Spotlight on the Disc-Damage Likelihood Scale (DDLS)

Kelvin KW Cheng, Andrew J Tatham Princess Alexandra Eye Pavilion, Edinburgh, UKCorrespondence: Andrew J TathamPrincess Alexandra Eye Pavilion, Edinburgh, UKTel +44 131 536 3753Email andrewjtatham@gmail.comAbstract: The disc damage likelihood scale (DDLS) is a tool for classifying glaucomatous structural changes to the optic disc based on the radial width of the neuroretinal rim at its thinnest location, or if no rim is present, the extent of absence of the rim. Unlike cup disc ratio (CDR), the DDLS also considers disc size. Twenty years after its first description, the aim of this review was to critically appraise evidence for the DDLS and evaluate its role in current practice. A literature search by two independent authors identified 33 relevant articles for inclusion. Five studies evaluated reproducibility, 5 diagnostic performance, and 2 studies examined ability to detect progression. Eleven studies evaluated correlation between DDLS and other markers of glaucoma. Despite the widespread availability of imaging devices such as optical coherence tomography (OCT), clinical examination of the optic disc remains an essential component of glaucoma diagnosis and monitoring. The DDLS provides a reliable method for semi-quantitative clinical grading of the optic disc in glaucoma, with higher reproducibility than methods such as CDR.Keywords: glaucoma, cup-to-disc ratio, rim-to-disc ratio, disc damage likelihood scale