Structural imaging plays an integral but not solo role in glaucoma management

Imaging is an essential part of glaucoma management, but while structural damage is frequently apparent before identifiable visual field loss occurs, both functional testing and quantitative imaging should always be performed in eyes with either early or moderate disease, said David F. Garway-Heath, MD.

Dr. Garway-Heath, consultant ophthalmologist, Moorfields Eye Hospital, London, addressed the question of what is the best way to detect change in the optic disc and retinal nerve fiber layer (RNFL) during a glaucoma symposium held during the World Ophthalmology Congress.

In deciding what imaging technique to use, stereodisc photography should be considered the minimum requirement in the management of patients with suspect and established glaucoma. Among the advantages of sterodisc photography are: that it is the only imaging technique that provides full color, it has high resolution, and the images are similar to what the ophthalmologist sees in the clinical evaluation. However, this technique has limitations. Obtaining good image quality is difficult in eyes with media opacity, there is a lack of adequate systems for viewing the photos in the clinic, interpretation is highly subjective and observer-dependent, and changes that occur cannot be quantified.

Modern imaging devices, including confocal scanning laser tomography, scanning laser polarimetry, and optical coherence tomography, provide objective data and measurements that are highly repeatable. Nevertheless, these devices still lack statistical support, and the clinical relevance of the findings remains uncertain - as it is not known how to translate the structural change they detect into future functional loss.

"Irrespective of what imaging approach is used, always perform an adequate clinical exam and recording the findings in the chart with an accurate drawing and description of the quality of the RNFL. That information has value both as a comparator against the results obtained in the imaging studies and for future monitoring," said Dr. Garway-Heath.