High-pass resolution perimetry and a Humphrey Field Analyzer as indicators of glaucomatous optic disc abnormalities. A comparative study

BACKGROUND

The "neural capacity (NC)" of high-pass resolution perimetry (HRP) may be correlated to the neuroretinal rim area of the optic disc. The authors compared HRP with conventional differential light sensitivity (DLS) perimetry in terms of correlation with glaucomatous optic disc changes.

METHODS

Thirty-seven eyes of 37 normal-tension glaucoma (NTG) patients were examined. The authors used an Ophthimus system for HRP and a Humphrey Field Analyzer (HFA) for DLS perimetry. The total rim area and the area of temporal, superior, nasal, and inferior quadrants were determined using a confocal laser tomographic scanner. Quadrant NC (QNC) was calculated using the resolution thresholds corresponding to a given quadrant. Quadrant mean deviation (QMD) was calculated from the total deviations of HFA.

RESULTS

In all eyes, NC and MD showed significant correlations with total rim area (Spearman rank correlation coefficient [rs] = 0.375, P < 0.05 for NC; rs = 0.336, P < 0.05 for MD). A significant correlation was observed in 21 eyes with early visual field changes (rs = 0.469, P < 0.05), but not in 16 eyes with advanced visual field changes. Both QNC and QMD showed significant correlations with inferior rim area (rs = 0.575, P < 0.01 for QNC; rs = 0.431, P < 0.01 for QMD). However, no significant correlations were found between QNC or QMD and superior rim area.

CONCLUSIONS

The NC may relate to glaucomatous optic disc changes better than does MD in NTG, especially in eyes with early-stage visual field changes.

Evaluation of the effect of aging on the retinal nerve fiber layer thickness using scanning laser polarimetry

PURPOSE

The scanning laser polarimeter is a new diagnostic scanning laser instrument that uses the polarizing properties of the retinal nerve fiber layer to measure its thickness in vivo. We first ascertained the measurement reproducibility of this instrument and then evaluated the effects of aging on the retinal nerve fiber layer.

METHODS

We performed three consecutive measurements in six glaucomatous and six age-matched normal healthy eyes to evaluate the instrumentation. The mean thickness of the peripapillary retinal nerve fiber layer within the rings 1. 0, 1. 5, and 2. 0 disk diameters from the center of the optic nerve head was calculated. We then evaluated aging effects on the retinal nerve fiber layer thickness in 75 eyes of 75 normal volunteers 20-66 years of age.

RESULTS

The mean coefficients of variation of the measurements of the 1. 0, 1. 5, and 2. 0 disk diameters were 3. 64, 3. 59, and 4. 10, respectively, for the normal subjects, and 10. 20, 5. 65, 6. 08, respectively, for the patients with glaucoma. We found a significant, inverse linear correlation between age and the retinal nerve fiber layer thickness when measured along the 1. 5 disk diameter ring (R = 0. 16, p = 0. 0004). Significant decreases with aging also were observed in the nasal (R = 0. 17, p = 0. 0003) and inferior (R = 0. 09, p = 0. 0091) retinal nerve fiber layer thickness.

CONCLUSIONS

Our results indicate that scanning laser polarimetry is sufficiently reliable to assess the retinal nerve fiber layer thickness in vivo. The retinal nerve fiber layer thickness decreases with age in the normal healthy eye.