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To report the central corneal thickness (CCT) in healthy white, African-American, and Hispanic children from birth to 17 years of age.
Prospective observational multicenter study. Central corneal thickness was measured with a hand-held contact pachymeter.
Two thousand seventy-nine children were included in the study, with ages ranging from day of birth to 17 years. Included were 807 white, 494 Hispanic, and 474 African-American individuals, in addition to Asian, unknown and mixed race individuals. African-American children had thinner corneas on average than that of both white (p< .001) and Hispanic children (p< .001) by approximately 20 micrometers. Thicker median CCT was observed with each successive year of age from age 1 to 11 years, with year-to-year differences steadily decreasing and reaching a plateau after age 11 at 573 micrometers in white and Hispanic children and 551 micrometers in African-American children. For every 100 micrometers of thicker CCT measured, the intraocular pressure was 1.5 mmHg higher on average (p< 0.001). For every diopter of increased myopic refractive error (p< 0.001) CCT was 1 micrometer thinner on average.
Median CCT increases with age from 1 to 11 years with the greatest increase present in the youngest age groups. African-American children on average have thinner central corneas than white and Hispanic children, while white and Hispanic children demonstrate similar central corneal thickness.
The Ocular Hypertension Treatment Study (OHTS) generated clinical interest in the measurement of central corneal thickness (CCT).1 Racial differences in CCT were one of the novel findings. The OHTS investigators also found individuals with CCT greater than 600 micrometers. These data suggest that basing applanation tonometry on average CCT, may be inaccurate as it does not account for wide individual variation in CCT. Following the OHTS publication, studies in adult subjects confirmed racial differences in CCT between white and African-American adults, but not between white and Asian or Hispanic adults. More recently, heredity2 and refractive error3 have been reported to influence CCT. If differences in CCT produce substantial errors in measurement of applanation intraocular pressure (IOP)4 then CCT could have a direct impact on the clinical assessment of glaucoma risk.
There are limited data for CCT among children. Most studies have relatively small sample sizes (less than 100 per racial or ethnic group) and few or no subjects younger than 5 years of age. One study performed among European Caucasian subjects found no difference in the mean CCT of children compared with adults.5 However, the study did not include children younger than 5 years of age. Another study demonstrated that African-American children had thinner CCT than that of white children, and both groups showed an increase in CCT after 10 years of age.6 No association between CCT and gender, axial length, or family history of glaucoma was found.6 Dai reported similar CCT values in Hispanic and white children, but thinner CCT in African-American children.7 This report was also limited in that most subjects were older than 5 years of age.
Our primary objective was to determine the CCT of a large cohort of healthy children from birth to 17 years of age, and to determine whether CCT varies by age, race, or ethnicity. Secondarily, we sought to determine the age at which childhood CCT stabilizes and to examine associations between CCT and other clinical characteristics such as refractive error and IOP.
The study was supported through a cooperative agreement with the National Eye Institute of the National Institutes of Health, Department of Health and Human Services and was conducted by the Pediatric Eye Disease Investigator Group (PEDIG) at 36 clinical sites. The protocol and Health Insurance Portability and Accountability Act (HIPAA) compliant informed consent forms were approved by the institutional review boards for participating sites, and a parent or guardian of each study subject gave written informed consent. The study adhered to the tenets of the Declaration of Helsinki. The protocol is available on the Pediatric Eye Disease Group (PEDIG) website (www.pedig.net) and is summarized below.
Major eligibility criteria included age from day of birth to 17 years, ability to have CCT measured in the clinic or under general anesthesia, cycloplegic refraction performed upon enrollment or within 6 months of enrollment, and presence of healthy corneas without ocular or systemic conditions that would influence CCT or IOP measurements. Acceptable ocular conditions included strabismus, nasolacrimal duct obstruction, and refractive error. Major exclusion criteria included anterior segment dysgenesis, congenital cataract, contact lens use, periocular steroid use within 3 months of enrollment or current systemic steroid use, uveitis, corneal structural abnormality, microphthalmia, Marfan syndrome, glaucoma, history of intraocular or refractive surgery, optic nerve edema or other optic nerve abnormality, and history of prematurity (defined as birth <37 weeks post-menstrual age).
The study exam consisted of 3 CCT measurements per eye using the DGH 55 handheld Pachmate (DGH Technology, Inc., Exton, PA) and 2 intraocular pressure (IOP) measurements by Tonopen (Reichert, Inc., Depew, NY) in the right eye. A third IOP measurement with the Tonopen was required if the first two differed by 2 mmHg or more. A cycloplegic refraction with dilated fundus examination was performed, if not done within the prior 6 months. Measurements could be taken in the clinic setting or under general anesthesia. The Tonopen and Pachmate were calibrated for use each day prior to the initial subject testing. The accuracy of CCT testing with the Pachmate after successful calibration is ≤5 micrometers.8 For CCT measurements, the pachymeter was placed on the central 3 mm of the cornea after instillation of a drop of 0.5% proparacaine. Each measurement was an average value recorded by the instrument, taken during a single attempt, which was based on 1 to 25 measurements (98% of averages reported in this study were based on 25 measurements). The CCT average, number of measurements included in the average, and standard deviation were calculated by the instrument. Each average measurement took a few seconds to obtain. IOP measurements were taken after instillation of proparacaine 0.5% for subjects in the clinic setting. Subjects under general anesthesia had IOP measured within 2 minutes of anesthesia induction, if possible. Time in minutes from induction to IOP measurement was documented. The reliability of the IOP measurement was recorded as good, poor, or could not obtain to reflect the child’s level of cooperation. Cycloplegic refraction was performed using 1% or 2% cyclopentolate or Cyclomydril© (Alcon Laboratories, Inc.) as per investigator’s routine.
A planned sample size of 70 subjects per age group was chosen to allow mean CCT to be estimated with a half width of a 95% confidence interval of 10 micrometers within each of 10 age groups, separately by race or ethnicity (White, African American, and Hispanic). There were no specific targets for other racial groups as it was not considered feasible to enroll the necessary numbers in a reasonable time frame. The age groups were: 0 to <6 months, 6 to <12 months, 12 to <24 months, 2 to <3 years, 3 to <4 years, 4 to <6 years, 6 to <8 years, 8 to <10 years, 10 to <13 years, and 13 to <18 years. Age groups were used to define recruitment goals and guarantee a greater number of subjects in the age range at which CCT was suspected to be most rapidly changing, based on results of previous studies of CCT in children,7, 9 but the age groups were not used in analyses; age was analyzed as a continuous factor.
CCT measurements with standard deviation greater than 5.0 micrometers were excluded from analysis. The median of the CCT measurements for each eye was computed weighting by the number of measurements, and the medians of the 2 eyes were averaged to obtain a subject-level measurement used for analysis (Pearson correlation for right eye versus left eye medians=0.95). For subjects with data for only one eye, the median for that eye was used as the subject-level measurement.
Subjects were classified into a racial/ethnic group based on parental report of race and ethnicity as follows: White = white race and non-Hispanic ethnicity; Hispanic = white race and Hispanic or Latino ethnicity; African American = African-American race, regardless of ethnicity; and East Asian = originating from the Far East or Southeast Asia, regardless of ethnicity. Subjects of other racial/ethnic groups were included in analyses that were not specific to racial/ethnic group. However, derivation of reference percentiles by race/ethnicity was limited to the 3 groups (White, Hispanic, and African-American) for which sufficient numbers were enrolled to ensure statistical validity.
CCT was compared among age, racial/ethnic (White, Hispanic, African-American, and East Asian), and gender groups using a linear model with age as a continuous factor. The Tukey-Kramer adjustment for multiple comparisons was used for racial group comparisons. CCT at different ages was compared using linear contrasts. As the growth curve for CCT was not linear with age, models with higher order polynomial terms for age were fit, with non-statistically-significant higher order terms eliminated one at a time, to reach a final model (which contained a linear and a quadratic term for age). The age of CCT stabilization was defined as the age at which the 95% confidence interval for the slope estimate of the growth curve first contained zero. Data for infants (age 0 to 11 months) were not included in the model due to the small sample size of this age group. Models including interactions for age by race and gender also were tested to allow for the possibility that the growth curve for CCT differed by these criteria. The same model was used to develop the reference percentiles reported in the tables for the racial/ethnic groups using the method of Altman,10 except race was treated as a stratification factor rather than a covariate to allow for separate derivation of reference percentiles of African-Americans, and data was pooled across genders, and for Hispanic and white subjects. Due to small sample size in African-American subjects younger than 4 years of age, the reference percentile derivation for these subjects was limited to ages 4 years and older. A reference range for white infants 6 to 11 months of age was derived assuming normally distributed data with constant mean and standard deviation across the age range.
It has been reported that inhalation anesthetics lower IOP within a few minutes of anesthesia induction.11, 12 IOP measurements with poor reported reliability or taken more than 2 minutes after induction of general anesthesia were excluded from analyses. The association of CCT with IOP and spherical equivalent refractive error was evaluated using linear regression models adjusting for age, racial/ethnic group, and gender. The model for IOP also included an adjustment for exam setting. The spherical equivalent model included averaged data from both eyes while the IOP model included data from right eyes only. Infants younger than 6 months of age with cycloplegic refraction performed more than 30 days prior to enrollment were excluded from the refractive error analysis as these measurements may not reflect their refraction at time of CCT measurement.
The study enrolled 2,199 subjects; 2,079 (95%) were included in analysis. Reasons for exclusion from analysis were: subject found to be ineligible after enrollment (29 subjects), procedural deviation when obtaining measurements (11 subjects), standard deviation greater than 5.0 micrometers or missing for all measurements (79 subjects), and subject cooperation precluding any measurement (1 subject).
After exclusions, the recruitment goal of 70 subjects per age and racial/ethnic group was met for all age groups of white subjects except 0 to <6 months (N=24), and met for all age groups older than 4 years for Hispanic subjects and African-American subjects. Two subjects were enrolled on the day of birth. The 132 East Asian subjects enrolled were insufficient for derivation of reference percentiles, but were sufficient for comparison of mean CCT with other racial groups. Measurements were made in 407 (20%) of the subjects under general anesthesia. 2607 eyes (65%) had 3 measurements with a standard deviation less than 5 micrometers, 904 eyes (23%) had 2 measurements, and 496 (12%) had 1 measurement. Of eyes with at least 2 measurements, the difference between the maximum and minimum measurement was 20 micrometers or less in 93%.
The mean age of the 1672 subjects tested with topical anesthesia in the office was 8.7 years (range 0 to 17 years), and the mean age of the 407 subjects tested with general anesthesia was 2.7 years (range 0 to 16 years). Fifty-three percent of subjects were female (eTable 1). Sixty-four percent of eyes had a spherical equivalent refractive error between −1.00 diopter (D) and +3.00 D. Other than refractive error, common diagnoses included normal eye exam, strabismus, nasolacrimal duct obstruction, and amblyopia.
A thicker median CCT was observed with each successive year of age from 1 to 11 years (95% confidence interval on slope of CCT by year of age excluded zero), but was stable thereafter. The median CCT for subjects 12 to 17 years of age differed by 1 micrometer or less per year. However, there was substantial variability across the age range (R2 = 0.03 (Figure 1), R2 = 0.006 (Figure 2)). Median CCT for subjects 12 to 17 years of age was 573 micrometers in white and Hispanic subjects and 551 micrometers in African-American subjects (Tables 1 and and2;2; Figures 1 and and22).
There was no significant difference in CCT between white and Hispanic subjects, while African-American subjects had significantly thinner central corneas on average by about 20 micrometers compared with both Hispanic and white subjects of similar age (p<0.001, Table 3). East Asian subjects had corneas that were significantly thinner on average than white subjects by 10 micrometers (p=0.03), and thicker than African-American subjects by 14 micrometers (p=0.001, Table 3). Females had thinner corneas than that of males by an average difference of approximately 5 micrometers (p=0.003). There was no evidence that the differences observed with age in the median CCT differed by race or gender.
Because of the similarity of CCT for Hispanic and white subjects, their data were pooled for derivation of reference percentiles, while reference percentiles for African-American subjects were derived separately (Tables 1 and and2).2). Similarly, data for both genders were pooled as the small difference between them was judged to be clinically irrelevant. White and Hispanic subjects had a median CCT of 561 micrometers at age 4 years, and 574 micrometers at age 15 years. African-American subjects had a similar increase from 541 to 551 micrometers over the same age range.
Spherical equivalent refractive error for the cohort ranged from −17.50 D to +13.00 D. A regression analysis showed that mean CCT was 1 micrometer thinner for every 1.00 D of lower (less hypermetropia, more myopia) spherical equivalent refractive error, although there was considerable variability in CCT unrelated to refractive error (R2=0.005, p<0.001, adjusted for age, race, and gender; Figure 3). An analysis limited to subjects with spherical equivalent of −6.00 to +8.00 D was similar confirming that this result was not due to a small number of subjects with high myopia and thin central corneas or high hyperopia and thick central corneas.
IOP ranged from 5 to 29 mmHg, with the majority (95%) of subjects having IOP 21 mmHg or lower. A relationship was seen between IOP and CCT, with IOP 1.5 mmHg higher on average for every 100 micrometers of thicker central cornea (p<0.001, Figure 4). There was considerable variability in the relationship between IOP and CCT, with CCT explaining only 2% of the variation in IOP based on the partial R2.
The median CCT for the 24 white infants younger than 6 months of age was 563 micrometers (range 468 to 687), and the median CCT for 6 African-American infants younger than 6 months of age was 544 micrometers (range 517 to 666). The median CCT for 74 white infants 6 to 11 months of age was 548 micrometers (range 471 to 627; 5th – 95th percentiles 495 to 601), and the median CCT for 17 African-American infants 6 to 11 months of age was 551 micrometers (range 483 to 629). We did not enroll a sufficient number of white infants younger than 6 months of age or African-American infants to derive normative percentiles for those groups.
Significant changes in axial length, corneal diameter, and refractive state occur with the growth of a child’s eye. We demonstrated that CCT in healthy children also changes modestly with age, with most of the change occurring before age 11 years. This increase with age occurred in the white, African-American, and Hispanic racial/ethnic groups. Hispanic and white subjects had similar thickness at each age, while African-American subjects were significantly thinner at all ages. This relationship between thicker CCT and older age occurred in the white, African-American, and Hispanic racial/ethnic groups. The range of CCT measurements by the Pachmate at each age was approximately 120 micrometers, and was similar across racial groups. The clinical significance of this range is unknown.
Several studies of CCT among children of varying age have been reported. Hussein et al9 studied CCT measurements in 108 children and found mean CCT to increase with age, reaching adult thickness by 5 years of age. However, the study had only 18 patients older than 10 years of age. Consistent with our results, Haider found mean CCT to be thicker in both white and African-American children 10 to 18 years old compared to younger children.6 Hussein reported higher CCT in children 5 to 9 years old, compared to children younger than 4 years of age.9 They did not have sufficient numbers of older children to determine whether this trend continued beyond age 9 years.
Conversely, other investigators have not found CCT to increase with age. Zheng and colleagues13 studied 926 children 8 to 16 years of age and found no association between CCT and age. They reported a significant difference in CCT between children (mean=550 micrometers) and adults (mean=537 micrometers). Nevertheless, they may have missed the age effect in children found in this study and others by excluding children younger than 8 years. Dai and Gunderson7 analyzed CCT in 106 children of various racial groups, and found no age effect, but their sample size was too small to be able to reliably detect an age effect of the size seen in the current study. They also noted that CCT was similar in white and Hispanic children, but lower in African-American children.
Racial differences associated with CCT found in this study were similar to those reported in adults.1, 3, 14 White and Hispanic children had similar CCT, whereas African-American children had lower CCT than that of white or Hispanic children across all age groups. Although the number of East Asian children enrolled in our study was small, the mean CCT in East Asian children was intermediate between that of white and Hispanic children and that of African-American children. The clinical significance of the racial difference is unknown. It is unclear if thinner corneas in children are associated with an increased risk of glaucomatous optic neuropathy.
CCT was found in our analyses to be associated with IOP measured by Tonopen. This relationship was true for subjects in the office and under general anesthesia. IOP was 1.5 mm Hg higher for every 100 micrometers of increased CCT after combining data from both settings. Biomechanical properties of the cornea may contribute to this observation. Recent research suggests that the effect of CCT on IOP measurements may be increased in eyes with stiffer corneas compared to softer corneas.15 To understand the clinical impact of this observation, consider the range of CCT in an age group. The range of normal CCT between the 5th and 95th reference percentiles at any age is about 120 micrometers. For a CCT falling within the 5th and 95th reference percentiles, the effect of CCT would cause variation in IOP of at most 2 mmHg and should not influence the clinical decision about the presence or absence of glaucoma. Alternatively, if a child’s IOP is 2 mmHg or more higher than expected and the CCT is within the 5th and 95th percentiles, the measured IOP should not be attributed to normal variation in CCT.
There were two statistically significant, but not clinically relevant associations. We observed a 1 micrometer thinner cornea on average for each 1.00 D myopic shift in refractive error. Females had CCT that was an average 5 micrometers thinner than males.
Normative CCT data by age and race in children are shown in Tables 1 and and2.2. These may be helpful in clinical practice. Healthy children with mildly elevated IOP by tonometry, but no other signs of glaucoma may be managed more conservatively if their CCT is found to be substantially higher than normal for their age and race. In contrast, a child with mildly elevated IOP and substantially lower CCT than the normative measurement for his/her age and race may need more vigilant monitoring for signs of glaucoma.
Our study has a number of strengths. We used a single type of corneal pachymeter, the DGH 55 Pachmate, to measure CCT. Greater than 96% of the children were able to cooperate for measurements. The CCT data obtained in 98% of measurements in this study were based on 25 sequential individual CCT measurements per reading, the highest number of measurements the pachymeter could average to produce a reading allowing a standard deviation of less than 5 micrometers for the CCT measurement. The small CCT test-retest difference for the large majority (93%) of eyes suggests that pachymeter measurements were taken within the same area of the cornea. An additional strength is that the sample included a large number of children across a wide age range for three ethnic groups. Nearly all of our age groups had over 100 patients per group, with older age groups having approximately 300 patients.
Limitations of this study include inadequate number of infants younger than 6 months of age, as well as inadequate number of Asian children in all age groups. Another limitation may be that the CCT measurement obtained in the office setting might not have been in the central 3 mm of the child’s cornea, depending on patient cooperation and examiner skill. Because our study did not include measurements of axial length, corneal diameter, or corneal hysteresis, we do not know how these specific ocular features might affect CCT during childhood.
In summary, we found higher CCT with age among healthy children from 0 to 11 years of age, appearing to plateau after age 11 years. African-American children had lower CCT than that of white and Hispanic children. There is a minimal increase in measured IOP with increasing corneal thickness among normal children. There is no clinically important association between CCT and refractive error.
Writing Committee: (Lead Authors) Yasmin S. Bradfield, MD; B. Michele Melia, ScM; Michael X. Repka, MD; Brett M. Kaminski; Additional authors (alphabetical): Bradley V. Davitt, MD; David A. Johnson, MD, PhD; Raymond T. Kraker, MSPH; Ruth E. Manny, OD, PhD; Noelle S. Matta; Katherine K. Weise, OD, MBA; Susan Schloff, MD All authors had full access to all the data in the study and take responsibility for the integrity of the data and the accuracy of the data analysis.
The Pediatric Eye Disease Investigator Group
Clinical Sites that Participated in this Protocol
Sites are listed in order by number of subjects enrolled into the study. Personnel are listed as (I) for Investigator, (C) for Coordinator, and (E) for Examiner.
Saint Paul MN - Associated Eye Care (437)
Susan Schloff, (I); E. Denise Daffron, (C); Valori E. Host, (C); Rebecca A. Wolf, (C)
Lancaster PA - Family Eye Group (268)
David I. Silbert, (I); Eric L. Singman, (I); Noelle S. Matta, (C); Cristina M. Brubaker, (E); Tiffany L. Burkhart, (E); Sidney A. Garcia, (E); Tiffiny D. Gilmore, (E); Diane M. Jostes, (E); Christine M. Keefer, (E); Alyson B. Keene, (E); Garry L. Leckemby, (E)
Miami FL - Bascom Palmer Eye Institute (167)
Susanna M. Tamkins, (I); Adam S. Perlman, (I); Eva M. Olivares, (C); Marlon Parra, (C); Yaidy Exposito, (E); Sonia M. Fernandez, (E); Darren S. Singh, (E)
St. Louis MO - Cardinal Glennon Children's Hospital (143)
Oscar A. Cruz, (I); Bradley V. Davitt, (I); Joshua S. Anderson, (C); Emily A. Miyazaki, (C); Faisel Ahmad, (E); Aaron D. Grant, (E); William Shultz, (E); Brad E. Talley, (E)
Wilmington NC - Eye Associates of Wilmington (130)
David A. Johnson, (I); Kellie Drake, (C)
West Des Moines IA - Wolfe Clinic (104)
Donny W. Suh, (I); Myra N. Mendoza, (I); Autumn Parrino, (C); Rhonda J. Countryman, (E); Shannon L. Craig, (E); Lisa M. Fergus, (E); Alex D. Hall, (E); Jamie L. Spillman, (E); Gayle A. Spooner, (E); David C. Taylor, (E)
Birmingham AL - University of Alabama at Birmingham School of Optometry (100)
Marcela Frazier, (I); Kristine T. Hopkins, (I); Wendy L. Marsh-Tootle, (I); Jessica M. Walk, (I); Katherine K. Weise, (I); Cathy H. Baldwin, (C); Michael P. Hill, (C)
Fullerton CA - Southern California College of Optometry (97)
Susan A. Cotter, (I); Carmen N. Barnhardt, (I); Angela M. Chen, (I); Raymond H. Chu, (I); Lisa M. Edwards, (I); Catherine L. Heyman, (I); Kristine Huang, (I); Tawna L. Roberts, (I); Erin Song, (I); Jolyn X. Wei, (I); Maedi M. Bartolacci, (C); Susan M. Parker, (C)
Chicago Ridge IL - The Eye Specialists Center, L.L.C. (78)
Benjamin H. Ticho, (I); Alexander J. Khammar, (I); Deborah A. Clausius, (C); James B. Coletta, (C); Sharon L. Giers, (E); Barbara C. Imler, (E); Connie Silva, (E)
Houston TX - University of Houston College of Optometry (78)
Ruth E. Manny, (I); Karen D. Fern, (I); Gabynely G. Solis, (C)
Durham NC - Duke University Eye Center (63)
Laura B. Enyedi, (I); Sharon F. Freedman, (I); Alice A. Lin, (I); David K. Wallace, (I); Tammy L. Yanovitch, (I); Terri L. Young, (I); Sarah K. Jones, (C); Courtney E. Fuller, (E); Cassandra W. Headen, (E); Namita X. Kashyap, (E); Ivonne J. Rodriguez, (E)
Erie PA - Pediatric Ophthalmology of Erie (55)*
Nicholas A. Sala, (I); Benjamin H. Whitling, (I); Rhonda M. Hodde, (C); Veda L. Zeto, (C)
Salt Lake City UT - Rocky Mountain Eye Care Associates (54)
David B. Petersen, (I); J. Ryan McMurtrey, (C); Beth A. Morrell, (C); Kristin L. Sylvester, (C)
Lisle IL - Progressive Eye Care (47)
Patricia L. Davis, (I); Kathy A. Anderson, (I); Katie R. Hulett, (C); Carrie S. Bloomquist, (E); Sarah J. Velazquez, (E)
Rochester NY - University of Rochester Eye Institute (44) *
Matthew D. Gearinger, (I); Doreen Francis, (C); Justin D. Aaker, (E); Lynne M. Addams, (E)
Atlanta GA - The Emory Eye Center (36)
Scott R. Lambert, (I); Amy K. Hutchinson, (I); Phoebe D. Lenhart, (I); Rachel A. Robb, (C); Marla J. Shainberg, (C); Fatema Q. Esmail, (E); Vidya P. Phoenix, (E)
Baltimore MD - Wilmer Institute (33) *
Michael X. Repka, (I); Alex X. Christoff, (C); Carole R. Goodman, (C); Xiaonong Liu, (C)
Calgary - Alberta Children's Hospital (33)
William F. Astle, (I); Linda L. Cooper, (I); Kenneth G. Romanchuk, (I); Ania M. Hebert, (C); Heather J. Peddie, (C); Stacy Ruddell, (C); Heather N. Sandusky, (C); Trena L. Beer, (E); Christine Berscheid, (E); Catriona Kerr, (E); Stacy X. Liu, (E); Melissa K. Racine, (E)
Columbus OH - Pediatric Ophthalmology Associates, Inc. (29)
Don L. Bremer, (I); Cybil M. Cassady, (I); Richard P. Golden, (I); David L. Rogers, (I); Gary L. Rogers, (I); Rae R. Fellows, (C); Amy J. Wagner, (C)
Philadelphia PA - Children's Hospital of Philadelphia (29)
Brian J. Forbes, (I); William V. Anninger, (I); Gil Binenbaum, (I); Stefanie L. Davidson, (I); Monte D. Mills, (I); Graham E. Quinn, (I); Karen A. Karp, (C); Suzanne Kilmartin, (C)
Minneapolis MN - University of Minnesota (27) *
C. Gail Summers, (I); Jill S. Anderson, (I); Erick D. Bothun, (I); Stephen P. Christiansen, (I); Ann M. Holleschau, (C); Anna I. de Melo, (E); Sara J. Downes, (E); Kathy M. Hogue, (E); Kim S. Merrill, (E)
Portland OR - Casey Eye Institute (20)
Daniel J. Karr, (I); Leah G. Reznick, (I); Ann U. Stout, (I); Allison I. Summers, (I); David T. Wheeler, (I)
Cincinnati OH - Children's Hospital Medical Center (19)
Dean J. Bonsall, (I); Sarah L. Lopper, (I); Robert B. North, (I); Corey S. Bowman, (C)
Nashville TN - Vanderbilt Eye Center (16) *
Sean P. Donahue, (I); LoriAnn F. Kehler, (I); David G. Morrison, (I); Lisa A. Fraine, (C); Christine C. Franklin, (E)
Charleston SC - Medical Univ of South Carolina, Storm Eye Institute (15)
Ronald W. Teed, (I); Kali B. Cole, (I); Margaret E. Bozic, (C); Carol U. Bradham, (C)
Rockville MD - Stephen R. Glaser, M.D., P.C. (15)
Stephen R. Glaser, (I); Monica M. Pacheco, (I); Noga Senderowitsch, (C)
Ft. Lauderdale FL - Nova Southeastern University College of Optometry, The Eye Institute (12)
Nadine M. Girgis, (I); Yin C. Tea, (I); Julie A. Tyler, (I); Annette Bade, (C)
Milford CT - Eye Physicians & Surgeons, PC (10)
Darron A. Bacal, (I); Donna Martin, (C); Kelly D. Moran, (C)
Sacramento CA - University of California, Davis Dept. of Ophthalmology (9)
Mary O'Hara, (I); Maedi M. Bartolacci, (C); Maria Van Wolferen, (E)
Albuquerque NM – Family & Children's Eye Center of New Mexico (7)
Todd A. Goldblum, (I); Angela Alfaro, (C)
Madison WI - University of Wisconsin, Dept. of Ophthalmology & Visual Sciences (7)
Yasmin S. Bradfield, (I); Thomas D. France, (I); Barbara H. Soderling, (C)
Iowa City IA - University of Iowa Hospitals and Clinics (6) *
Susannah Longmuir, (I); Alejandro Leon, (I); Richard J. Olson, (I); Wanda I. Ottar Pfeifer, (C)
Fall River MA - Center for Eye Health Truesdale Clinic (5)
John P. Donahue, (I); Mary E. Silvia, (C); Deborah P. Branco, (E)
Waterbury CT - Eye Care Group, PC (4)
Andrew J. Levada, (I); Cheryl Capobianco, (C); Tabitha L. Walker, (C); MaryJane J. Abrams, (E); LeAnne J. Ingala, (E); Gina Silva, (E)
Indianapolis IN - Indiana University Medical Center (1)
Daniel E. Neely, (I); Michele E. Whitaker, (C)
La Jolla CA - Abraham Ratner Children's Eye Center, UCSD (1)
Shira L. Robbins, (I); Erika F. Castro, (C); Adele Roa, (E)
*Center received support utilized for this project from an unrestricted grant from Research to Prevent Blindness Inc., New York, New York.
PEDIG Coordinating Center (as of June 29th, 2010):
Raymond T. Kraker, Roy W. Beck, Christina M. Cagnina-Morales, Debora A. Cagnina, Danielle L. Chandler, Laura E. Clark, Chelsea Costa, Elise R. Diamond, Quayleen Donahue, Brooke P. Fimbel, Nicole C. Foster, Megan R. Gumke, Brett M. Kaminski, Elizabeth L. Lazar, Stephanie V. Lee, Lee Anne Lester, B. Michele Melia, Pamela S. Moke, Michael Philips, Diana E. Rojas, Sydney L. Shrader
National Eye Institute – Bethesda, MD:
Donald F. Everett
Central Corneal Thickness Study Steering Committee
Yasmin S. Bradfield, Michael X. Repka, Bradley V. Davitt, Daniel E. Neely, Raymond T. Kraker, B. Michele Melia
Central Corneal Thickness Planning Committee
Yasmin S. Bradfield, Bradley V. Davitt, Sharon F. Freedman, Jonathan M. Holmes, B. Michele Melia, Daniel E. Neely, Michael X. Repka, David I. Silbert, Donny W Suh, Diane L. Tucker
PEDIG Executive Committee
Jonathan M. Holmes (chair), Darron A. Bacal (2009), Roy W. Beck, Eileen E. Birch, Stephen P. Christiansen, Susan A. Cotter, Donald F. Everett, Darron L. Hoover (2008), Pamela A. Huston (2009), Raymond T. Kraker, Katherine A. Lee, Noelle S. Matta, David G. Morrison, Michael X. Repka, Robert P. Rutstein (2009), Mitch M. Scheiman (2008), David K. Wallace (2009)
This study was supported by the National Eye Institute of the National Institutes of Health, Department of Health and Human Services EY011751 and EY018810. The sponsor or funding organization had no role in the design or conduct of this research.
Conflict of interest: The authors have no financial or conflicting interests in the subject of this report to disclose.
This article contains online-only materials. The following elements should appear online only: eTable 1.