Evaluating the optic nerve and retinal nerve fibre layer: the roles of Heidelberg retina tomography, scanning laser polarimetry and optical coherence tomography.

INTRODUCTION: For many years, ophthalmologists have looked at the optic nerve head to evaluate the status of glaucoma. Clinical examination of the optic nerve head and retinal nerve fibre layer (RNFL) is however, subjective and sometimes variable. Recent developments in computer-based imaging technologies have provided a means of obtaining quantitative measurements of the optic nerve head topography and peripapillary retinal nerve fibre layer thickness.

METHODS: Multiple searches using Medline were carried out. Additional searches were made using reference lists of published papers and book chapters.

RESULTS: Studies involving three imaging technologies namely, confocal scanning laser ophthalmoscopy, scanning laser polarimetry and optical coherence tomography were reviewed. Overall, these technologies were reproducible and demonstrate good sensitivity and specificity in the range of 70 to 80%. Inclusion of age and ethnicity normative database will make these technologies more effective in screening and diagnosis. Quantitative measurements provide useful parameters for monitoring of patients.

CONCLUSION: There is no consensus on the best technology for assessing structural damage in glaucomatous optic neuropathy. Therefore, as with any investigation, the clinician should exercise clinical correlation and judgment before instituting the appropriate treatment.