, 1,901 (95.0%; 3,802 eyes) with a mean age of 9.1 ± 1.6 years (standard deviation; range, 6-12 years) had reliable IOP. The mean spherical equivalent refraction was 0.5 ± 1.3 D for the right eye and 0.6 ± 1.2 D for the left eye. Mean IOP in the right eye was 15.1 ± 2.5 mm Hg (median, 15.0; range, 8.0-27.0 mm Hg); in the left eye, 15.2 ± 2.5 mm Hg (median, 15.0; range, 9.0-28.0 mm Hg). In multiple regression analyses, the mean IOP was significantly lower among asthmatic children compared to normal participants (P = 0.007). The measured IOP was significantly higher in myopic participants than hyperopic patients (P = 0.003).

CONCLUSIONS

This study provides a useful normative IOP database using the noncontact tonometer for healthy Iranian school children.

Changes in preoperative corneal measurements following same-day intraocular pressure testing with rebound tonometry

Purpose:

To evaluate the extent to which rebound tonometry affects corneal surface properties and preoperative corneal measurements.

Setting:

Four cornea specialty private practices.

Design:

Prospective case series.

Methods:

Visual acuity testing, corneal topography, keratometry, and grading of corneal staining were performed on both eyes of 60 randomly selected, previously scheduled patients. Technicians then performed rebound tonometry on one randomly selected eye only. Immediately following, intraocular pressure measurement, corneal topography, keratometry, and corneal staining were repeated on both eyes.

Results:

None of the 60 study eyes developed increased staining scores following intraocular pressure testing with the Icare ic100. For corneal staining, mean keratometry, and total corneal cylinder, no statistically significant difference was found from the first measurement to the second measurement between the study eyes and control eyes.

Conclusion:

Rebound tonometry with the Icare ic100 may be used on any patient at any time during the exam without affecting the results of other tests, allowing clinicians to test intraocular pressure prior to preoperative cataract or refractive surgery measurements on the same day. This may allow for significant improvement in patient flow in the office and save patients from the cost and time of extra visits.

Feeling the pressure: a cross-sectional study exploring feasibility of a healthcare Pop-Up for intraocular pressure measurements in shopping centres in England

OBJECTIVES

To test the hypothesis that a shopping centre Pop-Up health check combining an intraocular pressure (IOP) check with a general health check (blood pressure (BP)) is more readily accepted by the general public than an IOP check only. We investigate public awareness of IOP compared with BP and the feasibility of measuring IOP in large numbers in a Pop-Up.

DESIGN

A cross-sectional study using a tailor-made healthcare Pop-Up.

SETTING

The 'Feeling the Pressure' Pop-Up was sited in eight regionally-different shopping centres in England.

PARTICIPANTS

Adult members of the public in shopping centres.

METHODS

On one day we measured IOP only and on another measured BP and IOP. IOP was measured by Icare IC100 tonometer (Helsinki, Finland). Potential participants were asked about their awareness of IOP and BP and when they last visited their optometrist.

RESULTS

More people attended the combined BP + IOP days (461; 60%; 95% CI 56% to 64%) than IOP-only days (307; 40%, 95% CI 37% to 43%) over 16 days of testing. We recorded IOP in 652 participants (median (IQR) age and IOP of 54 (42 to 68) years and 13 (11 to 15) mm Hg, respectively). Fewer people reported awareness about IOP (19%, 95% CI 16% to 23%) compared with BP (71%, 95% CI 66% to 75%). Of 768 participants, 60 (8%) reported no previous optometric eye examination and 185 (24%) reported >2 years since their most recent examination.

CONCLUSIONS

Measuring IOP in large numbers of the public via a shopping centre Pop-Up is feasible. Public engagement was greater when a BP check was offered alongside an IOP check, suggesting unfamiliar health checks can be promoted by aligning them with a more familiar check. Our findings hint at strategies for public health schemes that engage the public with their eye health.

A comparison of Icare PRO and Perkins tonometers in anesthetized children

AIM

To compare intraocular pressure (IOP) measurements obtained with the Perkins applanation tonometer and Icare PRO (ICP) rebound tonometer in anesthetized aphakic or strabismus children. Furthermore, intra-operator correlation and inter-operator correlation have been evaluated, along with the effects of central corneal thickness (CCT) on IOP measurements.

METHODS

Seventy children undergoing examination under anesthesia with sevoflurane for aphakic patients and for surgery for strabismus were included. IOP have been measured twice immediately after anesthesia induction with both Perkins applanation tonometer (PAT) and ICP in one eye and by two different operators with both devices in the fellow eye. Furthermore, CCT was measured with ultrasound pachymetry Pacline (Optikon). Agreement between the device measurements has been evaluated using Bland-Altman analyses. Repeatability and reproducibility of the device have been evaluated with intraclass correlation coefficient (ICC) with a value > 0.75 associated with excellent reliability. The relationship between IOP and CCT has been evaluated with Spearman's correlation coefficient r and determination coefficient r².

RESULTS

Mean difference in IOP measurements between ICP and PAT was 1.97 mmHg ± 1.23 mmHg (p < 0.05). This difference appeared to be higher in aphakic patients (mean difference 2.15 ± 1.35) than in patients undergoing strabismus surgery (mean difference 1.83 mmHg ± 1.12). Intraclass correlation coefficient (ICC) is used to evaluate repeatability and reproducibility, which are both high for PAT (repeatability 0.96, reproducibility 0.76) compared with ICP (repeatability 0.81, reproducibility 0.70). Correlation coefficient between CCT and IOP is 0.66 for both ICP and PAT.

CONCLUSION

ICP tends to overestimate IOP compared to PAT. Repeatability and reproducibility are both high for PAT as compared to ICP. A significant correlation between IOP and CCT for both instruments has been demonstrated.

Icare-Pro Rebound Tonometer Versus Hand-held Applanation Tonometer for Pediatric Screening

PURPOSE

To compare intraocular pressure (IOP) measurements obtained using the new rebound tonometer Icare-Pro (Icare, Tiolat Oy, Helsinki, Finland) and the hand-held version of the Goldmann applanation tonometer (Perkins; Clement Clarke, Haag-Streit, Harlow, United Kingdom) in healthy children during clinical practice.

METHODS

In this prospective study, three IOP measurements were made using each tonometer in a single session, starting with the Icare-Pro. Participants were 173 non-anesthetized patients aged 1 to 16 years. Measurements were made in both eyes but only data for the right eye were entered in the analysis. Central corneal thickness, anterior chamber depth, and axial length were also measured in each patient. Data were compared by determining interclass correlation coefficients (ICCs) for each tonometer and representing the differences detected as Bland-Altman plots.

RESULTS

Good linear correlation was observed between IOP readings obtained using the Perkins and Icare-Pro tonometers (r = 0.87, P < .001), although the Icare-Pro readings were slightly higher (mean IOP difference: 0.26 ± 1.58 mm Hg, P = .037). The 95% limits of agreement between the two methods were 2.8 to -3.4 mm Hg. The ICC was 0.857 (95% confidence interval: 0.810 to 0.893), indicating good agreement. For both tonometers, a low but significant correlation was detected between IOP and central corneal thickness or age. However, no correlation of IOP was found with axial length or anterior chamber depth.

CONCLUSIONS

Pediatric IOP measurements determined using the new Icare-Pro rebound tonometer showed good correlation with those obtained using the hand-held Perkins applanation tonometer in a routine clinical examination with no need for general anesthesia. [J Pediatr Ophthalmol Strabismus. 2018;55(6):382-386.].

Intraocular pressure elevation after cataract surgery and its prevention by oral acetazolamide in eyes with pseudoexfoliation syndrome

PURPOSE

To examine whether intraocular pressure (IOP) increases immediately after cataract surgery in eyes with pseudoexfoliation (PXF) syndrome and to assess whether orally administered acetazolamide can prevent the IOP elevation.

SETTING

Hayashi Eye Hospital, Fukuoka, Japan.

DESIGN

Prospective case series.

METHODS

Patients with PXF syndrome scheduled for phacoemulsification were randomly assigned to 1 of 3 groups: (1) oral acetazolamide administered 1 hour preoperatively (preoperative administration group), (2) administered 3 hours postoperatively (postoperative administration group), and (3) not administered (no administration group). The IOP was measured using a rebound tonometer 1 hour preoperatively, upon completion of surgery, and at 1, 3, 5, 7, and 24 hours postoperatively.

RESULTS

The study comprised 96 patients (96 eyes). The mean IOP increased at 3, 5, and 7 hours postoperatively in all groups. At 1 hour and 3 hours postoperatively, the IOP was significantly lower in the preoperative administration group than in the postoperative group and no administration group (P ≤ .001). At 5, 7, and 24 hours postoperatively, the IOP was significantly lower in the preoperative group and postoperative administration group than in the no administration group (P ≤. 045). An IOP spike higher than 25 mm Hg occurred less frequently in the preoperative administration group than in the postoperative administration group and the no administration group (P = .038).

CONCLUSIONS

Intraocular pressure increased at 3, 5, and 7 hours after cataract surgery in eyes with PXF syndrome. Oral acetazolamide administered 1 hour preoperatively reduced the IOP elevation throughout the 24-hour follow-up; acetazolamide administered 3 hours postoperatively reduced the elevation at 5 hours postoperatively and thereafter.

Agreement among Goldmann applanation tonometer, iCare, and Icare PRO rebound tonometers; non-contact tonometer; and Tonopen XL in healthy elderly subjects

PURPOSE

To evaluate the inter-device agreement among the Goldmann applanation tonometer (GAT), iCare and Icare PRO rebound tonometers, non-contact tonometer (NCT), and Tonopen XL tonometer.

METHODS

Sixty healthy elderly subjects were enrolled. The intraocular pressure (IOP) in each subject's right eye was measured thrice using each of the five tonometers. Intra-device agreement was evaluated by calculating intraclass correlation coefficients (ICCs). Inter-device agreement was evaluated by ICC and Bland-Altman analyses.

RESULTS

ICCs for intra-device agreement for each tonometer were >0.8. IOP as measured by iCare (mean ± SD, 11.6 ± 2.5 mmHg) was significantly lower (p < 0.05) than that measured by GAT (14.0 ± 2.8 mmHg), NCT (13.6 ± 2.5 mmHg), Tonopen XL (13.7 ± 4.1 mmHg), and Icare PRO (12.6 ± 2.2 mmHg; Bonferroni test). There was no significant difference in mean IOP among GAT, NCT, and Tonopen XL. Regarding inter-device agreement, ICC was lower between Tonopen XL and other tonometers (all ICCs < 0.4). However, ICCs of GAT, iCare, Icare PRO, and NCT showed good agreement (0.576-0.700). The Bland-Altman analysis revealed that the width of the 95% limits of agreement was larger between the Tonopen XL and the other tonometers ranged from 14.94 to 16.47 mmHg. Among the other tonometers, however, the widths of 95% limits of agreement ranged from 7.91 to 9.24 mmHg.

CONCLUSION

There was good inter-device agreement among GAT, rebound tonometers, and NCT. Tonopen XL shows the worst agreement with the other tonometers; therefore, we should pay attention to its' respective IOP.

CLINICAL TRIAL REGISTRATION

Japan Clinical Trials Register; number: UMIN000011544.

Intraocular pressure monitoring by rebound tonometry in children with myopia

BACKGROUND/PURPOSE:

Topical atropine treatment is generally accepted to retard the progression of myopia, but it is associated with side effects such as photophobia and elevation of intraocular pressure (IOP). IOP measurements in children are challenging. The traditional applanation tonometry by direct contact with the cornea will require patient's cooperation. The rebound tonometer, using a dynamic electromechanical method for measuring IOP, shows good correlation with traditional tonometry. The purpose of this study is to evaluate the IOP of myopic children under atropine treatment using rebound tonometer and to compare the characteristics between rebound tonometry and applanation tonometry.

METHODS:

This study is a prospective study measuring IOP by rebound tonometer in myopic children under regular low-dose atropine treatment. We recruited children with refraction error showing myopia over −0.5 D with 0.15%, 0.3%, or 0.5% atropine eye drops use every night or every other night for myopia control. Children with treatment duration of atropine <1 month were excluded from the study. IOP measurements were performed by applanation tonometer (Tono-Pen XL, Reichert) and rebound tonometer (ICARE). The reliability of rebound tonometer was analyzed with percentage. Comparison of IOP between rebound tonometer and applanation tonometry was presented.

RESULTS:

The rebound tonometry was well tolerated by all participants and caused no complaints, discomfort, or adverse events. Totally 42 myopic eyes of 42 subjects were included in the study. The average age of these participants was 10 years old, range from 5 to 16. Median = 10 years old. The average IOP of the right eye by rebound tonometer was 17.4 ± 3 mmHg, and 17.1 ± 3 mmHg by applanation tonometry. Nearly 19%, 33%, and 24% of difference of IOP readings between rebound tonometer and Tono-Pen applanation are within 0 mmHg, 1 mmHg, and 1–2 mmHg, respectively.

CONCLUSIONS:

Rebound tonometry has good correlation with applanation tonometry and 76.1% of differences between two tonometers are <2 mmHg. The advantage of drop-free rebound tonometry has made it easier to obtain IOP readings in myopia children under atropine treatment.

Wound stability and surgically induced corneal astigmatism after transconjunctival single-plane sclerocorneal incision cataract surgery

PURPOSE

To compare intraocular pressure (IOP) immediately after cataract surgery, and surgically induced corneal astigmatism (SIA) and corneal shape changes between eyes with transconjunctival single-plane sclerocorneal incisions (TSSIs) and eyes with clear corneal incisions (CCIs).

METHODS

Bilateral eyes of 64 patients undergoing phacoemulsification were randomized to undergo 2.4-mm temporal TSSI or CCI. IOP was measured preoperatively, and in the immediate postoperative periods. SIA was determined using vector analysis, and corneal shape changes and irregular astigmatism were evaluated using a videokeratography preoperatively, and in the early postoperative periods.

RESULTS

Wound hydration was performed in 23 eyes (35.9 %) of the TSSI group and in 60 (93.8 %) of the CCI group (P < 0.0001). Mean IOP was significantly higher in the TSSI group than in the CCI group at 30, 60, and 120 min postoperatively (P ≤ 0.0179). SIA tended to be smaller in the TSSI group than the CCI group, but the difference was not significant. The higher order irregular astigmatism was smaller in the TSSI group than in the CCI group at 2 days (P = 0.0312). The videokeratography revealed a wound-related flattening postoperatively in both groups; this change disappeared within 4 weeks in the TSSI group, whereas it persisted until 12 weeks in the CCI group.

CONCLUSION

IOP was significantly higher immediately after TSSI than after CCI and required less wound hydration, suggesting better stability with TSSI. Higher order irregular astigmatism and wound-related corneal flattening were smaller after TSSI than after CCI in the early periods, suggesting that fewer corneal shape changes with TSSI.

Features of measurement of intraocular pressure in children

This review discusses the results of various studies conducted in recent years on the comparison of modern methods of measuring intraocular pressure (IOP) in children: pneumotonometry, Maklakov applanation tonometry, and tonometry using Perkins tonometer, Goldmann tonometer, Icare tonometer, Ocular Response Analyzer, TonoPen handheld tonometer, transpalpebral tonometer TIOP01, or a dynamic contour Pascal tonometer. This study discusses the advantages and disadvantages of different methods of measurement of IOP in children, including the evaluation of patients with fibrous lens capsules that might affect the measurement of IOP and an analysis of the characteristics of evaluation of IOP in children with congenital glaucoma.

The measurement of intraocular pressure over positive soft contact lenses by rebound tonometry

PURPOSE

To investigate if the accuracy of intraocular pressure (IOP) measurements using rebound tonometry over disposable hydrogel (etafilcon A) contact lenses (CL) is affected by the positive power of the CLs.

METHODS

The experimental group comprised 26 subjects, (8 male, 18 female). IOP measurements were undertaken on the subjects' right eyes in random order using a Rebound Tonometer (ICare). The CLs had powers of +2.00D and +6.00D. Measurements were taken over each contact lens and also before and after the CLs had been worn.

RESULTS

The IOP measure obtained with both CLs was significantly lower compared to the value without CLs (t test; p<0.001) but no significant difference was found between the two powers of CLs.

CONCLUSIONS

Rebound tonometry over positive hydrogel CLs leads to a certain degree of IOP underestimation. This result did not change for the two positive lenses used in the experiment, despite their large difference in power and therefore in lens thickness. Optometrists should bear this in mind when measuring IOP with the rebound tonometer over plus power contact lenses.

A Comparison of Rebound to Indentation Tonometry in Supine Sedated Children with Glaucoma

PURPOSE

To compare intraocular pressure (IOP) measurements by rebound tonometry (Icare PRO; Icare Finland Oy, Helsinki, Finland) to measurements by indentation tonometry (Pneumotonometer Model 30 classic and Tono-Pen XL; Reichert, Buffalo, NY, USA) in supine sedated children with glaucoma.

METHODS

Prospective comparative observational study of Saudi Arabian children with glaucoma undergoing chloral hydrate sedation for ophthalmic examination (February 2012 - February 2013). Nonglaucomatous eyes were included as controls. Eyes with corneal scars or prior corneal transplant or lamellar surgery were excluded.

RESULTS

Fifty-two eyes (26 OD, 26 OS) of 28 children were included. Thirty-six eyes had glaucoma (32 primary congenital glaucoma, two Sturge-Weber related, and two aphakia related). Sixteen eyes did not have glaucoma (six with pediatric cataract, five normal eyes, two strabismic eyes, two eyes with simple megalocornea, and one eye had peripheral corneal laceration repair. In the glaucoma group, the mean IOP was 17.55 ± 5.97 mmHg (range, 8-31.5 mmHg) with the Icare PRO and 20 ± 6.4 mmHg (range, 8-35.5 mmHg) with the Pneumotonometer from 20.47 ± 6.81 mmHg (range, 10-43 mmHg) with the Tono-Pen XL. The Icare PRO readings were significantly lower than each of the indentation tonometers. For the control group, there was no statistically significant difference in IOP measured by the Icare PRO and the indentation tonometers.

CONCLUSIONS

In this population of supine sedated children with glaucoma, IOP measurements with the Icare PRO tend to be lower than readings from the Pneumotonometer and Tono-Pen XL.

Intradevice and Interdevice Agreement Between a Rebound Tonometer, Icare PRO, and the Tonopen XL and Kowa Hand-held Applanation Tonometer When Used in the Sitting and Supine Position

PURPOSE

The aim of the study was to investigate the agreement between a new portable tonometer, Icare PRO, and the Tonopen XL and Kowa hand-held applanation tonometers (HAT).

METHODS

The right eyes of 127 healthy subjects were enrolled. Intraocular pressure (IOP) was measured in both sitting and supine positions using the Icare PRO, Tonopen XL, and Kowa HAT tonometers. The repeatability of the IOP measurements was evaluated by calculating intraclass correlation coefficients. Between-method agreements of tonometer measurements were evaluated using Bland-Altman analysis.

RESULTS

Intradevice agreement: The intraclass correlation coefficients (sitting, supine) of Icare PRO, Tonopen XL, and Kowa HAT were (0.863, 0.656), (0.845, 0.819), and (0.957, 0.956), respectively.Interdevice agreement: The Bland-Altman analysis revealed that, in the sitting position, the mean differences between Icare PRO and Tonopen XL, and between Icare PRO and Kowa HAT were -0.43 and 0.43 mm Hg, respectively (95% limits of agreement: -6.24 to 5.34 mm Hg, -4.04 to 4.90 mm Hg). In the supine position, the corresponding mean differences were -0.88 and 0.14 mm Hg (95% limits of agreement: -5.66 to 3.91 mm Hg, -4.06 to 4.33 mm Hg). IOP differences between Icare PRO and the other tonometers were unaffected by central corneal thickness.

CONCLUSIONS

The repeatability of Icare PRO was slightly lower in the supine position than in the sitting position. Although Icare PRO underestimated IOP values in eyes with higher IOP when compared with Tonopen XL and Kowa HAT in both positions, we observed good interdevice agreement between Icare PRO and both Tonopen XL and Kowa HAT.

Comparison of Intraocular Pressure Measurements Obtained by Rebound, Noncontact, and Goldmann Applanation Tonometry in Children

PURPOSE

To compare intraocular pressure (IOP) among rebound, noncontact, and Goldmann applanation tonometry (GAT) and their relationships to central corneal thickness in children.

DESIGN

Diagnostic protocol comparison and evaluation.

METHODS

In right eyes of 419 children, mean IOP, rates of successful measurement with 3 tonometries, and intermethod agreement by Bland-Altman plot were assessed. The influences of central corneal thickness, and of average IOP of 3 tonometries on IOP differences between tonometries, were evaluated.

RESULTS

The mean age was 8.89 ± 3.41 years (3-15 years). There was significant difference in mean IOP of each tonometry; GAT showed the lowest values (P < .05). The IOP was successfully measured by noncontact tonometry in 89%, by rebound tonometry in 75%, and by GAT in 64% of children less than 10 years old, and in 100%, 98%, and 94% of children older than 10 years, respectively. The IOP of each tonometer positively correlated with central corneal thickness (P < .05). The mean differences and limits of agreement were 0.81 ± 6.19 mm Hg (noncontact minus rebound), 2.56 ± 4.62 mm Hg (rebound minus GAT), and 1.81 ± 4.76 mm Hg (noncontact minus GAT). Rebound and noncontact tonometry overestimated IOP relative to GAT for thicker central corneal thicknesses. Rebound tonometry overestimated IOP relative to GAT and noncontact tonometry at higher average IOP of 3 tonometries.

CONCLUSIONS

Rebound, noncontact, and Goldmann applanation tonometries can be considered appropriate methods for children, though noncontact tonometry is the most accessible. Given the risk of false-positive diagnosis of pediatric glaucoma, attention should be devoted to children with IOP within a suspicious range or thicker cornea.

Twenty-four-hour efficacy of preservative-free tafluprost for open-angle glaucoma patients, assessed by home intraocular pressure (Icare-ONE) and blood-pressure monitoring

PURPOSE

To evaluate the effect of preservative-free (PF) tafluprost on diurnal variation of intraocular pressure (IOP) and ocular perfusion pressure (OPP), measured by use of home IOP and blood-pressure (BP) monitoring devices, for primary open angle glaucoma (POAG) patients.

METHODS

Twenty-two eyes from 22 patients with POAG were studied. Initially, IOP was measured at the hospital by Goldmann applanation tonometry (GAT) and Icare-ONE rebound tonometry. Each patient was then instructed how to use the Icare-ONE and BP home monitoring devices. IOP and BP were measured at home by the patients, every 4 h, before and 2 weeks after once daily treatment with PF tafluprost (0.0015%) ophthalmic solution.

RESULTS

Intraclass correlations between different IOP measurements were greater than 0.8. PF tafluprost reduced mean diurnal IOP significantly for patients with POAG, from 15.7 ± 1.2 mmHg at baseline to 12.5 ± 0.6 mmHg 2 weeks after treatment (p < 0.001). It increased mean diurnal OPP from 48.5 ± 7.3 mmHg at baseline to 51.3 ± 7.0 mmHg post-treatment (p < 0.017).

CONCLUSIONS

Icare-ONE enables glaucoma patients to measure their own diurnal IOP fluctuations. Patient-measured Icare-ONE IOP readings showed that PF tafluprost effectively reduced diurnal IOP in eyes with POAG.

Intraocular pressure in children: the effect of body position as assessed by Icare and Tono-Pen tonometers

PURPOSE

To explore the effect of body position (sitting vs supine) on intraocular pressure (IOP) in children, as assessed by the Icare PRO and the Tono-Pen.

DESIGN

Prospective clinical study.

METHODS

Children with known or suspected glaucoma and those without glaucoma were recruited from the Duke Eye Center pediatric clinic. Subjects underwent tonometry in both eyes while upright (sitting), after instillation of topical anesthetic, with either the Icare PRO or the Tono-Pen first, and then the second instrument (order randomized). Goldmann applanation tonometry (GAT) was then performed by a clinician masked to the previous measurements. The subjects were then placed in the supine position for 5 minutes, and tonometry using the Icare PRO and the Tono-Pen was obtained, in the same order used when they were the sitting position.

RESULTS

Enrolled were 47 children (94 eyes). Mean seated IOP for GAT, Icare PRO and Tono-Pen were 16.4 ± 4.2, 17.5 ± 3.5, and 18.0 ± 3.9 mm Hg, respectively. The mean supine IOP for the Icare PRO and Tono-Pen were 18.4 ± 4.5 and 18.8 ± 4.2 mm Hg, respectively. This rise was +0.9 ± 2.3 mm Hg for Icare PRO (P = 0.01) and +0.7 ± 1.8 mm Hg for Tono-Pen (P = 0.009), respectively.

CONCLUSION

In children, Icare PRO tonometry correlates well with GAT in the sitting position, and with the Tono-Pen in both the sitting and supine positions. IOP rises when a child changes position from sitting to supine when measured by the Icare PRO or the Tono-Pen. However, the increase, which is less than 1 mm Hg, seems clinically insignificant and is unlikely to alter glaucoma management in children.

The effect of repeated measurements and the use of topical anesthetic on rebound tonometry values in children

Measurement of intraocular pressure (IOP) in children is important in the management of pediatric glaucoma. Availability of the Icare rebound tonometer has greatly facilitated our ability to obtain awake IOP in infants and children, but little has been reported on either the effect of repeated sequential IOP measurements with Icare or the effect of topical anesthetic on subsequent Icare tonometry. This prospective study of 20 eyes of 10 cooperative children (12 normal eyes, 8 with suspected or known glaucoma) found that neither 8 sequential Icare measurements nor application of topical anesthetic produced a statistically or clinically signficant change in measured IOP by rebound tonometry.

Intraocular pressure and wound status in eyes immediately after scleral tunnel incision and clear corneal incision cataract surgery

PURPOSE

To compare intraocular pressure (IOP) and wound architecture immediately after cataract surgery using a scleral tunnel incision or clear corneal incision.

DESIGN

Prospective randomized clinical trial.

METHODS

Bilateral eyes of 64 patients undergoing phacoemulsification were randomized to 2 groups: 2.4 mm scleral tunnel incision or 2.4 mm clear corneal incision. IOP was adjusted upon completion of surgery to between 15 and 30 mm Hg. The wound was hydrated in 87.5% of eyes in the clear corneal incision group. IOP was measured using a rebound tonometer preoperatively; at the conclusion of surgery; and at 5, 10, 15, 30, and 60 minutes postoperatively. The Seidel test and anterior segment optical coherence tomography (AS OCT) were performed at 30 minutes postoperatively.

RESULTS

In the scleral tunnel incision group, mean IOP decreased to the preoperative level within 15 minutes postoperatively and did not change significantly for up to 60 minutes. In the clear corneal incision group, IOP decreased to lower than the preoperative IOP at 30 minutes postoperatively. Mean IOP was significantly higher in the scleral tunnel incision group than in the clear corneal incision group throughout the postoperative period (P≤.0339). Hypotony (<10 mm Hg) was observed in 7 eyes (10.9%) that underwent clear corneal incision and in no eyes that underwent scleral tunnel incision (P=.0131). Wound leakage and loss of wound coaptation were not observed in any eyes.

CONCLUSIONS

IOP was significantly higher immediately after scleral tunnel incision without hydration than after clear corneal incision with hydration, and both incisions closed within 30 minutes postoperatively without leakage based on AS OCT.

Test-retest reliability of retinal oxygen saturation measurement

PURPOSE

To determine intrasession and intersession repeatability of retinal vessel oxygen saturation from the Oxymap Retinal Oximeter using a whole image-based analysis technique and so determine optimal analysis parameters to reduce variability.

METHODS

Ten fundus oximetry images were acquired through dilated pupils from 18 healthy participants (aged 22 to 38) using the Oxymap Retinal Oximeter T1. A further 10 images were obtained 1 to 2 weeks later from each individual. Analysis was undertaken for subsets of images to determine the number of images needed to return a stable coefficient of variation (CoV). Intrasession and intersession variability were quantified by evaluating the CoV and establishing the 95% limits of agreement using Bland and Altman analysis. Retinal oxygenation was derived from the distribution of oxygenation values from all vessels of a given width in an image or set of images, as described by Paul et al. in 2013.

RESULTS

Grouped in 10-μm-wide bins, oxygen saturation varied significantly for both arteries and veins (p < 0.01). Between 110 and 150 μm, arteries had the least variability between individuals, with average CoVs less than 5% whose confidence intervals did not overlap with the greater than 10% average CoVs for veins across the same range. Bland and Altman analysis showed that there was no bias within or between recording sessions and that the 95% limits of agreement were generally lower in arteries.

CONCLUSIONS

Retinal vessel oxygen saturation measurements show variability within and between clinical sessions when the whole image is used, which we believe more accurately reflects the true variability in Oxymap images than previous studies on select image segments. Averaging data from vessels 100 to 150 μm in width may help to minimize such variability.

Immediate changes in intraocular pressure after clear corneal micro-incision versus small-incision cataract surgery

PURPOSE

We sought to examine changes in intraocular pressure (IOP) in the immediate period after clear corneal micro-incision cataract surgery (MICS) and after small-incision cataract surgery (SICS).

METHODS

Sixty-eight eyes of 34 patients scheduled for coaxial phacoemulsification were randomized into one of two groups: (a) eyes that were to undergo a 2.0-mm MICS, and (b) a 2.65-mm SICS. At the conclusion of surgery, the IOP was adjusted to the range between 15-40 mmHg with stromal hydration. The IOP was measured using a rebound tonometer preoperatively, at the conclusion of surgery, and at 3, 6, 9, 12, and 15 min postoperatively. The Seidel test and anterior segment-optical coherence tomography were performed at 20 min postoperatively.

RESULTS

Mean IOP at the conclusion of surgery was 27.7 ± 4.7 mmHg in the MICS group and 29.7 ± 5.1 mmHg in the SICS group (p = 0.1239). In both groups, mean IOP decreased to the preoperative level within 9 min postoperatively and did not change significantly for up to 15 min. Mean IOP was similar between the MICS and SICS groups throughout the observation period (p ≥ 0.1239). Hypotony (≤10 mmHg), positive Seidel test, and loss of wound coaptation were not detected in all eyes.

CONCLUSIONS

After adjusting the IOP to a relatively high level at the conclusion of surgery, the IOP decreased within 9 min and was stable within 15 min without hypotony. The IOP was comparable between eyes after MICS and SICS, and both incisions virtually closed within 20 min postoperatively.

Short-term effect of standard automated perimetry testing on intraocular pressure in patients with open-angle glaucoma

Purpose. To evaluate the short-term effect of standard automated perimetry (SAP) testing on intraocular pressure (IOP) in patients with open-angle glaucoma (OAG). Methods. We tested 45 patients (71 eyes) with OAG that had stable IOP under medical treatment. IOP was measured four times using an iCare rebound tonometer (RBT) immediately before, immediately after, 10 minutes after, and 20 minutes after SAP testing. Logistic regression analyses were performed to determine the relationships among SAP test duration, mean deviation of the SAP result, type of glaucoma medications, patient age, and significant IOP change (exceeding 2 mmHg) from baseline IOP. Results. The mean baseline IOP was 13.29 ± 3.06 mmHg. Although IOP changes immediately and 20 minutes after SAP testing were not statistically significant, the IOP change 10 minutes after SAP testing (-0.57 ± 1.84 mmHg) was statistically significant. However, the changes were within the margin of error of the RBT. Test duration, mean deviation, patient age, and type of glaucoma medications did not have a significant influence on IOP change (all P > 0.14). Conclusions. IOP measured by RBT did not vary significantly after SAP testing in patients with OAG. It may be not necessary to reject IOP measured after SAP testing in patients with OAG.

[Evaluation of the self-tonometer Icare ONE in comparison to Goldmann applanation tonometry]

OBJECTIVE

The aim of this clinical study was to demonstrate the practicability of self-measured intraocular pressure and to evaluate the reliability by comparing the data with those obtained by Goldmann applanation tonometry (GAT).

METHODS

A total of 40 patients aged between 44 and 82 years with glaucoma were introduced to the handling of the tonometer. The self-measurements were done for 1-3 days following the medical measurement by GAT. The data were saved as "correct" or in the case of wrong handling as "false". The impressions of the patients were obtained by a questionnaire.

RESULTS

A total number of 191 single measurements were registered by the Icare ONE and of these there were 97 (50.8%) signed "false". Of the patients 45% reached a maximum difference of ±5 mmHg between GAT and self-measurement in every single measurement. In the subgroup of under 60-year-old patients 70% reached this result. There were no indications of a systematic error. Of the probands 60% considered the handling of the Icare ONE as difficult. Nevertheless, 80% could imagine using the self-tonometer at home.

CONCLUSIONS

The differences between the self-measurements and the GAT were highly fluctuating in some cases. In the group of patients younger than 60 years the agreement was better, so problems with the handling of the Icare ONE may be an important factor. However, the acceptance in the patients tested was high and continuous pressure measurements at home could be reasonable. Advancements in the handling and reliability are needed to improve clinical application of the measured values.

Comparison of handheld rebound tonometry with Goldmann applanation tonometry in children with glaucoma: a cohort study

OBJECTIVE

To test agreement of two methods to measure intraocular pressure (IOP): rebound tonometry (RBT) and gold standard Goldmann applanation tonometry (GAT) in children with glaucoma.

DESIGN

Observational prospective cohort study.

SETTING

Tertiary paediatric glaucoma clinic at a single centre.

PARTICIPANTS

102 individuals attending a paediatric glaucoma clinic, mean (SD) age 11.85 (3.17), of whom 53 were male.

PRIMARY AND SECONDARY OUTCOME MEASURES

Intraocular pressure, central corneal thickness, child preference for measurement method.

RESULTS

Limits of agreement for intraobserver and interobserver were, respectively, (-2.71, 2.98) mm Hg and (-5.75, 5.97) mm Hg. RBT frequently gave higher readings than GAT and the magnitude of disagreement depend on the level of IOP being assessed. Differences of 10 mm Hg were not uncommon. RBT was the preferred method for 70% of children.

CONCLUSIONS

There is poor agreement between RBT and GAT in children with glaucoma. RBT frequently and significantly overestimates IOP. However, 'normal' RBT readings are likely to be accurate and may spare children an examination under anaesthesia (EUA). High RBT readings should prompt the practitioner to use another standard method of IOP measurement if possible, or consider the RBT measurement in the context of clinical findings before referring the child to a specialist clinic or considering EUA.

Intraocular pressure in a cohort of healthy eastern European schoolchildren: variations in method and corneal thickness

Background

Intraocular pressure (IOP) in the developing eye of a child is not always easy to measure and there is no technique that is known to be the most accurate for the young eye. Measurements are needed on many cohorts of children with different tonometers to determine how the values correlate between instruments, whether corneal parameters affect readings and whether correlations between age and IOP values can be discerned. The aim of this study was to undertake a comparative analysis of three different tonometers on a group of healthy children to see whether differences exist and whether these may be related to central corneal thickness and/or radius of curvature. In addition, the study adds to the relatively small body of literature on IOP in the growing eye which will collectively allow trends to be identified and ultimately norms to be established.

Methods

IOP was measured on 115 eyes in a group of Polish children, aged between 5–17 years (mean ± standard deviation [SD] 11.3 ± 3.0 years) using three different tonometers: non-contact (NCT), the ICare and Goldmann applanation (GAT). Readings obtained were compared between instruments and with central corneal thickness and radius of curvature.

Results

The ICare tonometer provided statistically higher IOP values (16.9 ± 3.4 mmHg) than the GAT (14.7 ± 2.9 mmHg) regardless of corneal thickness and whether or not a correction factor was applied. A correlation was found between central corneal thickness (CCT) and IOP values obtained with all three tonometers but only the IOP values detected with the ICare tonometer showed a statistically significant correlation with radius of curvature (p < 0.004). No correlations with age or gender were found for IOP values measured with any of the instruments.

Conclusions

IOP measurements on children vary significantly between instruments and correlations are affected by the corneal thickness. Further studies on children are needed to determine which instrument is most appropriate and to derive a normative IOP scale for the growing eye.

The use of the iCare tonometer reduced the need for anesthesia to measure intraocular pressure in children

PURPOSE

To determine whether the introduction of iCare rebound tonometry in a pediatric ophthalmology clinic resulted in fewer examinations under anesthesia to evaluate children with glaucoma.

METHODS

The medical records of consecutive glaucoma patients were retrospectively reviewed. The numbers of examinations under anesthesia (EUAs) and office visits that included measurement of intraocular pressure (IOP) were compared for three periods relative to introduction of the Icare (Icare Finland Oy, Helsinki, Finland) rebound tonometer into our clinical practice: before device introduction, learning/transition period, and routine use.

RESULTS

A total of 87 subjects were included: 48 subjects met inclusion criteria for the first period; 58 patients met inclusion criteria for the third period (some subjects straddled all three periods). The average patient age for the first period was 4.2 years and 4.9 years (P = 0.3) for the third period. The number of EUAs performed before the introduction of the Icare was 55 and after the introduction of the Icare was 18 (P < 0.001). The number of office visits at which IOP was measured increased from 34 to 151 (P < 0.001). Data from the transition period suggest a trend and a short learning period.

CONCLUSIONS

The use of Icare tonometry decreased the need for EUAs to evaluate children with glaucoma and significantly increased successful IOP measurement in clinic.

Icare ONE rebound versus Goldmann applanation tonometry in children with known or suspected glaucoma

PURPOSE

To compare Icare ONE tonometry by clinic examiner and parent/guardian to Goldmann applanation in children with known/suspected glaucoma; to evaluate the trend in intraocular pressure (IOP) with 4 repeated measurements using Icare ONE; and to evaluate the feasibility of instructing parents on the use of the Icare ONE device in the clinic setting.

DESIGN

Nonrandomized, prospective clinical study.

METHODS

Patients with known or suspected glaucoma were recruited from the Duke pediatric glaucoma clinic. Parent(s) of all subjects gave informed consent (and children gave assent) for participation in this research study. IOP was measured using Icare ONE by clinic examiner and parent/guardian, then using Goldmann applanation (masked physician). Each parent/guardian completed an ease-of-use survey.

RESULTS

Sixty eyes (60 children) were included. Absolute value of mean IOP difference (ICare ONE clinic examiner vs Goldmann applanation) was 3.3 ± 4.0 mm Hg (P = .001). Icare ONE IOP by clinic examiner was within 3 mm Hg of Goldmann applanation in 68% (n = 41 eyes). In eyes with >3 mm Hg difference, Icare ONE was higher than Goldmann applanation in 84%. IOP demonstrated a statistically significant downward trend with repeated sequential measurements with Icare ONE (P = .0053, r(2) = 0.9894). All parents accomplished Icare ONE tonometry on at least 1 eye; 98% reported it was "easy to learn to use."

CONCLUSION

Icare ONE tonometry appears accurate and well-tolerated compared to Goldmann applanation, and holds promise for clinic and home tonometry in children. IOP trends downward with successive measurements using Icare ONE, demonstrating a possible effect from presumed patient relaxation.

[Comparison of the iCare tonometer with the Goldmann tonometer in Malawi]

BACKGROUND

The risk for glaucoma is 4-5 times higher in patients from sub-Saharan Africa. Thus, especially in developing countries an easy and effective method for assessing the intraocular pressure (IOP) is needed.

METHODOLOGY

In this hospital-based survey 150 eyes were divided into 3 groups concerning the IOP (group I < 16 mmHg, group II 16-23 mmHg and group III > 23 mmHg) and underwent examination with ultrasound pachymetry followed by iCare tonometry (ICT) and Goldmann applanation tonometry (GAT). Agreement of the measurements by two tonometers was assessed with the Bland-Altman method and the influence of the central corneal thickness (CCT) on the ICT measurements was determined.

RESULTS

The mean difference between the IOD measured with GAT and ICT was 0.84 ± 2.63 mmHg. The differences were similar in all three groups (0.77-0.97 mmHg), however, the standard deviation in group III (4.04 mmHg) was greater than in groups I (1.98 mmHg) and II (1.79 mmHg). The mean CCT was 513.51 ± 36.22 µm.

CONCLUSIONS

The agreement of measurements by GAT and ICT was good for lower IOP values but less accurate in patients with higher IOP values (group III). A dependency of the CCT on the ICT measurements was observed. In comparison to other countries the lowest CCTs were found in Malawian patients.

Age variations in intraocular pressure in a cohort of healthy Austrian school children

PURPOSE

Limited data exist detailing the normal range of intraocular pressure (IOP) for healthy school age children. This study aims to describe the mean and normal range of IOP measurements that may be expected using the Icare rebound tonometer and to examine associations between visual function measures and IOP.

METHODS

Six measurements of IOP from each eye were obtained from 211 normal children aged 6-15 years (79 females and 132 males) using the Icare tonometer. Other measures of visual function obtained included: visual acuity, non-cycloplegic retinoscopy, amplitude of accommodation, accommodative facility, and accommodative response.

RESULTS

Statistical analysis (Mann-Whitney U test) demonstrated that the male subjects were more likely to have higher IOP measurements than the female subjects (mean IOP males 15.02 mm Hg (SD 2.19), mean IOP females 14.44 (SD 2.01) P=0.041). Analysis (Spearman's rho) showed a statistically significant association between age and IOP (right eye) in males (P<0.001) but no association for females (P=0.459). Using Spearman's rank analysis, statistically significant associations were found between IOP and amplitude of accommodation in males, for the whole data set (P=0.09) and for data up to age 11 (P<0.001). For females no statistically significant association was found for the whole data set (P=0.253) or for data up to age 11 (P=0.08). IOP was not significantly associated with visual acuity, refractive error, accommodative facility, or accommodative response.

CONCLUSION

This study provides useful normative IOP data using the Icare tonometer for a European cohort of school age children.

Home assessment of diurnal intraocular pressure in healthy children using the Icare rebound tonometer

BACKGROUND

Although intraocular pressure (IOP) is known to vary with the circadian cycle in nonglaucomatous and glaucomatous eyes of adults, the clinical assessment of IOP often relies on periodic measurements obtained at office visits during daytime hours. Little has been reported on diurnal IOP patterns in healthy children. The purpose of this study was to evaluate diurnal IOP in normal eyes of healthy children with the Icare rebound tonometer and when recorded by a parent at home.

METHODS

This was a prospective study of IOP in normal eyes of healthy children. Children were recruited from a pediatric eye clinic. A parent was instructed on the use of the Icare rebound tonometer by a study physician and demonstrated proficiency its use in the clinic, at which time a masked IOP reading was also made with Goldmann applanation by a different study clinician. Home IOPs were then obtained and recorded 6 times daily at 2- to 3-hours intervals during 2 consecutive days by a parent.

RESULTS

A total of 22 normal eyes (of 11 children) were included. We found that children without glaucoma demonstrate mean diurnal IOP fluctuation of 4-6 mm Hg, with similar IOP between right and left eyes, fair repeatability between consecutive days, and a tendency for higher early morning and lower late evening IOP.

CONCLUSIONS

Healthy children without glaucoma demonstrate some diurnal fluctuation in IOP, comparable with that reported in nonglaucomatous eyes of adults. This information should prove as comparative for assessment of IOP fluctuation in children with known or suspected glaucoma.

Home tonometry for management of pediatric glaucoma

PURPOSE

To use iCare rebound tonometry in the home setting for documentation of diurnal intraocular pressure (IOP) fluctuations in children.

DESIGN

Nonrandomized, prospective clinical study.

METHODS

Pediatric ophthalmology clinic patients were recruited between October 2009 and February 2010 who were able to cooperate with IOP measurement by iCare rebound tonometry and whose caregiver was willing and able to obtain iCare measurements at home. The child's IOP was measured first by iCare tonometry followed by a second method (Goldmann applanation [GAT]). The caregiver was instructed on the use of the iCare tonometer. The subject's IOP was measured by the caregiver at home at designated time periods for at least 2 consecutive days.

RESULTS

Seventeen children (17 eyes) with known or suspected glaucoma and 11 normal children were included. Excellent reliability was obtained by caregivers in 70% of iCare measurements. Mean difference between iCare and GAT in clinic was 2.0 ± 4.0 mm Hg, P = .08. Daily IOP fluctuation occurred in both subjects with glaucoma and normal subjects. In children with known or suspected glaucoma, relative peak and trough IOPs occurred in the early morning (45%) and late evening (43.5%), respectively. Comparison of the peak IOP measured at home vs in the clinic was >6 mm Hg in 5 of 16 subjects (31%) and affected glaucoma management in several subjects.

CONCLUSIONS

In selected children with glaucoma, home tonometry by iCare rebound tonometry was reliable, easily performed by caregivers, and well tolerated, and offered IOP information valuable in clinical management.

Icare rebound tonometry in children with known and suspected glaucoma

BACKGROUND

Accurate intraocular pressure (IOP) measurement, important in managing pediatric glaucoma, often presents challenges. The Icare rebound tonometer shows promise for screening healthy children and has been reported comparable with Goldmann applanation in adults with glaucoma. The purpose of this study was to evaluate the Icare tonometer against Goldmann applanation for clinic IOP measurement in pediatric glaucoma.

METHODS

This was a prospective study comparing Icare versus Goldmann tonometry in pediatric glaucoma. Children with known or suspected glaucoma were recruited from scheduled clinic visits. IOP was measured with the Icare tonometer by a clinician and subsequently measured with Goldmann applanation tonometry (GAT) by a different single masked clinician.

RESULTS

A total of 71 eyes of 71 children with known or suspected glaucoma were included. IOP by GAT ranged from 9 to 36 mm Hg. Icare readings ranged from 11 to 44 mm Hg. Mean difference between Icare and GAT was 2.3 ± SD 3.7 mm Hg, p < 0.0001. Icare IOPs were within ± 3 mm Hg of GAT in 63%. Icare IOPs were ≥GAT IOPs in 75%. The following factors were not associated with Icare IOPs greater than GAT: child's age, glaucoma diagnosis, strabismus, nystagmus, central corneal thickness, Icare instrument-reported reliability, number of glaucoma surgeries or medications, corneal abnormalities, and visual acuity.

CONCLUSIONS

IOP by Icare tonometry was within 3 mm Hg of IOP by GAT in 63% and greater than GAT in 75%. This device may be reasonable to estimate IOP in selected children with known or suspected glaucoma whose IOP cannot otherwise be obtained in clinic; however, correlation of Icare IOPs with clinical findings must continue to be considered in each case.