Article

Evaluation of a combined index of optic nerve structure and function for glaucoma diagnosis

Glaucoma Service, Dana Center for Preventive Ophthalmology, Wilmer Eye Institute, Johns Hopkins University, Baltimore, MD, USA.
BMC Ophthalmology (Impact Factor: 1.08). 02/2011; 11:6. DOI: 10.1186/1471-2415-11-6
Source: PubMed

ABSTRACT The definitive diagnosis of glaucoma is currently based on congruent damage to both optic nerve structure and function. Given widespread quantitative assessment of both structure (imaging) and function (automated perimetry) in glaucoma, it should be possible to combine these quantitative data to diagnose disease. We have therefore defined and tested a new approach to glaucoma diagnosis by combining imaging and visual field data, using the anatomical organization of retinal ganglion cells.
Data from 1499 eyes of glaucoma suspects and 895 eyes with glaucoma were identified at a single glaucoma center. Each underwent Heidelberg Retinal Tomograph (HRT) imaging and standard automated perimetry. A new measure combining these two tests, the structure function index (SFI), was defined in 3 steps: 1) calculate the probability that each visual field point is abnormal, 2) calculate the probability of abnormality for each of the six HRT optic disc sectors, and 3) combine those probabilities with the probability that a field point and disc sector are linked by ganglion cell anatomy. The SFI was compared to the HRT and visual field using receiver operating characteristic (ROC) analysis.
The SFI produced an area under the ROC curve (0.78) that was similar to that for both visual field mean deviation (0.78) and pattern standard deviation (0.80) and larger than that for a normalized measure of HRT rim area (0.66). The cases classified as glaucoma by the various tests were significantly non-overlapping. Based on the distribution of test values in the population with mild disease, the SFI may be better able to stratify this group while still clearly identifying those with severe disease.
The SFI reflects the traditional clinical diagnosis of glaucoma by combining optic nerve structure and function. In doing so, it identifies a different subset of patients than either visual field testing or optic nerve head imaging alone. Analysis of prospective data will allow us to determine whether the combined index of structure and function can provide an improved standard for glaucoma diagnosis.

0 Bookmarks
 · 
105 Views
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Aims To describe two approaches for improving the detection of glaucomatous damage seen with optical coherence tomography (OCT). Methods The two approaches described were: one, a visual analysis of the high-quality OCT circle scans and two, a comparison of local visual field sensitivity loss to local OCT retinal ganglion cell plus inner plexiform (RGC+) and retinal nerve fibre layer (RNFL) thinning. OCT images were obtained from glaucoma patients and suspects using a spectral domain OCT machine and commercially available scanning protocols. A high-quality peripapillary circle scan (average of 50), a three-dimensional (3D) scan of the optic disc, and a 3D scan of the macula were obtained. RGC+ and RNFL thickness and probability plots were generated from the 3D scans. Results A close visual analysis of a high-quality circle scan can help avoid both false positive and false negative errors. Similarly, to avoid these errors, the location of abnormal visual field points should be compared to regions of abnormal RGC+ and RNFL thickness. Conclusions To improve the sensitivity and specificity of OCT imaging, high-quality images should be visually scrutinised and topographical information from visual fields and OCT scans combined.
    British Journal of Ophthalmology 07/2014; 98 Suppl 2:ii1-ii9. DOI:10.1136/bjophthalmol-2014-305156 · 2.81 Impact Factor
  • Source
  • [Show abstract] [Hide abstract]
    ABSTRACT: Purpose: To estimate the potential outcomes of spectral domain optical coherence tomography (SD-OCT) screening among African American patients in the US, a decision analysis model was used to synthesize the current evidence and to project visual function outcomes over a 10 year time horizon. The secondary intent of this study was to assess the cost of the screening implementation. Methods: Using a Monte Carlo micro-simulation model with a 10 year time horizon, we evaluated the impact of SD-OCT screening among African American patients on visual field loss and evaluated the associated costs of screening and treatment. Results: Based upon the model, screening decreased the prevalence of undiagnosed glaucoma from 75% to 38%, and decreased the prevalence of severe visual field loss in patients with glaucoma from 29.1% to 23.9%. Conversely, screening increased the prevalence of mild visual field loss in patients with glaucoma from 9.2% to 18.7%. From initial screening through confirmatory eye examination, the screening program ("screen only") cost $98 per screened individual, and $2561 per new diagnosis of glaucoma. When considering the costs of initial screening though the resultant treatment, the screening program ("screen and treat") had an average annual cost of $79 and $2,138, respectively, over a 10 year time period. The cost of one quality-adjusted life year (QALY) gained by screening, including management and treatment, in comparison to opportunistic case finding ranged from $46,416 - $67,813. Conclusions: Our findings suggest that SD-OCT screening in an African American population will minimize glaucoma related visual morbidity.
    Investigative ophthalmology & visual science 05/2014; 55(6). DOI:10.1167/iovs.14-14014 · 3.43 Impact Factor

Full-text (2 Sources)

Download
38 Downloads
Available from
Jun 2, 2014