Spotlight on the Disc-Damage Likelihood Scale (DDLS)

Abstract

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.

Disc damage likelihood scale: its correlation with field indices and its accuracy in diagnosis of glaucoma

“…Also, compared to CD ratio the inter observer (85% versus 74%) and intra observer (98% versus 85%) were far superior in the rim to disc ratio which the DDLS utilizes as has been shown in a study. 10 In our study, DDLS staging shows a very strong correlation with CD ratio, a good correlation with VFI and MD and weak correlation with foveal sensitivity. Which was also observed by Lutaka et al who observed significant correlation between visual field index and MD.…”

Longitudinal Assessment of Retinal Nerve Fiber Layer and Ganglion Cell Complex Thicknesses in Patients With Large Optic Disc Cups and Normal Intraocular Pressure and Visual Fields

“…4,18 However, it does not consider disc size, focal neuroretinal rim loss, or low reliability. [18][19][20] Low reliability means that some patients have small cup-to-disc ratios but significant visual field loss, whereas others have large cup-to-disc ratios with little visual field loss. 18 Therefore, it is difficult for clinicians to distinguish between physiological large disc cupping and early glaucomatous optic disc changes.…”

“…Among the various parameters representing glaucomatous optic disc change, the vCDR is the most commonly used and has advantages, such as being a user-friendly self-evident system with moderate reproducibility 4,18 . However, it does not consider disc size, focal neuroretinal rim loss, or low reliability 18–20 . Low reliability means that some patients have small cup-to-disc ratios but significant visual field loss, whereas others have large cup-to-disc ratios with little visual field loss 18 .…”

DDLSNet: A Novel Deep Learning-Based System for Grading Funduscopic Images for Glaucomatous Damage

“…Cup-to-disc ratio has been repeatedly shown to be inferior to DDLS in grading glaucomatous damage. 40 Several papers addressed detection of the minimum optic disc rim width, an important component of calculating the DDLS score. 41 , 42 , 43 However, few have used automated DDLS calculation due to the complexity of the challenge.…”