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Editors Selection IGR 7-1
Clinical examination methods: Progression: predicitive factors
Comment by Yoshiaki Kitazawa on:
12376 Predictive factors for progressive optic nerve damage in various types of chronic open-angle glaucoma, Martus P; Stroux A; Budde WM et al., American Journal of Ophthalmology, 2005; 139: 999-1009
This prospective observational cohort study by Martus et al. (544) evaluated whether various types of chronic open-angle glaucoma differ in predictictive factors for progression of glaucomatous optic nerve damage. They studied 517 eyes of 300 Caucasian patients with chronic open-angle glaucoma with elevated intraocular pressure (IOP) (primary open-angle glaucoma, n = 289, secondary open-angle glaucoma, n = 50) and with normal IOP ( normal pressure glaucoma, n = 178). IOP elevation in secondary open-angle glaucoma patients was attributable mostly to pseudoexfoliation or pigment dispersion syndrome. At baseline of the study 299 eyes (57.8%) of the whole study group had glaucomatous visual fields defects and glaucomatous changes of optic nerve head and 218 eyes (42.2%) had preperimetric glaucoma defined by glaucomatous abnormalities of the optic nerve head and normal white-on-white visual fields. During follow-up (median: 49 months, 6 to 130 months) IOP was equal to or less than 21 mmHg in all individuals and anitiglaucoma therapy was used as needed to achieve this IOP level. The progression of glaucoma was defined as neuroretinal rim loss during the study period.
For patients with elevated IOP, significantly predictive factors for progression were older age, advanced perimetric damage, smaller neuroretinal rim, and larger area of β -zone of parapapillary atrophy. In contrast, in NPG patients, a significant predictive factor was presence of optic disk hemorrhages at baseline. Within the patients with elevated IOP the primary open-angle glaucoma group and the secondary open-angle glaucoma group did not differ in predictive factors for progression.
The risk factors identified were predictive for morphologic progression and may not be identical to those predictive for functional progression. Nevertheless, most risk factors identified in POAG and SOAG patients are in good agreement with those reported by other prospective studies in which the functional progression was the main outcome measure. In particular, advanced optic nerve damage or a smaller neuroretinal rim and marked perimetric loss are generally considered to exhibit an increased risk of progression indicating a need of more intensive antiglaucoma therapy.
Chronic open angle glaucoma and normal pressure glaucoma differ in predictive factors for progression
It is noteworthy that presence of an optic disk hemorrhage at baseline was only parameter significantly associated with an increased frequency of progression in NPG. Thus, chronic open-angle glaucoma and NPG differ in predictive factors for eventual progression of glaucomatous optic neuropathy. The authors conclude the findings may be interesting for differentiating so-called NPG and so-called high-pressure glaucoma.
A limitation of the study is , as the authors admit, that factors such as the actual level of IOP were not taken into account. Although the patients were generally in relatively good control in IOP it is not clear whether or not attempts were made to maintain IOP at a certain level depending on glaucoma type and/or the severity of structural changes. The issue seems to be of considerable importance in interpreting the analytical results in NPG in this well-executed study.
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