Estimating glaucomatous anatomical damage by computerized automated perimetry

Systems for staging the amount of optic nerve damage in glaucoma: a critical review and new material

The evaluation of the appearance of the optic disk is central to the diagnosis and management of patients with glaucoma. Grouping patients into categories, monitoring change, and quantitating the rate of change all require some type of quantitative staging of the amount of damage. Though the scientific literature regarding the appearance of the optic disk in glaucoma is extensive, there is remarkably little about quantitative staging of the amount of damage. We have identified eight systems, including the cup/disk ratio system of Armaly. Most of the earlier systems suffer from a failure to take into account the importance of the size of the optic disk. Furthermore, only one system includes early amounts of damage. This review is a critical appraisal of the known methods for staging optic disk damage in glaucoma, including the recent Disk Damage Likelihood Scale, which appears to offer substantial advantages over the other systems.

Enhanced Glaucoma Staging System (GSS 2) for classifying functional damage in glaucoma

PURPOSE

To introduce a new method, derived from the Glaucoma Staging System (GSS), for classifying glaucomatous visual field defects.

PATIENTS AND METHODS

Four sample groups composed respectively of 471 (sample #1), 128 (sample #2), 185 (sample #3), and 131 (sample #4) patients with either ocular hypertension or chronic glaucoma were considered. The GSS 2 uses both the MD and CPSD/CLV or PSD/LV perimetric indices to classify visual field defect in 6 stages and in 3 types (generalized, localized, and mixed). The formulas were determined using sample #1. A new borderline stage was created, on the basis of sample #2. The relationship between the PSD/LV and CPSD/CLV values was studied on sample #3 to verify the possibility of using the uncorrected indices instead of the CPSD/CLV. The relationship with other classification methods was studied on sample #4.

RESULTS

The GSS 2 showed a strong level of association with the AGIS and the Hodapp-Parrish-Anderson methods in staging defect severity. A good correlation was also found with a classification based on the Bebie curve.

CONCLUSIONS

The GSS 2 was able to correctly classify both damage severity and perimetric defect type in the sample studied, using either the corrected or uncorrected visual field indices. It is a quick and easy method, and its formulas can be introduced in any software.