Abstract
Purpose::
To characterize the optic nerve head (ONH) in a normal pediatric African American (AA) population, using the Heidelberg Retina Tomograph II (HRT II) and to establish normative ONH data for this population. The effects of age, gender, and refractive error on ONH parameters were investigated.
Methods::
The optic nerve heads from 77 randomly selected normal AA subjects (42 females and 35 males) aged 4-18 years were imaged with the HRT II. Both eyes (total of 154 eyes) were imaged for each subject but only the parameters of the right eye were evaluated. Stereometric parameters were analyzed with respect to baseline variables, including age, gender, and refractive error. Statistical analysis was performed using Pearson’s correlation, Student’s t-test, and multiple regression analysis.
Results::
The mean disc area of the subjects was 2.37 ± 0.55 mm2 (mean± SD). The mean rim area was 1.79 ± 0.31 mm. The mean cup area was 0.58 ± 0.40 mm. The mean cup disc area ratio was 0.23 ± 0.16. The mean cup depth was 0.22 ± 0.10 mm. The mean retinal nerve fiber layer (RNFL) thickness was 0.25 ± 0.07 mm. Disc area was significantly positively correlated with all of the topographic parameters except height variation contour and mean RNFL thickness. Age had a significant positive correlation with four parameters including cup area, cup/disc area ratio, linear cup/disc ratio, and mean cup depth. Refractive error had a significant negative correlation with rim area, but not the other parameters. Significant gender-related differences were detected only for linear cup/disc ratio (P < 0.05), with a mean linear cup/disc ratio of 0.41 in females and 0.49 in males.
Conclusions::
Results of this study contribute to the development of a data base of normal ONH parameters in the pediatric population. A knowledge of the differences and/or normal variations in ONH morphology based on age, refractive error, gender and race could assist in the diagnosis of optic nerve pathologies including optic nerve hypoplasia, megalopapilla and glaucoma.