Optic disc size may influence the accuracy of glaucoma classification

J Glaucoma. 2009;18(5): 385-389.

Optic disc size and the severity of morphologic glaucomatous damage may influence the diagnostic accuracy of glaucoma classification systems.

Researchers evaluating the accuracy of the glaucoma probability score — an automated classification feature of the Heidelberg retina tomograph 3 — in a database of 273 eyes with glaucoma and 276 healthy controls noted an increase in area under the receiver operating characteristic curve with more advanced disease.

As well, area under the curve was best for medium-sized discs (between 2.1 mm² and 2.49 mm²) and worst for discs larger than 3.1 mm². The glaucoma probability score, which calculates disease classification based on shape of the optic nerve head and posterior pole, was more sensitive than Moorfields regression analysis, an algorithm in earlier versions of the Heidelberg system that compares measured neuroretinal rim area against a normative database, according to the study.

Glaucoma probability score delivered similar classifications as the Bathija classification system, and both had higher area under the curve than Iester, Mikelberg and Mardin classification systems. In terms of diagnostic accuracy, the glaucoma probability score was best for stage 1 and stage 4 glaucoma on the Jonas scale, whereas Bathija's classification was best for stages 2 and 3.