- Email: [email protected]
The effect of repeated measurements and the use of topical anesthetic on rebound tonometry values in children
Volume 18 Number 6 / December 2014
Dosunmu et al
619
Literature Search The authors conducted a search of English and Spanish language articles to date (April 2014) in PubMed, Google Scholar, and SciELO, linking the following terms: retinoblastoma, intra-arterial chemotherapy, ophthalmic artery chemosurgery. References cited in relevant literature were also reviewed. References
FIG 2. Fundus photograph of the left eye of patient 2. A, Before IAC, there was active inferonasal peripheral recurrence (white arrow) 1 month after plaque I125 therapy. The patient underwent 2 IAC procedures (as in patient 1). B, Complete tumor regression 6 months after last procedure. The reflection on image is secondary to intraocular lens reflex.
approximately US $500 for each cycle. Another benefit of IAC is that it can avoid costs of repetitive focal therapies that are often necessary with chemoreduction. The large cost difference for IAC in the US versus Chile is partly explained by Chile’s public system budget and cost controls. Gobin and colleagues7 reported an 82% ocular survival for those treated primarily with IAC and 58% for those treated secondarily. Shields and colleagues8 reported globe salvation in 72% of primary-treated cases and 62% of secondary-treated cases. They noted encouraging results specifically for primary IAC based on the International Classification of Retinoblastoma group (group B [100%], group C [100%], group D [94%], group E [36%]). IAC is a powerful treatment that can avoid the inevitable bilateral enucleation, particularly in a developing country like Chile, where enucleation was previously the only option for failed chemoreduction and focal therapy. In both of our cases, IAC allowed globe salvage in these children, who were facing bilateral enucleation. Our local cost analysis and feasibility for IAC treatment may not be generalizable to other countries but could be applied to transitional countries with similar situations in public health system and funding.
Journal of AAPOS
1. Shields CL, Fulco EM, Arias JD, et al. Retinoblastoma frontiers with intravenous, intra- arterial, periocular, and intravitreal chemotherapy. Eye 2013;27:253-64. 2. World Economic Forum, The Global Competitiveness Report 2013-2014. Available at: http://reports.weforum.org/the-globalcompetitiveness-report-2013-2014/. 3. Kivel€a T. The epidemiological challenge of the most frequent eye cancer: retinoblastoma, an issue of birth and death. Br J Ophthalmol 2009;93:1129-31. 4. Trincado A, Gonzalez M, Villaseca E, et al. Retinoblastoma en pediatrıa, experiencia en un hospital pediatrico. Rev Chil Pediatr 2008;79:614-22. 5. Chantada GL, Fandino AC, Schvartzman E, Raslawski E, Schaiquevich P, Manzitti J. Impact of chemoreduction for conservative therapy for retinoblastoma in Argentina. Pediatr Blood Cancer 2014;61:821-6. 6. Aziz H, LaSenna C, Vigoda M, et al. Retinoblastoma treatment burden and economic cost: impact of age at diagnosis and selection of primary therapy. Clin Ophthalmol 2012;6:1601-6. 7. Gobin YP, Dunkel IJ, Marr BP, Brodie SE, Abramson DH. Intra-arterial chemotherapy for the management of retinoblastoma. Arch Ophthalmol 2011;129:732-7. 8. Shields CL, Manjandavida FP, Lally SE, et al. Intra-arterial chemotherapy for retinoblastoma in 70 eyes: outcomes based on the International Classification of Retinoblastoma. Ophthalmology 2014;121:1453-60.
The effect of repeated measurements and the use of topical anesthetic on rebound tonometry values in children Eniolami O. Dosunmu, MD,a Inna Marcus, MD,b Irene Tung, MD,c Warakorn Thiamthat, MD,d and Sharon F. Freedman, MDe
Author affiliations: aDepartment of Ophthalmology, Cincinnati Children’s Hospital Medical Center, University of Cincinnati, Cincinnati, Ohio; bVirginia Eye Institute, Richmond, Virginia; cUniversity of Texas Medical Branch in Galveston, Galveston, Texas; d Department of Ophthalmology, Lerdsin Hospital, Medical Bureau Ministry of Public Health, Bangkok, Thailand; eDuke University Eye Center, Durham, North Carolina Presented in part at the 39th Annual Meeting of the American Association for Pediatric Ophthalmology and Strabismus, Boston, Massachusetts, April 3-7, 2013. Submitted February 16, 2014. Revision accepted July 30, 2014. Published online November 12, 2014. Correspondence: Sharon F. Freedman, MD, Duke University Eye Center, 2351 Erwin Road, Durham, NC, 27710 (email: [email protected]). J AAPOS 2014;18:619-621. Copyright Ó 2014 by the American Association for Pediatric Ophthalmology and Strabismus. 1091-8531/$36.00 http://dx.doi.org/10.1016/j.jaapos.2014.07.167
620
Dosunmu et al
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.
T
onometry often presents challenges in infants and small children. The Icare rebound tonometer (Icare Finland Oy, Helinski, Finland) is a portable device that does not require the use of topical anesthetic. Published reports note that Icare rebound tonometry is well-tolerated by children, yields reproducible results, and correlates with intraocular pressure (IOP) measured by Goldmann applanation tonometry (GAT).1-4 Repeated measurements and sometimes more than one tonometry device are required to complete adequate tonometry in awake children, but there is little relevant published data regarding the effect of repeated measurements or prior topical anesthetic application with rebound tonometry in children. Published data in adults suggest variation in IOP with repeated applanation IOP measurement5 as well as lower measured IOP after prior topical anesthetic use using noncontact tonometry.6
Methods This prospective study was approved by Duke University Health System Institutional Review Board. Subjects were recruited from children scheduled in the Duke Eye Center pediatric glaucoma clinic who were known or expected to be cooperative with applanation tonometry. Written informed consent was obtained for all enrolled children. Patients with corneal abnormalities or nystagmus known to preclude accurate GAT were excluded. The Icare rebound tonometer was used to obtain 8 consecutive IOP measurements on each eye before the application of topical anesthetic. The right eye was always measured first, and this was repeated in the same manner (right then left eye) until 8 (paired) measurements were obtained from each eye. The Icare IOP measurements and reliability data was recorded, accepting only very reliable Icare measurements (“Psolid” or “Pbottom”).4 Topical anesthetic (Proparacaine Hydrochloride Ophthalmic Solution 0.5%) was then placed into each eye, and 3 additional IOP measurements were made on each eye using the Icare tonometer. Fluorescein sodium and benoxinate hydrochloride ophthalmic solution 0.25%/ 0.4% was instilled into each eye and GAT measurements were obtained by the same examiner (SFF), who was masked to prior IOP readings. For data analysis, both eyes of each subject were included. Subject characteristics were tabulated using
Volume 18 Number 6 / December 2014 Table 1. Patient demographicsa Characteristics (n 5 10) Sex Male Female Ethnicity African American Asian White Diagnoses (n 5 20 eyes) Glaucoma Primary congenital Suspect Uveitic Other Normal
Number of subjects (%) 6 (60) 4 (40) 4 (40) 1 (10) 5 (50) Number of eyes (%) 2 (10) 2 (10) 2 (10) 2 (10) 12 (60)
a
No nystagmus or significant corneal pathology in this study cohort.
number and percent for categorical data, and median, range, and standard deviation (SD) for continuous variables. The same Icare rebound tonometer was used throughout the study, and was in good working order. Icare rebound tonometry was performed by an ophthalmologist not performing GAT (EOD, IM, ITT). Mean values were compared by paired and unpaired t tests, as appropriate. All statistical tests were two sided, with the threshold for significance at a 5 0.05, and were performed using Microsoft Excel (Microsoft Corp., Redmond, WA), and Prism 6 (GraphPad, San Diego, CA) software. Power calculations were performed using Power and Sample Size Calculator (Statistical Solutions, LLC, 2014).
Results A total of 20 eyes of 10 children were included. Mean patient age was 10.7 years (range, 6-15). Additional demographic and clinical data are noted in Table 1. All enrolled subjects completed the study. Mean IOP by Icare tonometry preanesthetic (n 5 8 measurements per eye) was 18.7 mm Hg (range, 9-41), and exceeded the mean IOP by GAT (16.3 mm Hg; range, 8-32) by 2.4 mm Hg (P \ 0.001). The mean initial (1st) Icaremeasured IOP reading was 19.25 mm Hg (range, 10-37); the mean final (8th) measurement was 19.15 mm Hg (range, 10-36). The mean change in IOP by Icare rebound (8th minus 1st preanesthetic measurement) was -0.1 2.7 mm Hg, P 5 0.87. To quantify the variability of the Icare IOP measurements over the 1st through 8th readings, we calculated the average coefficient of variation for all eyes, which was 8.0%. We compared the mean Icare IOP preanesthetic (18.70 mm Hg, n 5 8 measurements) versus the mean Icare IOP post-anesthetic (18.73 mm Hg, n 5 3 measurements); the mean change in IOP(postanesthetic preanesthetic), 0.03 2.1 mm Hg, was not statistically significant (P 5 0.95). When calculations were repeated for the right eye only of each subject, neither of the corresponding mean changes in Icare rebound IOP was statistically significant
Journal of AAPOS
Volume 18 Number 6 / December 2014
Dosunmu et al
621
Icare rebound tonometry involves brief contact of a much smaller probe tip with the cornea, and thus does not seem to have an effect on IOP. In the current study IOP measured with Icare rebound tonometry in children’s eyes did not change significantly after the application of topical anesthetic, in contrast to published data using noncontact tonometry in adults.6 This result suggests that Icare tonometer use is reasonable after failure of attempted GAT or tonopen tonometry in the awake child. Our results must be considered in light of several limitations. The enrolled children in this study were cooperative with tonometry and therefore may not be representative of the all pediatric patients. The relatively small sample size limited our ability to identify any statistically significant small changes that may have occured with repeated IOP measurements or with pre- and postanesthetic changes. However, statistically significant small changes (\1 mm Hg) in recorded IOP would not be considered clinically significant. Finally, although GAT was used as the “gold standard” in this study, it may turn out that another tonometry modality actually provides more accurate IOP measurements in the eyes of children. FIG 1. Effect of multiple, sequential Icare intraocular pressure (IOP) measurements . Plotted are Icare-measured IOP (y-axis) for all right eyes of the study eyes (n 5 10), shown by reading the number on the x-axis (8 sequential preanesthetic readings were taken for each eye). The mean change in Icare rebound IOP (8th minus 1st preanesthetic measurement) was -0.5 2.3 mm Hg, whereas the mean change in IOP (post-anesthetic - pre-anesthetic) was 0.44 1.6 mm Hg, P 5 NS for both).
(Figure 1). Hence, mean change in IOP by Icare rebound (8th minus 1st pre-anesthetic measurement), -0.4 2.7 mm Hg, was not statistically significant (P 5 0.61). Similarly, the mean change in IOP (post-anesthetic minus pre-anesthetic), -0.2 2.2 mm Hg, was not statistically significant (P 5 0.78). The study had a beta power of 88% to find a change in IOP of 2 mm Hg between the repeated IOP measurement pre-anesthestic and similarly to find a change in IOP of 2 mm Hg comparing pre- to post-anesthetic measurements.
Discussion To our knowledge, this is the first report of repetitive rebound tonometry measurements in children. In our study cohort measured IOP did not change appreciably with repetitive Icare rebound tonometry over a wide range of initial IOP. Unlike GAT, which reportedly reduces measured IOP in adults after repeated mesaurements,5
Journal of AAPOS
Literature Search The authors searched PubMed and Google on February 8, 2014 for English-language articles from the past 20 years using the following terms: rebound tonometry, intraocular pressure repeat measurements, repeated intraocular pressure, and reproducibility of intraocular pressure. The literature was reviewed for both adults and children. References 1. Sahin A, Basmak H, Niyaz L, Yildirim N. Reproducibility and tolerability of the Icare rebound tonometer in school children. J Glaucoma 2007;16:185-8. 2. Fernandes P, Diaz-Rey JA, Queiros A, Gonzalez-Meijome JM, Jorge J. Comparison of the Icare rebound tonometer with the Goldmann tonometer in a normal population. Ophthalmic Physiol Opt 2005;25: 436-40. 3. Gandhi NG, Prakalapakorn SG, El-Dairi MA, Jones SK, Freedman SF. Icare ONE rebound versus Goldmann applanation tonometry in children with known or suspected glaucoma. Am J Ophthalmol 2012;154:843-9. 4. Flemmons MS, Hsiao YC, Dzau J, Asrani S, Jones S, Freedman SF. Icare rebound tonometry in children with known and suspected glaucoma. J AAPOS 2011;15:153-7. 5. Gaton DD, Ehrenberg M, Lusky M, et al. Effect of repeated applanation tonometry on the accuracy of intraocular pressure measurements. Curr Eye Res 2010;35:475-9. 6. Almubrad TM, Ogbuehi KC. Clinical investigation of the effect of topical anesthesia on intraocular pressure. Clin Ophthalmol 2007;1: 305-9.
Dosunmu et al
619
Literature Search The authors conducted a search of English and Spanish language articles to date (April 2014) in PubMed, Google Scholar, and SciELO, linking the following terms: retinoblastoma, intra-arterial chemotherapy, ophthalmic artery chemosurgery. References cited in relevant literature were also reviewed. References
FIG 2. Fundus photograph of the left eye of patient 2. A, Before IAC, there was active inferonasal peripheral recurrence (white arrow) 1 month after plaque I125 therapy. The patient underwent 2 IAC procedures (as in patient 1). B, Complete tumor regression 6 months after last procedure. The reflection on image is secondary to intraocular lens reflex.
approximately US $500 for each cycle. Another benefit of IAC is that it can avoid costs of repetitive focal therapies that are often necessary with chemoreduction. The large cost difference for IAC in the US versus Chile is partly explained by Chile’s public system budget and cost controls. Gobin and colleagues7 reported an 82% ocular survival for those treated primarily with IAC and 58% for those treated secondarily. Shields and colleagues8 reported globe salvation in 72% of primary-treated cases and 62% of secondary-treated cases. They noted encouraging results specifically for primary IAC based on the International Classification of Retinoblastoma group (group B [100%], group C [100%], group D [94%], group E [36%]). IAC is a powerful treatment that can avoid the inevitable bilateral enucleation, particularly in a developing country like Chile, where enucleation was previously the only option for failed chemoreduction and focal therapy. In both of our cases, IAC allowed globe salvage in these children, who were facing bilateral enucleation. Our local cost analysis and feasibility for IAC treatment may not be generalizable to other countries but could be applied to transitional countries with similar situations in public health system and funding.
Journal of AAPOS
1. Shields CL, Fulco EM, Arias JD, et al. Retinoblastoma frontiers with intravenous, intra- arterial, periocular, and intravitreal chemotherapy. Eye 2013;27:253-64. 2. World Economic Forum, The Global Competitiveness Report 2013-2014. Available at: http://reports.weforum.org/the-globalcompetitiveness-report-2013-2014/. 3. Kivel€a T. The epidemiological challenge of the most frequent eye cancer: retinoblastoma, an issue of birth and death. Br J Ophthalmol 2009;93:1129-31. 4. Trincado A, Gonzalez M, Villaseca E, et al. Retinoblastoma en pediatrıa, experiencia en un hospital pediatrico. Rev Chil Pediatr 2008;79:614-22. 5. Chantada GL, Fandino AC, Schvartzman E, Raslawski E, Schaiquevich P, Manzitti J. Impact of chemoreduction for conservative therapy for retinoblastoma in Argentina. Pediatr Blood Cancer 2014;61:821-6. 6. Aziz H, LaSenna C, Vigoda M, et al. Retinoblastoma treatment burden and economic cost: impact of age at diagnosis and selection of primary therapy. Clin Ophthalmol 2012;6:1601-6. 7. Gobin YP, Dunkel IJ, Marr BP, Brodie SE, Abramson DH. Intra-arterial chemotherapy for the management of retinoblastoma. Arch Ophthalmol 2011;129:732-7. 8. Shields CL, Manjandavida FP, Lally SE, et al. Intra-arterial chemotherapy for retinoblastoma in 70 eyes: outcomes based on the International Classification of Retinoblastoma. Ophthalmology 2014;121:1453-60.
The effect of repeated measurements and the use of topical anesthetic on rebound tonometry values in children Eniolami O. Dosunmu, MD,a Inna Marcus, MD,b Irene Tung, MD,c Warakorn Thiamthat, MD,d and Sharon F. Freedman, MDe
Author affiliations: aDepartment of Ophthalmology, Cincinnati Children’s Hospital Medical Center, University of Cincinnati, Cincinnati, Ohio; bVirginia Eye Institute, Richmond, Virginia; cUniversity of Texas Medical Branch in Galveston, Galveston, Texas; d Department of Ophthalmology, Lerdsin Hospital, Medical Bureau Ministry of Public Health, Bangkok, Thailand; eDuke University Eye Center, Durham, North Carolina Presented in part at the 39th Annual Meeting of the American Association for Pediatric Ophthalmology and Strabismus, Boston, Massachusetts, April 3-7, 2013. Submitted February 16, 2014. Revision accepted July 30, 2014. Published online November 12, 2014. Correspondence: Sharon F. Freedman, MD, Duke University Eye Center, 2351 Erwin Road, Durham, NC, 27710 (email: [email protected]). J AAPOS 2014;18:619-621. Copyright Ó 2014 by the American Association for Pediatric Ophthalmology and Strabismus. 1091-8531/$36.00 http://dx.doi.org/10.1016/j.jaapos.2014.07.167
620
Dosunmu et al
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.
T
onometry often presents challenges in infants and small children. The Icare rebound tonometer (Icare Finland Oy, Helinski, Finland) is a portable device that does not require the use of topical anesthetic. Published reports note that Icare rebound tonometry is well-tolerated by children, yields reproducible results, and correlates with intraocular pressure (IOP) measured by Goldmann applanation tonometry (GAT).1-4 Repeated measurements and sometimes more than one tonometry device are required to complete adequate tonometry in awake children, but there is little relevant published data regarding the effect of repeated measurements or prior topical anesthetic application with rebound tonometry in children. Published data in adults suggest variation in IOP with repeated applanation IOP measurement5 as well as lower measured IOP after prior topical anesthetic use using noncontact tonometry.6
Methods This prospective study was approved by Duke University Health System Institutional Review Board. Subjects were recruited from children scheduled in the Duke Eye Center pediatric glaucoma clinic who were known or expected to be cooperative with applanation tonometry. Written informed consent was obtained for all enrolled children. Patients with corneal abnormalities or nystagmus known to preclude accurate GAT were excluded. The Icare rebound tonometer was used to obtain 8 consecutive IOP measurements on each eye before the application of topical anesthetic. The right eye was always measured first, and this was repeated in the same manner (right then left eye) until 8 (paired) measurements were obtained from each eye. The Icare IOP measurements and reliability data was recorded, accepting only very reliable Icare measurements (“Psolid” or “Pbottom”).4 Topical anesthetic (Proparacaine Hydrochloride Ophthalmic Solution 0.5%) was then placed into each eye, and 3 additional IOP measurements were made on each eye using the Icare tonometer. Fluorescein sodium and benoxinate hydrochloride ophthalmic solution 0.25%/ 0.4% was instilled into each eye and GAT measurements were obtained by the same examiner (SFF), who was masked to prior IOP readings. For data analysis, both eyes of each subject were included. Subject characteristics were tabulated using
Volume 18 Number 6 / December 2014 Table 1. Patient demographicsa Characteristics (n 5 10) Sex Male Female Ethnicity African American Asian White Diagnoses (n 5 20 eyes) Glaucoma Primary congenital Suspect Uveitic Other Normal
Number of subjects (%) 6 (60) 4 (40) 4 (40) 1 (10) 5 (50) Number of eyes (%) 2 (10) 2 (10) 2 (10) 2 (10) 12 (60)
a
No nystagmus or significant corneal pathology in this study cohort.
number and percent for categorical data, and median, range, and standard deviation (SD) for continuous variables. The same Icare rebound tonometer was used throughout the study, and was in good working order. Icare rebound tonometry was performed by an ophthalmologist not performing GAT (EOD, IM, ITT). Mean values were compared by paired and unpaired t tests, as appropriate. All statistical tests were two sided, with the threshold for significance at a 5 0.05, and were performed using Microsoft Excel (Microsoft Corp., Redmond, WA), and Prism 6 (GraphPad, San Diego, CA) software. Power calculations were performed using Power and Sample Size Calculator (Statistical Solutions, LLC, 2014).
Results A total of 20 eyes of 10 children were included. Mean patient age was 10.7 years (range, 6-15). Additional demographic and clinical data are noted in Table 1. All enrolled subjects completed the study. Mean IOP by Icare tonometry preanesthetic (n 5 8 measurements per eye) was 18.7 mm Hg (range, 9-41), and exceeded the mean IOP by GAT (16.3 mm Hg; range, 8-32) by 2.4 mm Hg (P \ 0.001). The mean initial (1st) Icaremeasured IOP reading was 19.25 mm Hg (range, 10-37); the mean final (8th) measurement was 19.15 mm Hg (range, 10-36). The mean change in IOP by Icare rebound (8th minus 1st preanesthetic measurement) was -0.1 2.7 mm Hg, P 5 0.87. To quantify the variability of the Icare IOP measurements over the 1st through 8th readings, we calculated the average coefficient of variation for all eyes, which was 8.0%. We compared the mean Icare IOP preanesthetic (18.70 mm Hg, n 5 8 measurements) versus the mean Icare IOP post-anesthetic (18.73 mm Hg, n 5 3 measurements); the mean change in IOP(postanesthetic preanesthetic), 0.03 2.1 mm Hg, was not statistically significant (P 5 0.95). When calculations were repeated for the right eye only of each subject, neither of the corresponding mean changes in Icare rebound IOP was statistically significant
Journal of AAPOS
Volume 18 Number 6 / December 2014
Dosunmu et al
621
Icare rebound tonometry involves brief contact of a much smaller probe tip with the cornea, and thus does not seem to have an effect on IOP. In the current study IOP measured with Icare rebound tonometry in children’s eyes did not change significantly after the application of topical anesthetic, in contrast to published data using noncontact tonometry in adults.6 This result suggests that Icare tonometer use is reasonable after failure of attempted GAT or tonopen tonometry in the awake child. Our results must be considered in light of several limitations. The enrolled children in this study were cooperative with tonometry and therefore may not be representative of the all pediatric patients. The relatively small sample size limited our ability to identify any statistically significant small changes that may have occured with repeated IOP measurements or with pre- and postanesthetic changes. However, statistically significant small changes (\1 mm Hg) in recorded IOP would not be considered clinically significant. Finally, although GAT was used as the “gold standard” in this study, it may turn out that another tonometry modality actually provides more accurate IOP measurements in the eyes of children. FIG 1. Effect of multiple, sequential Icare intraocular pressure (IOP) measurements . Plotted are Icare-measured IOP (y-axis) for all right eyes of the study eyes (n 5 10), shown by reading the number on the x-axis (8 sequential preanesthetic readings were taken for each eye). The mean change in Icare rebound IOP (8th minus 1st preanesthetic measurement) was -0.5 2.3 mm Hg, whereas the mean change in IOP (post-anesthetic - pre-anesthetic) was 0.44 1.6 mm Hg, P 5 NS for both).
(Figure 1). Hence, mean change in IOP by Icare rebound (8th minus 1st pre-anesthetic measurement), -0.4 2.7 mm Hg, was not statistically significant (P 5 0.61). Similarly, the mean change in IOP (post-anesthetic minus pre-anesthetic), -0.2 2.2 mm Hg, was not statistically significant (P 5 0.78). The study had a beta power of 88% to find a change in IOP of 2 mm Hg between the repeated IOP measurement pre-anesthestic and similarly to find a change in IOP of 2 mm Hg comparing pre- to post-anesthetic measurements.
Discussion To our knowledge, this is the first report of repetitive rebound tonometry measurements in children. In our study cohort measured IOP did not change appreciably with repetitive Icare rebound tonometry over a wide range of initial IOP. Unlike GAT, which reportedly reduces measured IOP in adults after repeated mesaurements,5
Journal of AAPOS
Literature Search The authors searched PubMed and Google on February 8, 2014 for English-language articles from the past 20 years using the following terms: rebound tonometry, intraocular pressure repeat measurements, repeated intraocular pressure, and reproducibility of intraocular pressure. The literature was reviewed for both adults and children. References 1. Sahin A, Basmak H, Niyaz L, Yildirim N. Reproducibility and tolerability of the Icare rebound tonometer in school children. J Glaucoma 2007;16:185-8. 2. Fernandes P, Diaz-Rey JA, Queiros A, Gonzalez-Meijome JM, Jorge J. Comparison of the Icare rebound tonometer with the Goldmann tonometer in a normal population. Ophthalmic Physiol Opt 2005;25: 436-40. 3. Gandhi NG, Prakalapakorn SG, El-Dairi MA, Jones SK, Freedman SF. Icare ONE rebound versus Goldmann applanation tonometry in children with known or suspected glaucoma. Am J Ophthalmol 2012;154:843-9. 4. Flemmons MS, Hsiao YC, Dzau J, Asrani S, Jones S, Freedman SF. Icare rebound tonometry in children with known and suspected glaucoma. J AAPOS 2011;15:153-7. 5. Gaton DD, Ehrenberg M, Lusky M, et al. Effect of repeated applanation tonometry on the accuracy of intraocular pressure measurements. Curr Eye Res 2010;35:475-9. 6. Almubrad TM, Ogbuehi KC. Clinical investigation of the effect of topical anesthesia on intraocular pressure. Clin Ophthalmol 2007;1: 305-9.