Optic nerve head morphometry in healthy adults using confocal laser scanning tomography.

Background/aims: To study the optic nerve head (ONH) characteristics in a cross sectional study with confocal laser scanning tomography using the Heidelberg retina tomograph (HRT I) and thereby to obtain a new HRT database for comparison of healthy and glaucomatous eyes.

Methods: White adults with no history of ocular pathology were eligible for the study. The examination comprised: assessment of visual acuity; slit lamp examination of the anterior and posterior segment; Goldmann applanation tonometry; computerised perimetry, and optic nerve head tomography with HRT. Eyes with ocular pathology were excluded. Mean (standard deviation, SD) and difference between right and left eye (RE-LE) were calculated for HRT I measurements. Differences in mean topographic parameters between male and female participants and between the age quartiles were analysed. The study included 1764 eyes of 882 healthy adults (154 females and 728 males, mean age of 46.8 (SD 8.6) years). The population investigated was larger and older in comparison with similar studies using confocal laser scanning tomography.

Results: With HRT I, a mean disc area of 1.82 (SD 0.39) mm(2), a mean cup area of 0.44 (SD 0.32) mm(2) and a mean cup:disc area ratio of 0.22 (SD 0.13) was observed. Right eyes showed a larger mean retinal nerve fibre layer thickness (RNFLT) (0.263 (SD 0.066) mm) compared with left eyes (0.252 (SD 0.065) mm, p<0.001). Higher values in younger volunteers (mean age 35.7 years) in comparison with elderly participants (mean age 59.1 years) were noted for disc area (1.84 mm(2)v 1.78 mm2) and mean RNFLT (0.263 (SD 0.06) mm v 0.249 (SD 0.07) mm) but were not significant (p>0.01). The presented results differ from published data on ONH measurements of healthy volunteers with different techniques.

Conclusion: The observed differences in ONH measurements between left and right eyes seem not to be of clinical importance. This is also true for age or sex dependent changes in ONH topographies. The presented data provide a new basis for comparison of optic disc characteristics between healthy eyes and glaucomatous eyes.