Optic nerve head sector analysis recognizes glaucoma most effectively around disc poles

Abstract

ABSTRACT.Purpose: To analyze the topography of normal and glaucomatous discs with the goal of developing improved strategies to discriminate between normal and glaucomatous eyes. Subjects and methods: Raster tomography was performed in both eyes of 225 healthy subjects and in 296 eyes of 214 glaucoma patients. Cup area, average cup radius, rim area and minimal rim width were measured in 24 sectors around the optic nerve head at nine different depths from the reference plane. Receiver Operating Curves (ROC) for numerous combinations of parameter, sector and depth were calculated and compared. Results: Discrimination between glaucomatous and normal eyes varied widely between single sectors of the optic disc, and was best at the vertical poles of the disc, intermediate in nasal sectors and worst in temporal sectors. When single sectors or combinations of sectors at the superior pole were combined with their counterparts at the inferior pole of the optic nerve, the gain in sensitivity exceeded the loss in specificity, and discrimination improved. Separation declined dramatically if any of the 8 temporal sectors were involved in such analysis. Depth influenced discrimination only slightly. Conclusion: Single sectors located close to the vertical meridian yielded better discrimination than global measurements. When two or more sectors at the superior pole were combined with each other, as well as with their counterparts at the inferior pole, discrimination improved even further. Localized changes concurred frequently, but asymmetrically at both poles of the disc. The depth from reference plane used to define the cup was not critical for separation between normal and glaucomatous eyes.

Comparison of ranked segment analysis (RSA) and cup to disc ratio in computer‐assisted optic disc evaluation

“…These physiologically narrow temporal rims yield wide significance limits for high ranks (Gundersen & Åsman 1997). On the other hand, glaucomatous disc damage is most often observed around the superior and inferior poles of the optic disc where, in normal optic discs, the neuroretinal rim is usually wide (Pedersen & Anderson 1980;Jonas 1989;Gundersen et al 1999). Jonas and co-workers described a change of optic cup configuration from horizontally oval to circular as the earliest visible sign of glaucomatous disc change (Jonas et al 1988).…”

“…In this region, the neuroretinal rim measurements may vary between normal individuals from very high to almost zero. Glaucomatous damage, on the other hand, usually occurs at the superior or inferior poles (Pedersen & Anderson 1980;Jonas 1989;Gundersen et al 1999) where normal variability is considerably smaller.…”

Evaluation of the Structure-Function Relationship in Glaucoma

“…Several partial maps of the topographic correlations have been published. [11][12][13][14] Iester et al 15 found that the superior and inferior 90°sectors were more informative in predicting visual field loss than the temporal or nasal sectors; Gunderseon et al 16 similarly reported that the polar areas of the ONH were more informative for predicting glaucoma. Emdadi et al 17 found that the neuroretinal rim narrowing in the superior and inferior temporal sectors was associated with glaucoma.…”

The Effect of Education on the Assessment of Optic Nerve Head Photographs for the Glaucoma Diagnosis

“…The database has been described previously [18,19]. All glaucoma subjects were patients at the Department of Ophthalmology, Malmö University Hospital.…”