DEC 14, 2011
The authors of this study published in September in the Archives of Ophthalmology examined the central corneal thickness (CCT) of children and found that it increases modestly with age, reaching a plateau at age 11. The results, based upon measurements taken of 2,079 children, also indicate that white and Hispanic children have similar CCT that is significantly thicker than that of African-American children on average.
The study included children ranging in age from birth to 17 years who were white, Hispanic, African American, Asian, mixed race or of unknown race. CCT was measured with a handheld contact pachymeter.
The corneas of African-American children were found to be thinner by approximately 20 μm on average than corneas of both white and Hispanic children (P <0 .001) at all ages. East Asian subjects had corneas that were significantly thinner on average than white subjects by 10 μm (P = 0.03) and thicker than African American subjects by 14 μm (P = 0.001).
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 573μm in white and Hispanic children and 551 μm in African-American children. Median CCT differences observed with age did not appear to differ by race or sex. The range of CCT measurements at each age was approximately 120 μm and was similar across racial groups. The authors say that the clinical significance of this range and of the racial differences found is unknown. They also say that it is unclear whether thinner corneas in children are associated with an increased risk of glaucomatous optic neuropathy.
For every 100 μm of thicker CCT measured, IOP was 1.5 mmHg higher on average (P < 0.001). For every diopter of increased myopic refractive error, CCT was 1 μm thinner on average (P < 0.001), although the authors note that this relationship was not clinically important and there was considerable variability in CCT unrelated to refractive error.
They say that the normative pediatric CCT data by age and race produced by this study may be helpful in clinical practice. They conclude that healthy children with mildly elevated IOP as measured by tonometry but no other signs of glaucoma may be managed more conservatively if their CCT is substantially higher than normal for their age and race. However, children with mildly elevated IOP and substantially lower CCT than normative measurements for their age and race may need more vigilant monitoring for signs of glaucoma.