Structure and function in patients with glaucomatous defects near fixation.

Purpose: To assess relations between perimetric sensitivity and neuroretinal rim area using high-resolution perimetric mapping in patients with glaucomatous defects within 10° of fixation.

Methods: One eye was tested in each of 31 patients with open-angle glaucoma enrolled in a prospective study of perimetric defects within 10° of fixation. Norms were derived from 110 control subjects free of eye disease, aged 21 to 81 years. Perimetric sensitivity was measured using the 10-2 test pattern with the Swedish Interactive Threshold Algorithm (SITA) standard algorithm on the Humphrey Field Analyzer (HFA) II-i; Carl Zeiss Meditec), stimulus size III. Area of the temporal neuroretinal rim was measured using the Heidelberg retina tomograph 3. Decibel values were converted into linear units of contrast sensitivity averaged across locations corresponding to the temporal rim sector. Both measures were expressed as percent of mean normal, and the Bland-Altman method was used to assess agreement. Perimetric locations corresponding to the temporal sector were determined for six different optic nerve maps.

Results: Contrast sensitivity was moderately correlated with temporal rim area (r2 >30%, p < 0.005). For all six optic nerve maps, Bland-Altman analysis found good agreement between perimetric sensitivity and rim area with both measures expressed as fraction of mean normal and confidence limits for agreement that were consistent with normal between-subject variability in control eyes.

Conclusions: By using high-resolution perimetric mapping in patients with scotomas within 10° of fixation, we confirmed findings of linear relations between perimetric sensitivity and area of temporal neuroretinal rim and showed that the confidence limits for agreement in patients with glaucoma were consistent with normal between-subject variability.