What Are the Key Clinical Skills and Investigative Techniques for Disc Evaluation

The definition of glaucoma is inseparable from observable optic nerve head (ONH) damage, but is usually associated with raised intraocular pressure (IOP) and visual field changes. Disc damage is clinically assessed under the headings of structural change (optic nerve and retinal nerve fibre layer) and functional loss (visual fields), and these features can be correlated to cellular level changes at the posterior pole. Various studies have shown that anatomical damage in glaucoma precedes the functional damage, hence timely detection of the morphological changes helps to inform for early diagnosis and effective screening. This chapter presents a detailed explanation of the specific signs and clues, like nerve fibre layer defects, haemorrhages, notch, configuration, size, shape of neuro-retinal rim, importance of peripapillary atrophy, etc. that are the hallmarks of early through to advanced glaucoma. Accompanying this is a discussion of the different imaging modalities that can be used to record and quantify anatomical changes in the nerve based on retinal nerve fibre layer thickness, surface ONH topography, optic nerve head parameter, and ganglion cell complex mass measurements.