Characteristics and appearance of the normal optic nerve head in 6-year-old children
- 1Department of Ophthalmology, Centre for Vision Research, Westmead Millennium Institute (Westmead Hospital), University of Sydney, Westmead, Australia
- 2Centre for Eye Research Australia, University of Melbourne, Melbourne, Australia
- 3Singapore Eye Research Institute, National University of Singapore, Singapore
- Correspondence to Dr Paul Mitchell, University of Sydney, Eye Clinic, Westmead Hospital, Hawkesbury Road, Westmead 2145, Australia;
Contributors Design and conduct of the study: PM, CS; collection and management of the data: PM, CS; analysis of the data: CS, PM, PRH; interpretation of the data: PM, PRH, CS; preparation of the first draft manuscript: CS; review and approval of the manuscript: AP, YT, PRH, TYW, PM, CS.
- Accepted 6 February 2011
- Published Online First 17 March 2011
Aim To document planimetric measures of normal optic nerve head parameters in 6-year-old children and to report prevalence and associations of common optic nerve signs.
Methods The Sydney Childhood Eye Study examined 1765 children aged 6 years. Complete retinal photographs were available for 1225 participants, captured using a digital camera. Optical coherence tomography optic-disc measurements were acquired using the ‘fast’ optic-disc protocol. Statistical analyses were conducted using SAS version 9.1.3.
Results The mean (95% CIs) planimetric optic-disc area was 2.29 mm2 (2.27 to 2.32), mean cup area 0.48 mm2 (0.47 to 0.50), mean vertical disc diameter 1.81 mm (1.80 to 1.82) and mean vertical cup diameter 0.72 mm (0.71 to 0.73), resulting in a mean vertical cup/disc ratio of 0.40 (0.39 to 0.40). Similarities existed between vertical, horizontal and area cup/disc ratios (p>0.05) measured by planimetry and optical coherence tomography, but only for vertical disc diameters between 1.75 and 1.96 mm. Visible lamina cribrosa pores were present in 4.9%. This sign was associated with larger optic nerve parameters. The prevalence of optic disc tilt and cyclotorsion was 1.6% and 8.7%, respectively, and the prevalence of α- and β-peripapillary atrophy was 43.3% and 20.2%, respectively. Neither sign was associated with myopia, after adjusting for age, sex and ethnicity, although eyes with β-peripapillary atrophy had a longer mean axial length (p=0.04). Cilioretinal arteries were present in 27% and tended to be located temporally.
Conclusions The mean vertical cup/disc ratio was 0.4 in this 6-year-old sample. Planimetric optic nerve head measures and population prevalence findings for optic disc signs in this population could be regarded as normative data for ophthalmologists in clinical settings.
- Optical coherence tomography
- optic nerve
- digital planimetry
- lamina cribrosa pores
- disc tilt, cyclotorsion
- alpha peripapillary atrophy
- β peripapillary atrophy
- cilioretinal artery
- Sydney Childhood Eye Study
- Sydney Myopia Study
- diagnostic tests/investigation
- child health (paediatrics)
Funding Australian National Health & Medical Research Council, Canberra, Australia (Grant 253732) and the Vision Co-operative Research Centre.
Competing interests None.
Ethics approval Ethics approval was provided by the Human Research Ethics Committee, University of Sydney, the Department of Education and Training, and the Catholic Education Office, New South Wales, Australia.
Provenance and peer review Not commissioned; externally peer reviewed.