Estimation of the Disc Damage Likelihood Scale in primary open-angle glaucoma: the Glaucoma Stereo Analysis Study

Spotlight on the Disc-Damage Likelihood Scale (DDLS)

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.

Comparisons between retinal vessel calibers and various optic disc morphologic parameters with different optic disc appearances: The Glaucoma Stereo Analysis Study

The Glaucoma Stereo Analysis Study (GSAS) is a multicenter collaborative study of the characteristics of glaucomatous optic disc morphology using a stereo fundus camera. This study evaluated the retinal vessel calibers and correlations using GSAS fundus photographs between retinal vessels and 38 optic nerve head (ONH) morphologic parameters comprehensively. In all 240 eyes, the mean central retinal arteriolar equivalent (CRAE) and central retinal venular equivalent (CRVE) were 138.4 and 216.5 μm, respectively; the CRAE correlated with age, visual field scores and 19 ONH parameters and CRVE correlated with age, intraocular pressure, visual field scores and 11 ONH parameters. Among the different optic disc appearances including focal ischemia (FI) (n = 53, 22%), generalized enlargement (GE) (n = 53, 22%), myopic glaucoma (MY) (n = 112, 47%), and senile sclerosis (SS) (n = 22, 9%), the CRAE did not differ significantly; CRVE was significantly narrower in SS than in FI and MY. In FI, GE, MY, and SS disc types, CRAE correlated with 3, 14, 9, and 2 ONH parameters, respectively, and CRVE corelated with 9, 0, 12, and 6 ONH parameters, respectively. We confirmed previous observations on the effect of retinal vessel narrowing on glaucomatous changes in the ONH and visual field. The associations between retinal vessel caliber and ONH morphologic parameters vary among different optic disc appearances, suggesting different effects of vascular changes in each disc type.

Validation of formula-predicted glaucomatous optic disc appearances: the Glaucoma Stereo Analysis Study

AIMS

The Glaucoma Stereo Analysis Study (GSAS) is a multicentre collaborative study of the characteristics of glaucomatous optic disc morphology using a stereo fundus camera. Using the GSAS dataset, we previously established a formula for predicting different appearances of glaucomatous optic discs, although the formula lacked validation in an independent dataset. In this study, the formula was validated in another testing dataset.

SUBJECTS AND METHODS

Testing dataset contained three-dimensionally analysed optic disc topographic parameters from 93 eyes with primary open-angle glaucoma; six topographic parameters (temporal and nasal rim-disc ratios, mean cup depth, height variation contour, disc tilt angle and rim decentring absolute value) were used for predicting different appearances of glaucomatous optic discs. The agreement between grader-classified optic disc types, that is, focal ischemic (FI), generalized enlargement, myopic glaucomatous (MY), and senile sclerotic (SS) and formula-predicted optic disc types, that is, pFI, pGE, pMY and pSS, were assessed.

RESULTS

Based on this formula, the eyes were classified with pFI (21 eyes, 22.6%), pGE (27 eyes, 29.0%), pMY (26 eyes, 28.0%) and pSS (19 eyes, 20.4%) when the top predictive element based on the formula was considered as the optic disc appearance in each eye. The six topographic parameters used in the formula differed significantly among the four predicted optic disc types. Substantial agreement (κ = 0.7496) was seen for the top two predictive elements based on the formula that agreed with the graders' classification in 76 (81.7%) eyes. Among the four optic disc types, the levels of agreement were relatively lower in the SS type (κ = 0.3863-0.5729) compared with the other three optic disc types (κ = 0.7898-0.8956) even though the unclassifiable and mixed optic disc types were excluded from the testing dataset.

CONCLUSION

The GSAS classification formula can predict and quantify each component of different optic disc appearances in each eye and provide a novel parameter to describe glaucomatous optic disc characteristics.

A Small Disc Area Is a Risk Factor for Visual Field Loss Progression in Primary Open-Angle Glaucoma: The Glaucoma Stereo Analysis Study

Purpose

The Glaucoma Stereo Analysis Study, a cross-sectional multicenter collaborative study, used a stereo fundus camera (nonmyd WX) to assess various morphological parameters of the optic nerve head (ONH) in glaucoma patients. We compared the associations of each parameter between the visual field loss progression group and no-progression group.

Methods

The study included 187 eyes of 187 patients with primary open-angle glaucoma or normal-tension glaucoma. We divided the mean deviation (MD) slope values of all patients into the progression group (<−0.3 dB/year) and no-progression group (≧−0.3 dB/year). ONH morphological parameters were calculated with prototype analysis software. The correlations between glaucomatous visual field progression and patient characteristics or each ONH parameter were analyzed with Spearman's rank correlation coefficient.

Results

The MD slope averages in the progression group and no-progression group were −0.58 ± 0.28 dB/year and 0.05 ± 0.26 dB/year, respectively. Among disc parameters, vertical disc width (diameter), disc area, cup area, and cup volume in the progression group were significantly less than those in the no-progression group. Logistic regression analysis revealed a significant association between the visual field progression and disc area (odds ratio 0.49/mm² disc area).

Conclusion

A smaller disc area may be associated with more rapid glaucomatous visual field progression.

Secondary glaucoma in uveitis: comparison of the optic nerve head morphology among a nonmydriatic fundus camera, HRT, and SD-OCT

PURPOSE

To assess the correlation between the disc damage likelihood scale (DDLS) objectively measured by a nonmydriatic fundus camera, confocal laser scanning ophthalmoscopy (HRT3), and spectral-domain optical coherence tomography (SD-OCT) in uveitic glaucoma.

METHODS

A total of 59 patients with uveitic glaucoma (21 female, 38 male; mean age 56.8 ± 18.7 years) were included in this prospective cross-sectional study. All patients were measured by the Kowa Nonmyd WX 3D camera (2D/3D nonmydriatic retinal camera, Kowa Company), the HRT3 (Heidelberg Engineering), and SD-OCT (Carl Zeiss Meditec) by one examiner on the same day. All 3 devices graded the optic disc topography. Statistical data were calculated using SPSS (v 20.0, SPSS).

RESULTS

In patients showing borderline results in one of the modalities (n = 45), the DDLS showed a significant correlation with the retinal nerve fiber layer (p = 0.016), while Moorfields regression analysis (p = 0.550) and glaucoma probability score (p = 0.629) did not correlate significantly. The highest predictive power was demonstrated by the objectively measured DDLS (area under the receiver operating characteristic curve 0.445-0.588), compared to R. Burk (0.149-0.375) and F.S. Mikelberg (0.033-0.450) coefficients considering HRT and optical coherence tomography.

CONCLUSIONS

In this study cohort, the objective DDLS showed the highest predictive power and thus is a reliable tool in diagnosing uveitic glaucoma. These 3 devices cannot be used interchangeably. As diagnosis and follow-ups are challenging in uveitis patients, the stereophotography is additionally a valuable tool.

The disc damage likelihood scale: Diagnostic accuracy and correlations with cup-to-disc ratio, structural tests and standard automated perimetry

Our objective was to compare the diagnostic accuracies of and to determine the correlations between the disc damage likelihood scale (DDLS) and anatomical and functional tests used for glaucoma detection. A total of 54 healthy subjects (54 eyes) and 47 primary open-angle glaucoma patients (47 eyes) were included in this cross-sectional observational study. DDLS scores and cup-to-disc (C/D) ratios were evaluated. Subjects underwent standard automated perimetry (SAP), optic disc and retinal nerve fiber layer (RNFL) imaging with time and spectral-domain optical coherence tomography (TD and SD-OCT), Heidelberg Retina Tomograph (HRT II), and scanning laser polarimetry (GDx-VCC). Areas under the receiver operating characteristic curves (AROCs) for DDLS and diagnostic tests parameters were calculated. DDLS correlations (Spearman's rank) among these parameters were analyzed. Fifty-four eyes were healthy and 47 had glaucoma, including 16 preperimetric glaucoma. DDLS, vertical and horizontal C/D ratios had the largest AROCs (0.92, 0.94 and 0.91, respectively). DDLS diagnostic accuracy was better than the accuracies of HRT II parameters, TD and SD-OCT RNFL thicknesses, and SAP mean deviation (MD) index. There were no significant differences between the accuracies of the DDLS and the C/D ratios, TD-OCT vertical (0.89) and horizontal (0.86) C/D ratios, TD-OCT C/D area ratio (0.89), and GDx-VCC NFI (0.81). DDLS showed significant strong correlations with vertical (r = 0.79) and horizontal (0.74) C/D ratios, and with the parameters vertical C/D ratio and C/D area ratio from HRT II (both 0.77) and TD-OCT (0.75 and 0.72, respectively). DDLS had significant moderate correlations with most of the other structural measurements and SAP MD. The optic disc clinical evaluation with DDLS system and C/D ratio demonstrated excellent accuracy in distinguishing glaucomatous from healthy eyes. DDLS had moderate to strong correlations with most structural and functional parameters. These findings stress the importance of optic disc clinical examination to detect glaucoma in a clinical scenario.

Differentiation of glaucomatous optic discs with different appearances using optic disc topography parameters: The Glaucoma Stereo Analysis Study

The Glaucoma Stereo Analysis Study (GSAS) is a multicenter collaborative study of the characteristics of glaucomatous optic disc morphology using a stereo fundus camera. Using GSAS dataset, the formulas for predicting different glaucomatous optic disc appearances were established. The GSAS dataset containing three-dimensionally-analyzed optic disc topographic parameters from 187 eyes with primary open-angle glaucoma was assessed with discrimination analyses to obtain formulas predictive of glaucomatous optic disc appearances: focal ischemic (FI); generalized enlargement (GE), myopic glaucomatous (MY), and senile sclerotic (SS). Using 38 optic disc parameters-substituted discrimination analyses with a stepwise forward-selection method, six parameters (temporal and nasal rim-disc ratios, mean cup depth, height variation contour, disc tilt angle, and rim decentering absolute) were selected into the formulas. The area under the receiver operating characteristic curves for predicting the four disc types with established formulas were 0.88, 0.91, 0.93, and 0.86 for FI, MY, SS, and GE, respectively. Age, visual acuity, refractive error, glaucoma (normal or high-tension glaucoma), and baseline intraocular pressure differed significantly among the four optic disc types, suggesting the appearances represent different clinical glaucoma phenotypes. Using six optic disc topographic parameters obtained by stereo fundus camera, the GSAS classification formulas predicted and quantified each component of different optic disc appearances in each eye and provided a novel parameter to describe glaucomatous optic disc characteristics.