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Editors Selection IGR 8-1
Glaucoma staging system
Comment by Roger Hitchings on:
13443 Categorizing the stage of glaucoma from pre-diagnosis to end-stage disease, Mills RP; Budenz DL; Lee PP et al., American Journal of Ophthalmology, 2006; 141: 24-30
See also comment(s) by Anders Heijl •The authors of this pragmatic and thoughtful paper, Mills et al. (278), have identified a weakness in the international glaucoma community, namely the lack of a universally accepted system for classifying the stages of glaucoma. To rectify this they have modified an existing system, the (Bascom Palmer (Hodapp-Anderson-Parrish) GSS. The system has six stages, from 0 (pre-diagnosis or full visual field) to 6, 'end stage'. The consultation process introduced some flexibility into the staging process, and the whole system was validated by independent reviewers using preexisting visual field data sets. Finally, the glaucoma stages have been related to treatment costs, and could be of value in stimulating case finding in some communities.
The authors noted that the Bascom Palmer system was easy to use, and was one with which US ophthalmologists would be familiar. However, a group of European ophthalmologists used it in a retrospective case note review and found it to be both useful for a cost per stage study and workable (Traverso CE et al., British Journal of Ophthalmology 2006; 89: 1245-1249). A comparison with the Octopus perimeter has also been performed.
As with all staging systems based on function the results may not accurately represent the stage of the disease, or the degree of glaucoma induced functional loss. It is recognised that glaucoma (as evidenced by diagnostic and acquired distortion of the optic nerve head) may not be associated with other than stage 0 in this system. At the very least, equating 0 with 'category normal' in this system ignores other psychophysical tests. This would need to be recognised by the clinician and the patient, so as to not leave either in a stage of reduced awareness of need.
Secondly, the staging process may be confounded by both co-morbidity and patient performance, so independent comment needs to be observed that the visual field stage is/or is not solely due to glaucoma.
Thirdly, the patient's view of visual disability is colored by binocular perception, so that caution needs to be exercised when relating stage with disability. Here at least a concept of rate of change would be of value in the discussion
The Glaucoma Staging System addresses several needs: conformity in the global glaucoma community, appreciation of progression characteristics and better communication of disease status with our patients. The authors are to be congratulated in developing a system that could meet these needs. Extended use of such a system will inevitably identify improvements and perhaps some caveats, recognition of which can only improve the whole
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