Diagnostic approaches for early detection of glaucoma progression

Background: To monitor the efficiency of glaucoma therapy it is necessary to detect progression of the disease as soon as possible. This survey presents the results on functional and morphological approaches to detect glaucoma progression. Material and Methods: Risk factors identified in the therapeutic intervention studies should be used to evaluate the possible risk for progression. The functional test approaches of standard achromatic perimetry (SAP), short wavelength automated perimetry (SWAP) and frequency doubling technology (FDT) are described. Furthermore, morphologic changes are described by means of optic nerve head and nerve fiber photography, optic nerve head tomography, optic coherence tomography and nerve fiber polarimetry. Results: The risk factors identified in the interventional studies were as follows: 1. higher intraocular pressure, 2. worse mean deviation (MD), 3. older age, and 4. frequent disc hemorrhages. Additionally, in patients with normal pressure glaucoma, migraine headaches were identified. Patients with ocular hypertension showed a higher risk of conversion into open angle glaucoma in case of higher pattern standard deviation (PSD), thinner central corneal thickness and larger vertical cup-to-disc ratio. The optic nerve head photography was the standard procedure of morphological monitoring in the interventional studies. A direct comparison of the available techniques on nerve fiber thickness and optic nerve head morphology is not yet available. SAP represents the functional methodology with the most validated results. SWAP and FDT showed that progression in early glaucoma can be detected before SAP damage occurs. Conclusion: Glaucoma patients should be regularly tested with SAP and optic nerve head photography. Automated nerve fiber or optic nerve head morphology measuring techniques might be favourable to complete the diagnostic monitoring. In patients without glaucomatous damage SWAP and FDT may be able to detect changes earlier than SAP. The results of a review of the literature are presented and discussed for each technology.